Astronomers have found the strongest evidence yet that a rocky planet beyond our solar system has managed to hold onto an atmosphere — a crucial ingredient for life as we know it.

The discovery marks the first time scientists have detected an atmosphere surrounding a rocky planet orbiting in the habitable zone of another star, the region around a star where temperatures could enable liquid water to exist on a planet's surface. The findings, published July 16 in the journal Science, could help astronomers narrow the search for potentially habitable worlds beyond our cosmic backyard.

"It's absolutely exciting," Edward Schwieterman, associate professor of astrobiology at the University of California, Riverside, who was not involved in the study, told Live Science in an email. "We are getting closer to studying the atmospheres of worlds that could plausibly harbor life, with evidence of that life embedded in their observable spectra."

The planet, known as LHS 1140 b, lies about 48 light-years away from Earth and orbits a small, cool red dwarf star. At roughly 5.6 times Earth's mass, the exoplanet is classified as a super-Earth: a rocky planet larger than our own but much smaller than gas giants like Neptune.

It receives less than half the sunlight Earth gets, giving it an estimated surface temperature of around minus 53 degrees Fahrenheit (minus 47 degrees Celsius), according to previous estimates not accounting for an atmosphere. That makes the planet cold, but in the range astronomers consider potentially habitable.

Cosmic gas leak

Scientists have discovered thousands of exoplanets over the past few decades, including many rocky worlds. But determining whether those planets have atmospheres has proven far more difficult, because atmospheres around rocky planets are incredibly thin compared with those of giant planets, making them much harder to detect across vast cosmic distances.

Instead of looking for the atmosphere directly, the researchers behind the new study searched for a subtle clue that one existed: helium gas leaking into space. Using the WINERED spectrograph on the Magellan Clay Telescope in Chile, the team watched LHS 1140 b cross in front of its star and let a sliver of starlight filter through the planet's atmosphere on its way to Earth. As it did, the team looked for a tiny dip in the star’s light at the exact wavelength of infrared light that helium blocks — a telltale sign that gas was streaming off the planet and into space.

The prediction rested entirely on a mathematical model that had never been confirmed for a rocky planet. However, in September 2024, the team caught LHS 1140 b and a smaller, hotter neighboring planet, LHS 1140 c, transiting their star on the same night, less than 40 minutes apart. The researchers detected a clear helium signal from LHS 1140 b, while LHS 1140 c showed nothing.

The contrast matters: LHS 1140 c orbits much closer to its star than LHS 1140 b does and receives roughly five times the radiation, yet it's also smaller and less gravitationally bound — conditions that should make any escaping gas easier, not harder, to spot. Finding nothing there suggests LHS 1140 c's atmosphere was stripped away long ago, while LHS 1140 b, sitting farther out in cooler, calmer conditions, has managed to hold onto its own.

The discovery addresses a question astronomers have been working to answer for decades.

"Twenty years ago we wondered whether other terrestrial-type planets even existed," study co-author Robin Wordsworth, a professor of Earth and planetary sciences at Harvard, said in a statement. "Then we learned they're common, and found some in the habitable zone. The next question was whether any of them had managed to keep an atmosphere. Now we know at least one has."

A step forward in the hunt for life

The find is especially notable because red dwarf stars like LHS 1140 can bombard nearby planets with high-energy radiation capable of stripping atmospheres away over time. Based on the star's estimated age of at least 3.1 billion years, the researchers say LHS 1140 b's atmosphere has likely persisted despite that bombardment, suggesting some rocky planets around these common stars can hang onto their atmospheres for far longer than once assumed.

But the researchers caution that detecting helium does not mean the planet is inhabited — or even that it is habitable. The observations reveal only the planet's thin upper atmosphere, not its full composition. Scientists still don't know whether LHS 1140 b has oxygen, carbon dioxide, water vapor or other gases that could make its surface more Earth-like and hospitable to life.

Instead, the discovery opens a new way to study distant rocky worlds.

"The study demonstrates that, at least in some cases, we will be able to begin characterizing the atmospheres of potentially habitable planets," Schwieterman said. "If only rocky planets orbiting Sun-like stars retained atmospheres, we might have to wait one to two decades for the launch of the Habitable Worlds Observatory to search for biosignatures on rocky planets. I'm certainly excited about what comes next!"

Future observations will aim to determine what the rest of LHS 1140 b's atmosphere is made of and investigate whether it may harbor oceans or other features associated with habitability.

Scientists have discovered the building blocks of life inside a meteorite that smashed through a New Jersey home two years ago. The space rock contains amino acids, carbon compounds and other "prebiotic" molecules similar to what may have helped kick-start life on our planet, a new study shows.

Scientists on the study team — led by Peter Jenniskens, a meteor astronomer with affiliations at the SETI Institute and NASA's Ames Research Center — praised the homeowner in Hillsborough, N.J., for quickly preserving the meteorite after it fell through the roof on July 16, 2024, despite the adverse circumstances. His actions included using disposable gloves and aluminum foil to place pieces of the meteorite fragments into glass jars.

"I was at home at the time, heard a loud crash and found a hole in the ceiling of the master bedroom," the homeowner, who was not named, said in a statement from the SETI Institute. "I smelled a strong, sulfur-like odor and saw many black fragments, along with debris and black dust that covered my bed, carpet and surrounding areas."

Those meteorite pieces were precious, the scientists said, and likely came from an ancient solar system planet that wasn't fully formed. "A forensic study of the fragments revealed that they contained preserved bits from near the surface of a small primitive asteroid where it experienced concentrated salty fluids — a process not previously known from this type of protoplanet world," Jenniskens said in the statement.

The study, published July 15 in the journal Science Advances, also traced how the meteorite got to the house. Earlier on July 16, 2024, at least 60 observers in New York, New Jersey and other Northeastern states spotted a meteor later confirmed to be traveling at 32,000 mph (51,500 km/h). At least 16 people in New York and New Jersey reported feeling the meteor's shock wave.

The rock broke apart in midair, with observer reports stopping when the meteor reached 22 miles (35 kilometers) in altitude, although Newark Liberty International Airport briefly tracked pebbles falling from the sky with Doppler weather radar after that. Fragments from only one meteorite ‪—‬ called Hillsborough, after the town where it crashed through the New Jersey home ‪—‬ were recovered.

The American Meteor Society used its cameras in Northford, Connecticut, and Douglassville, Pennsylvania — along with a doorbell camera in Wayne, New Jersey — to figure out the meteor's origin, Mike Hankey, an operations manager at the American Meteor Society and co-author of the study, said in the statement. "The path traced back to low in the asteroid belt."

Hillsborough is the second stony meteorite of its type ever spotted in a fall. Later analysis showed that the meteorite is full of ancient brines or salt. Scientists classified the meteorite as a type of stony space rock called a carbonaceous chondrite.

Scientists will compare the salt minerals to samples of asteroids Ryugu and Bennu, both of which contain ingredients of life and are samples of another carbonaceous chondrite type that formed earlier than Hillsborough. This analysis could help scientists further trace the origins of life-friendly chemistry in the early solar system.

Humans have been searching the stars for alien radio signals for decades — and so far, E.T. has not phoned home. But that doesn’t mean intelligent life isn’t out there, a new study hints. Rather, something else could be interfering: according to the research, space weather surrounding alien planets could be preventing us from detecting technological signals from extraterrestrial civilizations.

The findings, published March 5 in The Astrophysical Journal, offer a potential answer to the Fermi paradox: Given the size of the universe, there are many potentially habitable planets that could support life, and yet we have not detected technosignatures from any of them ‪— so, "Where is everyone?" physicist Enrico Fermi famously posited in 1950.

In the new study, researchers found that space weather caused by a planet's star could broaden hypothetical technosignals, dissipating their power over a larger range of frequencies and making them more difficult to detect.

"If a signal gets broadened by its own star's environment, it can slip below our detection thresholds, even if it's there, potentially helping explain some of the radio silence we've seen in technosignature searches," Vishal Gajjar, an astronomer at the SETI Institute and first author of the paper, said in a statement.

One way astronomers search for alien life is by looking for very narrowband signals, which are sharp spikes in the power of a radio emission. This spike usually only covers a few hertz.

"These don't occur naturally," Evan Keane, an astronomer at Trinity College Dublin who was not involved in the research, told Live Science. "So, if you see something very narrowband, you know that it is from something of interest." Astronomers would, for example, be able to easily detect some narrowband technosignatures on Mars, coming from the Mars rovers. But they have not observed any such signals from a clearly non-human origin.

Distorting signals

The new research argues that astronomers may have been looking for the wrong signal shape. In the new study, the researchers found that alien signals could be distorted by stellar space weather surrounding their home stars, which could explain why they have not been detected.

Space weather refers to changes in the space environment caused by charged particles, radiation and giant lumps of plasma called coronal mass ejections emitted by the sun. Other stars also generate space weather in their vicinity.

Gajjar and SETI colleague Grayce Brown investigated how space weather has historically impacted communications between Earth and spacecraft such as Mariner IV, which flew by Mars in the 1960s, and the Viking probes, which launched in 1977 for a voyage through the solar system and beyond. They created one of the largest collections of signal broadening examples and used that information to determine how other sunlike stars would affect the environment around their exoplanets. From this, the team calculated what would happen to a hypothetical alien narrowband signal that originated on one of them.

Then, they turned their attention to M dwarf stars, the most common type in the Milky Way. These stars account for three out of four stars in our galaxy, and some have been around since the early universe. That gives them a lot of time to have developed technologically advanced life, according to the paper.

There are no actual measurements of space weather around these stars, so Gajjar and Brown modeled what might happen to a narrowband technosignal that emerged from exoplanets and had to travel through interplanetary plasma. They found that hypothetical narrowband signals from these exoplanets were more likely to be smeared by space weather, making them even harder to detect.

In the paper, the authors propose a framework to estimate how much broadening would happen to a signal, given its frequency and the type of star its exoplanet was orbiting.

This new framework doesn’t totally answer Fermi’s infamous question, but it does give us a potential reason for the silence. The Fermi paradox "is not solely evidence for the absence of transmitters, but also a reflection of our detection limitations arising from a mismatch between the assumed signal morphology" and shape, the researchers wrote.

A step forward for SETI

Michael Garrett, an astrophysicist at the University of Manchester in the U.K. who was not involved in the study, welcomed the research.

"It is a solid contribution that SETI researchers and signal-processing teams should pay attention to," he told Live Science. "One of the strengths of the paper is that it's grounded in real measurements too, drawing on decades of spacecraft observations."

However, he emphasized that the paper focused on narrowband radio signals, which was only one way of potentially detecting an alien civilization. By contrast, Garrett's work explores the possible combined radio leakage from a technological civilization across a large range of frequencies.

Andrew Siemion, director of Breakthrough Listen Oxford Hub in the U.K. who was not involved in the research but collaborates with the SETI Institute, said this is the first paper to explore the space around exoplanets and its impact on detectability.

"The work offers a very concrete mechanism through which a candidate signal might ultimately be validated as having a likely origin with a distant planetary system," he told Live Science.

The authors recommended that future searches, especially with sensitive next-generation telescopes such as SKA-Low, take note of signal broadening when searching for civilizations beyond Earth.

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Over five decades ago, astronomer Frank Drake used one of Earth's largest radio antennas to beam a coded message into space, hoping that it might one day reach the eyes, ears or other inscrutable sensory organs of intelligent aliens. Slicing silently through the Milky Way at light speed, the now-famous Arecibo message has traveled roughly 50 light-years from Earth — about 10 times the distance to the nearest star, Proxima Centauri, but only one-five-hundredth the way to its intended destination in the Hercules constellation.

The search for extraterrestrial intelligence (SETI) is a waiting game — but for radio astronomer Emma Chapman, an astrophysicist at the University of Nottingham, whether humans will ever make contact with extraterrestrial life isn't a question of if but when. The universe is too vast and too plentiful with planets for humanity to be the only game in town, Chapman writes in her new book, "The Echoing Universe: How Radio Astronomy Helps Us See the Invisible Cosmos" (Basic Books, 2026). And when we do hear from our hypothetical alien neighbors, radio astronomers will be the first to know.

In this excerpt from Chapman's book, she tells us the intriguing story of Drake's message to the stars, the initial fears that it would awaken the attention of "malevolent or hungry" aliens, and why the search for extraterrestrial intelligence is still so valuable today.

During public lectures, I'm often asked, "Do you think aliens exist?"

I am always a little taken aback, as is the audience, when they hear my emphatic answer: "Absolutely. I have no doubts at all."

My surprise comes about because, as a radio astronomer, I have no doubt that life is out there, and I sometimes forget that there can even be a question about the matter.

There is little controversy amongst astronomers, not since the avalanche of exoplanet observations showed us that it was only a matter of time before we found Earth 2.0. Even if habitable worlds are scarce or the emergence of life is rare, the sheer number of planets in the Milky Way, let alone the universe, makes it implausible to think we are alone.

I am not engaging here in a willful misunderstanding of what we mean by "alien." When I say I believe there are aliens, I mean intelligent, complex lifeforms, not just basic, microbial life.

The audience is often silent for a beat after I have answered, not expecting such certainty. People expect heated debate over the question of alien life, I think, because there is a conflation, even in the scientific world, between a belief in alien life and a belief in UFOs, or alien abductions. "Have aliens visited our planet?" is a fundamentally different question, and one which I can answer just as emphatically: "Absolutely not. I have no doubts at all."

There is no evidence for interference by extraterrestrial life on Earth. No aliens building the pyramids, no UFOs creating intricate crop circles, and no secret government cover-ups. Many UFO sightings turn out to be Venus gleaming on the horizon, optical illusions or simply shaky camera work. One only needs note how UFO sightings have not increased in line with smartphone ownership and the ability to capture supposed otherworldly events. These claims belong firmly in the realm of conspiracy theories.

SETI, however, stands apart as a rigorous, science-based pursuit, almost exclusively led by radio astronomers. For SETI researchers, the question isn't whether life exists elsewhere ‪—‬ we take that as a given. We want to make contact. We want to find out where these aliens live and communicate with them across the light-years, using radio telescopes as our telephone.

Frank Drake makes the call

In 1974, Frank Drake was the director of the Arecibo Observatory. Drake lived and breathed SETI, and he had become impatient at the pace of the search. SETI is passive. It is about listening and intercepting signals that extraterrestrial life has sent, purposefully or not. Drake wanted to take the initiative, to beam a message out ourselves. And so, METI (messaging extraterrestrial intelligence) was born.

Drake decided to send his signal using the 305-meter dish's antenna as the transmitter, at a

celebration honouring the recent renovation of the dish.

The message consisted of 1,679 binary digits, each representing one of two possible values. Frank Drake envisaged encoding a picture in this way, much like a "paint by numbers" canvas. A radio tone at one wavelength would indicate a solid square, while a tone at a second wavelength would represent an empty square.

Since the message would be transmitted as a long sequence of radio bursts, the challenge for any receiving extraterrestrial intelligence would be to determine how to arrange this list into a meaningful 2D image. The image contains a wealth of information: heavily pixellated diagrams of a human and the Arecibo dish, for example, along with a representation of our Solar System, and the major chemical elements making up our DNA.

Drake selected the number 1,679 deliberately because it is a prime number and also the product of two other primes: 23 and 73. Prime numbers are significant within mathematics, and Drake hoped that any intelligent beings receiving the flow of data would experiment with reshaping the sequence in configurations involving these primes. If they did so, they would discover the intended image, unlocking the deeper meaning of the message.

Drake also converted the message into audio, allowing the audience gathered next to the dish in the Puerto Rican jungle to listen in real time as the two-toned signal was broadcast into space. For three minutes, Earth transmitted a signal 10 million times brighter than our radio sun, making us unmistakably visible to any extraterrestrial intelligence with their own Arecibo within the target area.

I've listened to the signal myself. The "Moonlight Sonata" it certainly is not, but if you close your eyes and reflect on the poignancy of us announcing our presence to the cosmos, it's deeply moving, and I can only imagine it brought a tear to the eye of more than one person in the crowd.

The message was aimed at M13, a dense cluster of stars (and presumably planets) about 21,000 light-years away, in the Hercules constellation. This system was chosen partly for the press release optics of its dense population of potential life-bearing star systems, but mostly because it was above the dish at the time of the ceremony. Awkwardly, by the time the Drake signal reaches the intended coordinates, M13 may have drifted out of the way of the tight beam of the signal. The act was symbolic but still, the first intended message is out there, and we cannot undo it now.

By the time the 1974 ceremony lunch was over, that signal had reached the orbit of Pluto, and by now it is over fifty light-years away, about as far from us as 51 Pegasi b, the first exoplanet to be discovered around a sun-like star.

"Malevolent or hungry" aliens

Drake did this all without needing anyone's permission, and many saw his act as setting a dangerous precedent. Why should the decision to contact alien life be autocratic when any risk is shared by everyone on the planet? England's Astronomer Royal, Sir Martin Ryle, reacted with scathing letters to the International Astronomical Union demanding a ban on any future messages, since "for all we know, any creatures out there might be malevolent ‪—‬ or hungry,"

Drake and, by this time, the majority of SETI scientists considered the argument moot. Electromagnetic radiation has been escaping Earth's atmosphere since radio and television were invented.

Whether we're at risk of invasion depends on two things: first, whether they manage to develop interstellar travel, and second, whether they decide such an endeavour is worth the colossal energy cost. Imagine our own situation ‪—‬ would humanity, in the midst of an energy crisis, unite to devote gargantuan resources into building and launching an interstellar colonisation fleet?

In his excellent book "Is Anyone Out There?" Frank Drake makes his position clear: "If I believed the ETs would come out of the sky, I wouldn't bother. I would just sit outside in a lawn chair and wait for them to show up." I am inclined to agree.

Far more likely than any invasion is contact by radio signal. In that case, my hunch is that, once the existence of extraterrestrial intelligence is confirmed, it would then quickly settle into the background of everyday life. After all, aliens have long been a fixture of our entertainment culture ‪—‬ we are primed to accept their existence.

In addition, the news cycle relating to any "conversation" would simply be too long for it to capture the popular imagination even sporadically. TRAPPIST-1, for example, is just over forty light-years away and a message sent there today will not receive a reply for eighty years ‪—‬ more like opening a letter from your grandmother's pen pal than having a lively chat.

For decades, the value of SETI has sparked lively debate among scientists, politicians, policymakers, journalists. Yet, despite harsh budget cuts and scepticism, SETI persists. Our longing to answer the question of whether we are alone in the universe burns so brightly in some that they dedicate their lives to the search, fully aware that only future generations may uncover the truth.

Whatever form that life takes, we know how we can expect to be contacted, because the laws of physics do not vary across the galaxy. Whether that planet has a yellow-green sky, whether it has five moons, or its people five legs, radio waves will be the form of light that is used for long- distance communication.

Perhaps, forty light-years away and forty years ago, a little green person on TRAPPIST-1 e switched on a shiny radio telescope and began to send messages towards the star systems all around, crossing all twenty fingers that someone out there would hear them. Perhaps one day we'll turn our dishes towards TRAPPIST-1, and tune in just as that alien message reaches us. It could be in a hundred years. It could be tomorrow. Until that fateful day, we look at the stars, we wait and we listen.

Excerpted from "The Echoing Universe: How Radio Astronomy Helps Us See the Invisible Cosmos," by Emma Chapman. Copyright © 2026 by Emma Chapman. Available from Basic Books, an imprint of Hachette Book Group Inc.

In mid-November 1969, a trio of NASA astronauts launched to the moon on the Apollo 12 mission and would soon become the second group of humans ever to set foot on the lunar surface.

Now, more than half a century later, the crew's historic mission is capturing the public's attention again — not because of what the astronauts did, but because of what they saw.

On Nov. 19, mission commander Charles "Pete" Conrad Jr. and lunar module pilot Alan L. Bean descended to the lunar surface in a landing craft dubbed Intrepid. (The third crewmember, Richard F. Gordon, spent a lonely 31 hours piloting the empty command module through lunar orbit.)

While looking through the lander's alignment optical telescope — a small, periscope-like device that offered a narrow, unmagnified view outside the spacecraft — Bean saw something that perplexed him.

"You can see these lights — particles of light, flashes of light… just sailing off in space," Bean told mission control, according to a transcript of the communication. While this transcript has been publicly available for decades, it was resurfaced among a tranche of declassified UFO-related files released by the U.S. Department of Defense (DOD) on Friday (May 8).

Bean initially thought the particles were leaking from the lander's water boiler, but he soon added, "It looks like some of those things are escaping the moon. They really haul out of here and just press off at the stars."

Newly released images from the crew's lunar excursion may reveal what they were seeing. In a series of lightly altered photographs — declassified Friday along with roughly 150 other files, videos and images of alleged UFO sightings from various government agencies — unidentified lights dance in the sky over the lunar horizon, as seen from the Apollo 12 landing site.

The lights, which look bluish in some of the images, appear on their own or in small groups; one particularly packed photo highlights the unidentified lights in five separate regions of the sky.

Like the transcripts, these astronaut images have been publicly available since the Apollo era. But in the newly released versions, NASA has highlighted and zoomed in on the light sources, hinting that they were once the subject of an agency investigation. (NASA has made no conclusions about the source or nature of these lights.)

Later in the transcript, mission control asks the astronauts if the strange flashes could be electromagnetic interference — unwanted signals emitted either from human-made technology or sources of cosmic radiation, like solar flares. The astronauts agree this is possible and leave the investigation at that.

This case, along with all the other newly declassified files, remains unresolved due to poor-quality data. Scant scientific information can be gleaned from these blurry, decades-old images and off-the-cuff remarks.

NASA maintains that unidentified anomalous phenomena (UAP, the government's preferred name for UFOs) are real but they have nothing to do with aliens. The space agency has been hunting for evidence of extraterrestrial intelligence for decades, using the most advanced and expensive telescopes ever created, and so far, they've turned up nothing. Some dancing lights on the moon won't overturn decades of scientific research.

The more likely sources of UAP are far more mundane: airborne debris, photo defects (like glare) and optical illusions are all common, according to a 2022 DOD investigation. Down on Earth, birds, weather balloons and foreign spy craft are regular culprits.

These NASA-altered photos may not be a giant leap for UAP studies, but their declassification — decades after being snapped — is a small step for government transparency.

See more Space Photos of the Week

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Editor's note: On Friday (May 22) the Department of Defense released a second tranche of UFO files, adding another 60 documents to its ongoing database. These include new videos from the military, and documents dating back to the 1970s. This article, originally published May 8, has been updated as Live Science reviews the files for possible items of interest.

UFOs have come to Washington again — this time, in a newly released tranche of more than 150 previously classified documents that cover nearly 80 years of alleged sightings.

Available to read today (May 8) on the Department of Defense website, the 162 newly declassified documents, photos, and videos cover reports of UFOs and UAP (unidentified anomalous phenomena, the government's preferred name for such sightings today) dating back as far as 1947.

The reports come from agencies across the government, including the Department of Defense (DOD), the FBI and NASA. The NASA offerings include images, audio files and transcripts of Apollo-era astronauts reporting anomalous sightings in space. However, most of these materials have been available for decades and never resulted in any compelling answers.

"The materials archived here are unresolved cases, meaning the government is unable to make a definitive determination on the nature of the observed phenomena," DOD representatives wrote on the agency's website. "This can occur for a variety of reasons, including a lack of sufficient data."

Are there any aliens?

Due to the poor data quality, the reports do not contain any compelling evidence of alien intelligence.

While NASA has not weighed in directly on the newly declassified files — save for a statement of support from Administrator Jared Isaacman — the space agency's official position remains that UAP are real but they have nothing to do with aliens.

"Are there any data supporting the idea that UAP are evidence of alien technologies?

"No," NASA's official UAP webpage states. "Most UAP sightings result in very limited data, making it difficult to draw scientific conclusions."

Indeed, NASA conducted its own independent investigation into UAP sightings in 2022 and 2023 and found no evidence of alien activity, again pointing to low-quality data among the alleged sightings.

What did the NASA astronauts see?

Some of the most interesting documents, from a historical perspective, are files related to UFO sightings reported by NASA astronauts in the 1960s. They include a transcript and audio recording of two NASA astronauts reporting an unidentified object in Earth orbit during the 1965 Gemini VII mission.

Just four hours into the flight on Dec. 5, 1965, astronauts Frank Borman and Jim Lovell reported seeing a "bogey" (military slang for an unidentified aircraft) out their spacecraft window, which Borman describes as "hundreds of little particles going by."

When NASA ground control pressed Borman on whether it could be a piece of the recently detached rocket booster, the astronauts said no, maintaining that they could see the booster in a separate part of orbit. The Gemini spacecraft soon drifted away from the object, never to see it again.

The files also include photos and transcripts from the Apollo 11, Apollo 12 and Apollo 17 missions, in which astronauts describe seeing various unidentified "flashes" and "particles of light" on the moon. These cases, like the others, remain unresolved due to a lack of sufficient data.

The underlying files have been available in public archives for decades. However, some newly released images from the Apollo 12 mission show zoomed-in boxes to highlight anomalous phenomena on the moon.

What are UAP?

So, if they're not aliens, what are UAP? According to a 2022 DOD investigation, most UAP sightings can be explained by birds, optical illusions, poor-quality photographs and foreign surveillance technology.

Many UAP files remain classified not due to the object sightings themselves, but because of the sensitive military technology used to record them, according to NASA.

The DOD plans to release additional declassified UAP documents every few weeks for the near future.

Editor's note: This article was updated at 12:30 p.m. ET on May 22 to link to the second tranche of declassified files.

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A rock discovered by NASA's Curiosity Mars rover contains "the most diverse collection" of the building blocks of life ever seen on the Red Planet, including seven never found there before, new research confirms.

In 2020, Curiosity discovered and drilled into the rock, which has now been confirmed to contain organic molecules that bear the life-friendly element carbon. While scientists can't yet prove if the molecules formed due to biological or geologic processes, their findings add new evidence to the theory that ancient Mars was hospitable to life.

"Their discovery renewed confirmation that ancient Mars had the right chemistry to support life," officials at NASA's Jet Propulsion Laboratory (JPL), which manages the mission, wrote of the organics. "What's more, the molecules join a growing list of compounds known to be preserved in rocks even after billions of years of exposure on Mars to radiation, which can break down these molecules over time."

By the Martian seashore

The new analysis, published April 21 in the journal Nature Communications, shows that the rock sample included 21 carbon-containing molecules, including seven never seen before on the Red Planet. The newly found molecules included nitrogen heterocycle (a predecessor to RNA and DNA) as well as benzothiophene, which may have been key to bringing life-friendly chemistry to solar system planets aboard meteorites, the authors wrote.

The sample was nicknamed "Mary Anning 3," after the English paleontologist famous for discovering the first fossil ichthyosaur and plesiosaur. Much like the aquatic fossil environments Anning sought out, the Martian organics were found in an area of Mars that was teeming with lakes and streams before the planet dried out billions of years ago.

