Up to 90% of Earth's population may be able to see the enormous "God of Chaos" asteroid Apophis zoom past our planet in less than three years, scientists say. The skyscraper-size space rock will come closer to us than some satellites, making it clearly visible to the naked eye during the "once-in-a-millennium" skywatching event.

This will be the first time humans have ever been able to predict a flyby of an asteroid visible to the naked eye, and it could be a once-in-a-lifetime experience for the up to 7.6 billion people who manage to see it, scientists said at the Apophis T-3 Years workshop, held June 18-19 at the University of Padua in Italy.

"Sighting Apophis as it passes by is a way of feeling a shared cosmic experience, realizing the smallness of Earth in the vastness of space," Richard Binzel, a planetary scientist and asteroid expert at MIT who helped organize the recent workshop and create new maps of the flyby, told Live Science in an email.

The asteroid, dubbed 99942 Apophis (or simply Apophis), is a peanut-shaped object that spans about 1,500 feet (450 meters) across at its widest point, or around as wide as the Empire State Building is tall, making it large enough to wipe out a city if it ever impacted our planet. Apophis likely originated from the solar system's main asteroid belt between Mars and Jupiter, but it now resides between the orbits of Venus and Earth, circling our home star roughly every 10.5 months. The name Apophis comes from Apep, the Egyptian serpent god of darkness and disorder, which has earned the space rock the nickname "God of Chaos."

On April 13, 2029, Apophis will make a superclose flyby of Earth, reaching a minimum distance of around 19,000 miles (30,600 kilometers) from our planet, according to The Planetary Society. That's much farther away than the International Space Station and the thousands of other spacecraft in low Earth orbit, but it's closer than several hundred satellites stationed in an elevated geosynchronous orbit. (Apophis poses no threat to these high-altitude satellites because they can easily be maneuvered away from its projected path.)

There is currently zero chance that Apophis will impact our planet during the flyby or within the next 100 years. However, some experts have suggested that there is still a slim chance that the asteroid's trajectory could change before it reaches us. Other experts worry that the upcoming flyby could permanently alter the space rock or nudge it off course, potentially increasing the chances it could hit us in the future.

Therefore, scientists are keen to monitor the flyby in great detail and will coordinate observations from telescopes around the world to understand the potentially hazardous asteroid better. Several spacecraft, including NASA's OSIRIS-APEX, will also attempt to fly past Apophis to study its structure and trajectory. The event is so significant that the United Nations has declared 2029 the International Year of Asteroid Awareness and Planetary Defence.

Researchers also hope the flyby will provide a unique opportunity to inspire the next generation of space scientists. "I hope people will find the Apophis flyby intriguing, as it is not anything fearful or frightening at all," Binzel said. "Who knows how many young people might find a spark of curiosity that leads them on a path to a career in space studies."

Who will see Apophis?

The new maps help break down who might be able to see Apophis throughout the roughly seven-hour period it passes by our planet. The asteroid will be visible only to people who are positioned within its path at twilight or night amid clear skies and limited light pollution.

At the start of the flyby, when Apophis is farthest from Earth, the asteroid could be visible to around 4.5 billion people across Australia and most of Asia. By the end of the flyby, when the space rock reaches its closest point to us, it might be visible to around 1.9 billion people in eastern South America, northern Africa and parts of Europe, according to the new maps.

Peak visibility will occur around halfway through the flyby, when Apophis might be seen by as many as 5.7 billion people across eastern Africa, Southern Europe, Australia, and all of Asia and the Middle East. At this point, astronomical observatories situated on Spain's Canary Islands will likely snap the best photos of the asteroid's flyby, according to Live Science's sister site Space.com.

North America is the only continent that will not get a clear view of Apophis.

For those who are lucky enough to see the passing space rock, the asteroid will appear as a "modest star passing slowly across the sky, much like a slow-moving satellite," Binzel said, and it will shine as brightly as the stars in the Big Dipper.