"This oasis surged and dried up multiple times in the planet's ancient past, eventually enriching the area with clay minerals, which are especially good at preserving organic compounds," JPL officials wrote.

Drilling for life

Last year, Curiosity also found the largest-ever organic molecules on Mars. These were "long-chain" hydrocarbons, including decane, undecane and dodecane.

These organic finds in 2020 and 2025 used an instrument on Curiosity called Sample Analysis at Mars (SAM). Curiosity first drills rocks using its robotic arm. Then, it turns the rocks into powder samples and lets the powder fall into SAM. The instrument contains a high-temperature oven that heats up the powder, allowing the compositions of the gases inside the rover to be measured.

SAM also contains small cups of solvent that can perform "wet chemistry." The Mary Anning 3 sample was the first to use tetramethylammonium hydroxide (TMAH) — a substance that breaks apart organic molecules, of which Curiosity only carries two cups — because the sample was considered of the highest value.

Curiosity's findings were verified on Earth using a space rock that's well known to science, the Murchison meteorite, which is 4 billion years old and includes organic molecules.

"A Murchison sample exposed to TMAH was found to break much larger molecules into some of the ones seen in Mary Anning 3, including benzothiophene," JPL officials wrote. "That result verifies that the Martian molecules found in Mary Anning 3 could have been generated from the breakdown of even more complex compounds relevant to life."

Curiosity, which has been on Mars since 2012, recently used its last TMAH cup on "weblike boxwork ridges, which were formed by ancient groundwater," according to JPL. The results will be written up in a future study.

What do you know about the Red Planet? Test your knowledge with our Mars quiz!

President Donald Trump directed the Pentagon and other federal agencies to begin releasing government files related to UFOs and unidentified anomalous phenomena — called UAP — in February 2026, following years of pressure from Congress, military whistleblowers and the public.

Congress formally mandated UAP investigations through the National Defense Authorization Act in December 2022. The Pentagon's official UAP investigative body, the All-domain Anomaly Resolution Office, AARO, now carries a caseload exceeding 2,000 reports dating back to 1945. Defense Secretary Pete Hegseth confirmed this figure earlier this year.

The cases were submitted by military personnel, pilots and government employees describing aerial objects that could not be explained as known aircraft, drones or weather phenomena. Governments in Japan, France, Brazil and Canada also have their own formal UAP investigation programs.

Yet modern research universities remain almost entirely absent from this conversation. No major university has established a dedicated UAP research center. No federal science agency offers competitive grants for UAP inquiry. No doctoral programs train researchers in UAP methodology. The gap between what governments openly acknowledge and what universities are willing to study is, at this point, difficult to explain on purely intellectual grounds.

I have navigated this gap while conducting my own UAP research. My work developing the temporal aerospace correlation tool, a standardized framework for correlating civilian UAP sighting reports with documented rocket launch activity from Cape Canaveral, is currently under peer review at Limina: The Journal of UAP Studies.

Designing that framework meant making methodological decisions without community standards, without institutional funding and without the professional infrastructure many researchers in established fields take for granted. What is missing is not interest or data — it is the shared scaffolding that turns isolated curiosity into cumulative science.

Stigma is measurable

The most rigorous evidence for the gap between faculty interest in UAP and faculty willingness to study it comes from peer-reviewed studies by Marissa Yingling, Charlton Yingling and Bethany Bell, published in the scholarly journal Humanities and Social Sciences Communications.

Across 14 disciplines at 144 major U.S. research universities, 1,460 faculty responded to their 2023 national survey. Most surveyed believed UAP research was important. Curiosity outweighed skepticism in every discipline that was part of the study. Nearly one-fifth had personally observed something aerial they could not identify. Yet fewer than 1% had ever conducted UAP-related research.

The gap was not explained by intellectual dismissal, but it was in part explained by fear. Researchers were not primarily deterred by intellectual skepticism because they doubted the topic's merits. Instead, they feared they might lose funding, face ridicule from colleagues or find their careers quietly derailed. Faculty reported being told to "be careful."

A 2024 follow-up study found that roughly 28% said they might vote against a colleague's tenure case for conducting UAP research, even when they personally believed the topic warranted study.

Historian and philosopher of science Thomas Kuhn argued that scientific communities suppress anomalous questions not because those questions are unanswerable, but because they fall outside the boundaries the community has collectively decided are worth investigating.

Sociologist Thomas Gieryn called this suppression "boundary work," referring to the active process by which scientists police what counts as legitimate science.

For UAP researchers, the data and tools to study the phenomenon exist. What may not exist is social permission to use them without professional consequence.

Creating an academic discipline

Academic disciplines do not emerge spontaneously. They require dedicated journals, agreed-upon methods, graduate programs and professional societies.

The history of cognitive neuroscience demonstrates how disciplines emerge. Before the 1980s, researchers at the intersection of neuroscience and cognitive psychology faced resistance from both parent disciplines.

These fields achieved mainstream acceptance only after targeted funding from the Alfred P. Sloan Foundation, new brain-imaging tools and the gradual formation of academic programs that created career pathways for researchers. Researchers at the nexus of these fields did not wait for central questions to be resolved. They built infrastructure, and the infrastructure made progress possible.

UAP studies as a discipline is developing some of these elements, but largely outside universities. The Society for UAP Studies, a nonprofit of scholars and researchers, operates Limina as a double-blind, peer-reviewed journal and has convened international symposia drawing researchers from physics, philosophy of science and the social sciences. But a nonprofit scholarly society without tenured faculty does not constitute a discipline.

To turn UAP studies into a recognized academic field would require three things.

First, funding. The Yingling studies found that competitive research grants would do more to unlock faculty participation than any other single factor. Without grants, researchers cannot hire students to assist them, maintain instruments or sustain the multiyear projects that produce meaningful results.

Second, shared methodological standards — these would entail agreed-upon procedures for collecting, recording and evaluating UAP reports — would mean findings from one research group can be compared and built upon by others.

Third, institutions could publicly affirm that they will evaluate appropriately rigorous UAP scholarship on its scientific merits during tenure reviews. Several universities have already done this for gun violence research and psychedelic-assisted therapy studies.

These are not isolated examples. Research into near-death experiences and adverse childhood experiences followed similar trajectories, moving from being a professional liability to mainstream legitimacy after the removal of institutional barriers.

The international comparison

This gap in UAP scholarship is unique to the United States. France's GEIPAN, a dedicated investigation unit within its national space agency, has operated since 1977. It has publicly archived approximately 5,300 French UAP cases, of which about 2% to 3% remain unexplained after rigorous analysis.

In 2020, Japan formalized UAP reporting protocols for its Self-Defense Forces, the branch of the Japanese military responsible for national defense. By June 2024, more than 80 lawmakers had formed a parliamentary UAP investigation group that by May 2025 had formally proposed a dedicated UAP research office to the defense minister. Canada launched its own multiagency UAP investigation survey in 2023.

None of these actions has produced a corresponding response from American research universities. Universities provide independent, peer-reviewed analyses that government programs structurally cannot.

The University of Würzburg in Germany became the first Western university to officially recognize UAP as a legitimate object of academic research in 2022, when it formally added UAP investigation to its research canon. Researchers at Stockholm University and the Nordic Institute for Theoretical Physics in Sweden have been actively publishing peer-reviewed UAP research since 2017, most recently in Scientific Reports in October 2025.

Congress has passed legislation, the Pentagon is reporting on its investigations, and the president has directed federal agencies to begin releasing records. So the question no longer is whether governments take UAP seriously — it is whether universities will follow, and which ones will get there first.

This edited article is republished from The Conversation under a Creative Commons license. Read the original article.

"Extremophile" bacteria could survive asteroid impacts strong enough to launch them into space, a new lab experiment shows — hinting that these space-rock crashes could spread any potential alien life between worlds.

In the new study, published March 3 in the journal PNAS Nexus, researchers sandwiched Deinococcus radiodurans, a type of bacteria that has been shown to survive in space for years, between two steel plates. Then, they squished the "sandwich" very hard and fast to simulate asteroids slamming into a planet, and measured how many of the microbes survived.

The sandwich-squishing pressures were chosen based on what it would take for asteroids striking Mars to launch microbes and bits of planet into space. The team tested pressures from 1.4 to 2.9 gigapascals (GPa) — about 14,000 to 29,000 times the atmospheric pressure on Earth at sea level. Roughly 60% of the microbes survived being struck with 2.4 GPa, and up to 95% survived when the pressure was lowered to 1.4 GPa.

In most previous studies that tested such scenarios, the survival rates of the microbes were orders of magnitude lower. The study authors theorized that this may be because the microbes tested in the new study were different: stronger; more resilient; and able to withstand extreme radiation exposure, desiccation (getting extremely dried out) and high temperatures.

An extreme form of life

The researchers chose to test D. radiodurans because it can endure the cold, empty vacuum of space. A 2020 study found that D. radiodurans survived being exposed to space for three years while attached to the exterior of the International Space Station, which is not a friendly place for life. (Moss doesn't seem to mind it, though.)

The team also looked at how the microbes recovered after the impacts by incubating the cells at 98.6 degrees Fahrenheit (37 degrees Celsius) for a few hours and measuring which genes the microbes expressed. They found that, after being hit with higher-pressure impacts (hard enough to damage cell membranes), the microbes prioritized genes related to repairing cell damage rather than creating new cells. They also ate more iron and repaired their DNA.

An understanding of how life might travel between planetary bodies is important for sample-return missions, the study authors noted in the paper. For example, samples returned from Mars must go through rigorous procedures to prevent possible Martian microbes from hitching a ride to Earth and possibly contaminating our planet. If asteroid impacts could transport microbes elsewhere in the solar system, samples returned from other places might need additional precautions to prevent contamination as well.

Beyond that, the study shows that certain forms of life can survive being hurled violently into space. This may affect how and where we might look for life in the solar system.

Extraterrestrials quiz: Are you an alien expert, or has your brain been abducted?

Jupiter's ice-covered moon Europa appears to have life-friendly molecules on its surface.

Al Emran, a researcher with NASA's Jet Propulsion Laboratory, spotted ammonia on the surface of Europa while looking through old data from the Galileo mission, which studied Jupiter and its moons from 1995 to 2003.

Data gathered from Galileo's near-infrared mapping spectrometer in 1997 showed "faint signals of ammonia" near cracks on the frozen moon's surface, NASA officials wrote in a statement describing the findings, which were published late last year in The Planetary Science Journal.

It is the "first such detection at Europa" and therefore has important implications for the habitability of the icy moon, which is considered one of the most likely places in the solar system to host extraterrestrial life, according to the statement.

Alien ice moon

Ammonia is a nitrogen-bearing molecule and one of the ingredients of life as we know it, alongside carbon, hydrogen, oxygen and water. In the new paper, Emran said the finding was therefore of "astrobiological significance, given nitrogen's essential role in the chemistry of life."

The Galileo spacecraft worked in the Jupiter system between 1995 and 2003, before it ran low on fuel. Engineers deliberately steered the spacecraft into the giant planet to avoid any risk of contaminating Europa or other icy moons. Although the mission concluded operations more than 20 years ago, scientists sometimes find new insights in older datasets, either by using newer tools or knowledge, or by examining information that was not previously scrutinized.

In the new research, NASA spotted traces of ammonia near fractures on the icy surface of Europa. It is believed that these fractures included liquid water with ammonia compounds; the ammonia lowers the freezing point of water, sort of like antifreeze, the agency said.

The ammonia may have come "from either the moon's subsurface ocean, or its shallow subsurface," NASA officials said in the statement. That's because ammonia doesn't last long in space because it gets broken down by ultraviolet light and cosmic radiation. Cryovolcanism, or icy volcanism, likely pushed the ammonia compounds to the surface, they explained.

A follow-up mission may reveal more insight: Europa Clipper, which launched in October 2024, is expected to arrive at the Jupiter system in April 2030. The mission will specifically look for chemical signs of habitability on the icy moon.

One of the largest searches for alien intelligence in history is nearing completion, thanks to the help of more than 2 million citizen scientists and the legendary Arecibo Observatory.

Launched in 1999, the SETI@Home project enlisted millions of volunteers around the world to help identify unusual radio signals in data from the Arecibo Observatory — a massive radio telescope in Puerto Rico that collapsed in 2020 due to a cable failure. Though the project ended prematurely with the telescope's demise, citizen scientists nonetheless identified more than 12 billion signals of interest in 21 years of data.

Now, the researchers behind the project have narrowed that daunting list down to the top 100 candidate signals, which they are studying in detail with China's Five-hundred-meter Aperture Spherical Telescope (FAST) — now the world's largest single-dish radio telescope, following the death of Arecibo.

So far, there is no smoking-gun evidence of alien transmissions from any of these radio sources. However, the team is enthusiastic that their vast dataset will help make future hunts for extraterrestrials even more effective.

"If we don't find ET, what we can say is that we established a new sensitivity level. If there were a signal above a certain power, we would have found it," computer scientist and project co-founder David Anderson said in a statement. "We have a long list of things that we would have done differently and that future sky survey projects should do differently."

ET enters the group chat

The search for extraterrestrial intelligence (SETI) is a branch of science that aims to detect and communicate with advanced alien civilizations using radio signals — the idea being that, if humans have made it this far technologically, hypothetical alien lifeforms might have too.

The Arecibo telescope was a star player in the SETI field; in 1974, a team of scientists including Carl Sagan and Frank Drake sent a radio transmission from Arecibo to a nearby star cluster in hopes of reaching an intelligence audience. The famous "Arecibo Message," transmitted in binary code, included a human stick figure, a double-helix DNA structure, a model of a carbon atom and a diagram of a telescope. (Sadly, E.T. has yet to phone home about it.)

One big challenge for SETI is that space is overflowing with radio waves; everything from cold hydrogen molecules to exploding stars emits some form of radio energy. Finding a meaningful detection of radio signals from intelligent aliens among all this cosmic noise borders on the impossible.

To help narrow the search, the co-founders of SETI@Home turned to crowd sourcing. The team asked volunteers to download a free software program to their home computers, borrowing each computer's processing power to analyze Arecibo's latest scans of the night sky.

Starting in the mid-1990s, the team planned their project with 50,000 volunteers in mind. But within a year of the project starting, more than 2 million users in 100 countries were running SETI@Home on their computers.

"It went way, way, way beyond our initial expectations," Anderson said. "I would like to let that community and the world know that we actually did some science."

Expanding the search

In two papers published in 2025 in The Astronomical Journal, Anderson and his colleagues describe the vast dataset their contributors collected, and how the team analyzed it for the top candidate signals.

The project focused on radio signals coming from the Milky Way near the radio wavelength of 21 centimeters, which is the wavelength used to map hydrogen gas in the galaxy. Astronomers routinely observe the universe at this frequency; a hypothetical alien civilization would know that, and make use of that frequency to boost their chances of being detected, the researchers explained.

Using a supercomputer provided by the Max Planck Institute for Gravitational Physics in Germany, the team eliminated billions of false signals and Earth-based sources of radio interference, dropping the candidate pool down to a million. The team then analyzed the most promising 1,000 radio sources manually, whittling them down to the top 100 contenders.

So far, nothing unusual has jumped out of the results.

"We are, without doubt, the most sensitive narrow-band search of large portions of the sky, so we had the best chance of finding something," astronomer and SETI@Home project director Eric Korpela said in the statement. "So yeah, there's a little disappointment that we didn't see anything."

However, what is computationally possible today far outpaces what was possible in 1999, when the project began, Korpela added. Similar surveys are being conducted by FAST and other radio telescopes around the world; the hunt for alien intelligence will continue, and the data analysis will only get faster and more reliable going forward.

"There's still the potential that ET is in that data and we missed it just by a hair," Korpela concluded.

Advanced alien civilizations may communicate via a series of flashing lights, similar to how fireflies do, a new paper hints. This would potentially make extraterrestrials much harder to spot if we continue to rely on our current observation techniques, the researchers argue.

However, while this thought experiment raises interesting questions about alien intelligence, it does not provide any evidence that these signals actually exist.

So far, the quest to uncover alien intelligence has focused on finding evidence of distant human-like civilizations. For example, the Search for Extraterrestrial Intelligence (SETI) Institute — the world's leading organization dedicated to searching for alien life — spends most of its time searching for radio signals from distant exoplanets or heat given off by technological megastructures, such as the theoretical Dyson sphere.

However, some scientists believe that these searches suffer from an "anthropocentric bias" — meaning we're trying to understand nonhuman entities through a distinctly human lens — and do not account for potential civilizations that are wholly different from our own. Due to this bias, we may be overlooking promising signs of life.

In the new study, uploaded Nov. 8 to the preprint server arXiv, researchers proposed a new way that an alien civilization could communicate — by flashing to one another like fireflies. These flashing signals could be used for specific and complex communications. However, the researchers argue that they are more likely being widely broadcast to other civilizations, like a luminous repeating beacon. (This paper has not yet been peer reviewed, but is now under consideration for publication in the journal PNAS.)

On Earth, fireflies communicate via a series of regularly repeating flashes caused by internal chemical reactions. These flashes are mainly used to find mates. But while these signals are simple, they do allow distinct firefly species to tell each other apart.

The researchers argue that similar flashing could be used as "here we are" signals by an alien civilization. And space is plentiful with repetitive bursts of light.

In the new paper, researchers analyzed the flashes of more than 150 pulsars — rapidly spinning, highly magnetized neutron stars that shoot out regular beams of electromagnetic radiation — as a proxy for what these signals may look like. And while they found no evidence of any artificial signals, they did note some similarities between the pulsars and firefly signals, and proposed ways of being able to detect future firefly-like flashes from other natural objects, like pulsars.

The study team argues that these signals could be more likely to evolve in long-lasting alien civilizations that progress past the need for widespread use of radio waves. A similar progression is already happening on Earth, where the use of communications satellites with more specific and concentrated radio signals is making our planet appear more "radio quiet" from afar, the researchers wrote.

And just because we may not naturally think to communicate in this way, it doesn't mean that other civilizations wouldn't, they added.

"Communication is a fundamental feature of life across lineages and manifests in a wonderful diversity of forms and strategies," study co-author Estelle Janin, a doctoral candidate at the School of Earth and Space Exploration at Arizona State University, recently told Universe Today. "Taking non-human communication into account is essential if we want to broaden our intuition and understanding about what alien communication could look like, and what a theory of life ought to explain."

This is just one example of what non-human signals may look like, and the researchers encourage others to think outside of the anthropocentric box to come up with other ways that a non-human-like civilization could communicate.

"Our study is meant as a provoking thought-experiment and an invitation for SETI and animal communication research to engage more directly and to draw more systematically on each other's insights," Janin said.

More than 70 years ago, astronomers at the Palomar Observatory in California photographed several star-like flashes that appeared and vanished within an hour — years before the first satellite, Sputnik 1, was launched into orbit.

New peer-reviewed research revisiting those midcentury sky plates reports that these fleeting points of light, called transients, appeared on or near dates of Cold War nuclear weapons tests and coincided with a spike in historical UFO reports. Could these things all be related? Researchers are trying to find out.

While such flashes can sometimes be traced to natural phenomena such as variable stars, meteors or instrumental quirks, several of the Palomar events share distinctive features — including some sharp, point-like shapes that appear to line up in straight rows — that the authors of the new research say defy known natural or instrumental causes.

"We've ruled out some of the prosaic explanations, and it means we have to at least consider the possibility that these might be artificial objects from somewhere," study co-author Stephen Bruehl, an anesthesiologist at the Vanderbilt University School of Medicine in Tennessee who is interested in UFOs, told Live Science. Bruehl co-authored two recent papers with Beatriz Villarroel, an astronomer at the Nordic Institute for Theoretical Physics in Sweden.

"If it turns out that transients are reflective artificial objects in orbit — prior to Sputnik — who put them there, and why do they seem to show interest in nuclear testing?" Bruehl added.

Not all researchers agree with this interpretation of the images, however — with some experts noting that technological restrictions of the time make this data very hard to interpret with any certainty. Michael Garrett, director of the University of Manchester's Jodrell Bank Centre for Astrophysics in the U.K. who was not involved with the new studies, praised Villarroel's team for their creative use of archival data but cautioned against interpreting these results too literally.

"My main worry is not the quality of the research team but the quality of the data at their disposal," he said. Before Sputnik, the data are poor — especially the anecdotal UFO, or UAP (Unidentified Anomalous Phenomenon) reports, which Villarroel's team acknowledges it did not assess for validity.

"The scientific method is well suited to investigating such anomalies, but it takes time, replication and patience," Garrett told Live Science. "I suspect that with better data, these apparent correlations would go away."

Vanishing lights in the sky

Transient objects are a recurring phenomenon in astronomy. Modern sky surveys such as the Zwicky Transient Facility in California and the Pan-STARRS in Hawaii have already detected thousands of these fleeting events, and the upcoming Vera C. Rubin Observatory is expected to identify millions each night over the next decade.

Many of these transients have been successfully linked to known astrophysical processes, including sudden flares from comets and asteroids, explosive deaths of stars, variability in accreting black holes, and neutron-star mergers that produce kilonova afterglows.

To search for such events in the pre-space-age sky, the new research examined digitized images from the first Palomar Observatory Sky Survey (POSS-I), conducted between 1949 and 1958. That survey relied on about 2,000 photographic glass plates, each coated with a light-sensitive emulsion that reacted to incoming light, preserving an imprint of stars, galaxies and other celestial objects. These were manually loaded into the Samuel Oschin Schmidt Telescope for 50-minute exposures that captured broad stretches of the northern sky, and were later scanned and converted into a digital archive.

Villarroel's team examined 2,718 days of survey data and found transient sky events on 310 nights, with as many as 4,528 flashes appearing on a single day across multiple locations but absent from images taken immediately before or after the events, and from all later sky surveys.

When compared with the UFOCAT database of historical UFO reports, the researchers found that transients were 45% more likely to occur within 24 hours of aboveground nuclear tests conducted by the U.S., Soviet Union and Great Britain, and that each additional UAP report on a given day corresponded to an 8.5% rise in transients.

The analysis, published Oct. 20 in the journal Scientific Reports, describes these as "associations beyond chance" between transients, nuclear testing and UAP reports. A companion study the team published Oct. 17 in the journal Publications of the Astronomical Society of the Pacific suggests that some transients appeared in aligned groups and dropped by about 30 percent in sky regions within Earth's umbral shadow — a pattern the authors argue is best explained by sunlight glinting off unknown reflective objects in high, potentially geosynchronous, orbit.

According to the researchers, this finding echoes long-standing speculations that extraterrestrials might be drawn to human nuclear activity, though the authors emphasize that the data do not prove any causal link.

But what if it’s the opposite? A more straightforward explanation, some experts say, is that the flashes, and perhaps some of the reported UFOs, were by-products of the nuclear detonations themselves. Michael Wiescher, a nuclear astrophysicist at the University of Notre Dame in Indiana, told Scientific American that such explosions can inject metallic debris and radioactive dust into the upper atmosphere, where they might appear as brief, star-like bursts of light through a telescope.

Villarroel and Bruehl said they considered that possibility but countered that radiation-induced glows or fallout contamination would produce diffuse smudges or streaks, not the star-like points seen on Palomar's sky plates. And if the flashes were fragments of bomb casings hurled into orbit, those objects would need to reach roughly 22,000 miles (35,000 kilometers) above Earth, where modern geostationary satellites reside, to appear motionless over a 50-minute exposure.

Such a scenario seems implausible "unless a miracle occurred," Bruehl told Live Science. "There's no easy explanation for what these transients are and why they show up at nuclear tests."

The imperfect past

Several other astronomers suggest that the mystery likely lies not in the skies but in imperfect photographic plates and error-prone records of the time.

Robert Lupton, an astronomer at Princeton University who develops algorithms to extract meaning from optical data and was not involved with the papers, noted that astronomy has a long history of misinterpreting apparent alignments — including early debates over quasars, when astronomers once thought their apparent pairings in the sky meant they were physically connected, only to later learn they were chance alignments.

"The thing that's hard is to know what the anomalies in the data really look like, and the number of other weird things that we could have seen," Lupton told Live Science. "I thought that using pre-Sputnik data was clever, but hard."

Apparent alignments like those seen in the Palomar Observatory data may stem from imperfections in the photographic material itself, said Nigel Hambly, a survey astronomer at the University of Edinburgh in the U.K. who examined this issue in a 2024 paper. Spurious linear features, he said, can arise from mundane causes — diffraction spikes from bright stars that look like lines, dust, hair and other debris adhered to the emulsion that mimic aligned transients. In some cases, scratches introduced during the copying or digitization of old photographic plates can also create such artifacts, he said.

These problems are especially common when researchers work with copies rather than the originals, as was the case with Villarroel's team, because flaws can persist through generations of reproductions, Hambly said.

A turning point in UFO studies?

Researchers interviewed for this story agree that independent analyses are essential, and several proposed reexamining the same historical data and other archives of scanned plates from observatories active before 1957, ideally from the Northern Hemisphere and with complete, time-series images like those from the Palomar Mountain. Revisiting the original Palomar plates themselves and conducting a microscopic "forensic" examination could help determine whether the reported transients truly appear on the originals or were introduced later, Hambly added.

Inspecting the plates by eye can often reveal the difference between a genuine detection and a spurious blemish in the emulsion "at a level of detail that is lost in the digital scans, even with very high-resolution imaging," Hambly said.

Whether these mysterious flashes prove to be evidence of UAPs, classified military technology, or simply artifacts of a bygone imaging process, the ongoing debate underscores how science probes the unknown and tests the extraordinary.

"I suspect that we may eventually look back to see the publication of these results as a turning point for mainstream acceptance of UFOs as a legitimate research topic, worthy of academic scientific investigation and earnest coverage in the media," David Windt, a research scientist at Columbia University who was not involved with the papers, told Live Science.

Editor's note: This article was updated on Dec. 2 to include a description of the authors' companion paper, published Oct. 17.

A powerful blast spotted from a dwarf star was strong enough to strip away the atmosphere of any Earth-like planets that might have been lurking close by, new research suggests.

The study, published Wednesday (Nov. 12) in the journal Nature, was the first to confirm a coronal mass ejection (CME) — a massive, high-speed blast of plasma — from a star besides the sun. As scientists search for habitable worlds, understanding how strongly and frequently stars erupt will be essential to figuring out where to center our search, the study's authors argue.

A fast CME is visible in a "type II radio burst," which occurs due to the shock wave a CME creates as it moves from a star's atmosphere into interplanetary space. That burst in radio waves was spotted in a star 40 light-years from Earth, which is about 10 times farther from us than the nearest star system, Alpha Centauri. While extrasolar CMEs have been proposed before, this is the first type II radio burst definitively detected coming from another star, making it the most convincing detecting yet.