A hefty, never-before-seen asteroid is racing toward Earth at around 20,000 mph (32,000 km/h) and will zoom past our planet closer than some satellites on Monday (May 18), scientists say. You can watch the unusually close encounter for yourself, even if you don't have access to stargazing equipment.

The asteroid, dubbed 2026 JH2, was discovered May 10 by astronomers at the Mount Lemmon Observatory near Tucson, Arizona, who also spotted the superbright Comet Lemmon last year. The space rock, which has since been verified by other observatories across the globe, likely circles the sun every 3.7 years on an elliptical orbit that takes it as far out as Jupiter, according to the Small-Body Database Lookup from NASA's Jet Propulsion Laboratory.

2026 JH2 is up to 115 feet (35 meters) across, or just above the maximum length of Earth's largest animal, the blue whale (Balaenoptera musculus). This puts the space rock on a par with the Chelyabinsk meteor, which spectacularly exploded above Russia in 2013 and is the largest space rock to have entered Earth's atmosphere in nearly 120 years.

How close will it get?

At around 6 p.m. EDT Monday, 2026 JH2 will shoot over Earth's surface at an altitude of around 56,000 miles (91,000 kilometers) — around a quarter the distance between our planet and the moon. At this height, the hefty space rock will sail over most of Earth's satellites but be closer to us than a handful of spacecraft, such as the Transiting Exoplanet Survey Satellite (TESS). (There is currently no suggestion that these spacecraft are at risk of being hit by 2026 JH2.)

Due to limited observations, there is some level of uncertainty about how close the asteroid may get to Earth, scientists say. However, there is zero chance that it will impact our planet.

Near its closest approach, 2026 JH2 is expected to reach a peak brightness of around magnitude 11.5, making it fairly easy to spot with a good telescope or a pair of stargazing binoculars. (A detailed, up-to-date breakdown of where to look for the asteroid can be found at TheSkyLive.com.)

However, you can also view it online. The Virtual Telescope Project, which is run by astronomer Gianluca Masi, will be sharing a livestream of the flyby as seen from a telescope in Manciano, Italy.

It is extremely rare for an asteroid the size of 2026 JH2 to come so close to Earth, although smaller space rocks do impact our planet all the time, as evidenced by a recent surge of "fireball" meteors.

The next sizable space rock that will get this close to Earth will likely be the "God of Chaos" asteroid, 99942 Apophis, which will fly within 20,000 miles (32,000 km) of Earth on April 13, 2029 — potentially making it visible to the naked eye.

However, unlike 2026 JH2, Apophis has the potential to cause serious harm to our planet because it is over 1,100 feet (340 m) across. There is currently zero chance that Apophis will hit Earth while on its current trajectory, but there is a very slim possibility that its course could be altered by interactions with other asteroids over the next three years. As a result, scientists are keeping a very close eye on Apophis and will send a probe to rendezvous with it during the flyby.

After Apophis, the next major flyby will be from the "city killer" asteroid 2024 YR4, which will zoom past the moon at a minimum distance of around 13,200 miles (21,200 km) in 2032. This space rock made headlines last year, when it was temporarily predicted to have a roughly 3% chance of hitting Earth and then a 4% chance of striking the moon. Scientists are now confident that 2024 YR4 will not impact either body.

All of these flybys are a reminder of the potential risk asteroids pose to our planet and highlight the need to seek them out and continue to work on ways of stopping them, if needed.

A "potentially hazardous" asteroid contains all of the "letters" that make up DNA, suggesting that these key ingredients for life may be common in the solar system.

Researchers made the discovery after analyzing samples collected from asteroid Ryugu, a 3,000-foot-wide (900 meters) space rock shaped like a spinning top.

The scientists detected a complete set of canonical nucleobases, which are the building blocks for DNA — the genetic foundation for all life on Earth — and its lesser-known cousin RNA, according to a new study published Monday (March 16) in the journal Nature Astronomy.

This "does not mean that life existed on Ryugu," study lead author Toshiki Koga, a biogeochemist at the Japan Agency for Marine-Earth Science and Technology, told AFP, per Phys.org. "Instead, their presence indicates that primitive asteroids could produce and preserve molecules that are important for the chemistry related to the origin of life."