The star, called StKM 1-1262, is an M dwarf. Statistically, M dwarfs are smaller than the sun and far more active, meaning they send off more solar flares and CMEs. M dwarfs are nevertheless popular targets for life searches, because they are common in our universe. It's also easier to spot planets around these stars; because M dwarf are so small, planets tend to form much closer to them (and are therefore easier to detect) than those around larger sun-like stars.

But there's a caveat: Because M dwarfs are more active, and the "Goldilocks zone" where water could exist on a theoretical rocky planet's surface is closer to the dimmer star than Earth is to the sun, any Earth 2.0 would likely be more exposed to more CMEs than we experience with the sun.

"One of the problems could be [that] these CMEs happen so regularly, and they're hitting the planets so regularly, that they strip the atmosphere," lead study author Joe Callingham, a radio astronomer at the Netherlands Institute for Radio Astronomy, told Live Science in an interview. "So, great — you're in the Goldilocks zone, but you've got no help here, because the stellar activity destroyed [the chances for life].”

An atmosphere-shredding storm

The researchers spotted the initial burst in radio waves with the Low Frequency Array (LOFAR) radio telescope — a European network of antennas located primarily in the Netherlands — and assisted by new data processing methods from co-authors at the Paris Observatory. LOFAR is the most sensitive radio telescope ever built, Callingham noted, adding that the algorithms allowed the researchers to "get lucky" in finding the small burst of light in the sky.

Follow-up observations with the European Space Agency's XMM-Newton space telescope showed the star's temperature, confirming that it is an M dwarf, along with its rotation (20 times faster than the sun) and its brightness in X-rays.

The rotation and brightness revealed the motion of the CME, which was moving at nearly 1,500 miles per second (2,400 kilometers per second) — a speed seen in only 5% of similar bursts happening on the sun. The combined telescope observations also showed that the CME is moving fast enough, and with enough density, to blow away atmospheres of any planets in a close orbit with the star.

While LOFAR is powerful, Callingham said the challenge is that this observation (paired with the new data processing techniques) is approaching the telescope's resolution limit. To see more extrasolar CMEs, the research team is looking forward to science operations of the Square Kilometer Array, an enormous radio telescope project being built in Australia and South Africa, in the 2030s.

Callingham said the Square Kilometer Array should be able to spot "tens to hundreds" of extrasolar CMEs within the first year, which would allow the team to better chart how often an atmospheric-stripping blow would occur and how CMEs vary by types of star.

"It's so impactful," he said of the search, "because we really are, as astronomers, trying to find a habitable planet. … It's one of the key goals of astronomy over the next, I would hope, decade. But maybe it's going to take longer, or maybe the rest of my life, to find Earth 2.0."

On October 29, Comet 3I/ATLAS reached its closest point to the sun.

This point, known as perihelion, was around 210 million kilometers from the sun, or 1.4 times the distance between the sun and Earth, and it was on the opposite side of the sun to Earth. This means the sun had been blocking the comet from our view (from Earth). Now, ground telescopes have begun watching it again.

The comet is the third interstellar object (hence the "3I") we've detected flying through our Solar System.

When it was first detected on July 1 2025 by the Asteroid Terrestrial Last Alert System (or "ATLAS"), one of the first questions people asked was "but is it aliens?".

This isn't the first time the alien question has come up in the context of a new astronomical discovery. But although it might be fun, it can also detract from the real (and very cool) science, and fuel misinformation.

A long history of speculation

Similar alien speculation arose when the first two interstellar objects were discovered: 1I/2017 U1 'Oumuamua and Comet 2I/Borisov.

And it doesn't just happen for interstellar objects.

In 2019, I wrote my first public article about a discovery I made as a PhD student. I had found radio light coming from a binary star system, the first object found by the MeerKAT telescope to be changing brightness over time. Even though this had nothing to do with aliens, the editor asked me to include speculation about them.

In 1967, Jocelyn Bell Burnell, then a PhD student, discovered a rapidly repeating flash of radio light.

As a joke, she labelled it LGM 1 for "Little Green Men", but the astronomers working on it did not really believe they had discovered aliens. They were, however, concerned about the possibility that alien-related media coverage would sensationalize the discovery and hinder their scientific investigations.

A 7 billion-year-old visitor

This concern remains for astronomers today.

Comet 3I/ATLAS is possibly the oldest thing we've ever seen in our Solar System. Our Solar System formed 4.6 billion years ago, while recent research points to Comet 3I/ATLAS possibly being more than 7 billion years old.

It has spent a lot of that time zipping through the universe just to spend a few months in our Solar System. When the comet reached perihelion, that's probably the closest it's been to a star in at least millions of years.

Research has shown the comet has more carbon dioxide in its outer layers than has been seen in most comets in our Solar System. It also has a higher ratio of nickel to other elements than has been seen in local comets.

These chemical signatures give us a unique insight into the chemical composition of the cloud of gas that formed the solar system where the comet came from.

This is one of the key reasons why we should only be asking about aliens when all other possibilities are exhausted. When we talk about aliens first, we might miss all this amazing information.

As astronomer Carl Sagan said (in his rewording of a principle by French mathematician Pierre-Simon Laplace), "extraordinary claims require extraordinary evidence". It's true we can't completely explain every detail of the comet yet, but not knowing everything is not evidence of aliens.

Embrace the uncertainties

Talking about aliens also leaves room for misinformation to spread.

For example, there have been claims of things such as trajectory shifts and Comet 3I/ATLAS "hiding" behind the sun. Despite no evidence to support this, I received many questions along these lines when I spoke about the comet online. This demonstrates how easy it is for misinformation to be generated and spread when we're talking about "aliens".

There are ways to see the comet while it's on the other side of the sun. For example, the European Space Agency plans to observe the comet using the Mars Express, ExoMars Trace Gas Orbiter and the Jupiter Icy Moons Explorer.

And if you'd like to see the trajectory of Comet 3I/ATLAS and find out where it is right now, you can.

There might be something to be learned from poets here. Romantic poet John Keats wrote about something he called "negative capability". It's a strange name, but the concept is about being able to sit with "uncertainties, mysteries and doubts" and be content with not knowing.

There's a lot we don't know about Comet 3I/ATLAS and about the universe. It wouldn't be much fun to be an astronomer if we knew everything already. But when there's something unknown, we humans like to fill that gap.

For astronomy mysteries, the gap tends to be filled with aliens. However, not knowing all the answers is not proof of aliens. It just means that we have work to do.

This edited article is republished from The Conversation under a Creative Commons license. Read the original article.

TRAPPIST-1 is a red dwarf star located about 40 light years away that hosts seven Earth sized rocky planets, with at least three orbiting in the habitable zone where liquid water could potentially exist. This makes it one of the most Solar System like exoplanet systems discovered, with TRAPPIST-1e considered among the best potentially habitable exoplanets. The system's proximity and multiple potentially habitable worlds make it an ideal target for searching for technological civilizations.

The research team conducted their search using the Five hundred meter Aperture Spherical Telescope (FAST) to exploit its unprecedented sensitivity. The observations consisted of five independent L-band pointings, each with a 20 minute integration, for a total time of 1.67 hours. The frequency coverage spanned 1.05 to 1.45GHz with a spectral resolution of ~7.5Hz allowing them to detect extremely weak radio signals that might indicate alien technology.

The team led by Guang-Yuan Song from the Dezhou University in China looked for very precise radio frequencies that slowly changed over time due to planetary motion.

Related: Will the James Webb telescope lead us to alien life? Scientists say we're getting closer than ever.

Such signals would be virtually impossible to produce naturally and would strongly suggest artificial origin from an advanced civilization. Based on the configuration of FAST, the researchers had the ability to detect radio signals as weak as 2.04×10^10 watts. This means they were able to detect fainter signals than any previous studies. If there were aliens transmitting radio signals regularly on a specific frequency, this study would be more likely to find them than earlier attempts.​​​​​​​​​​​​​​​​

Alas, the search found no convincing evidence of alien technology. However, rather than being disappointing, this result still provides valuable scientific information. It places upper limits on the presence of certain types of alien transmitters in the TRAPPIST-1 system and demonstrates the remarkable capabilities of modern SETI searches.

It may be some years or even decades before we can completely rule out life in the TRAPPIST-1 system but at least for now, it remains a compelling target for future SETI efforts. The team plans to expand their search to look for other types of signals, including periodic or transient transmissions that might be missed by current methods.

The search for extraterrestrial intelligence remains one of our most profound scientific endeavors, with the potential to fundamentally transform our understanding of our place in the universe. As we continue to peer out into space with ever greater precision, we're not just looking for aliens, we're taking the first steps toward what may be the most significant moment in human history.​​​​​​​​​​

Who hasn't looked into the sky and wondered if there's life out there, somewhere, looking back at us? Is it possible there's alien life closer to home — within the bounds of our solar system?

The short answer is yes, there are several places researchers are looking for signs of life within our solar system, and there are some hints that life might be hiding in unexpected places.

Is there life on Mars?

While there don't seem to be any "little green men" inhabiting Mars, it's possible there was microbial life in the past. Mars is currently a frigid desert, but thanks to Mars rovers that have studied the planet's rocks, we know that a long time ago, it had liquid water — an important condition for life.

"The Curiosity rover was built to search for habitable environments, the kind that could have supported microbial life on Mars in the past, if life ever arose on the Red Planet," said Amy Williams, a geology professor at the University of Florida and a member of both NASA's Curiosity and Perseverance science teams. "Curiosity's payload was selected to accomplish this task by looking for the conditions that we know life on Earth requires — liquid water, a source of carbon, and chemical energy to power a metabolism," she told Live Science.

In addition to studying the Martian environment, the Perseverance rover has been collecting promising rock samples to be returned to Earth for advanced analysis. The Mars Sample Return mission is currently under development by NASA and ESA to travel to Mars, collect the sample cores, and bring them back to Earth. (The Donald Trump administration has proposed cutting NASA funding to pay for this mission, however.)

"At least one of the cores collected has qualities that fit the definition of a possible indicator of ancient microbial life," Williams said of a particularly interesting rock sample. "Returning samples to Earth with the Mars Sample Return architecture would enable us to address some of humanity's most profound questions, including whether we are alone in the universe."

Related: How would we give aliens directions to Earth?

Could there be life on Venus?

Even though it's commonly called Earth's "twin," Venus is probably not the first place anyone might look for life in the solar system. Its surface temperature is hot enough to melt lead, and the average surface pressure is more than 90 times that of Earth. It's wrapped in thick, dense clouds that are mostly made from sulfuric acid, a highly corrosive substance that mixes with water to form acid rain on Earth, damaging flora, fauna and soil.

Despite those hostile conditions, extremophile microbial life might be able to survive high in Venus' atmosphere, where the temperatures and pressures aren't so extreme; perhaps life could find ways to protect itself from sulfuric acid's destructive nature. To find out, MIT is putting together the Morning Star Missions, which will travel to Venus' atmosphere with the ultimate goal of collecting a sample of the planet's clouds and returning it to Earth for better analysis.

"Microbial life might exist in Venus's clouds, despite their composition of concentrated sulfuric acid," Sara Seager, a professor at MIT and the director of the Morning Star Missions, told Live Science. "If we find compelling signs of life on Venus, it would upend our understanding of habitability and prove that life can exist in non-water solvents, opening up the range of worlds where life is possible."

When looking for life, scientists often focus on the search for liquid water because it's a requirement for life on Earth. Finding life on Venus would shatter that limitation — meaning alien life could be a lot stranger than we've thought and there could be a lot more places to look for it.

In 2020, a possible detection of phosphine gas in Venus' clouds became the center of a controversy about signs of life on Venus. Phosphine gas was an unexpected find because most known chemical processes that produce it come from living organisms or from extreme pressures on gas giants. However, the signal was small and critics said it might have been noise in the data. The Morning Star Missions to Venus will give us much more information about the planet's chemistry and possibly confirm if there's phosphine floating in the clouds.

Is there life on the moons of Saturn and Jupiter?

Further out in the solar system, there are several moons orbiting Saturn and Jupiter that could potentially host life, particularly Enceladus and Europa.

Saturn's moon Enceladus has a global subsurface ocean hiding underneath a thick icy shell. The moon constantly spits giant plumes of salty water into space that give scientists a rare opportunity to directly sample the interior of a celestial body other than Earth. The Cassini mission performed several flybys of Enceladus from 2005 through 2017, collecting images and even direct samples from the plumes that are still being analyzed. A 2023 paper in Nature announced that scientists had detected phosphates on Enceladus — meaning scientists have now detected all the basic chemical ingredients for life in the moon's ocean.

Several missions to study astrobiology on Enceladus, with the goal of collecting more samples from the plumes, have been in the works by teams at ESA and NASA, although they're still a long way from getting to the launch pad.

Like Enceladus, Jupiter's moon Europa is an icy world with a global subsurface ocean and water plumes erupting from its surface. Jupiter's massive gravitational pull on the moon provides energy and motion that fuels active geologic activity, and is thought to be the main reason the ocean is warm enough to be liquid. Interactions between the salty ocean and the rocky interior could possibly host life similar to the life found around hydrothermal vents on Earth.

ESA's Jupiter Icy Moons Explorer (Juice) launched on April 14, 2023 with an expected arrival at Jupiter in July 2031, where it will study Jupiter and three of its moons: Europa, Callisto and Ganymede. NASA's Europa Clipper mission launched on Oct. 14, 2024 to reach Jupiter in 2030 and conduct flybys of Europa to study if conditions for life are present.

Titan, another of Saturn's moons, is an extremely unique place in the solar system. It has a methane cycle like Earth's water cycle and a thick nitrogen and methane atmosphere. The Cassini mission performed over 50 flybys of Titan from 2004 through 2017 and launched the Huygens probe that landed on the moon's surface in 2005. These two missions collected data that indicated Titan's atmosphere could probably create complex molecules that are building blocks for life. NASA is putting together a car-sized octocopter to fly on Titan and collect samples at different landing sites.

Where else could life be in the solar system?

There are quite a few other places we might find life in the solar system, including dwarf planets like Ceres. Ceres is thought to have a lot of liquid water under an icy and rocky crust, thanks to images taken by NASA's Dawn mission which visited it in 2015.

The more we explore the solar system, the more places we find that have conditions that could support life. If there is life out there, it's likely not advanced enough to reach out to us, so we'll have to be the first to say hello.

Extraterrestrials quiz: Are you an alien expert, or has your brain been abducted?

On Jan. 21, at 12:22 a.m. local time, in the silence and darkness of Chile's Patagonia region, a camera trap used to monitor wildlife for a project run by the University of Magallanes (UMAG) captured, in 2 seconds, three photographs showing intense lights moving downward.

Everyone was baffled.

"On a camera located at the edge of a meadow, quite far from any public road and focused on a flat horizon, some lights appeared that we cannot explain," biologist Alejandro Kusch said in a UMAG podcast in August. "Apparently, these lights, which are initially distant, approach and remain in front of the camera, dazzling it, in a movement that appears to be descending."

Kusch is one of the leaders of the Public Baseline project, which uses 65 camera traps distributed between continental Patagonia and Tierra del Fuego, on the southern tip of Chile, to record terrestrial animals, particularly felines. Since the project began in November 2023, at least 365,000 images and videos have been collected; however, only these three photographs show this phenomenon.

UMAG shared the images with a variety of organizations, from Chile's General Directorate of Civil Aeronautics (SEFAA)to the La Serena UFO Museum, and to several people who analyze anomalous aerial phenomena.

Potential explanations ranged from an arachnid coming very close to the camera lens to that of a "plasmoid," a short-lived form of plasma rarely observed in nature that may be behind phenomena such as ball lightning. However, all specialists agreed: for now, there is no conclusive explanation.

This sighting is unique because it was recorded within the framework of a scientific project, said Rodrigo Bravo, a researcher with the Environmental Studies Group (GEA) at UMAG and a member of the Public Baseline project. That means there is no possibility of fraud or manipulation, as the camera traps operate under rigorous protocols and are equipped with an infrared system, motion sensor, and other features that would preclude people tampering with them, he argued.

"This is not the first time these phenomena have been described in the area, but it is the first time they have been recorded in this way," Bravo told Live Science.

Related: No aliens in NASA's debut UFO report — but big questions remain

Bad lights

The local Mapuche people traditionally speak of "bad lights," which they believe are spirits that appear in the fields. This raises the possibility that the camera traps are finally capturing a phenomenon that has long been recognized in the region.

But even if these strange flashes are the "bad lights" the Mapuche speak of, what are they?

One possibility is that the lights are unidentified aerial phenomena (UAP), possibly from a mysterious flying object. Some declassified Pentagon files on UAP show similar characteristics, Bravo added. Generally poor-quality data means that most UAP sightings cannot be confirmed or explained, but common explanations include foreign spy drones and "airborne clutter" such as birds and weather balloons.

To address that possibility, UMAG sent photos and video to Freddy Alexis, who discusses UFOs and other unknown phenomena on his TV programs on UCVTV, the station of the Catholic University of Valparaíso.

Alexis wrote two reports on his findings, which included trajectory, spectrographic, and relief analyses of the photographs and videos. In the second report, he wrote that only a single "luminous stimulus" is visible, not two, and that the other "lights" are internal lens reflections.

According to Alexis, the primary light may be a plasmoid, or a bubble of incandescent ionized gas that is confined by Earth's local magnetic field, and that can remain stable for a few seconds. The most familiar atmospheric example is ball lightning, usually associated with storms. But that is where his explanation hits a wall. "It was summer, with 48  degrees Fahrenheit [8 degrees Celsius], and there were no electrical storms," Alexis told Live Science. "There were no atmospheric conditions for a storm, so it is very unlikely that ball lightning could have formed."

But more exotic plasmoids have been proposed under special conditions, such as transient, localized changes in Earth's magnetic field.

Still, Alexis noted that there may be other, poorly understood atmospheric plasmoids, similar to the "mysterious lights" of Hessdalen, Norway. Like the Magallanes phenomenon, these lights defy conventional explanations and could involve plasma structures that are still poorly understood.

In one of his reports, Alexis also calculated that, assuming this was a distant, flying object, it would have been moving at a speed of 590 mph (947 km/h), or roughly 0.7 times the speed of sound. Alexis suggested that the lights might not be a flying object, but some plasmoids can move at high speeds, he added.

A strange creature

In a separate report, technicians from La Serena UFO Museum suggested that a spider or moth may have inadvertently tripped the camera's sensor. That's because in the first photo, what appears to be an insect or arachnid can be seen along one edge of the image. However, the insect does not appear in the subsequent photos.

While one possibility is that the insect triggered the camera, this would only explain why the photo was taken, not why a bright, blob-like light appears, said

Cristian Riffo, director of the La Serena UFO Museum, who was also consulted for the UMAG report.

Riffo noted that the camera traps are designed to minimize false positives caused by insects, lasers or other stimuli. He thinks the rapid sequence of photos, in which the light appears to move toward the camera, is baffling and hard to explain.

"It could be two different phenomena: one natural, which triggered the camera, and the other, a light phenomenon, which remains unexplained," Riffo told Live Science.

Museum researchers analyzed before and after photographs taken by the same camera, during the day and at night, in the presence of wildlife and under different atmospheric conditions, and reviewed the manufacturer's manuals to rule out technical failures. So far, "they have not found an explanation," Riffo said.

For this reason, researchers from the La Serena UFO Museum are planning to carry out their own on-site fieldwork in the area to collect additional data and analyze other local parameters, such as the terrain, lighting conditions, and environmental factors.

Bravo added that the monitoring project in the area is scheduled to continue for up to 10 more years, and more camera traps are planned, raising hopes that this strange phenomenon may be captured again.

"The scientists involved are eager to know what this was. This is also science: it's about discovering what happens in nature," Bravo said.

Meanwhile, the mystery remains, and so scientists and those interested in anomalous aerial phenomena are working together to understand it.

Imagine a planet twice as wide as Earth, covered in an ocean that smells like sweet cabbage.

Every day, a faint red star warms this ocean world and the uncountable masses of hungry, plankton-like creatures that inhabit it. They rise to the surface by the billions, joining together in a living, floating continent larger than Australia — spewing out a pungent gas as they knit sunlight into food.

The sulfurous gas steams out of the alien bloom, filling the air so fully that a lone telescope floating 700 trillion miles (over a quadrillion kilometers) away can sense it — faintly, for just a few hours every month, when the watery planet glides in front of its small, red star. For those few hours, the alien algae of the pungent planet make themselves known to Earth.

It sounds like science fiction ... but is it?

For the past two years, this question has been the subject of intense debate among alien-hunting scientists, with the James Webb Space Telescope (JWST) at its center. Captured in the powerful telescope's crosshairs is the planet K2-18b, located around 120 light-years from Earth. There's no question that the planet itself is real. But its surface conditions, as well as its likelihood of harboring life, remain contested.

One group of researchers who has studied K2-18b with JWST for the last few years claims to have detected signs of dimethyl sulfide (DMS). This compound, which has a cabbage-like odor, is what many Earthlings think of as "the smell of the sea" and is only known to be produced by living, breathing phytoplankton. The team first reported hints of DMS in K2-18b’s atmosphere in 2023, and has followed up with several papers since.

Outside researchers remain skeptical of this alleged DMS detection, however. They've cautioned that the team's detection relies on questionable data modeling and falls short of the threshold required to signify a new scientific discovery. Only further observations of the planet can truly settle the question.

But what isn't in doubt is that JWST's ultrapowerful infrared vision is giving humans the best-ever shot at finding extraterrestrial life.

Thanks to JWST, "we're learning more just in the last few years than we've learned in the preceding decades about the compositions of atmospheres outside the solar system," Eddie Schwieterman, an assistant professor of astrobiology at the University of California, Riverside who studies exoplanet habitability with JWST, told Live Science.

It's dogma in the search for alien life that where there's an atmosphere, there may also be water on a planet's surface — and where there's flowing water, there may be life. For the first time, JWST is bringing those alien atmospheres into focus.

"We are at a really important time in the search for life, in that we now have the technological capability to do it," said Victoria Meadows, a professor of astronomy at the University of Washington and director of the astrobiology graduate program. "Prior to JWST, we really did not have the capability to do this."

The breath of aliens

In the hunt for habitable planets — those that orbit in the "Goldilocks zone" of their home star, where liquid water can flow on the surface — JWST is in a class of its own.

Unlike Hubble and other optical telescopes, JWST can't directly image the surfaces of faraway planets. Nor can it detect radio waves and other potential "technosignatures" emitted by any advanced alien civilizations that might exist. The signs of life JWST seeks are far more elemental. They're not blurry snapshots of alien trackways or mysterious radio signals, but hints of molecules tumbling invisibly through space, far above a planet's surface.

"The first step in finding life is to find an atmosphere," Sebastian Zieba, a postdoctoral researcher at the Harvard and Smithsonian Center for Astrophysics, told Live Science. "In order to have liquid water on the surface, you need an atmosphere."

Compared with its predecessor — NASA's infrared Spitzer Space Telescope (launched in 2003 and retired in 2020) — JWST is "better in every way," Zieba said. It can look farther across space and detect a broader range of infrared wavelengths than any telescope before it. Infrared emissions are crucial to the hunt for life, because those wavelengths are best at encoding information about the types of molecules that are absorbing or reemitting starlight in a planet's atmosphere.

For JWST to detect hints of an exoplanet's atmosphere, scientists must wait for a transit — the moment when a planet swoops in front of its home star, forcing that star's light to shine through the planet's atmosphere as seen from our perspective on Earth. In the case of K2-18b, for example, that happens once every 33 days.

"The planet passes in front of the star, and it backlights the atmosphere," Meadows said. "It's like a little halo around the planet."

That "halo" contains important clues about an alien world. As starlight streams through the planet's atmosphere, airborne molecules either absorb or reemit different wavelengths of light, changing what JWST sees when observing at those wavelengths. The unique signature of light compiled from these different wavelengths, called a spectrum, can reveal which molecules are in the atmosphere. This information, in turn, allows scientists to infer the planet's size, surface conditions, geography — and chances of supporting life.

For example, Meadows said, if JWST captures the spectrum of a planet that reveals high levels of methane and carbon dioxide absorption in its atmosphere, it could indicate a habitable world akin to Earth in the Archean eon (roughly 4 billion to 2.5 billion years ago), when primitive microbes were breaking down CO2 and spewing vast quantities of methane.

Proving those conditions exist on a planet trillions of miles away is the hard part.

The devil in the data

After making a promising biosignature detection, the challenge then becomes proving that it can't be explained by a geological process, such as volcanism. Then, scientists must demonstrate that their detection meets statistical significance — a rigorous undertaking that requires many repeat observations of the planet and verification from independent researchers using their own data models.

"Webb data is very complex," René Doyon, a professor at the University of Montreal and principal investigator of JWST's Near Infrared Imager and Slitless Spectrograph (NIRISS) instrument, told Live Science. "People have been publishing results that are not always consistent. Depending on who reduced the data, you get a different answer."

It's here that early studies of K2-18b have fallen under scrutiny. Despite the tentative detection of DMS reported in two studies by a team of University of Cambridge-led researchers, outside experts have so far been unable to verify the result when looking at the same observations with different data models. Furthermore, the DMS detection only reached the three-sigma level of statistical significance, falling far short of the required five-sigma level. (A three-sigma level is around a 3 in 1000 chance of being a fluke, while a five-sigma value means a result has a probability of 1 in 3.5 million of being a fluke).

Nikku Madhusudhan, a professor of astrophysics at Cambridge and lead author of the two DMS studies, said this is no reason to ignore K2-18b as a candidate for a habitable world "teeming with microbial life."

"We have initial feelers for what we are seeing, but we could be wrong," Madhusudhan told Live Science. "So let's be open to being wrong and get more data. Only then can we confirm what we're seeing."

Schwieterman thinks it was "premature" to announce the detection of DMS on K2-18b, given the questionable statistical significance. However, he agrees that DMS is a promising signature of life that JWST should continue hunting for on other potentially habitable ocean worlds.

"The question we want to ask is, how common are global biospheres in the universe?" Schwieterman said. If there's complex life out there, including intelligent life, then "a big part of that question is, how common are the biospheres from which those more complex forms of life would originate?"

Hitting a "bull's-eye"

Even if life doesn't ultimately materialize on K2-18b, the distant planet is just one of many being targeted by JWST's keen infrared eye.

The telescope's search list includes some of the usual suspects, such as the TRAPPIST-1 system — the single most-studied star system beyond our own. The system contains seven rocky planets, at least three of which may be in the star's habitable "Goldilocks" zone.

So far, JWST has not been able to confirm an atmosphere around any of the three potentially habitable planets TRAPPIST-1b, c, or d. However, a study published Sept. 8 in The Astrophysical Journal Letters has offered preliminary evidence of a possible nitrogen-based atmosphere around TRAPPIST-1e, making it one of the most hopeful contenders for an Earth-like planet beyond our solar system.