This isn't the first time an asteroid has been found to be carrying all five nucleobases. NASA recovered the same set of nucleobases from asteroid Bennu in 2023, courtesy of the OSIRIS-REx spacecraft. Researchers have also detected the nucleobases on meteorites. Taken together, these findings suggest that nucleobases could be widespread in the solar system.

Cosmic origins of life?

Scientists aren't sure how life got started on Earth. Some theories posit that it originated here, such as in deep-sea vents. However, there's also a possibility that life — or the building blocks of life — didn't form on Earth at all but were carried here on comets or asteroids.

César Menor Salván, an astrobiologist at the University of Alcalá in Spain who was not involved in the study, emphasized in an interview with AFP that the new results "do not suggest that the origin of life took place in space."

However, "with this and the results from Bennu, we have a very clear idea of which organic materials can form under prebiotic conditions anywhere in the universe," Salván added.

The Japan Aerospace Exploration Agency (JAXA) collected the Ryugu samples as part of its Hayabusa2 mission, which launched in 2014. The uncrewed Hayabusa2 spacecraft landed on the asteroid in 2019, before collecting two dust samples from the asteroid's surface and returning them to Earth in 2020.

The samples weigh just 5.4 grams (0.19 ounces) each, less than the weight of a quarter, but have excited scientists for years. Preliminary analysis of a tiny fraction of the sampled material in 2023 revealed that the asteroid contained many of the building blocks for life, including one nucleobase (uracil) and numerous other organic materials, including 15 amino acids, which are the foundation of proteins. These are prebiotic molecules, and although they're not life, they're found in all life.

One study also revealed microorganisms crawling all over one asteroid Ryugu sample. But these microorganisms closely matched Earth's bacteria, and their presence was almost certainly the result of contamination after the sample returned to Earth. (Even NASA has had trouble keeping Earth bacteria off its interplanetary spacecraft in ostensibly sterile rooms).

The closest look yet

For the new study, researchers did a much more comprehensive analysis of nucleobases than was done during the preliminary research, using more sample material and optimized analytical techniques.

This time, the researchers found all of the nucleobases — adenine, guanine, cytosine, thymine and uracil. These natural compounds mix with ribose and phosphate to form DNA and RNA. The researchers also looked at the ratio of nucleobases and compared them to those discovered on Bennu and on two meteorites (Murchison and Orgueil) that had fallen to Earth.

Nucleobases are split into two groups based on their chemical structure. Adenine and guanine are purines, which are known for their double-ring structure, while cytosine, thymine and uracil belong to the single-ring-structured pyrimidines.

The researchers found that Ryugu had equal amounts of purines and pyrimidines, while Bennu and Orgueil were more enriched in pyrimidines and Murchison was more enriched in purines. Notably, the researchers also identified a strong correlation between the purine-pyrimidine ratio and the concentrations of ammonia in Ryugu, Bennu and Orgueil, suggesting that ammonia, another life-friendly molecule, may have been a key factor driving similar nucleobase formation pathways in the rocks' distinct environments, according to the study.

"Because no known formation mechanism predicts such a relationship, this finding may point to a previously unrecognized pathway for nucleobase formation in early solar system materials," Koga said.

Ryugu and Bennu are a common type of asteroid known as carbonaceous asteroids, which make up 75% of all asteroids in our solar system. James Webb Space Telescope (JWST) observations suggest that both asteroids may originate from the same parent asteroid that broke apart billions of years ago. The Orgueil meteorite also derived from a carbonaceous asteroid.

These ancient rocks are left over from when the solar system was still forming around 4.5 billion years ago, when the Earth was also forming. The detection of nucleobases, therefore, suggests that carbonaceous asteroids may have helped Earth get its life-forming chemicals.

"The detection of diverse nucleobases in asteroid and meteorite materials demonstrates their widespread presence throughout the Solar System and reinforces the hypothesis that carbonaceous asteroids contributed to the prebiotic chemical inventory of early Earth," the researchers wrote in the study.