Meanwhile, Doyon favors studying a world called LHS 1140 b, located 50 light-years from Earth in the constellation Cetus. Doyon and team's observations with JWST reveal that the exoplanet, once thought to be a rocky "super-Earth" six times as massive as our planet, is a much bigger oddball — or, perhaps, an eyeball.

"It may be a bull's-eye planet," Doyon said, describing a mostly ice-coated planet with a single blue "iris" of liquid water pointed toward its home star.

Using JWST data from two transits of LHS 1140 b, Doyon and colleagues reestimated the mass and radius of the planet and found "it cannot be explained as a rocky planet — it must have something between 10% and 20% of its mass in water," Doyon said. "It's a potential waterworld, and it's right in the habitable zone."

According to Doyon, LHS 1140 b doesn't resemble Earth so much as it resembles our solar system's icy moons Europa and Enceladus, both of which are suspected to harbor subsurface oceans that could support life. But unlike those moons, this planet is so close to its home star that some of its ice may have sublimated into gas, forming an atmosphere. It's even possible that the sun-facing side of the planet (which, like Earth's moon, is tidally locked) could heat up enough for the ice to melt there, revealing a liquid-water ocean beneath a cloudy sky. As such, this warm, blue "iris" could host life.

Doyon thinks this is one the likeliest known exoplanets to harbor an atmosphere.

"If I had to bet a beer on whether it has an atmosphere, it probably has one," he said.

Pushed to the limits

Sadly, Doyon's beer will likely have to wait.

Although Doyon and his colleagues detected "hints" of a nitrogen-rich atmosphere around LHS 1140 b, he said it will take about a dozen more transits to prove whether there are other molecules indicative of an Earth-like atmosphere, such as carbon dioxide. Because LHS 1140 b becomes visible from Earth only four times a year, scientists would have to observe every possible transit for years to come before making any firm conclusions. It's a schedule that "really pushes JWST to its limits," Doyon added.

This underscores one of the telescope's biggest limitations: time.

In 2024, researchers around the world requested a total of more than 78,000 hours of JWST observation time — about nine times more than is available, according to the Space Telescope Science Institute (STScI), which manages JWST proposals each year. Of the more than 2,300 submissions, only 274 proposals were ultimately accepted, with exoplanet habitability research accounting for a small percentage.

That discrepancy is likely to widen with the passage of the Trump administration's proposed budget for 2026, which includes a nearly 50% cut to NASA's science budget, according to Live Science's sister site Space.com. If approved by Congress, the cuts would amount to a roughly 25% to 35% reduction in JWST operations, Neill Reid, multimission project scientist at STScI, said in July at the 246th meeting of the American Astronomical Society in Anchorage, Alaska.

Finding the unforgettable

In the end, JWST may not uncover a smoking gun in the search for extraterrestrial life. But even if it doesn't, it will likely help scientists determine where to search next. Future telescopes will build on JWST's revelations, helping to fill in the missing gaps.

One major gap is oxygen. While the gas makes up about 21% of Earth's atmosphere and is a potent biosignature, "JWST can't do oxygen," Meadows said.

Multiple studies — including one co-authored by Meadows, in which researchers modeled what JWST would see if it studied Earth's atmosphere — have found that the telescope is simply not sensitive enough to detect oxygen. That poses a clear challenge to detecting Earth-like atmospheres.

Forthcoming telescopes could help account for that. For example, the Extremely Large Telescope — a powerful optical/near-infrared telescope being constructed in Chile that could see first light in 2029 — will be more sensitive to oxygen and water in planetary atmospheres than JWST is, Meadows said. It will also be able to peer all the way down to the surfaces of rocky planets — closer to where life and its byproducts are more likely to be, unlike the high upper atmospheres that are JWST's domain.

Further down the line, NASA's recently announced Habitable Worlds Observatory will take a census of planets around sunlike stars close to our solar neighborhood. Parsing visible, infrared and ultraviolet light signatures, the powerful observatory could potentially confirm atmospheres around dozens of Earth-like worlds. Currently, however, there is no planned launch date.

With JWST expected to remain operational at least into the 2030s, its era of discovery is just beginning. Will it find alien life? Maybe, maybe not. But in its first years, it's already leading scientists closer to that first tantalizing glimpse of evidence than any telescope has before.

And once that evidence is found — even if it's on a distant exoplanet that no human or probe will ever lay eyes on — there's no going back. Finding evidence of even one other inhabited planet would imply that there could be countless others out there, raising big questions about the prevalence of life in the universe, and where humans fit into it. The discovery of an alien world would change how we view the cosmos, as well as ourselves.

"Once we find a credible hint of evidence for life on an exoplanet … I don't think we're ever going to forget about that planet," Schwieterman said. "It's going to be both a scientific and cultural touchstone. Kids are going to learn about it in school."

Editor's note: This article was updated on Sep. 10 at 2 p.m. ET to include details from a new study on the exoplanet TRAPPIST-1e.

New NASA research hints that Ceres — the closest dwarf planet to Earth — may have once had an ancient "power source" that could have sparked the evolution of extraterrestrial life-forms in the tiny world's hidden ocean.

Ceres is the largest object within the solar system's main asteroid belt, which is located between the orbits of Mars and Jupiter. The wee world is around 600 miles (950 kilometers) wide, roughly one-quarter the moon's diameter, meaning it is not large enough to be considered a planet. But it is large enough to be considered a "dwarf planet" like Pluto, which lost its full planetary status in 2006.

There are five official dwarf planets in our cosmic neighborhood, with others waiting to be properly recognized by the International Astronomical Union, and many more discoveries expected in the coming decades. However, Ceres is the only one located within the inner solar system. The rest of the dwarf planets, which include Haumea, Makemake and Eris, are located far beyond the orbit of Neptune.

In recent years, scientists have learned a lot about Ceres thanks to NASA's Dawn probe, which visited the object between 2014 and 2018. One of the most intriguing discoveries from the Dawn mission is that the giant space rock is likely a water world: Traces of water and salty minerals on the dwarf planet's icy surface suggest a large reservoir of brine is trapped miles below. Other studies have hinted that this underground ocean could also contain organic carbon, which is a key component of all life on Earth.

However, until now, scientists thought that life was unlikely to have emerged on Ceres because the dwarf planet has no energy source capable of kick-starting life.

But in a new study, published Aug. 20 in the journal Science Advances, researchers revealed this was not always the case.

Related: James Webb telescope spots potential conditions for life on 2 dwarf planets beyond Neptune

The study team created computer models based on data collected by the Dawn mission to simulate how the rocky body's core changed over time. This revealed that the dwarf planet's innards probably used to emit large amounts of energy in the form of heat — raising hopes that tiny alien microbes could have emerged within Ceres' hidden ocean.

This could also have "big implications" for the potential of finding life in other parts of the solar system, study lead author Samuel Courville, a planetary scientist at Arizona State University and a former intern at NASA’s Jet Propulsion Laboratory, said in a NASA statement.

The researchers believe that Ceres' core once emitted significant amounts of heat from the gradual decay of radioactive isotopes. The team believes that this heating lasted between 0.5 and 2 billion years after the giant rock was created, which was likely shortly after the rest of the solar system, around 4.6 billion years ago. At its hottest, the core likely reached around 530 degrees Fahrenheit (280 degrees Celsius), the researchers wrote.

This is not the first time that scientists have proposed that Ceres had a radioactive core. However, this is the best evidence yet that it generated enough heat to potentially support life.

In addition to heating the dwarf planet's subsurface ocean to a habitable temperature, the radiation could also have caused jets of hot, mineral-rich water to shoot up through the ocean's floor, similar to the hydrothermal vent systems on Earth that support diverse microbial communities in the crushing dark depths of our oceans.

"On Earth, when hot water from deep underground mixes with the ocean, the result is often a buffet for microbes — a feast of chemical energy," Courville said.

Astrobiologists have proposed that similar systems may support extraterrestrial life on other water worlds in the solar system, including Saturn's moons Enceladus and Titan, as well as Jupiter's moons Europa and Ganymede.

However, since Ceres' radioactive core went dead around 2.5 billion years ago, any alien microbes would likely have died out from the cold, meaning there is practically zero chance that the dwarf planet supports life today, the researchers said.

The search for alien life should consider the impact of cosmic rays, a new study suggests.

When scientists look for signs of life beyond Earth, first they check the extraterrestrial worlds inside the "Goldilocks zone" — the area around a star where sunlight makes it neither too hot nor too cold for liquid water to exist on a planet's surface. But a team of researchers has proposed another region where living things might exist: the "radiolytic habitable zone," where cosmic rays (also known as cosmic radiation) can generate enough energy to support life deep underwater or in ice.

"Life might be able to survive in more places than we ever imagined," Dimitra Atri, an astrophysicist at New York University Abu Dhabi in the United Arab Emirates and co-author of the new study, said in a statement. "Instead of looking only for warm planets with sunlight, we can now consider places that are cold and dark, as long as they have some water beneath the surface and are exposed to cosmic rays."

The research, published July 28 in the International Journal of Astrobiology, investigated the potential for life on Mars, as well as on Jupiter's moon Europa and Saturn's moon Enceladus. These icy worlds are fairly hostile to life as we know it, at least on the surface. But beneath the surface, they hold vast quantities of liquid or frozen water. The researchers studied whether cosmic radiation may be able to energize chemical reactions in water enough to support biological activity.

Cosmic rays consist of highly energetic particles and atomic nuclei that move through space at nearly the speed of light. They are produced by stars, supernovas and, in some cases, black holes. On Earth, most cosmic rays fail to penetrate our planet's thick atmosphere. But on worlds with thinner atmospheres, like Mars, they can reach the surface — and possibly belowground.

Related: Tiny photosynthetic aliens could be lurking in hidden bubbles in Mars' ice — and could soon be replicated on Earth

In the new study, the team used computer simulations to model how much energy this cosmic radiation might deliver to the subsurface ice and water on Mars and worlds such as Jupiter's moon Europa. They found that some energetic particles could make it below the surface. Once there, the rays would then break apart the existing water molecules, releasing electrons in a process called electrolysis. This could potentially generate enough energy to support — and maybe even kick-start — life.

The researchers predicted that Saturn's icy moon Enceladus has the highest potential for supporting life, followed by Mars and Europa. Astrobiologists plan to study these worlds more closely in the coming years, using data from telescopes such as the Atacama Large Millimeter/submillimeter Array and probes like NASA's Europa Clipper, which is currently en route to the Jovian moon.

But the new study also has implications for the search for life beyond our solar system "This discovery changes the way we think about where life might exist," Atri said in the statement.

A lunar crater immortalized in one of the most famous photographs ever taken has just played a key role in the hunt for alien life in our solar system.

Stretching nearly 25 miles (40 kilometers) across the far side of the moon, the lunar impact crater formerly known as "Pasteur T" may be the most-viewed lunar crater in history. Countless Earthlings have seen it spreading prominently through the foreground of the iconic "Earthrise" photo snapped by American astronaut William Anders on Dec. 24, 1968, during the Apollo 8 mission. The majestic photo, which shows a half-lit Earth rising majestically above the lunar horizon, became so famous that the crater was renamed "Anders' Earthrise" in 2018.

Now, nearly 60 years after Anders' flyby put his eponymous crater on the map, another spacecraft has glimpsed it from orbit — this time, with extraterrestrial science in mind.

The Jupiter Icy Moons Explorer (JUICE) spacecraft, which launched from Earth in April 2023 and is expected to reach Jupiter's orbit in 2031, flew past the moon nearly a year ago. Mission scientists used this encounter to test the spacecraft's 10 science instruments, which will eventually be used to hunt for signs of habitability on the many moons of Jupiter.

This lunar flyby presented the first opportunity to test the performance of JUICE's instruments on a solid surface in space, representatives from the European Space Agency (ESA) said in a statement. Of particular importance was the Radar for Icy Moon Exploration (RIME) instrument, which uses radio wave echoes to measure elevation on rocky bodies.

"RIME's task at Jupiter is to peer below the icy surfaces of moons Europa, Ganymede and Callisto to map the invisible rocky layers below," ESA representatives wrote in the statement.

Related: 32 strange places scientists are looking for aliens

Because RIME needs to "listen" for precise changes in radio waves, the instrument requires as much silence as possible to get the best readings. That's where Anders' Earthrise crater comes into play. While JUICE sailed past the famous crater, ESA scientists silenced all of the probe's other instruments to let RIME observe it in peace for eight uninterrupted minutes.

RIME's radar mapped the moon's elevation in and around the crater, which researchers compared to earlier measurements taken by other spacecraft, such as NASA's Lunar Orbiter Laser Altimeter (LOLA). The team found that electronic noise within JUICE was throwing off RIME's measurements — kicking off a months-long project to correct the issue with a new algorithm.

ESA now reports that this project was a success. The new elevation map of Anders' Earthrise crater (above) shows peaks and valleys that perfectly match the elevations captured by LOLA during earlier lunar flybys. The data prove that RIME is ready for its big job: charting the subsurface depths of the largest moons in the solar system — and, hopefully, aiding in the search for extraterrestrial life.

With a long journey still ahead, JUICE is now headed toward Venus, where our neighboring planet's gravity will give the spacecraft a boost on the path to Jupiter. Ultimately, JUICE will complete 35 flybys of Jupiter's most massive moons, before settling into orbit around Ganymede from December 2034 to September 2035, according to ESA. Studying Jupiter and its moons will not only provide new insights about the formation of gas giants and planetary systems at large but also help to tease out signs of life and habitability beneath the icy shells of the enormous moons.

As many as 200 worlds beyond our solar system discovered by astronomers may be larger than estimated, which could influence the search for extraterrestrial life.

That's the theory of a team of researchers who looked at hundreds of extrasolar planets, or exoplanets, observed by NASA's Transiting Exoplanet Survey Satellite (TESS).

TESS hunts exoplanets by catching them as they cross the face of, or "transit," their parent star, which causes a tiny drop in light from that star. The study team discovered that light from stars neighboring the one being transited could "contaminate" TESS' data, making it look like the transiting planet is blocking less light than it actually is. And that would make the planet look smaller than it is.

"We found that hundreds of exoplanets are larger than they appear, and that shifts our understanding of exoplanets on a large scale," University of California, Irvine researcher and team leader Te Han said in a statement. "This means we may have actually found fewer Earth-like planets so far than we thought."

Exoplanets throw shade

Exoplanets are so distant and faint that it is only on rare occasions that astronomers can image them directly.

That means the transit method has become the most successful way of detecting worlds beyond the solar system. It requires the planet and its star to be at the right angle in relation to Earth, and for astronomers to wait for the planet to make two transits to confirm its existence.

The transit method is best at spotting short-period planets orbiting close to their host stars, because they make more frequent transits. The method also favors larger planets, which block more light.

"We're basically measuring the shadow of the planet," said team member and UC Irvine astronomer Paul Robertson.

Related: 12 strange reasons humans haven't found alien life yet

The team gathered hundreds of TESS observations of exoplanets, sorting them by the width of the exoplanets in question.

They then used computer modeling and data from the European Space Agency's (ESA) star-tracking mission Gaia to estimate how much light contamination TESS is experiencing during its observations.

"TESS data are contaminated, which Te's custom model corrects better than anyone else in the field," said Robertson. "What we find in this study is that these planets may systematically be larger than we initially thought. It raises the question: Just how common are Earth-sized planets?"

Move over Earth-like worlds: ocean planets could be more common

Because of the biases of the transit method mentioned above, the number of exoplanets detected with TESS having sizes and compositions similar to those of Earth was already low.

"Of the single-planet systems discovered by TESS so far, only three were thought to be similar to Earth in their composition," Han explained. "With this new finding, all of them are actually bigger than we thought."

The likely outcome of this is that those exoplanets are larger ocean planets or "hycean worlds" covered by a large single ocean. Those worlds could also be gas giants smaller than Jupiter, like Neptune and Uranus.

That impacts the search for life because, though hycean worlds are packed with water, they could be lacking other ingredients needed for life to arise.

"This has important implications for our understanding of exoplanets, including, among other things, prioritization for follow-up observations with the James Webb Space Telescope, and the controversial existence of a galactic population of water worlds," Roberston added.

The next step for Han, Roberston, and colleagues is to re-examine planets previously deemed uninhabitable due to their size, to see if they are larger than previously thought.

In the meantime, the research is a reminder to astronomers to be cautious when assessing TESS data.

The team's research was published July 14 in the Astrophysical Journal Letters.

This article was originally published on Space.com.

The newly discovered interstellar object 3I/ATLAS could be a piece of "possibly hostile" extraterrestrial technology in disguise, according to controversial research from a small group of scientists, including a renowned alien-hunting astronomer.

Their paper, which has not been peer-reviewed, echoes similar claims previously made about 'Oumuamua, the first-ever cosmic interloper that was discovered in 2017.

But experts have told Live Science that the new claims are "nonsense" and "insulting," and insist that the available evidence points toward the object being completely natural.

3I/ATLAS was discovered on July 1 barreling toward the sun at more than 130,000 mph (210,000 km/h), and was confirmed to be an interstellar object less than 24 hours later. Initial observations strongly suggest it is a large comet surrounded by a cloud of ice, gas and dust called a coma, stretching up to 15 miles (24 kilometers) across. A computer model simulating where it originated from hinted that it could be up to 3 billion years older than our solar system, potentially making it the oldest comet ever seen.

But in a new paper, uploaded July 16 to the preprint server arXiv, a trio of researchers have questioned whether the comet is actually some form of covert alien tech sent here by an advanced, potentially aggressive extraterrestrial civilization.

The researchers described the new paper as a "pedagogical exercise," or thought experiment, and offer no clear evidence of alien involvement. Instead, they point at the comet's "anomalous characteristics" and provide alternative theories to explain them.

Related: Interstellar comet 3I/ATLAS transforms into a giant 'cosmic rainbow' in trippy new telescope image

The study's most notable author is Avi Loeb, an astronomer at Harvard University who is renowned for linking extraterrestrial objects to intelligent aliens. He is the head of the Galileo Project, which is attempting to detect evidence of technosignatures and UFOs. In 2023, he led a controversial expedition that claimed to have collected pieces of possible alien tech left behind by an unconfirmed interstellar meteorite in the Pacific Ocean. (These claims have since been largely debunked by outside researchers).

Loeb was also the primary researcher who claimed that the unusual shape and non-gravitational acceleration of the interstellar object 'Oumuamua were signs that it was an alien probe.

Today, the general consensus is that 'Oumuamua was an asteroid that was leaking gas into space, similar to a comet. However, Loeb and his colleagues have continued to advocate its potential alien origin and have proposed missions to track down the wandering space rock.

Loeb's co-authors for the new study are both associated with the Initiative for Interstellar Studies (i4is), a U.K. institute dedicated to planning future missions to alien star systems.

In a blog post explaining the new paper, Loeb wrote that if 3I/ATLAS is a "technological artifact" it could be evidence of the dark forest hypothesis, which argues that the reason we have not found evidence of extraterrestrial life is that they are staying silent to remain invisible to potential predators or prey.

"The consequences, should the hypothesis turn out to be correct, could potentially be dire for humanity, and would possibly require defensive measures to be undertaken," he wrote.

Alien 'evidence'

Most of the points laid out in the new paper relate to the unusual trajectory of 3I/ATLAS. The object is moving significantly faster than the only other known interstellar objects — 'Oumuamua and Comet Borisov, which was spotted in 2019 — and has entered the solar system at a different angle from its predecessors, approaching the sun side-on relative to our star's orbit through the Milky Way.

Loeb wrote that the object's trajectory "offers various benefits to an extraterrestrial intelligence" that may be using it to subtly spy on Earth. One such benefit is that 3I/ATLAS will make relatively close approaches to three planets: Jupiter, Mars and Venus. And the minimum distances between the object and these worlds could enable aliens to discretely deploy "gadgets" there, Loeb wrote.

3I/ATLAS will also be hidden on the opposite side of the sun to Earth when it reaches its closest point to our home star in late October. "This could be intentional to avoid detailed observations from Earth-based telescopes when the object is brightest or when gadgets are sent to Earth from that hidden vantage point," Loeb wrote.

The unusually high speed of 3I/ATLAS also makes it very hard to launch a spacecraft to intercept it before it exits the solar system, which could be another potential sign of clandestine alien activity, the researchers argued.

Based on its current speed, Loeb also noted that 3I/ATLAS would have entered the outer boundaries of the solar system around 8,000 years ago, which is "roughly when human-made technologies became advanced enough to start documenting history on Earth." Although, it is unclear what he is trying to imply by saying this.

The researchers also argued that there is insufficient evidence to show conclusively that 3I/ATLAS is a comet, especially as researchers are yet to identify any "volatiles," or specific chemicals associated with comets, within its coma.

Controversial claims

Since 3I/ATLAS was discovered, researchers have been trying to identify it, and so far, the overwhelming consensus is that it is a comet.

"There have been numerous telescopic observations of 3I/ATLAS demonstrating that it's displaying classical signatures of cometary activity," Darryl Seligman, an astronomer at Michigan State University who led the first study quantifying 3I/ATLAS, told Live Science in an email.

"All evidence points to this being an ordinary comet that was ejected from another solar system, just as countless billions of comets have been ejected from our own solar system," added Samantha Lawler, an astronomer at the University of Regina in Canada who specializes in solar system dynamics.

Any assumptions about the object's lack of volatiles is also premature at this time. "The object is still pretty far away from the sun, so no, we wouldn't typically expect to find direct evidence of volatiles necessarily," Seligman said. Instead, these compounds will likely become apparent in the coming weeks and months, he added.

Loeb admits that the alien technology scenario is a long shot: "By far, the most likely outcome will be that 3I/ATLAS is a completely natural interstellar object, probably a comet," he wrote in the blog post.

Given the available evidence, many of the researchers who spoke to Live Science are disappointed with the new paper and pointed out that it distracts from the work of other scientists.

"Astronomers all around the world have been thrilled at the arrival of 3I/ATLAS, collaborating to use advanced telescopes to learn about this visitor," Chris Lintott, an astronomer at the University of Oxford who was part of the team that simulated 3I/ATLAS's galactic origins, told Live Science in an email. "Any suggestion that it's artificial is nonsense on stilts, and is an insult to the exciting work going on to understand this object."

Loeb is no stranger to this type of criticism and has defended his position, writing that "the hypothesis is an interesting exercise in its own right, and is fun to explore, irrespective of its likely validity."

However, while it is important to remain open-minded about any "testable prediction," the new paper pushes this sentiment to the limit, Lawler told Live Science in an email. "In my experience, the vast majority of scientists subscribe to the idea that extraordinary claims require extraordinary evidence, and the evidence presented is absolutely not extraordinary."

E.T., Stitch, Chewbacca, Groot — humans have a lot of ideas about what aliens might look like. But what is the science behind extraterrestrial life? Is it possible that humans will ever experience "first contact" with an alien species?

Many scientists hope so. They're looking for extraterrestrial life on planets with conditions that look like Earth's. A life-friendly planet would probably have water, for example. And for water to be a liquid, the planet must be the perfect distance from its sun for that water not to freeze or turn into a gas.

There's no evidence yet for life on other planets, but as scientists discover more and more planets outside our solar system, they're hopeful that some of these worlds will be "just right" for life to exist or evolve there.

5 fast facts about aliens

• Scientists have been listening for alien signals with special radio receivers since 1992. They haven't picked up any yet!
• Mars might have once hosted life — most likely tiny things like bacteria — but scientists can't say for sure.
• Jupiter's moon Europa has an ocean, and it might have hydrothermal vents, or cracks in the seafloor where hot water seeps through. Scientists think life on Earth may have evolved in hydrothermal vents.
• The "Goldilocks zone" is the space around a star where temperatures allow liquid water to exist. Many scientists think planets in the Goldilocks zone are those most likely to host life.
• The oldest known life on Earth is 4.2 billion years old.

Everything you need to know about aliens

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An unusual pulse signal has been detected in the light of nearby stars — and it's left scientists scratching their heads, a study searching for extraterrestrial intelligence finds.

The pulses saw the stars become fainter and brighter in a fraction of a second, suggesting that something passed in front of — and partially obscured — the stars' light. This doesn't mean aliens were zooming by in spaceships, but unknown alien activity is one of several possible explanations left on the table by the researcher who detected the signal.

Richard Stanton, a retired scientist who formerly worked at NASA's Jet Propulsion Laboratory, has spent years with a 30-inch telescope scrutinizing more than 1,300 sun-like stars for signs of extraterrestrial intelligence. He does this by measuring changes in light coming from individual stars.

This effort didn't yield anything particularly unusual until May 14, 2023, when Stanton detected two quick and identical pulses in the light of a star named HD 89389 — located around 102 light-years from Earth in the constellation of Ursa Major.

"No single pulse anything like these has ever been found in more than 1,500 hours of searching," Stanton wrote in the study, published April 23 in the journal Acta Astronautica.

Stanton checked historical data on starlight observations and found that a similar pair of pulse signals was recorded in 2019, this time in the light of a star called HD 217014, or 51 Pegasi. After completing his study, Stanton then detected a third double pulse event in the light of another star (HD 12051) on Jan. 18, 2025. The pulse signals are currently unexplained.

However, Seth Shostak, a senior astronomer at the Search for Extraterrestrial Intelligence (SETI) Institute in California who was not involved in the study, urged caution when attributing the pulses to potential alien activity.

"There's a history (going back more than a century) of astronomical discoveries that were, at first, attributed to extraterrestrial beings, but in fact turned out to be natural phenomena," Shostak told Live Science in an email. "Given that history, one should be cautious in saying that these 'starlight pulses' are due to extraterrestrials trying to get in touch."

Shostak added that he would expect any alien transmissions, be they optical, radio or something else, to convey information of some kind — because, as he puts it, clever aliens wouldn't go to the trouble and expense of sending empty signals into space.

"And as these signals seem to be both regular, kind of simple (two pulses) and repetitive, I'm more than a little inclined to say that we're dealing with astrophysical phenomena here — not an attempt by some alien society to send interstellar telegrams," he said.

Related: Did the James Webb telescope really find evidence of alien life? Here's the truth about exoplanet K2-18b.

Even so, the pulses of light coming from HD 89389 were "strange," according to Stanton's study. The star's light was reduced by about a quarter in one-tenth of a second. No known phenomenon could have caused the star itself to change in brightness and then revert back to normal so quickly, according to the study.

There are plenty of objects in and around Earth that regularly obscure stars in the night sky, causing their brightness to flicker. However, Stanton found that the usual suspects for obscuring stars, like airplanes, birds, satellites and meteors around Earth, didn't explain these pulses. For example, objects like airplanes and asteroids typically obscure all of the star's light, but HD 89389 never completely disappeared.

What's more, Stanton snaps images of the stars while measuring the photons they emit, and these images often pick up passing satellites that have obscured a star's light. However, there wasn't anything visible in the images of HD 89389 to explain the pulses.

"Nothing was found in any of these frames, suggesting that the source of the pulses was either invisible, such as due to some atmospheric effect, or too far away to be detected," Stanton wrote.

One possible explanation is the activity of an extraterrestrial intelligence (ETI), but it would have to be near to Earth (relatively speaking) because of how rapidly the stars changed in brightness.

"Whatever is modulating the star's light must be relatively close to Earth, implying that any ETI activity must be within our solar system," Stanton wrote.

The study explored several potential causes for the pulses but left many questions unanswered. Alongside aliens, possible explanations left on the table included gravitational waves — ripples in the fabric of space-time — and the starlight diffracting off some unseen space object.

"More and better data are needed, such as could be gathered using arrays of telescopes on the ground," Stanton wrote. "Data from this new source, or information from other approaches, may be the only way to unravel this mystery."

Extraterrestrials quiz: Are you an alien expert, or has your brain been abducted?

The trendiest planet in the universe right now is K2-18b, a potentially habitable world swirling around a small, red star in the constellation Leo. Located 124 light-years from Earth, the mysterious planet will never host human visitors — but a recent glimpse with the James Webb Space Telescope (JWST) hints that alien life may already thrive there in a vast, warm ocean.

In a University of Cambridge-led study published April 17, scientists using JWST reported the detection of possible signs of life in the alien planet's atmosphere, offering what a Cambridge statement called the "most promising" evidence yet of life beyond Earth. However, in the week since the study's publication, a growing number of scientists are already pushing back on this big claim.

"The statistical significance of the detection is marginal," Eddie Schwieterman, an assistant professor of astrobiology at the University of California, Riverside who was not involved in the research, told Live Science in an email. "There are some reasons to be skeptical."

"It's almost certainly not life," Tessa Fisher, an astrobiologist at the University of Arizona who was not involved in the research, told Nature.com.

So what did JWST actually find on K2-18b, and how close are we to solving the ultimate mystery of space? Here's everything you need to know.

What did JWST find on K2-18b?

Unlike optical telescopes such as Hubble, JWST cannot image the surfaces of distant planets directly; instead, its infrared instruments hunt for chemical signs of life — or biosignatures — in planetary atmospheres by mapping how starlight is absorbed or reemitted by molecules in those atmospheres. The resulting graphs of light, called spectra, can reveal the composition of that planet's atmosphere, providing clues about its surface conditions.

Related: 32 alien planets that really exist

In the new Cambridge-led study, scientists using JWST's Mid-Infrared Instrument (MIRI) peered into K2-18b's atmosphere to detect traces of two sulfur-based molecules called dimethyl sulfide (DMS) and dimethyl disulfide (DMDS) — compounds that are known to be produced only by microscopic life-forms like phytoplankton on Earth. If DMS can be produced by some natural mechanism, scientists currently don't know about it, and will have to run extensive tests to uncover it.

The findings add to earlier observations made by the same team using two different JWST instruments in 2023, which also reported possible traces of DMS in the planet's atmosphere.

While the Cambridge team admitted in the statement that they are "deeply sceptical" of their own results, the same release also trumpeted these detections as the "most promising" evidence yet of life beyond Earth, painting a picture of an oceanic planet that could be "teeming with life." (Other studies have argued that K2-18b's ocean may, in fact, be made of magma.)

Nikku Madhusudhan, lead author of both Cambridge studies, stressed that no actual life has been detected on K2-18b yet.

"That's not what we're claiming," Madhusudhan, a professor of astrophysics at Cambridge, told Live Science. "But in the best-case scenario, it's the potential for life."

The team's DMS detection reached the three-sigma level of statistical significance, meaning there is a 0.3% probability that the signals occurred by chance. However, this still falls far short of the required five-sigma level that denotes a statistically significant scientific discovery.

Responding to criticism that the team may have overstated their study's significance, Madhusudhan said it's in the public interest to know how this research is progressing.

"This is the taxpayer paying us, and they have a right to enjoy the process," Madhusudhan added. "If we're sending a robot to Mars, we're not waiting until it goes and finds life to celebrate the act of sending it. We announced that we are sending robots to Mars, and we're excited about the possibility. This is the equivalent of that."

"No strong evidence"

For now, the public has little more than the Cambridge team's study to go on. The complete set of MIRI data on which the team based their discovery will become publicly available April 27, according to NPR, at which point outside researchers can begin to comb through it and formulate peer-reviewed responses.

In the meantime, various researchers have already attempted to re-create the findings using their own data models and have come up short.

In January, a team of scientists independently analyzed K2-18b's atmosphere using the same JWST instruments used in the 2023 study. The team found "no statistically significant or reliable evidence" of DMS on K2-18b, the researchers wrote in a paper published to the preprint server arXiv.

More recently, on April 22, University of Oxford astrophysicist Jake Taylor reanalyzed the JWST spectra shared in the new Cambridge study, using a simple data model that's routinely utilized in exoplanet studies. Taylor's analysis, also published to arXiv, found no traces of DMS, either.

"There is no strong evidence for detected spectral features in K2-18b's MIRI transmission spectrum," Taylor wrote.

Looking only at the Cambridge team's study, Schwieterman also saw cause for hesitation in proclaiming that biosignatures exist on K2-18b.

"When DMS interacts with ultraviolet light from the star, it splits apart into components that reform into other molecules like ethane (C2H6) and ethylene (C2H4)," Schwieterman said. "The paper does not report the detection of these molecules, which is puzzling because you'd expect these gases to appear together."

What comes next?

Everyone, including the Cambridge team, agrees that more observations of K2-18b are necessary to bring clarity to this puzzle. This means researchers will have to request more time with JWST to observe the alien planet as it swoops in front of its star.

Luckily, this is a near-monthly occurrence, with K2-18b completing a transit of its star every 33 days. Budgeting more time to watch these transits should be "trivial" for the telescope, Madhusudhan said.

"One transit is eight hours, roughly," Madhusudhan added. "You only need about 16 to 24 hours of JWST time. To give you a sense of scale, JWST observes thousands of hours every year."

If additional observations can increase the statistical significance of the team's DMS detection, the next step will be to prove that some unknown natural process isn't producing the molecule instead, Schwieterman said. This will take rigorous experimentation and some creative thinking here on Earth. Finally, scientists will need to look at planets that are similar to K2-18b to see if DMS is a common signature around the cosmos.

Extraterrestrials quiz: Are you an alien expert, or has your brain been abducted?

Dyson spheres, the hypothetical mega-structures that advanced alien civilizations might use to enclose a star and harness its energy, suffer from a fatal flaw: They are catastrophically unstable. But now an engineer claims to have figured out a way to stabilize these structures — and all it takes is two stars.

In the 1960s, physicist and polymath Freeman Dyson cooked up the idea of these eponymous spheres. He envisioned that a sufficiently advanced society would have an insatiable need for living space and energy. And if they were industrious enough, they could solve both challenges by taking apart a planet and turning it into an enormous spherical shell. This sphere would enclose a star, providing billions of planets' worth of surface area and capturing vast amounts of solar energy.

Dyson calculated that a shell made from a planet with the mass of Jupiter could completely enclose the sun at roughly the orbit of Earth. But the gravity inside a hollow shell cancels out, which means there's nothing tethering the shell to the star. They are free to move in independent directions, which means that soon enough a star hosting a Dyson sphere will simply crash into the shell, destroying it.

In a paper published Jan. 29 in the journal Monthly Notices of the Royal Astronomical Society, Colin McInnes, an engineer at the University of Glasgow, found a way to theoretically stabilize a Dyson sphere. The trick is that you need a system with at least two stars.

Hunting for stable Dyson spheres

McInnes started by searching for any points within a binary star system that could host a stable Dyson sphere arrangement, where the sphere could stay in place and the gravitational forces exerted on it would be uniform. He found one arrangement, where the sphere surrounds both stars. But that situation was only mildly stable and likely to suffer the same problem as the single-star case.

Another stable point arises when the sphere orbits independently, surrounding neither star. While this might be useful for space station outposts, it doesn't provide the energy-capturing benefits of englobing a star.

Related: 'Perhaps it's only a matter of time': Intelligent life may be much more likely than first thought, new model suggests

But McInnes did find one stable — and useful — configuration. This only happens in binary systems in which one star is much smaller than the other. In that specific case, the Dyson sphere can enclose the smaller of the two stars. The motion of that smaller star acts like a gravitational anchor, keeping the Dyson sphere in motion with the same orbit around the larger star, preventing a catastrophic collision.

There are several caveats to this. The smaller star has to be no bigger than around one tenth the mass of the larger companion, otherwise the gravitational stable point disappears. And the sphere has to be extremely light and thin compared with the two stars, otherwise its own gravitational influence mixes into the dynamics of the system and destroys the stability.

And, of course, this analysis ignores any practical engineering considerations, like the stresses and tensions the sphere might experience, or how to build the thing in the first place.

While it's unlikely humans will build a Dyson sphere in the distant future — if ever — this research does help inform searches for extraterrestrial civilizations. Presumably, a sufficiently advanced civilization would have made the same realization before building its own Dyson sphere, and so we shouldn't look for them around solitary stars.

Instead, scientists could look for large, bright stars with a diffuse, infrared companion — the telltale sign of the heat leaking out of a Dyson sphere enclosing the smaller star of a larger companion.

This article was originally published April 12, 2025.

Earth-based lifeforms known as lichens may be tough enough to survive on Mars, a new study suggests.

Scientists came to this conclusion after blasting the lichens with a year's worth of Martian radiation in less than a day during a lab experiment — and the terrestrial lifeforms survived the process.

Mars is not an easy place to live. The Red Planet is essentially one giant desert with a minimal atmosphere, low temperatures and no liquid water at its surface. But the biggest barrier to life on Mars is the lack of a strong magnetic field, which protects against the constant bombardment of ionizing radiation from cosmic rays and solar flares, which can damage living cells and mutate their DNA.

One group of living things that may be able to survive these extreme conditions is lichens, symbiotic associations between fungi and photosynthetic bacteria and/or algae. These hybrid lifeforms, which are not considered true organisms but are listed as species on the three of life, work together to stay alive and many are extremophiles, capable of tolerating no hydration and extreme temperatures for long periods. Some species have even survived being directly exposed to the vacuum of space.

In the new study, published March 31 in the journal IMA Fungus, researchers tested how two lichen species — Diploschistes muscorum and Cetraria aculeata — reacted to ionizing radiation under Martian conditions. To do this, the team placed the lifeforms in a specialized vacuum chamber at the Space Research Centre of the Polish Academy of Sciences in Warsaw, which replicated the atmospheric pressure, temperatures and composition on the Red Planet. They bombarded the lichens with a year's worth of Martian radiation in just 5 hours. Both species were able to remain metabolically active throughout the tests.

Related: Which animals will be the first to live on the moon and Mars?

"These findings expand our understanding of biological processes under simulated Martian conditions and reveal how hydrated organisms respond to ionizing radiation," Kaja Skubała, a researcher at the Institute of Botany at the Jagellonian University in Krakow, Poland, said in a statement. "Ultimately, this research deepens our knowledge of lichen adaptation and their potential for colonizing extraterrestrial environments."

Of the two species, D. muscorum showed the greatest resistance to the radiation, sustaining less damage to its cells, which suggests that some lichens will be better suited to Martian conditions than others. However, it is unlikely that any species would be able to survive on Mars unattended for long periods, as there is no known liquid water at the surface, which all of Earth's lifeforms need to survive.

This is the reason why it is unlikely that there is any extraterrestrial life currently alive on Mars.

Martian candidates

According to the researchers, the new experiments show that lichens are prime candidates for being taken on future Mars missions, although there are several resilient species other than D. muscorum that could also make the trip.

But lichens are not the only lifeforms that could potentially survive on the Red Planet.

One extremophile group that has long been considered as future Martian tourists is tardigrades. These microscopic critters are nearly indestructible and can survive extreme temperatures, crushing pressures, total dehydration and the vacuum of space, largely thanks to an ability to switch off their metabolism and enter a state of suspended animation.

Other candidates include mosses — plants with similar abilities to lichens. Some desert moss species have even been shown to be resilient to gamma rays and liquid nitrogen, hinting that they too could fare well on Mars.

Single-celled microorganisms, such as bacteria, might also be able to survive on Mars if they were sheltered from radiation, living underground. Research has shown that these microbes could also survive for hundreds of millions of years beneath the surface in a hibernation-like state.

However, the first terrestrial lifeforms to touch down on Mars will likely be a species that is naturally very poorly suited to living on Mars — humans. NASA intends on launching the first crewed mission to the Red Planet sometime in the 2030s, when they will get a taste of how tough it is to survive there.

Editor's note: This article was originally published April 8, 2025

Hycean worlds, which are a possible kind of exoplanet with deep oceans surrounded by a thick envelope of hydrogen, could provide the best chance for the James Webb Space Telescope (JWST) to detect biosignatures, according to a new study.

Those potential signs of life are a group of chemicals called methyl halides, which on Earth are produced by some bacteria and ocean algae.

"Unlike an Earth-like planet, where atmospheric noise and telescope limitations make it difficult to detect biosignatures, hycean planets offer a much clearer signal," said Eddie Schwieterman, who is an astrobiologist at the University of California, Riverside, in a statement.

For now, the existence of hycean planets remains hypothetical. Their name is a portmanteau of "hydrogen" and "ocean," first coined in 2021 by planetary scientist Nikku Madhusudhan of the University of Cambridge.

Related: 'Hycean' exoplanets may not be able to support life after all

Hycean planets are expected to orbit red dwarf stars, and the best candidate for a hycean world is the planet K2-18b. This exoplanet, which is categorized as a "sub-Neptune" world, orbits in the habitable zone of a red dwarf star 124 light-years from Earth in the constellation of Leo, the Lion.

The Hubble Space Telescope discovered water vapor in K2-18b's atmosphere in 2019, and JWST has detected the presence of carbon dioxide and methane in the planet's atmosphere, along with a lack of carbon monoxide and ammonia — exactly as predicted by the hycean planet hypothesis. There's also tentative evidence that a compound called dimethyl sulfide, which on Earth is only produced by ocean plankton, also exists in K2-18b's atmosphere, but this evidence continues to prove contentious.

Now a team of researchers at the University of California, Riverside and ETH Zurich in Switzerland have gone a step further. They propose that another family of compounds called methyl halides, generated by microbial ocean life on Earth, could produce a biosignature — that is, a chemical signature of biological life — in the atmosphere of a hycean world that's more easily detectable than the signature of oxygen is on an Earth-like planet.

"Oxygen is currently difficult or impossible to detect on an Earth-like planet," said Michaela Leung of the University of California, Riverside, the first author of a new paper describing the research. "However, methyl halides on hycean worlds offer a unique opportunity for detection with existing technology."

Methyl halides are molecules that incorporate carbon atoms and three hydrogen atoms attached to a halogen atom such as bromine, chlorine or fluorine. (Halogens are group of reactive, non-metallic elements.) On Earth, methyl halides are produced by life, but they are far from abundant in our planet's atmosphere.

On hycean worlds, however, things could be different. Leung's team suspect that the conditions on such worlds, should they exist, would allow methyl halides to accumulate in large quantities in the atmosphere. Furthermore, methyl halides would have strong absorption features in infrared light, at the same wavelengths that the JWST is designed to observe.

"One of the great benefits of looking for methyl halides is, you could potentially find them in as few as 13 hours with James Webb. That is similar or lower, by a lot, to how much telescope time you'd need to find gases like oxygen or methane," said Leung. "Less time with the telescope means it's less expensive."

Related: The search for alien life

There are two caveats to what Leung's team propose. One is that we don't yet know whether hycean worlds actually exist. They were proposed as a possibility to explain certain properties of some warm sub-Neptune-type planets that have average densities that imply a thick hydrogen atmosphere and a deep ocean of liquid water. However, directly observing an ocean beneath such a world's hydrogen envelope is not currently feasible.

The second issue is that we don't know if such oceans could be habitable. A hycean world would be hot, and although the extreme conditions beneath the hydrogen envelope would prevent the ocean from evaporating, it is uncertain whether it would be too hot for life as we know it. However, a positive detection of methyl halides in the atmosphere of a candidate hycean world would be a strong indication that life could exist there in a deep ocean.

If life does exist on such a world, it would have to breathe hydrogen, not oxygen.

"These microbes, if we found them, would be anaerobic," said Schwieterman. "They'd be adapted to a very different type of environment, and we can't really conceive of what that looks like, except to say that these gases are a plausible output from their metabolism."

Anaerobic life — i.e., lifeforms making do without oxygen — exist on Earth, so it wouldn't be truly alien to life on our planet, even if the environment that it would live in is. Earth-like worlds orbiting red dwarfs could be in short supply, since red dwarfs are fierce little beasts, prone to unleashing bursts of harsh radiation that can strip away the atmosphere of an Earth-like planet. However, hycean worlds protected by their thick hydrogen atmospheres might be less vulnerable to attack from their star.

It could therefore be that hycean worlds are where life resides in red dwarf systems, and since red dwarfs make up about three-quarters of all stars in our Milky Way galaxy, there could be many more habitable hycean worlds in the cosmos than Earth-like worlds.

The research by Leung's team was published on March 11 in The Astrophysical Journal Letters.

Originally posted on Space.com.

The Extremely Large Telescope (ELT), currently under construction in northern Chile, will give us a better view of the Milky Way than any ground-based telescope before it.

It's difficult to overstate how transformative it will be. The ELT's primary mirror array will have an effective diameter of 39 meters. It will gather more light than previous telescopes by an order of magnitude, and it will give us images 16 times sharper than the Hubble Space Telescope. It's scheduled to come online in 2028, and the results could start flooding in literally overnight, as a recent study shows.

One of the most powerful features of the ELT will be to capture faint atmospheric spectra from the atmospheres of exoplanets. This is usually done as a planet passes in front of its star from our vantage point. A small bit of starlight passes through a planet's atmosphere to reach us, and by analyzing the absorption spectra we can determine the molecules contained in the planet's atmosphere, such as water, carbon dioxide, and oxygen. The James Webb Space Telescope (JWST) has gathered data on several exoplanet atmospheres, for example.

But sometimes the transit data we can gather is inconclusive. For example, when JWST looked for atmospheres on the planets of the TRAPPIST-1 system, it seemed that the planets b and c were airless, but the data isn't strong enough to rule out the presence of atmospheres. There might be thin atmospheres with spectral lines too faint for JWST to observe. The ELT's greater sensitivity should be able to settle the question.

Related: James Webb telescope spots 'rogue' planet with a cake-like atmosphere barrelling through space without a star

What's even more exciting is that the ELT should be able to gather spectra not just on exoplanets that transit their star, but also from non-transiting exoplanets via reflected starlight.

To determine just how powerful the ELT will be, this new study simulated results for several scenarios. They focused on planets orbiting nearby red dwarf stars, since those are the most common types of exoplanets, and looked at four test cases: a non-industrial Earth rich in water and photosynthesizing plants, an early Archean Earth where life is just starting to thrive, an Earth-like world where oceans have evaporated, similar to Mars or Venus, and a pre-biotic Earth capable of life but where there is none. For comparison, the team also considered Neptune-sized worlds, which should have significantly thicker atmospheres.

The idea was to see if the ELT could distinguish between the different Earth-like worlds, and more importantly, whether the data could trick us into a false positive or negative. That is, whether a lifeless world would appear to have life or a living world would appear barren.

Based on their simulations, the authors found that we should be able to make clear and accurate distinctions for nearby star systems. For the closest star, Proxima Centauri, we could detect life on an Earth-like world with only ten hours of observation. For a Neptune-sized world, the ELT could capture planetary spectra in about an hour.

So it seems that if life exists in a nearby star system, the ELT should be able to detect it. The answer to perhaps the greatest question in human history could be found in just a few years.

The original version of this article was published on Universe Today.

The burning of fossil fuels — coal, oil and gas — propelled humanity into the industrial revolution, remaking civilization in its wake. Gasoline powers many of the cars we drive; coal and natural gas are central to global energy. But if aliens were building their own society, would they have to go down the same path as humanity, relying on fossil fuels to build their advanced civilization? Or could they find an alternative?

To build a modern civilization, aliens would likely need to use a source of energy that's just as abundant as fossil fuels, said Lewis Dartnell, an astrobiologist and author of "The Knowledge: How to Rebuild Our World from Scratch" (Penguin Press, 2014). It would be hard for them to simply bypass the production of fossil fuels, he noted.

Dartnell drew a parallel with humans: In the 18th century, the world entered the industrial revolution by tapping into what appeared to be a limitless source of energy. Coal burned longer and produced more power than wood and charcoal.

"Prior to that, energy was the fundamental limitation on how much you could do," he said. "It would limit how much you could mine and move things around, what you could build, and what you could make."

The question of whether humans could have bypassed fossil fuels to reach alternative energy sources is "somewhat of a chicken-and-egg dilemma," Dartnell told Live Science. For instance, producing solar panels requires silicon, and extracting and refining this element demands a significant amount of energy.

Related: How do we turn oil into plastic?

The easiest way for intelligent aliens to create fuel would be to start by burning stuff, like humans did, until they can move to other sources of energy. They could perhaps harness the light of a star or of the kinetic energy of the wind. But wind energy on its own would not create the high temperatures needed for the smelting, forging and casting of metals, which would be needed for industrialization, Dartnell said.

Meanwhile, hydropower would only work if the planet had significant amounts of accessible liquid, which most planets we've found don't possess, added Seth Shostak, an astronomer and director of the Search for Extraterrestrial Intelligence (SETI) Institute.

Could other planets have fossil fuels?

Scientists still haven't found a planet with abundant oxygen in its atmosphere, though trace amounts have been found on Mars, Venus and Jupiter's moon Europa. Oxygen is the key ingredient in burning fossil fuels because it enables combustion, which is what releases the energy stored in coal, oil and gas.

Fossil fuels are created from life — they're the transformed remains of plants and animals that lived hundreds of millions of years ago. Dartnell suggested that plate tectonics are a crucial part of the puzzle of how these life forms came to exist. "There's good reason to suspect that in order to have intelligent life on an Earth-like planet, you need to have plate tectonics to regulate the climate for long periods of time," he said.

A 2022 study by researchers at the University of Sydney reported how Earth's tectonic plates move carbon between the deep Earth and the surface, forming what they call a "carbon conveyor belt." This process is key to maintaining Earth's "Goldilocks" climate, making the planet habitable, according to the study. What's more, plate tectonics also results in continental drift and the creation of conditions that produce large amounts of coal, a fossil fuel, he added.

Put another way, plate tectonics can help pave the way for life and create conditions to help it become fossil fuels; it can also create ideal conditions for life that may become intelligent enough to harness those fuels.

"In a sense, you get a two-for-one," Dartnell said. "If you have a planet with active plate tectonics, that regulates the climate, which allows for the evolution of intelligent complex life."

Scientists have yet to find another planet with active plate tectonics. Nor have they found fossil fuels in space. What they have discovered, however, is evidence of fossil fuels' chemical building blocks: hydrogen and carbon. Approximately 75% of the universe's mass is composed of hydrogen, said Shostak. Additionally, scientists have found a field of liquid hydrocarbons on Saturn's moon Titan. Intelligent aliens could, hypothetically, attempt to burn these elements to produce energy.

A human point of view

Of course, aliens aren't necessarily bound by the same constraints as humans, and our imagination often limits us to thinking in terms of a human timeline. "It's hard for us to predict what the aliens might do," Shostak told Live Science. It's like asking Julius Caesar what he thought the Romans would be doing with oil in 2025, when they were only using small amounts of oil for lamps. "Julius would probably have some ideas, all based on Roman knowledge," he said. "He would completely miss the [mark]. You have to keep that in mind."

An intelligent alien civilization could be nothing like what we expect, Shostak added. While aliens would likely need an abundant energy source to advance their civilization, who's to say what form that energy would take? The answer could lie beyond human understanding.

Extraterrestrials quiz: Are you an alien expert, or has your brain been abducted?

Is there anybody out there? Are we really alone in the universe, or are aliens just patiently waiting for us to become advanced enough to be worth speaking to?

There are so many mysteries about who or what might live among the stars, and whether they are advanced planet-hopping civilizations or microbes quietly doing what microbes do on a nearby moon. But some questions are easier to answer.

This extraterrestrial quiz is your chance to show whether you know the facts from the fiction about otherworldly entities, or if it's all alien to you. Remember to log in to put your name on the leaderboard; hints are available if you click the yellow button, and let us know your score in the comments.

Related: 32 strange places scientists are looking for aliens

More science quizzes

—Moon landing quiz: How quickly can you name all 12 Apollo astronauts that walked on the moon?

—Conspiracy theory quiz: Test your knowledge of unfounded beliefs, from flat Earth to lizard people

—Black hole quiz: How supermassive is your knowledge of the universe?

We often forget how wonderful it is that life exists, and what a special and unique phenomenon it is. As far as we know, ours is the only planet capable of supporting life, and it seems to have arisen in the form of something like today's single-celled prokaryotic organisms.

However, scientists have not given up hope of finding what they call LUCA (Last Universal Common Ancestor, the ancestral cell from which all living things we know are descended) beyond the confines of our planet.

Related: 12 strange reasons humans haven't found alien life yet

Where are we looking?

Since humans started dreaming about Martians, scientific understanding has changed significantly. The most recent vehicles to have traversed the Red Planet's surface — the Perseverance and Curiosity rovers — have identified compounds and minerals that suggest its conditions may once have been habitable, but that is the extent of it.

Right now, Mars is a reddish desert landscape — attractive but dead, and certainly not home to any little green men.

Other nearby planets offer even less hope. Mercury is a scorched rock too close to the Sun, Venus' atmosphere is dry and toxic, and the others in our solar system are either made of gas or very far from the Sun. So, apart from Mars, the search for other forms of life is focused on satellites, especially those orbiting Jupiter and Saturn.

Europa and Enceladus — moons of Jupiter and Saturn, respectively — appear to have large oceans of water under a thick crust of ice that could potentially harbour organic molecules, the building blocks for the origin of life as we know it. These would be nothing like E.T. — they would look more like the simplest terrestrial single-celled organisms.

Looking further afield, more than 5,500 planets have been detected orbiting stars other than the Sun. Only a few are considered potentially habitable and are currently being researched, but as Carl Sagan said in Contact, "the universe is a pretty big place. If it's just us, seems like an awful waste of space."

Looking for life in inhospitable places

Before the 1960s, the conditions on the solar system's most promising satellites would have seemed impossible for life.

The prevailing belief until then was that life could only occur under the conditions where we saw multi-cellular organisms survive. Water, mild temperatures between 0⁰ C and 40⁰ C, pH in neutral ranges, low salinity, and sunlight or an equivalent energy source were considered essential for life.

However, in the mid-20th century, microbiologist Thomas D. Brock discovered bacteria living in the hot springs of Yellowstone National Park, where temperatures exceed 70⁰C. Though unrelated to the search for extraterrestrial life at the time, his discovery broadened its scientific possibilities.

Since then, organisms known as extremophiles have been found inhabiting a range of extreme conditions on Earth, from the cold of cracks in polar ice to the high pressures of the deep ocean. Bacteria have been found attached to small suspended particles in clouds, in extremely saline environments such as the Dead Sea, or extremely acidic ones, such as Rio Tinto. Some extremophiles are even resistant to high levels of radiation.

What was most surprising, however, was finding them inside ourselves.

Martians in your stomach

In the 1980s, two Australian doctors, Barry Marshall and Robin Warren, began studying gastroduodenal ulcers. Until then, the condition had been attributed to stress or excess gastric acid secretion, which did little to help cure the condition.

Warren was a pathologist, and having identified bacteria in gastric biopsy samples from patients, he realised that they had to be considered a cause of the disease. However, he had to fight against the dogma that microorganisms could not grow in the highly acidic environment of the human stomach.

Warren conducted his research alone until 1981, when he met Barry Marshall, a fellow of the Royal Australasian College of Physicians. He approached Marshall and asked if he would like to work alongside "that crackpot Warren who's trying to turn gastritis into an infectious disease".

In 2005, Barry Marshall and Robin Warren received the Nobel Prize in Physiology or Medicine for their discovery of Helicobacter pylori and its role in gastric diseases, a discovery that revolutionised the field of gastroenterology.

H. pylori has an amazing array of factors that help it survive in hostile environments, such as flagella that allow it to surf stomach fluids to get close to the stomach wall, breaking through the protective mucus layer and attaching itself to it.

Using the enzyme urease, H. pylori degrades urea in the stomach into ammonia and CO₂, creating a higher pH microclimate that allows it to reproduce. As its numbers increase, it releases exotoxins that inflame and damage gastric tissue in the stomach. This is how ulcers eventually develop, as the underlying connective tissue is exposed to the acidity of the stomach.

Their discovery showed that even tucked away in our innards — in the walls of our stomachs, subjected to vinegar-like pH levels, total darkness, the violent movements of our digestive systems, harmful enzymes and churning tides of food — life is able to resist and proliferate.

The study of extremophile micro-organisms offers the hope that on other bodies in the solar system, or on one of the 5,500 known exoplanets, even in extreme conditions, the extraordinary phenomenon of life may be present. The Martians we dream of today might look more like H. pylori than anything else.

This edited article is republished from The Conversation under a Creative Commons license. Read the original article.

The emergence of human life may not have been as improbable as scientists once thought, a new model suggests. The finding increases the likelihood of intelligent life elsewhere in the universe, the researchers say.

Previously, scientists assumed that for human life to emerge on Earth, it needed to pass through a series of "hard steps" — flukes in evolution that are incredibly unlikely to occur within the lifetime of an average star. This makes our position as intelligent observers of the universe a rare occurrence and our chances of finding intelligent aliens low.

But a new model has challenged this decades-old assumption by proposing that human intelligence wasn't a long shot but instead an outcome that unfolded according to predictable geological processes. The researchers published their findings Feb. 14 in the journal Science Advances.

"We're arguing that intelligent life may not require a series of lucky breaks to exist," lead author Dan Mills, a researcher at the University of Munich, said in a statement. "Humans didn't evolve 'early' or ‘late' in Earth's history, but 'on time,' when the conditions were in place. Perhaps it's only a matter of time, and maybe other planets are able to achieve these conditions more rapidly than Earth did, while other planets might take even longer."

First proposed by physicist Brandon Carter in 1983, the hard steps model is an attempt to explain why humans emerged on Earth so late in the life of the sun — roughly 4.5 billion years into its 10 billion-year lifespan. Carter reasoned that intelligent life evolved through a chain of highly improbable evolutionary events — the formation of replicating molecules, the emergence of RNA and DNA, the evolution of multicellular organisms, and the inventions of sex and language.

Related: Alien life may look nothing like life on Earth — so how should we go about looking for it?

Carter's proposal quickly took root in astrobiology, encouraging the view that our own evolution was a remarkably uncommon accident and that the odds of us encountering human-like beings elsewhere in the universe was, therefore, dishearteningly low.

But it may not be true after all, the new research suggests. By combining expertise in physics and geobiology, they studied the key steps that led to the evolution of life on our planet.

This produced a model that explains our origins through the sequential openings of key "windows of habitability," such as oxygen and nutrient availability, ocean salinity and sea surface temperatures. According to this model, human life didn't emerge late on our planet but simply when the planetary conditions were right.

"We're taking the view that rather than base our predictions on the lifespan of the sun, we should use a geological time scale, because that's how long it takes for the atmosphere and landscape to change," Jason Wright, a professor of astronomy and astrophysics at Penn State and a co-author of the paper, said in the statement. "These are normal timescales on the Earth. If life evolves with the planet, then it will evolve on a planetary time scale at a planetary pace."

To test this new proposal, the researchers outlined a number of research projects that include testing unicellular and multicellular organisms at extreme temperatures and oxygen levels to ascertain the range of conditions in which they could have emerged. They also proposed scanning the atmospheres of distant exoplanets for key biosignatures, such as the existence of oxygen, and searching the evolutionary record for signs that singular innovations on the path to human life (such as photosynthesis and eukaryotic cells) evolved more than once.

"This is a significant shift in how we think about the history of life," co-author Jennifer Macalady, a professor of geosciences at Penn State, said in the statement. "It suggests that the evolution of complex life may be less about luck and more about the interplay between life and its environment, opening up exciting new avenues of research in our quest to understand our origins and our place in the universe."

We live in a golden age for space exploration. Scientists are gathering massive amounts of new information and scientific evidence at a record pace. Yet the age-old question remains unanswered: are we alone?

New telescope technologies, including space-based tools such as the James Webb Telescope, have enabled us to discover thousands of potentially habitable exoplanets that could support life similar to that on Earth.

Gravitational wave detectors have opened a new avenue for space exploration by detecting space-time distortions caused by black holes and supernovae millions of light-years away.

Commercial space ventures have further accelerated these advancements, leading to increasingly sophisticated spacecraft and reusable rockets, signifying a new era in space exploration.

NASA's OSIRIS-REx mission successfully touched down on asteroid Bennu when it was 207 million miles away from Earth and brought back rock and dust samples.

Several countries have developed the ability to deploy robots on the moon and Mars, with plans to send humans to these celestial bodies in the future.

A central driver of all these ambitious endeavours is still that fundamental question of whether life exists — or ever existed — elsewhere in the universe.

Related: Did people report seeing UFOs before the 20th century?

Defining life

Defining life is surprisingly challenging. While we intuitively recognize living organisms as having life, a precise definition remains elusive. Dictionaries offer various descriptions, such as the ability to grow, reproduce and respond to stimuli.

But even these definitions can be ambiguous.

A more comprehensive definition considers life as a self-sustaining chemical system capable of processing information and maintaining a state of low entropy, with little disorder or randomness.

Living things constantly require energy to sustain their molecular organization and maintain their highly organized structures and functions. Without this energy, life would quickly descend into chaos and disrepair. This definition encompasses the dynamic and complex nature of life, emphasizing its ability to adapt and evolve.

Life on Earth, as we currently understand it, is based on the interplay of DNA, RNA and proteins. DNA serves as the blueprint of life, containing the genetic instructions necessary for an organism's development, survival and reproduction. These instructions are converted into messages that guide the production of proteins, the workhorses of the cell that are responsible for a vast array of functions.

This intricate system of DNA replication, protein synthesis and cellular processes — all based on long strings of molecules linked by carbon atoms — is fundamental to life on Earth. However, the universe may harbour life forms based on entirely different principles and biochemistries.

Something other than carbon

Life elsewhere could use different elements as building blocks. Silicon, with its chemical similarities to carbon, has been proposed as a potential alternative.

If they exist, silicon-based life forms may exhibit unique characteristics and adaptations. For instance, they might use silicon-based structures for support, analogous to bones or shells in carbon-based organisms.

Even though silicon-based organisms have not yet been found on Earth, silicon plays an important role in many existing life forms. It is an important secondary component for many plants and animals, serving structural and functional roles. For example, diatoms, a type of algae found in the ocean, feature glassy cell walls made of transparent silicon dioxide.

This doesn't make diatoms silicon-based life forms, but it does prove silicon can indeed act as a building block of a living organism. But we still don't know if silicon-based life forms exist at all, or what they would look like.

The origins of life on Earth

There are competing hypotheses on how life arose on Earth. One is that that life's building blocks were delivered on or in meteorites. The other is that those building blocks came together spontaneously via geochemistry in our planet's early environment.

Meteorites have indeed been found to carry organic molecules, including amino acids, which are essential for life. It's possible that organic molecules formed in deep space and were then brought to Earth by meteorites and asteroids.

On the other hand, geochemical processes on early Earth, such as those occurring in warm little ponds or in hydrothermal vents deep in the ocean, could have also provided the necessary conditions and ingredients for life to emerge.

However, no lab has yet been able to present a comprehensive, certain pathway to the formation of RNA, DNA and the first cellular life on Earth.

Many biological molecules are chiral, meaning they exist in two forms that are mirror images of each other, like left and right hands. While both left- and right-handed molecules are typically naturally produced in equal amounts, recent analyses of meteorites have revealed a slight asymmetry, favouring the left-handed form by as much as 60 per cent.

This asymmetry in space-derived organic molecules is also observed in all biomolecules on Earth (proteins, sugars, amino acids, RNA and DNA), suggesting it could have arisen from the slight imbalance delivered from space, supporting the theory that life on Earth is extraterrestrial in origin.

Chances of life

The slight imbalance in chirality observed in many organic molecules could be an indicator that life on Earth originated from the delivery of organic molecules by extraterrestrial life. We could well be descendants of life that originated elsewhere.

The Drake equation, developed by astronomer Frank Drake in 1961, provides a framework for estimating the number of detectable civilizations within our galaxy.

This equation incorporates factors such as the rate of star formation, the fraction of stars with planets, and calculates the fraction of those planets where intelligent life may emerge. An optimistic estimate using this formula suggests that 12,500 intelligent alien civilizations might exist in the Milky Way alone.

The primary argument for extraterrestrial life remains probabilistic: considering the sheer number of stars and planets, it seems highly improbable that life wouldn't have arisen elsewhere.

The probability of humanity being the sole technological civilization in the observable universe is considered to be less than one in 10 billion trillion. Additionally, the chance of a civilization developing on any single habitable planet is better than one in 60 billion.

With an estimated 200 billion trillion stars in the observable universe, the existence of other technological species is highly likely, potentially even within our Milky Way galaxy.

This edited article is republished from The Conversation under a Creative Commons license. Read the original article.

Scientists have discovered the essential building blocks to life on a sample from a distant asteroid.

The sample, which the OSIRIS-REx spacecraft collected from the asteroid Bennu and returned to Earth in 2023, contains all five nucleobases — the "letters" that make up DNA and RNA — alongside mineral compounds, all of which have never previously been seen on extraterrestrial rocks.

The minerals are rich in carbon, sulfur, phosphorus, fluorine and sodium, making them resemble those left in the crusts of dried lake beds on Earth — except they date to the birth of the solar system 4.6 billion years ago. These elements, alongside the five nucleobases that make up DNA and RNA, are the basic building blocks for life on our planet.

The two teams of researchers who made the discoveries published their findings Jan. 29 in two papers in the journal Nature Astronomy.

"We now know from Bennu that the raw ingredients of life were combining in really interesting and complex ways on Bennu's parent body," study co-lead author Tim McCoy, curator of meteorites at the Smithsonian's National Museum of Natural History, said in a statement. "We have discovered that next step on a pathway to life."

Bennu is a potentially hazardous asteroid that has a 1-in-2,700 chance of striking Earth in the year 2182 — the highest odds of any known space object. But scientists are more interested in what's trapped on the space rock: As a carbon-rich asteroid, it likely contains many of the primordial molecules present when life first emerged on Earth.

Related: NASA's OSIRIS-REx mission almost bit the dust — then Queen guitarist Brian May stepped in

OSIRIS-REx launched in September 2016 and traveled 200 million miles (320 million kilometers) to reach Bennu.

Once there, the spacecraft orbited the asteroid for nearly two years as flight engineers searched for a landing site. Upon making contact with the space rock, OSIRIS-REx fired a burst of nitrogen from its Touch-and-Go Sample Acquisition Mechanism to stick the landing and prevent itself from sinking through the asteroid. The nitrogen burst captured a 4.29-ounce (121.6 grams) sample in the process.

In October 2023, the sample was brought to Earth aboard OSIRIS-REx's capsule, which reached speeds of up to 27,000 mph (43,000 km/h) before it deployed its parachute and landed safely in the Utah desert. To avoid contamination, the sample container was taken to a clean room before being opened.

The researchers behind the first study received slices of the Bennu sample, which they examined under a scanning electron microscope. This enabled the team to study features on the sample's surface with a resolution of one-hundredth the width of a human hair.

The scientists discovered sodium carbonate, typically found in evaporated lakes that once contained life on Earth, on the space rock's surface. Within the sodium carbonate, the team found 11 minerals that are important precursors for organic compounds. The mineral compositions differed subtly from those found on our planet; being rich in phosphorus and poor in boron, when the reverse is true in Earth’s lakes.

The researchers think brine similar to that found on Bennu could also exist on other bodies in the solar system, such as the dwarf planet Ceres and Saturn's icy moon Enceladus.

In the second study, conducted by scientists in Japan, a separate piece of the sample was also found to contain the five nucleobases — adenine, guanine, cytosine, thymine and uracil — which combine with ribose and phosphate to form DNA and RNA, the ladder-like structures that make up the genetic code of all life on Earth.

This is the first time that scientists have found these nucleobases on a distant asteroid. In 2023, a sample taken from the Ryugu space rock by the Hayabusa2 spacecraft was found to contain uracil, yet the other nucleobases were missing.

It's unclear what this means for life beyond our planet. While the existence of these minerals on Bennu is a sure indication that the asteroid had the right ingredients for life, the researchers are unsure if the asteroid's environment was too harsh for the compounds to grow into complex organic structures. To further investigate, the scientists plan to reexamine meteorites in their collection for similar salts and compounds.

"We now know we have the basic building blocks to move along this pathway towards life, but we don't know how far along that pathway this environment could allow things to progress," McCoy said.

When the cosmos' first stars exploded in spectacular supernovas, they may have unleashed enormous amounts of water that flooded the early universe — and potentially made life possible just millions of years after the Big Bang, new simulations suggest.

However, this theory clashes with our current understanding of cosmic evolution and will be extremely difficult to prove.

Water is one of the most abundant compounds in the universe, according to NASA. Aside from Earth, astronomers have found water in several places throughout the solar system, including scattered above and below the surface of Mars, inside the ice caps of Mercury, surrounding the shells of comets and buried in underground oceans on several major moons. Outside our cosmic neighborhood, researchers have also detected water on distant exoplanets and within massive clouds of interstellar gas that permeate the Milky Way.

Until now, scientists assumed that all this water gradually built up over billions of years as hydrogen, the most abundant element in the universe, combined with oxygen that has been forged in the hearts of stars and expelled via supernovas. But in the new study, uploaded Jan. 9 to the preprint server arXiv, researchers simulated the explosive deaths of giant, short-lived early stars — which each had a mass equivalent to around 200 suns — and found that they could create the conditions needed for water to take shape.

The water from these stellar explosions would likely have formed at the hearts of dense clouds of hydrogen, oxygen and other elements left behind by stars. It may have had concentrations up to 30 times higher than the water seen floating in interstellar space within the Milky Way, the researchers wrote in the study, which has not been peer-reviewed yet.

Related: Could a supernova ever destroy Earth?

If correct, the new findings would have big implications for scientists' understanding of galaxy evolution and extraterrestrial life.

"Besides revealing that a primary ingredient for life was already in place in the universe between 100 million and 200 million years after the Big Bang, our simulations show that water was likely a key constituent of the first galaxies," the researchers wrote.

Early cosmic uncertainty

One of the biggest issues with the new study is that scientists have never directly observed one of the early stars that the researchers are modeling, known as population III stars. Instead, researchers have only indirectly observed a few of these stellar trailblazers by analyzing the stars that were birthed from their remains, so it's still not certain what they were really like.

If there was abundant water in the early universe, it would also suggest that the cosmos should have accumulated much more water than we currently see in our surroundings.

One explanation for this that has been posited by other scientists is that the universe underwent a drying-out period during which large quantities of water were lost, according to Universe Today. However, it is unclear what the cause of this event could have been.

"There is also the fact that while water formed early, ionization and other astrophysical processes may have broken up many of these molecules," Universe Today reported, meaning that the water from the first supernovas may have been short-lived.

Although water is a key ingredient for life on Earth, there is also no guarantee that its presence in the early universe would have made extraterrestrial life more likely.

Every so often, claims of UFO sightings go viral and even spur serious research. But humans have been gazing at the sky for millennia, and reports of such sightings go way back. So what was the first recorded UFO sighting, and did it predate the mid-20th century, when reports of UFOs became more commonplace?

Unfortunately, the answer isn't clear-cut, at least when looking at pre-modern examples.

"There is no consensus on what constitutes the first recorded UFO sighting in history," Chris Aubeck, an independent researcher and director of the Magonia Exchange, an international UFO history archival project with members in 15 countries, told Live Science. This dispute is not due to a lack of accounts; many artifacts portray puzzling, celestial objects.

"There's no question that human beings have depicted or reported or chronicled things about strange, anomalous things in the sky dating back to the ancient world," Greg Eghigian, a professor of history and bioethics at Penn State, told Live Science.

Related: How would we give aliens directions to Earth?

Rather, the context and form of these accounts make it difficult to pinpoint what can be definitively described as the first recorded UFO sighting. For example, according to Aubeck, ancient texts like Sumerian and Babylonian cuneiform tablets, like those in the Šumma ālu series and other divination texts from the second and first millennia B.C., provide the first known recordings of potential UFO sightings, though these are interpreted as omens. These accounts describe changing shapes in the sky and black meteors, which, at the time, were regarded as religious harbingers. However, these texts lack visual depictions or illustrations.

"I can't put a lot of stock in those stories because they're completely decontextualized from the society in which they're made," Eghigian said. These accounts may not be claims of extraterrestrials visiting Earth, but rather religious scriptures or written stories. In these cases, it can be difficult to separate cultural lore from an individual's attempt to describe a sight they could not explain, from comets to lenticular clouds.

In one example, residents of Nuremberg, Germany reported a strange aerial battle on April 14, 1561. They wrote about seeing orbs, crosses, cylinders, and a giant, mysterious black arrow-shaped object, which crash-landed in the distance. According to Hans Glaser, a local artist who made a woodcut depicting the event, the different objects in the sky "all started to fight among themselves" until "they became fatigued … fell from the sun down upon the earth 'as if they all burned' and they then wasted away on the earth with immense smoke." However, he didn't mention UFOs, only writing that "Whatever such signs mean, God alone knows."

Because their interpretation isn't clear, these bygone examples aren't necessarily claims of a UFO sighting. What's more, although humans commonly believed in alien civilizations for centuries, "what was not common was to say aliens were visiting us," Eghigian said.

For Eghigian, the first definitive recorded "UFO sighting" was relatively recent. In June 1947, amateur pilot Kenneth Arnold was flying his plane around Mount Rainier in Washington in search of a crashed cargo plane, when he saw nine objects flying in formation at high speeds. According to Eghigian, Arnold suspected these were military aircraft that the public wasn't supposed to know about. He took this sighting to the local newspaper.

One reporter asked about how the aircraft moved, and Arnold described it as a saucer skipped across the water. This reporter turned that description into "flying saucer." The following summer, many more people reported sightings of flying saucers. In this way, the Arnold sighting kicked off modern UFO culture as we know it.

Aubeck agreed that this sighting "is widely regarded as the event that kick-started modern UFO culture."

Still, Eghigian said the public didn't immediately point to extraterrestrials in the mid-20th century. Instead, they suggested it was either the U.S. or Soviet military. This theme of paranoia and suspicion of other humans extends back to previous sightings. Eghigian said there were a number of dirigible sightings in England in 1912 and 1914, and civilians suspected the Germans.

Ultimately, understanding the history of UFO sightings helps us understand human storytelling. "Studying UFO sightings is valuable because they represent the urban legends of our time," Aubeck said. "They allow us to examine the interplay between human imagination and observation, helping us understand how cultural narratives shape our perceptions of unexplained phenomena."

We have only one example of biology forming in the universe — life on Earth. But what if life can form in other ways? How do you look for alien life when you don't know what alien life might look like?

These questions are preoccupying astrobiologists, who are scientists who look for life beyond Earth. Astrobiologists have attempted to come up with universal rules that govern the emergence of complex physical and biological systems both on Earth and beyond.

I'm an astronomer who has written extensively about astrobiology. Through my research, I've learned that the most abundant form of extraterrestrial life is likely to be microbial, since single cells can form more readily than large organisms. But just in case there's advanced alien life out there, I'm on the international advisory council for the group designing messages to send to those civilizations.

Detecting life beyond Earth

Since the first discovery of an exoplanet in 1995, over 5,000 exoplanets, or planets orbiting other stars, have been found.

Many of these exoplanets are small and rocky, like Earth, and in the habitable zones of their stars. The habitable zone is the range of distances between the surface of a planet and the star it orbits that would allow the planet to have liquid water, and thus support life as we on Earth know it.

The sample of exoplanets detected so far projects 300 million potential biological experiments in our galaxy — or 300 million places, including exoplanets and other bodies such as moons, with suitable conditions for biology to arise.

The uncertainty for researchers starts with the definition of life. It feels like defining life should be easy, since we know life when we see it, whether it's a flying bird or a microbe moving in a drop of water. But scientists don't agree on a definition, and some think a comprehensive definition might not be possible.

Related: 12 strange reasons humans haven't found alien life yet

NASA defines life as a "self-sustaining chemical reaction capable of Darwinian evolution." That means organisms with a complex chemical system that evolve by adapting to their environment. Darwinian evolution says that the survival of an organism depends on its fitness in its environment.

The evolution of life on Earth has progressed over billions of years from single-celled organisms to large animals and other species, including humans.

Exoplanets are remote and hundreds of millions of times fainter than their parent stars, so studying them is challenging. Astronomers can inspect the atmospheres and surfaces of Earth-like exoplanets using a method called spectroscopy to look for chemical signatures of life.

Spectroscopy might detect signatures of oxygen in a planet's atmosphere, which microbes called blue-green algae created by photosynthesis on Earth several billion years ago, or chlorophyll signatures, which indicate plant life.

NASA's definition of life leads to some important but unanswered questions. Is Darwinian evolution universal? What chemical reactions can lead to biology off Earth?

Evolution and complexity

All life on Earth, from a fungal spore to a blue whale, evolved from a microbial last common ancestor about 4 billion years ago.

The same chemical processes are seen in all living organisms on Earth, and those processes might be universal. They also may be radically different elsewhere.

In October 2024, a diverse group of scientists gathered to think outside the box on evolution. They wanted to step back and explore what sort of processes created order in the universe — biological or not — to figure out how to study the emergence of life totally unlike life on Earth.

Two researchers present argued that complex systems of chemicals or minerals, when in environments that allow some configurations to persist better than others, evolve to store larger amounts of information. As time goes by, the system will grow more diverse and complex, gaining the functions needed for survival, through a kind of natural selection.

They speculated that there might be a law to describe the evolution of a wide variety of physical systems. Biological evolution through natural selection would be just one example of this broader law.

In biology, information refers to the instructions stored in the sequence of nucleotides on a DNA molecule, which collectively make up an organism's genome and dictate what the organism looks like and how it functions.

If you define complexity in terms of information theory, natural selection will cause a genome to grow more complex as it stores more information about its environment.

Complexity might be useful in measuring the boundary between life and nonlife.

However, it's wrong to conclude that animals are more complex than microbes. Biological information increases with genome size, but evolutionary information density drops. Evolutionary information density is the fraction of functional genes within the genome, or the fraction of the total genetic material that expresses fitness for the environment.

Organisms that people think of as primitive, such as bacteria, have genomes with high information density and so appear better designed than the genomes of plants or animals.

A universal theory of life is still elusive. Such a theory would include the concepts of complexity and information storage, but it would not be tied to DNA or the particular kinds of cells we find in terrestrial biology.

Implications for the search for extraterrestrial life

Researchers have explored alternatives to terrestrial biochemistry. All known living organisms, from bacteria to humans, contain water, and it is a solvent that is essential for life on Earth. A solvent is a liquid medium that facilitates chemical reactions from which life could emerge. But life could potentially emerge from other solvents, too.

Astrobiologists Willam Bains and Sara Seager have explored thousands of molecules that might be associated with life. Plausible solvents include sulfuric acid, ammonia, liquid carbon dioxide and even liquid sulfur.

Alien life might not be based on carbon, which forms the backbone of all life's essential molecules — at least here on Earth. It might not even need a planet to survive.

Advanced forms of life on alien planets could be so strange that they're unrecognizable. As astrobiologists try to detect life off Earth, they'll need to be creative.

One strategy is to measure mineral signatures on the rocky surfaces of exoplanets, since mineral diversity tracks terrestrial biological evolution. As life evolved on Earth, it used and created minerals for exoskeletons and habitats. The hundred minerals present when life first formed have grown to about 5,000 today.

For example, zircons are simple silicate crystals that date back to the time before life started. A zircon found in Australia is the oldest known piece of Earth's crust. But other minerals, such as apatite, a complex calcium phosphate mineral, are created by biology. Apatite is a primary ingredient in bones, teeth and fish scales.

Another strategy to finding life unlike that on Earth is to detect evidence of a civilization, such as artificial lights, or the industrial pollutant nitrogen dioxide in the atmosphere. These are examples of tracers of intelligent life called technosignatures.

It's unclear how and when a first detection of life beyond Earth will happen. It might be within the solar system, or by sniffing exoplanet atmospheres, or by detecting artificial radio signals from a distant civilization.

The search is a twisting road, not a straightforward path. And that's for life as we know it — for life as we don't know it, all bets are off.

This edited article is republished from The Conversation under a Creative Commons license. Read the original article.

One night about 60 years ago, physicist Enrico Fermi looked up into the sky and asked, "Where is everybody?"

He was talking about aliens.

Today, scientists know that there are millions, perhaps billions of planets in the universe that could sustain life. So, in the long history of everything, why hasn't any of this life made it far enough into space to shake hands (or claws … or tentacles) with humans? It could be that the universe is just too big to traverse.

It could be that the aliens are deliberately ignoring us. It could even be that every growing civilization is irrevocably doomed to destroy itself (something to look forward to, fellow Earthlings).

Or, it could be something much, much weirder. Like what, you ask? Here are 12 unusual answers that scientists have proposed for the Fermi paradox.

Related: 'It's hard not to believe he saw something': Historian Greg Eghigian on how UFOs took over the world

We're looking in the wrong universe

Maybe we haven't found aliens because our universe isn't particularly conducive to life. Maybe Earth is an anomaly — a lucky blue dot adrift in a vast ocean of darkness and dead worlds. Maybe we'd have better luck looking for life in the next universe over.

That last idea is the premise of a 2024 study that assumes our cosmos is just one possible universe within an endless "multiverse" of realities, each one slightly different from the rest. To test whether our universe has the optimal conditions for life to emerge, the researchers compared star formation rates here to star formation rates in a host of hypothetical, parallel universes with different concentrations of matter and energy.

The main factor the team considered was a universe's density of dark energy — a mysterious force that drives the constant, accelerating expansion of the cosmos. A universe with too much dark energy would expand too quickly, scattering star-forming material and stunting the growth of large-scale structures like galaxy clusters. But in a universe with too little dark energy, gravity might become overwhelming, causing large structures to collapse before habitable planets had the chance to form.

The team's models revealed that the optimal density of dark energy within a universe would enable up to 27% of ordinary matter to turn into stars. But in our universe, only an estimated 23% of matter turns into stars — meaning there are fewer stars here than there could be and, as a result, fewer places for alien life to emerge. Better luck in the next universe!

Aliens don't live on planets

Every alien species needs a habitable planet to live on, right? Surprisingly, a 2024 study argues that may not always be the case.

In a paper accepted for publication in the journal Astrobiology, researchers proposed a scenario in which an alien colony could survive by floating freely in space, no planet required. It may sound wild, but it's not without real-world precedent; humans, for example, can live for hundreds of days without a planet while residing on the International Space Station (albeit with constant deliveries of crucial resources from their planet), and hardy tardigrades can survive the vacuum of space.

A theoretical planet-free alien colony would have to overcome many challenges, including a lack of resources, exposure to cosmic radiation and the vacuum of space, and access to enough sunlight. With this in mind, the researchers paint the picture of a species that could survive these trials: a free-floating colony of organisms measuring up to 330 feet (100 meters) across, encased in a thin, hard, transparent shell that could maintain a livable temperature and pressure through the greenhouse effect.

Finding such a species is a long shot, but it's not impossible. A free-floating alien colony could also explain why no intelligent aliens are answering our calls: They don't have a landline to use.

The aliens are hiding in underground oceans

If humans hope to converse with ET, we'll need to have a few icebreakers handy. No, seriously — alien life is probably trapped in secret oceans buried deep inside frozen planets.

Subsurface oceans of liquid water slosh beneath multiple moons in our solar system and may be common throughout the Milky Way, astronomers say. NASA physicist Alan Stern thinks clandestine water worlds like these could provide a perfect stage for evolving life, even if inhospitable surface conditions plague those plants. "Impacts and solar flares, and nearby supernovae, and what orbit you're in, and whether you have a magnetosphere, and whether there's a poisonous atmosphere — none of those things matter" for life that's underground, Stern told Space.com.

That's great for the aliens, but it also means we'll never be able to detect them just by glancing at their planets with a telescope. Can we expect them to contact us? Heck, Stern said — these critters live so deep, we can't even expect them to know that there's a sky over their heads.

Fortunately, NASA's Europa Clipper spacecraft is on the way to one such moon to look for evidence of life up-close. The Clipper will arrive at Jupiter's frozen moon Europa in 2030.

The aliens are imprisoned on "super-Earths"

No, "super-Earth" is not Captain Planet's dorky cousin. In astronomy, the term refers to a type of planet with a mass up to 10 times greater than Earth's. Star surveys have turned up oodles of these worlds that could have the right conditions for liquid water. This means alien life could conceivably be evolving on super-Earths all over the universe.

Unfortunately, we'll probably never meet these aliens. According to a study published in 2018, a planet with 10 times Earth's mass would also have an escape velocity 2.4 times greater than Earth's — and overcoming that pull could make rocket launches and space travel near impossible.

"On more-massive planets, spaceflight would be exponentially more expensive," study author Michael Hippke, a researcher affiliated with the Sonneberg Observatory in Germany, previously told Live Science. "Instead, [those aliens] would be to some extent arrested on their home planet."

We're looking in the wrong places (because all aliens are robots)

Humans invented the radio around 1900, built the first computer in 1945 and are now in the business of mass-producing handheld devices capable of making billions of calculations per second. Full-blown artificial intelligence may be right around the corner, and futurist Seth Shostak said that's reason enough to reframe our search for intelligent aliens. Simply put, we should be looking for machines, not little green men.

"Any [alien] society that invents radio, so we can hear them, within a few centuries, they've invented their successors," Shostak said at the Dent:Space conference in San Francisco in 2016. "And I think that's important, because the successors are machines."

A truly advanced alien society may be completely populated by super-intelligent robots, Shostak said, and that should inform our search for aliens. Instead of focusing all our resources on finding other habitable planets, perhaps we should also look to places that would be more attractive to machines — say, places with lots of energy, like the centers of galaxies. "We're looking for analogues of ourselves," Shostak said, "but I don't know that that's the majority of the intelligence in the universe."

We've already found aliens (but are too distracted to realize it)

Thanks to pop culture, the word "alien" probably makes you envision a spooky humanoid with a big, bald head. That's fine for Hollywood — but these preconceived images of E.T. could sabotage our search for alien life, a team of psychologists from Spain wrote earlier this year.

In a small study, the researchers asked 137 people to look at pictures of other planets and scan the images for signs of alien structures. Hidden among several of these images was a tiny man in a gorilla suit. As the participants hunted for what they imagined alien life to look like, only about 30% noticed the gorilla man.

In reality, aliens probably won't look anything like apes; they may not even be detectable by light and sound waves, the researchers wrote. So, what does this study show us? Basically, our own imagination and attention span limit our search for extraterrestrialsy. If we don't learn to broaden our frames of reference, we could miss the gorilla staring us in the face.

Humans will kill all the aliens (or already have)

The closer we get to finding aliens, the closer we get to destroying them. That's one likely eventuality, anyway, said theoretical physicist Alexander Berezin.

Here's his thinking: Any civilization capable of exploring beyond its own solar system must be on a path of unrestricted growth and expansion. And as we know on Earth, that expansion often comes at the expense of smaller, in-the-way organisms. Berezin said this me-first mentality probably wouldn't end when alien life is finally encountered — assuming we even notice it.

"What if the first life that reaches interstellar-travel capability necessarily eradicates all competition to fuel its own expansion?" Berezin wrote in a paper posted in 2018 to the preprint journal arXiv.org. "I am not suggesting that a highly developed civilization would consciously wipe out other life-forms. Most likely, they simply won't notice, the same way a construction crew demolishes an anthill to build real estate because they lack incentive to protect it." (Whether humans are the ants or the bulldozers in this scenario remains to be seen.)

The aliens triggered climate change (and died)

When a population burns through resources faster than its planet can provide them, catastrophe looms. We know this well enough from the ongoing climate-change crisis here on Earth. So, isn't it possible that an advanced, energy-guzzling alien society might run into the same issues?

According to astrophysicist Adam Frank, it's not only possible but extremely likely. Earlier this year, Frank ran a series of mathematical models to simulate how a hypothetical alien civilization might rise and fall as it increasingly converted its planet's resources into energy. The bad news is that in three out of four scenarios, the society crumbled and most of the population died. Only when the society caught the problem early and immediately switched to sustainable energy did the civilization manage to survive. That means that, if aliens do exist, the odds are pretty high they'll destroy themselves before we ever meet them.

"Across cosmic space and time, you're going to have winners — who managed to see what was going on and figure out a path through it — and losers, who just couldn't get their act together, and their civilization fell by the wayside," Frank said. "The question is, which category do we want to be in?"

Aliens used clean energy, but still triggered climate change (and died)

A sufficiently advanced alien species will inevitably heat up its planet as its society and its energy needs grow. This could trigger runaway climate change, as humans are doing on Earth, and may doom those aliens to an early extinction. But what if the fast-growing alien society made an early switch to eco-friendly, renewable energy? Could that spare them, allowing the aliens to grow, thrive and expand throughout the cosmos without consequence?

Sorry, but no, according to a bleak theoretical study published to the preprint database arXiv in September 2024. The study found that an exponentially growing alien species using 100% renewable energy would still heat up their planet with waste heat, which is inevitably produced from any energy expenditure according to the second law of thermodynamics. This waste heat would continue to build up as long as the society's energy demands grew, eventually triggering disastrous climate change within 1,000 years of that society's industrial revolution.

If true, this means that an energy-guzzling alien race would likely never survive long enough to venture deep into the cosmos and set up shop on nearby planets. It's not only a sad outlook for aliens but an urgent wake-up call for Earth.

The aliens couldn't evolve fast enough (and died)

File another excuse under "the aliens are dead already" category. The universe may be teeming with hospitable planets, but there's no guarantee they'll stay that way long enough for life to evolve. According to a 2016 study from Australia National University, wet, rocky planets like Earth very unstable when they start their careers; if any alien life hopes to evolve and thrive on such a world, it has a very limited window (a few hundred million years) to get the ball rolling.

"Between the early heat pulses, freezing, volatile content variation and runaway [greenhouse gases], maintaining life on an initially wet, rocky planet in the habitable zone may be like trying to ride a wild bull — most life falls off," the study authors wrote. "Life may be rare in the universe not because it is difficult to get started, but because habitable environments are difficult to maintain during the first billion years.

Dark energy is splitting us apart

As we've already established, the universe is expanding. Slowly but surely, galaxies are moving farther apart, with distant stars appearing dimmer to us, all thanks to the pull of the mysterious, invisible substance that scientist call dark energy. Scientists speculate that within a few trillion years, dark energy will stretch the universe so much that Earthlings will no longer be able to see the light of any galaxies beyond our closest cosmic neighbors. That's a scary thought: If we don't explore as much of the universe as possible before then, such investigations may be lost to us forever.

"The stars become not only unobservable, but entirely inaccessible," Dan Hooper, an astrophysicist at the Fermi National Accelerator Laboratory in Illinois, wrote in a study earlier this year. That means we're on a serious deadline to find and meet any aliens out there — and to keep a step ahead of dark energy, we'll have to expand our civilization into as many galaxies as we can before they all drift away.

Of course, fueling that kind of growth won't be easy, Hooper said. It might involve rearranging the stars.

Twist ending: We ARE the aliens

If you left your house today, you saw an alien. The woman delivering mail? Alien. Your next-door neighbor? Nosy alien. Your parents and siblings? Aliens, aliens, aliens.

At least, that's one implication of the fringe astrobiology theory called the "panspermia hypothesis." In a nutshell, the hypothesis says that much of the life we see on Earth today didn't originate here but was "seeded" here millions of years ago by meteors carrying bacteria from other worlds.

Proponents of this theory have variously suggested that octopi, tardigrades and humans were seeded here from other parts of the galaxy — but unfortunately, there's no real evidence to back up any of that. One big counterargument: If bacteria carrying human DNA evolved on another nearby planet, why haven't we found traces of humanity anywhere besides Earth? Even if this hypothesis turns out to be plausible, it still doesn't help us answer Fermi's nagging question … Where is everybody?

Editor's note: This article was originally published in July, 2018. It was updated on Dec. 2, 2024 with new studies and information.

Strange lights in the sky, little green men and crashed vessels secreted away to government labs — the relatively modern history of UFOs is replete with conspiracy theories and allegations of coverups.

But beyond the endless arguments between believers and debunkers over what could be behind the phenomena, the fact remains that many people have looked into the sky and reported seeing things they cannot explain. So what do UFO reports tell us about ourselves?

To discuss UFO sightings, how and why they first emerged, and the ways they tie into the cultural and political trends of the past and present, Live Science spoke with Greg Eghigian, a professor of history and bioethics at Penn State University, whose new book, "After The Flying Saucers Came" (Oxford University press, 2024), is one of the first social histories of UFOs, or unidentified anomalous phenomena (UAP). Here's what he had to say.

Ben Turner: A lot of people assume UFOs entered public consciousness with the Roswell incident. But your book says otherwise. When did it all begin?

Greg Eghigian: I think when we look at this as a social phenomenon — not just simply someone saw something strange in the sky, but that the object was made by somebody, and that one of the probable scenarios is they were extraterrestrials — we can mark the moment that starts to evolve in June 24, 1947.

The private pilot Kenneth Arnold sees these objects [that day] over Washington state when he's flying his plane. He lands and reports it to the military and to journalists. When asked how they flew, he answered that these things flew kind of like saucers skipping across the water. Then, within a day or two, a journalist comes up with this great headline: "Flying saucers."

Once we had flying saucers, everything else fell into place.

BT: But then Roswell happened just a few weeks later. How did a fairly small city in New Mexico become famous all over the world for UFOs, while Arnold's name remains relatively unknown?

GE: Here's the thing about Roswell that a lot of people don't realize. The story that came out of Roswell is that some material had been retrieved around an Air Force base there that they believe could be from a crashed flying saucer.

Within a day, the Air Force rolls that back, saying that it's not the case, the people who first found it were mistaken. The reality is that the people who were on the ground and found this stuff were not terribly qualified to talk about it.

They didn't understand what they had, literally, in their hands, and the people who usually dealt with the material were actually off at a conference. When they did finally get a chance to look at it, they said, "Oh this is pretty mundane stuff," and they corrected themselves.

So the Roswell thing gets a lot of air play, a lot of global news coverage for about 24 to 48 hours, and then it disappears. It's not really ever talked about, and leaves very little imprint on the UFO world for decades.

It's then only in the late 1970s that some ufologists (and this is a very common thing in the UFO world) go back over the records, dig deeper into the story and believe that they found all these contradictions in it. That's when Roswell became a focal point.

BT: Looking at the period of history where all of this kicked off, we have growing Cold War rivalry, the new existential threat of nuclear weapons, McCarthyism, fear of communism and Soviet Russia. It seems like a time that's ripe for paranoia and conspiracism. How much is all of the UFO stuff tied into that?

GE: Oh, it's very tied in. I make the point in the book that I don't think the UFO phenomenon as we know it would exist without the Cold War. There are a variety of reasons for that, but one of the often forgotten aspects of this is World War II.

WWII and the Cold War bring a number of critical things to the table for how UFO stories were built. Firstly, you have big governments — big governments and big militaries. You look at the United States federal government in 1900 and it's not a big thing, it's not this monstrosity. By 1945, the U.S. government was a large bureaucracy with a big military.

Secondly, what WWII taught everybody was that this institution can have secret programs that build remarkable technology, like the atomic bomb, as well as new kinds of airplanes such as jets. And of course, both conflicts also have a lot of spying.

So when the UFO phenomenon emerges, the initial thought of just about everybody is that it has to be one of these superpowers. This has to be somebody doing surveillance.

That's also a lot of the ways it's still spoken about today: Who's doing this? Who's keeping it a secret? What are their intentions? And could it harm us? So it's very much a part of it, and it haunts the story of UFOs for decades.

BT: There are also interesting preludes to the Kenneth Arnold moment in 1947. One thing that flashes to mind is Orson Welles' 1938 radio broadcast of the "War of The Worlds," which caused a mass panic that aliens were actually invading. Why did flying saucers take off in 1947 and not earlier?

GE: I think the game changer is the atomic bomb. That something could be invented that we had no idea about, that is just presented to the world, and has this enormous destructive power that could wipe out all of humanity almost in an instant.

When you ask why now, some people will respond that alien visitors have always been here and we're just noticing them now. But the argument that's usually presented is that it's probably because they [the aliens] saw us explode atomic bombs. This makes us capable of being conversed with, or a possible threat down the road.

BT: There's an appeal to a higher power in it too, right? In a time when religion is falling by the wayside, after all the horrors of the past century, people were looking for something that could save us from ourselves.

GE: There are certainly people who believe exactly that. The figure who lays all of this out is the psychologist Carl Jung. In the late 1950s, he wrote one of the first, and still one of the best, scholarly books on the topic.

It makes this argument that, real or not, what they [UFOs] represent to people is this idea of salvation from something, at least that's the hope. By the early 1950s you see the beginning of UFO religious communities, almost all of them tied to the New Age Movement.

BT: Everything you've said so far makes this seem like a firmly mid-20th century American phenomenon. I confess to having been partial to the History Channel's "Ancient Aliens" back in the day. Do sightings stretch across cultures and into the past, as they claimed? Or is that a post-hoc narrative?

GE: This is a question that people debate pretty vigorously. There's no question that people reported seeing strange things in the sky dating back to ancient times. The most famous example is probably meteorites. For a long time the idea that rocks could fall from the sky seemed patently absurd, until people found out the reason is because there are a lot of rocks in space.

The problem with going backward in time and retrospectively looking at stuff and saying: "Aha! Here's another example of a UFO," is that it's deeply, deeply problematic from a historical standpoint.

Most of the time it involves an unintentional, and sometimes outright deliberate misreading of documents, artifacts or paintings. I've seen very good art historians, for instance, talk about paintings and say: "Oh my gosh, these things are clearly flying saucers!" When the objects they're referring to are objects in a particular religious ritual, or serve as a very symbolic trope. So it's very, very difficult to do that stuff [accurately].

BT: This touches on the methodology in your book. You take an agnostic approach: You don't take reports at face value, but neither do you dismiss them out of hand. How does one go about impartially assessing a UFO report? That's going to seem like a weird concept to people.

GE: Yeah it is strange to people, and I know a lot of people who still don't like that I do that.

For me, as a historian, it's partly the idea that I don't feel qualified to adjudicate some of these matters. I think some of these things have to be done by a meteorologist, a physicist, an astronomer or an engineer — someone who is far better qualified than I am to say what's possible and what's anomalous.

But the other part is that this is the way I get to the things that most interest me, which are human beings. I say in the introduction of the book that UFOs don't make history, people make UFOs make history. That really is the main point; it's that I'm interested in the human part of that history.

As far as we know today, UFOs don't have a natural history, they have a human history. Everything about them is related to our perception of them, our speculations and our discussions about them. The social fact of the UFO is very real, and it needs to be chronicled now. Whether these things also have a natural history I'm going to leave up to the researchers who do that stuff for a living.

BT: When you work through these reports, I'm sure some of them on their surface are obviously bogus. But others come from people, pilots for instance, who have no interest in UFOs and are speaking out at significant personal and professional cost. Have you come across any real headscratchers?

GE: Yeah a lot of them can be, or at least certain elements of them.

Back in the 1950s, there was one case that the U.S. Air Force looked into that really set them back on their heels. These two seasoned civilian pilots for Eastern Airlines, reasonable fellows, who saw this very strange object during a flight, they could even make out details from it and it was like nothing they'd seen before.

That's eerie and strange. They didn't have any explanation for it and certainly had no call to make it up — they weren't seeking fame and that wasn't a time you could make any money off this stuff.

Then there's the case of Lonnie Zamora in the 1960s, he was a police officer in the American Southwest who stopped his vehicle because he thought he saw a crashed car. He sees this strange object with people in a kind of white uniform working around it. Then they flit off in it.

By everybody's assessment at the time, he was a mild mannered guy, very cool headed and with absolutely no interest in publicity. He comes across as very sheepish in the radio interviews. That's another case where you sit there and think it's hard not to believe he saw something. Then you try to come up with explanations for what the possibilities could be.

BT: How do the reports evolve over time? Do they change as the culture surrounding them comes into sharper focus?

GE: Some things don't change that much. The overwhelming number of them are seeing patterns of lights, orbs or spheres of some kind that move in a strange way then whoosh away with no sound. That remains relatively unchanged from the beginning. But people also see cigar shaped things or triangles. A lot of these things are common across the world.

What has changed more dramatically over the years and over different areas, has been the description of the occupants of these vessels, the aliens themselves. Early on in the 1950s and 1960s, a very common thing would have been to talk about seeing what appeared to be robots — looking like the Tin Man from the "Wizard of Oz." We don't tend to see robots anymore.

Another very common thing during the 1950s and 1960s were what were dubbed, "little men." They weren't really described as green but little and usually gendered male for some reason. They typically stood at about 4 feet [1.2 meters], and in places like Malaysia, they were under 6 inches [15 centimeters] tall. Another very common thing in their descriptions was they were wearing old divers suits.

Then you get to the 1970s and 1980s, and there's a veritable zoo of creatures: things that look like insects; in South America and [in] the Soviet Union big hairy creatures that look like a Bigfoot or a Sasquatch are particularly common.

The one we have come to know as "the gray" is not all that common until the publication of Whitley Strieber's "Communion" book in 1987, from that point the idea of what an alien looks like really crystallized.

BT: That's got to be one of the things debunkers point to: the fact that the culture is shaping what people see makes it easier to call it a mass delusion.

GE: Yeah, the debunkers look at it and do that. What debunkers would like to do is to get even more concrete than that and say why somebody would see something at a particular time. They say there was a television show two weeks before someone's sighting. Then the person comes back and says I never watched it, and they go back and forth.

I firmly believe that the media of all sorts plays a formative role shaping the way people think, talk about and even see things. But from my standpoint, this is where I might deviate from the debunkers. I don't think that simply explains things away. It just means that people are human beings, they are doing what we always do.

When something happens to us that is really bizarre or unexplainable, it's not a surprise that what we tend to do is turn to analogies and to metaphors. It helps us to say, "Well, this was a little like this."

BT: These debates persist up to the present day, but things have changed a lot too. We're sitting at the tail end of our own UFO — or should I say UAP — wave. And this time, after U.S. Navy footage of mysterious flying objects was released in 2017, we've seen a very different reaction from officials. There have been Senate hearings, task forces set up, and NASA has even been roped in. What happened? Is it because everyone in the U.S. government now also grew up on UFO lore?

GE: A number of things have changed that have led to this becoming something seen as legitimate to ask questions about, and considered, even in academic circles, to be respectable to discuss. One thing is the reality of new surveillance and sensors to detect surveillance. In the United States, China and Russia there is an awareness of those technologies and, of course, a Keeping up with the Joneses attitude about them.

The proliferation of drones is one thing. Drones are everywhere now. I was speaking to a Swedish ufologist a few years ago and he said that the number of sightings that involve drones has skyrocketed.

On the extraterrestrial dimension, since the late 1990s astronomers have found out that exoplanets are pretty ubiquitous. That introduces the idea that planets are really all over the place, and that habitable planets are really pretty likely. I think that's made it easier to conceive of these things as possible. I've heard debunkers say they believe it's probable that there are extraterrestrial civilizations out there, they just don't think they're visiting us.

You also have people who are actively involved in lobbying people to take this seriously. There's Robert Bigelow, the billionaire, who's funneled a lot of money into this cause. Lobbyists now have the ear of certain politicians in America who see this as a valuable issue to them in some ways.

I think you have to always be a little cynical about politicians — they tend to be very pragmatic, and the fact that they come to this subject doesn't necessarily mean they're interested in UFOs, but in other things they can achieve.

BT: What are politicians trying to achieve by embracing it?

GE: I could conceive of them using this as a way to say they're going to keep money away from the military because they're not being honest brokers about this.

The number one thing I keep hearing over and over again, from people on these committees and those who are maybe less interested, is spending and classification. U.S. military secrecy has been a big priority since at least WWII, certainly since the Manhattan Project, and it's only increased over the years. Then 9/11 really doubled, tripled down on that.

This makes the UFO/UAP thing a great example for all these folks to say, "We've got all these whistleblowers saying all this stuff is going on. We haven't heard anything about it. You're keeping this from us. It's all supposedly classified. So we want in."

BT: One of the frustrating things about covering these questions is that you get task forces that are essentially military task forces. People come out to say all kinds of spooky stuff, and when they're probed further they say we'll tell you the rest behind closed doors, and no we won't allow scientists into the bases where we saw this. Now that NASA's involved, do you have more faith for civilian science projects to get to the bottom of things?

GE: Yeah, spot on. I agree with you completely. It's why I always tell people that, personally, I don't think these military intelligence branches will be key to addressing these questions. I don't think you're ever going to get it from them. I'm also not someone who believes in full transparency, sometimes it's important to keep secrets.

NASA's endorsement of research in this area is unprecedented, and I think it's very welcome. I know a lot of scientists who have started to try to conduct research along these lines. The problem we have is it has not translated into funding yet. A lot of the current efforts are on shoestring budgets and it's unclear whether that money is ever going to be forthcoming. So far, at least in the United States, it has not been.

But there is a hope among a lot of researchers that that will change, because the climate has changed. Civilian scientists and researchers are going to be the key, because we operate in a world of transparency, with an openness that contractors and government don't have.

BT: Do you think we'll ever get a solid answer?

GE: I suspect we will be revisiting and speculating over this for a good long time to come. The world's been at this for over 75 years, and the most seasoned ufology veterans will tell you that not a lot has changed.

If there is an opportunity for serious, empirically driven researchers to get involved, maybe then we'll actually start to see some real progress.

But until that time, it seems to me we're still stuck in a cycle where we largely rely on hearsay and references to evidence that never turns up. Or, as you say, people saying I've got some information, but I can only tell you behind closed doors.

That just leaves us with the mystery, which I know some people are satisfied with.

Editors note: This interview has been condensed and edited for clarity.

An advanced alien civilization may want to cruise around the galaxy, and the best way to do that is by steering their binary star system, a researcher proposes in a new paper.

Long-lived civilizations may have many motivations for wanting to move somewhere else in the galaxy. They may need to escape an impending supernova, for example. Maybe they need to scout our new natural resources. Or maybe they just feel like exploring.

Given the enormous distances between the stars, however, interstellar travel is tremendously difficult and time-consuming. So, instead of leaving their system, an intrepid alien species might decide to take their system with them. The main advantage of accelerating their own star would be that they get to keep it with them as they travel. They would do this by causing their star to either radiate or evaporate in just one direction, which would propel the star, along with all of its planets, to a new location in the galaxy.

Astronomers have investigated whether "hypervelocity" stars (which, as their name suggests, are stars with an extraordinarily high velocity) may have been purposefully launched by alien civilizations, but the known candidates show no signs of artificial interference.

Related: Father-daughter team decodes 'alien signal' from Mars that stumped the world for a year

In a recent paper, Clement Vidal, a philosopher at the Vrije University Brussels in Belgium, pointed out that most stars are not solitary but rather belong to binary systems. This means we might be missing half of the potential artificially accelerated stars. Even better, binary systems offer many advantages over their solo counterparts, Vidal wrote in his paper, which has not been peer-reviewed or published in a scientific journal.

Vidal took a model system consisting of a neutron star with a low-mass star tightly orbiting it. This setup provides the most flexibility in steerability and thrust.

The alien civilization would have to figure out a way to eject material from the star. This could be from asymmetric magnetic fields or from some device that causes uneven heating on the stellar surface. No matter what, the goal would be to get the star to eject more material in one direction than another. This would create thrust, pushing the binary system in the opposite direction, Vidal explained.

If the civilization were to place the machinery on or near the neutron star, where the strong gravity could provide a ready source of energy, they could steer the binary system by carefully cycling the machine off and on. For example, if they activated the machine only at the exact same point in the orbit, they would send the binary system in one direction. If they left the machine activated slightly longer, they would adjust their course, pointing their movement in any direction they wished along the orbital plane.

They could even steer their system in new off-orbit directions by altering the direction in which their machine was pointed, effectively changing the orbit of the neutron star around its companion.

Amazingly, there are real systems in the universe that match these kinds of characteristics, like the "black widow" pulsar PSR J0610-2100 and the "redback" pulsar PSR J2043+1711. Both of those systems have significant accelerations. Although they are unlikely to be caused by alien engineering, they are worth looking into, Vidal concludes. At least, while they're still around.

UFOs came to Washington again last week.

The U.S. House of Representatives' Committee on Oversight and Accountability held a hearing titled "Unidentified Anomalous Phenomena: Exposing the Truth" at the Rayburn House Office Building in Washington, D.C. at 11:30 a.m. EST (1530 GMT) on Wednesday, Nov. 13. Unidentified anomalous phenomena (UAP) is a relatively new catch-all term that includes sightings of unexplained objects or events that take place in the air, underwater, in space, or that travel between those domains.

Like previous congressional UFO hearings, the event featured testimony from current U.S. military personnel who claim the American government has for decades hidden evidence of advanced technologies and otherworldly visitors from the public. A multitude of anecdotes were presented about flying orbs coming out of the ocean, disc-shaped objects, and craft "exhibiting flight and structural characteristics unlike anything in our arsenal." While such claims are nothing new, what is noteworthy about the hearing are the pedigrees of some of the whistleblowers who testified, including a former U.S. counterintelligence officer, a retired U.S. Navy rear admiral and a former NASA associate administrator. All of them stressed the need for more government transparency, less stigma about the UFO topic and new policies to bring UAP data out of the "black" classified world and into the public domain.

This isn't the U.S. government's first attempt to investigate the recent wave of UFO claims that began in 2017. A similar hearing was held last year, in which a whistleblower told Congress the U.S. government is hiding evidence of 'non-human intelligence.'

The Pentagon also created the All-Doman Anomaly Resolution Office (AARO) in 2022 to investigate UAP reports and government data about UFOs, but critics, including some government officials, are skeptical of the office's aims and methods.

Related: SETI searches for alien life in over 1,000 galaxies using unexplored radio frequencies

"AARO is unable, or perhaps unwilling, to bring forward the truth about the government's activities concerning UAPs," Representative Nancy Mace (R-South Carolina) said during the hearing's opening remarks. "I'm disturbed that AARO itself lacks transparency; even its budget is kept from the public. So if there is no 'there' there, then why are we spending money on it? And by how much? Why the secrecy?"

Other representatives stressed the need for transparency and data analysis, a common theme of other recent UAP studies. "We have evidence that what we are detecting things, and we know that we don't understand them, and this is worth investigating," Rep. Robert Garcia (D-CA) said. "I believe we can always be more transparent. To me, this hearing and others are simply about the truth and getting to the facts of what these UAPs actually are."

Luis Elizondo, a former U.S. counterintelligence officer who has been vocal about such claims in recent years, told the assembled representatives at the hearing that "excessive secrecy has led to grave misdeeds against loyal civil servants, military personnel and the public — all to hide the fact that we are not alone in the cosmos."

We are "in the midst of a multi-decade, secretive arms race  — one funded by misallocated taxpayer dollars and hidden from our elected representatives and oversight bodies," Elizondo stated during his testimony.

Elizondo, who claims to have previously investigated UFOs as part of a secret Pentagon program, suggested that the U.S. government create a "whole-of-government" approach to studying UAP, create a national UAP strategy and offer protections so that whistleblowers who are "desperate to do the right thing can come forward without fear."

During questioning, Elizondo was asked if some of the "advanced technologies" that have been seen monitoring sensitive military installations around the globe could be operated by aliens or private companies. "Maybe both," Elizondo replied.

Elizondo also stated point-blank to Rep. Mace's questioning that the U.S. government has programs to retrieve crashed UAP and reverse-engineer them, but avoided giving any specifics in an unclassified public setting such as the hearing.

Rep. Jared Moskowitz (D-FL) then questioned Elizondo, asking the former counterintelligence agent about a document he signed that limits him from speaking publicly about crash retrieval programs. "The document said you can't talk about crash retrieval. Well, you know, you can't talk about Fight Club if there's no Fight Club, correct?"

Like other witnesses, Elizondo stated that the alleged excessive government secrecy around UFOs harms national security. In response to questioning from Rep. Tim Burchett (R-TN), Elizondo stated that, if UAP sightings turned out to be technologies operated by adversarial nations, it would be "an intelligence failure eclipsing 9/11 in order of magnitude."

Retired U.S. Navy rear admiral Tim Gallaudet offered similar testimony as Elizondo. "We know from last year's UAP hearing and recent statements and publications by credible whistleblowers that UAP, NHI [non-human intelligence], and their technology of unknown origin (TUO) represent a new realization that we are not the only advanced intelligence in the universe," Gallaudet said on Wednesday, according to his published remarks.

"Unelected officials in the U.S. government do not have an exclusive right to this knowledge about the nature of reality. The American people have a right to that knowledge," Gallaudet said. The retired rear admiral also stressed the national security and airspace safety concerns related with UAP sightings, calling them "extensive."

When Rep. Garcia asked Gallaudet and other witnesses what UAP might represent, the retired rear admiral said he believes they are evidence of a "non-human higher intelligence."

Former NASA Associate Administrator for Space Policy and Partnerships Michael Gold also testified at the hearing, and previously served on NASA's UAP study team. Gold's testimony was more grounded; for example, he stressed the need for NASA to contribute its authority and expertise toward analyzing what UAP data it might already possess and helping dispel the stigma associated with the UFO topic.

"Our best tool for unlocking the mystery of UAP is science, but we cannot conduct a proper inquiry if the stigma is so overwhelming that just daring to be part of a NASA search team elicits such a vitriolic response," Gold said during the hearing. "Therefore, one of the most important actions that can be taken, relative to exposing the truth of UAP, is to combat the stigma, and this is where I believe that NASA can be eminently helpful."

Gold added that NASA has a massive archive of data that could possibly contain evidence of UAP, and suggested that artificial intelligence/machine learning algorithms could help sort through the agency's trove of data to help shine light on the UFO phenomenon. In addition, the former NASA associate administrator said the agency should develop specialized instruments that might be able to gather useful data about UAP.

Journalist Michael Shellenberger also testified, telling the representatives that there's a "growing body of evidence that the government is not being transparent about what it knows about unidentified anomalous phenomena (UAP), formerly called UFOs, and that elements within the military and IC [intelligence community] are in violation of their Constitutional duty to notify Congress of their operations."

Shellenberger stated that there is a secret program within the U.S. government known as "Immaculate Constellation" whose sole purpose is to collect UFO and UAP reports from military personnel and sensor data and quarantine them away from the rest of the government and military. While he noted that a Pentagon spokesperson has stated no such program exists, Shellenberger recounted prior examples in which the Department of Defense has initially denied knowledge of UAP-related information only to later change its stance and either admit the information exists or release it to the public.

"The U.S. government appears to know significantly more about UAPs than it is revealing," Shellenberger said at the hearing. "But even those who believe the U.S. government has revealed all that it knows should have no objection to Congressional demands for greater transparency."

To conclude the meeting, Rep. Mace asked each of the witnesses to define what non-human biologics or non-human intelligence mean to each of them.

"I don't think it's a stretch, when you look at the diversity of life on this planet and the size of this universe, to think that there will be more diverse, higher-order, non-human intelligence throughout the universe, and that's probably what's visiting us," Gallaudet said.

Elizondo stated he would take a scientific approach: "The definition would be the ability to react to a stimulus in a manner that requires an intellectual thought process."

Gold, meanwhile, questioned whether non-human intelligence necessarily implies life, suggesting sophisticated artificial intelligence might be responsible for some UAP encounters. Shellenberger simply stated he did not know what they might be.

In the hearing, as in other UFO hearings, there was a lot of telling and not a lot of showing. One of the core tenets of these whistleblower testimonies is that much of the credible UFO data is classified and can't be revealed to the public based on the military capabilities that some of that data could reveal.

Whistleblowers have attested for years that, because advanced or classified sensors and satellites sometimes capture footage or photos of unexplained phenomena or advanced craft, those photos or videos are likewise classified by the U.S. government in order to not reveal America's full surveillance or sensing capabilities.

Such was the case in 2023 when U.S. military aircraft shot down a mysterious object off the coast of Alaska. The American government has yet to release any imagery from the event, but a Canadian freedom of information request unveiled a photograph earlier this year of a balloon-like object.

Those incidents and others like it, such as a weeks-long drone incursion above Langley Air Force Base in Washington, D.C., were discussed in the hearing. "The origin of these drones and their operators remains a mystery," Rep. Glenn Grothman (R-Wis.) said. "This incident and other sightings near sensitive military installations highlights the complexity of the UAP challenge facing our intelligence, defense and homeland security committees."

Originally posted on Space.com.

Scientists have just come up with another potential explanation for why we have never found signs of extraterrestrial life in the cosmos — we may be living in the wrong universe.

A new theoretical model based on the famous Drake equation suggests that alien life is more likely to emerge in specific parallel universes that could potentially exist alongside ours in a never-ending multiverse. If this is the case, it means we do not live in the "optimal universe" for detecting extraterrestrial civilizations.

The Drake equation was a theoretical formula written by American astrophysicist Frank Drake in 1961 to help tackle the dichotomy between the high probability that extraterrestrial intelligence exists and the fact that we have no evidence for such aliens — a problem known as the Fermi Paradox. The Drake equation estimates the chances of detecting extraterrestrial life in the Milky Way. It primarily hinges on the number of stars in our galaxy, because aliens would likely need a star to spawn an exoplanet they could call home and provide the energy needed to spark their emergence and evolution, despite some theories to the contrary.

But in a new study, published Wednesday (Nov. 13) in the journal Monthly Notices of the Royal Astronomical Society, researchers took this idea and extrapolated it on a multiversal scale by calculating how differences in the density of dark energy — the mysterious force driving the expansion of the universe — may affect how many stars can form in different parallel universes.

The model revealed that the optimal density of dark energy in a universe would enable up to 27% of non-dark matter to turn into stars. But in our universe, the fraction of such matter that turns into stars is 23%, meaning there are fewer stars and, as a result, fewer places for aliens to emerge, according to a statement by researchers.

Related: 32 strange places scientists are looking for aliens

The new findings are completely hypothetical and assume that a multiverse exists, which is a theory that is far from being proved. However, "it will be exciting to employ the model to explore the emergence of life across different universes and see whether some fundamental questions we ask ourselves about our own universe must be reinterpreted," study co-author Lucas Lombriser, a cosmologist at the University of Geneva in Switzerland, said in another statement.

Dark energy is a currently-unidentifiable substance or force that works against gravity, causing space-time to expand rather than collapse in on itself. Astronomers think that dark energy exists because the universe's expansion is accelerating, but they have no clear idea what it is.

The amount of this mysterious energy in different parallel universes would influence the universes' respective star formation by impacting the rate of their cosmic expansion: If a universe has less dark energy than ours, it could expand more slowly, which would decrease star formation by enabling gravity to collapse large-scale structures, such as stellar clusters, galaxies or galactic superclusters. But if a universe has more dark energy than ours, it could increase star formation by dispersing matter more widely and enabling more large, star-forming structures to take shape.

However, too much dark energy would cause a universe to expand so quickly that it would reduce the amount of star formation by scattering matter too widely. As a result, the new model calculated the optimal density of dark energy that would maximize the rate of star formation, which turns out to be slightly higher than the density we observe in our own universe. That means intelligent beings in other universes may have better luck finding each other than we’ve had searching for aliens in ours.

The researchers also suspect that across the multiverse, the optimum dark energy density would be more common than other possible configurations of the mysterious force, such as the density of our universe's dark energy.

"We may not live in the most likely of universes," study lead author Daniele Sorini, a cosmologist at Durham university in England, said in the second statement.

What if we dropped the "terrestrial" from "extraterrestrial"? Scientists recently explored the intriguing possibility that alien life may not need a planet to support itself.

At first glance, planets seem like the ideal locations to find life. After all, the only known place life is known to exist is Earth's surface. And Earth is pretty nice. Our planet has a deep gravitational well that keeps everything in place and a thick atmosphere that keeps surface temperatures in the right ranges to maintain liquid water. We have an abundance of elements like carbon and oxygen to form the building blocks of biological organisms. And we have plenty of sunlight beaming at us, providing an essentially limitless source of free energy.

It's from this basic setup that we organize our searches for life elsewhere in the universe. Sure, there might be exotic environments or crazy chemistries involved, but we still assume that life exists on planets because planets are so naturally suited to life as we know it.

In a recent pre-paper accepted for publication in the journal Astrobiology, researchers challenge this basic assumption by asking if it's possible to construct an environment that allows life to thrive without a planet.

Related: If alien life exists on Europa, we may find it in hydrothermal vents

This idea isn't as crazy as it sounds. In fact, we already have an example of creatures living in space without a planet: the astronauts aboard the International Space Station. Those astronauts require tremendous amounts of Earth-based resources to be constantly shuttled to them, but humans are incredibly complex creatures.

Perhaps simpler organisms could manage it on their own. At least one known organism, the tiny water-dwelling tardigrades, are able to survive in the vacuum of space.

Any community of organisms in space needs to tackle several challenges. First, it needs to maintain an interior pressure against the vacuum of space. So a space-based colony would need to form a membrane or shell. Thankfully, this isn't that big of a deal; it's the same pressure difference as that between the surface of water and a depth of about 30 feet (10 meters). Many organisms, both microscopic and macroscopic, can handle these differences with ease.

The next challenge is to maintain a warm enough temperature for liquid water. Earth achieves this through the atmosphere's greenhouse effect, which won't be an option for a smaller biological space colony. The authors point to existing organisms, like the Saharan silver ant (Cataglyphis bombycina), that can regulate their internal temperatures by varying which wavelengths of light they absorb and which they reflect — in essence, creating a greenhouse effect without an atmosphere. So the outer membrane of a free-floating colony of organisms would have to achieve the same selective abilities.

Next, they would have to overcome the loss of lightweight elements. Planets maintain their elements through the sheer force of gravity, but an organic colony would struggle with this. Even optimistically, a colony would lose lightweight elements over the course of tens of thousands of years, so it would have to find ways to replenish itself.

Lastly, the biological colony would have to be positioned within the habitable zone of its star, to access as much sunlight as possible. As for other resources, like carbon or oxygen, the colony would have to start with a steady supply, like an asteroid, and then transition to a closed-loop recycling system among its various components to sustain itself over the long term.

Putting this all together, the researchers paint the portrait of an organism, or colony of organisms, floating freely in space. This structure could be up to 330 feet (100m) across, and it would be contained by a thin, hard, transparent shell. This shell would stabilize its interior water to the right pressure and temperature and allow it to maintain a greenhouse effect.

While such organisms may or may not exist in the universe, the research has important implications for future human endeavors in space. Whereas we currently construct habitats with metal and supply our stations with air, food and water transported from Earth, future habitats may use bioengineered materials to create self-sustaining ecosystems.

Originally posted on Space.com.

A father-daughter team has decoded a mock "alien" message after a year of trying. Now, citizen scientists are trying to figure out what the decoded missive truly means for Earth.

According to the European Space Agency (ESA), Ken and Keli Chaffin from the U.S. were the first to crack the code, which was sent from ESA's ExoMars Trace Gas Orbiter as part of a citizen science project in May 2023. Three radio observatories on Earth heard the message, and the data were made available to the public. The first step was to extract the signal from the raw data, and the second was to decode it.

The message is part of "A Sign in Space," a science/art project that explores how humanity might react after receiving a real alien message. It took only 10 days for an online community to extract the message from the raw data, but decoding it was more difficult: That wasn't achieved until June 7, 2024, when the Chaffins messaged Daniela de Paulis, the founder and artistic director of the project, with the solution. ESA publicly announced their success on Oct. 22.

The message turned out to be an image depicting the structure of five amino acids, the building blocks of proteins. It was the brainchild of a group of "simulated extraterrestrials," according to A Sign in Space, which included de Paulis, as well as a computer scientist, a poet, a radio engineer, a physicist and space lawyer, and several astronomers and astrobiologists.

Related: Infamous 'Wow! signal' that hinted at aliens may actually be an exceptionally rare cosmic event

The project had additional support from the SETI Institute — a nonprofit dedicated to the search for extraterrestrial life — and the Green Bank Observatory in West Virginia. Decoding the message required many hours of computer simulations. The Chaffins managed to crack the code when they figured out that the message included some biological features, ESA reported.

But what would aliens be trying to convey by sending a picture of five amino acids? That mystery still needs to be solved. Now, citizen scientists are gathering on a Discord server to debate and puzzle over the message's meaning. Do aliens come in peace? That question might be the toughest to answer.

Tiny photosynthetic microbes could be secretly thriving on Mars — hiding inside small bubbles of liquid water in the thin layers of dusty ice that litter the Red Planet's surface, a new NASA-led study reveals.

Researchers believe the icy patches could be among the most promising targets in the hunt for extraterrestrial life within our solar system — and plan to recreate them in the laboratory on Earth to test the predictions.

Mars is a surprisingly icy world: The planet has frozen sand dunes covering its north pole, giant slabs of carbon dioxide ice above its south pole and massive chunks of frozen water buried near its equator. However, it also has smaller sub-zero features, including patches of dusty water ice left behind by ancient snow drifts that clung to specific spots on the planet's surface, such as the bottoms of gullies and ravines.

In a new study, published Oct. 17 in the journal Communications Earth and Environment, researchers created computer models to simulate the conditions within this dusty surface ice and found that it could contain tiny bubbles of meltwater, which can act as miniature "habitable zones" for microbial life left over from Mars' watery past.

The researchers proposed that the hidden cavities could provide single-celled organisms with three key requirements for photosynthesis: liquid water, carbon dioxide gas from Mars' wispy atmosphere and sunlight, which shines through the thin ice above. The ice could also theoretically shelter microbes from potentially deadly solar radiation and cosmic rays, which bombard Mars' surface because of the planet's lack of magnetic shielding.

Related: NASA may have unknowingly found and killed alien life on Mars 50 years ago, scientist claims

It would be easy for future astronauts and colonists to reach the dusty ice and find these bubbles, which makes them an even more appealing place to look for extraterrestrial life, the researchers wrote. "If we're trying to find life anywhere in the universe today, Martian ice exposures are probably one of the most accessible places we should be looking," study lead author Aditya Khuller, a planetary scientist at NASA's Jet Propulsion Laboratory, said in a statement.

According to the researchers, grains of dark-colored dust buried beneath thin layers of surface ice can be heated by sunlight shining through the ice, creating pockets of space that fill up with melting water. This is perhaps one of the only places where liquid water could readily form on Mars because ice normally sublimates — or turns directly into gas — when it gets heated, the researchers wrote.

A similar process happens on our planet: When dust gets trapped within snow, glaciers and ice sheets, it creates spaces known as cryoconite holes, which often contain liquid water — and sometimes life.

"This is a common phenomenon on Earth," study co-author Phil Christensen, a planetary scientist at Arizona State University, said in the statement. "Dense snow and ice can melt from the inside out, letting in sunlight that warms it like a greenhouse, rather than melting from the top down."

A wide variety of photosynthetic organisms live in cryoconite holes, such as algae, fungi and cyanobacteria. During winter, when temperatures drop and the holes refreeze, these lifeforms enter into a hibernation-like stasis where they effectively pause all key functions until the holes reform in summer, the researchers wrote. Any potential Martian microbes may do something similar, they added.

Based on the new computer models, researchers think that the meltwater bubbles could form in ice up to 9 feet (3 meters) deep, as long as the dust content is low (less than 1%). However, this is only likely to happen at latitudes between 30 degrees and 60 degrees. Any closer to the planet's poles, and the ice will likely be too cold for bubbles to form.

The team plans to continue studying this proposed phenomenon, using additional computer models and Earth-based experiments to learn more about how and where it might happen.

"I am working with a team of scientists to develop improved simulations of if, where, and when dusty ice could be melting on Mars today," Khuller told Live Science's sister site Space.com. "Additionally, we are recreating some of these dusty ice scenarios in a lab setting to examine them in more detail."

In the coming weeks, NASA will launch a hotly anticipated new mission to Jupiter's fourth-largest moon, Europa.

Called Europa Clipper, the spacecraft will conduct a detailed study of the moon, looking for potential places where Europa might host alien life. (The launch window for the mission begins Oct. 10, but the launch has been temporarily postponed due to the impending landfall of Hurricane Milton.)

Europa Clipper is the largest planetary exploration spacecraft NASA has ever made: as wide as a basketball court when its solar sails are unfolded. It has a mass of about 6,000 kilograms — the weight of a large African elephant.

But why are we sending a hulking spacecraft all the way to Europa?

Looking for life away from Earth

The search for life in places other than Earth usually focuses on our neighbour Mars, a planet that's technically in the "habitable zone" of our Solar System. But Mars is not an attractive place to live, due to its lack of atmosphere and high levels of radiation. However, it's close to Earth, making it relatively easy to send missions to explore it.

But there are other places in the Solar System that could support life — some of the moons of Jupiter and Saturn. Why? They have liquid water.

Here on Earth, water is the solvent of life: water dissolves salts and sugars, and facilitates the chemical reactions needed for life on Earth to proceed. It's possible life forms exist elsewhere that rely on liquid methane or carbon dioxide or something else, but life as we know it uses water.

The reason there's liquid water so far out in the Solar System is because Jupiter and Saturn, the gas giants, wield immense gravitational power over their moons.

Saturn's moons, Titan and Enceladus, are stretched and compressed by gravity as they go around their host planet. This movement results in vast underground oceans with a surface of solid ice, with plumes of water vapour exploding 9,600 kilometres from the surface.

It is strongly suspected that Europa is the same. While we know a lot about Europa from more than four centuries of observation, we have not confirmed it has an under-ice liquid ocean like Titan and Enceladus.

Related: Jupiter's moon Europa lacks oxygen, making it less hospitable for sustaining life

But all clues point to yes. Europa has a smooth surface despite being hit by many meteors, suggesting the surface is young, recently replaced. Ice volcanoes raining down water over the surface would make sense.

It also has a magnetic field, suggesting that like Earth, Europa has a liquid layer inside (on Earth, this liquid is molten rock).

What will Europa Clipper do?

At the surface, Europa is bombarded by high levels of space radiation, concentrated by Jupiter. But deeper down, the thick ice sheet could be protecting life in the liquid subsurface ocean.

This means it would be difficult for us to find concrete evidence for life without drilling down deep. But where to look? Through flybys of the icy moon, Europa Clipper will be looking at areas where life could be dwelling under the icy shell.

To achieve this, Europa Clipper has nine scientific instruments. These include a wide-angle camera to study geologic activity and a thermal imaging system to measure surface texture and detect warmer regions on the surface.

There's also a spectrometer for looking at the chemical composition of the gases and surface of Europa, and for any explosive plumes of water from the surface. The mission also has tools for mapping the moon's surface.

Other instruments will measure the depth and salt levels of the moon's ocean and the thickness of its ice shell, and also how Europa flexes within the strong gravitational pull of Jupiter.

Excitingly, a mass spectrometer will analyze the gases of the moon's faint atmosphere and potential plumes of water. By examining the material ejected from the plumes, we can understand what is hidden within the under-ice oceans of Europa.

A dust analyser will also look at matter that has been ejected from Europa's surface by tiny meteorites or released from the plumes.

Unfortunately, we will have to wait a while for any discoveries. Europa Clipper will take more than five years to reach Jupiter. And the mission is only equipped to look for the potential of life, not life itself. If we see evidence that might point towards life, we will need future missions to return and explore Europa in depth.

So we must be patient. But this is an exciting opportunity for humanity to get one step closer to find life beyond our own home planet.

This edited article is republished from The Conversation under a Creative Commons license. Read the original article.

It may take less than 1,000 years for an advanced alien civilization to destroy its own planet with climate change, even if it relies solely on renewable energy, a new model suggests.

When astrophysicists simulated the rise and fall of alien civilizations, they found that, if a civilization were to experience exponential technological growth and energy consumption, it would have less than 1,000 years before the alien planet got too hot to be habitable. This would be true even if the civilization used renewable energy sources, due to inevitable leakage in the form of heat, as predicted by the laws of thermodynamics. The new research was posted to the preprint database arXiv and is in the process of being peer-reviewed.

While the astrophysicists wanted to understand the implications for life beyond our planet, their study was initially inspired by human energy use, which has grown exponentially since the 1800's. In 2023, humans used about 180,000 terawatt hours (TWh), which is roughly the same amount of energy that hits Earth from the sun at any given moment. Much of this energy is produced by gas and coal, which is heating up the planet at an unsustainable rate. But even if all that energy were created by renewable sources like wind and solar power, humanity would keep growing, and thus keep needing more energy.

"This brought up the question, 'Is this something that is sustainable over a long period of time?'" Manasvi Lingam, an astrophysicist at Florida Tech and a co-author of the study, told Live Science in an interview.

Related: 8 possible alien 'technosignatures' detected around distant stars in new AI study

Lingam and his co-author Amedeo Balbi, an associate professor of astronomy and astrophysics at Tor Vergata University of Rome, were interested in applying the second law of thermodynamics to this problem. This law says that there is no perfect energy system, where all energy created is efficiently used; some energy must always escape the system. This escaped energy will cause a planet to heat up over time.

"You can think of it like a leaky bathtub," Lingam said. If a bathtub that is holding only a little water has a leak, only a small amount can get out, he explained. But as the bathtub is filled more and more — as energy levels increase exponentially to meet demand — a small leak can suddenly turn into a flooded house.

In this case, the flooded house is the atmospheric temperature of a planet. A buildup of energy leakage, even from green energy, will eventually overheat any planet to the point where it is no longer habitable. If energy levels aren't curbed, this disastrous level of climate change could take less than 1,000 years from the start of energy production, the team found.

For astrobiologists, this 1,000-year limit also makes it much more difficult to find life elsewhere in the cosmos. After all, 1,000 years is a blink of an eye in cosmic terms, with planets like Earth taking hundreds of millions of years to become habitable in the first place. But alien extinction isn't the only potential outcome of exponential energy use, Lingam said.

However, there are other options, for both humans and alien civilizations. Instead of accepting extinction or developing the technology to move energy production off-world, a civilization could choose to flatline their growth, Lingam suggested.

"If a species has opted for equilibrium, has learned to live in harmony with its surroundings, that species and its descendants could survive maybe up to a billion years," he said.