"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?

The moon will officially be spared from an explosive encounter with a "city-killer" asteroid in 2032, new observations from the James Webb Space Telescope (JWST) reveal.

Collected on Feb. 18 and Feb. 26 with JWST's sensitive infrared instruments, the new observations of the near-Earth asteroid 2024 YR4 allowed NASA astronomers to refine previous estimates of the space rock's trajectory — dropping the chances of a lunar impact from 4.3% to zero.

Instead, the menacing asteroid will pass by the moon at a nail-biting 13,200 miles (21,200 kilometers) from the lunar surface, which is closer than some artificial satellites orbit Earth, according to a March 5 NASA statement. Meanwhile, 2024 YR4 will miss Earth by hundreds of thousands of miles when it swings back through the inner solar system on its close approach six years from now.

According to NASA, this latest round of observations was only possible thanks to JWST's extreme sensitivity, but it still pushed the telescope to its limits.

"Since spring of 2025, the asteroid has been unobservable from both Earth and space-based observatories except for this use of Webb," NASA officials said in the statement. These new JWST snapshots of 2024 YR4 are "among the faintest ever observations of an asteroid" in history, they added.

"The challenge was significant," representiteves from the European Space Agency (ESA), which co-manages JWST along with NASA and the Canadian Space Agency, said in a separate statement. "To use one of the most complex machines humankind has ever built to track an almost invisible object many millions of kilometres away – and then accurately predict its position almost seven years into the future."

Riskiest asteroid ever

Asteroid 2024 YR4 was discovered in late 2024 by the Asteroid Terrestrial-impact Last Alert System (ATLAS) network

Subsequent telescope observations soon showed that the space rock was a whopper, measuring between 174 and 220 feet (53 to 67 meters) in diameter — about as wide as the Leaning Tower of Pisa is tall — and that its trajectory would bring it extremely close to Earth. If an asteroid this size were to hit our planet, it could wipe out a city with the equivalent force of 500 Hiroshima bombs, Live Science previously reported, earning it the "city killer" nickname.

While telescope data on the asteroid was still limited, astronomers estimated that it had a slight chance of smashing into Earth. The predicted likelihood of a collision peaked at 3.1%, which were the highest odds of a potential asteroid collision ever. Within months, new data from JWST and other telescopes brought those odds down to zero, while the chances of a lunar collision remained at 4.3%.

What's next for 2024 YR4?

What would happen if such a large asteroid hit the moon? It certainly wouldn't be the first time the moon took a hit from a space rock, but it would have been the first time scientists could predict a large lunar impact from a known asteroid and watch it happen in real time.

Some astronomers theorized that the resulting explosion could have been visible from Earth with the naked eye, while others warned of a potential rain of debris that could trigger a brand-new meteor shower over our planet.

Now, with Earth and the moon officially safe from 2024 YR4, the asteroid will remain a tempting target for astronomers who want to test planetary defense models, and it could help us prepare for additional close encounters. NASA plans to watch the asteroid with JWST again in 2028, when it heads back our way — and passes by safely.

Update: This article was updated on March 6 at 11 a.m. ET to add new images and quotes from ESA

The newly commissioned Vera C. Rubin Observatory has issued 800,000 astronomy alerts in just one night — a staggering number of nightly discoveries that is expected to grow nearly tenfold by the end of this year.

The telescope, which scans the full sky from its perch atop Cerro Pachón mountain in Chile, produced the alerts to direct scientists to "new asteroids, exploding stars, and other changes in the night sky," representatives for the U.S. National Science Foundation (NSF) said in a statement.

And Rubin is just getting started, as scientists expect it will eventually issue 7 million alerts every night.

"By connecting scientists to a vast and continuous stream of information, [the observatory] will make it possible to follow the universe's events as they unfold, from the explosive to the most faint and fleeting," Luca Rizzi, an NSF program director for research infrastructure, said in the statement.

Catching supernovas, asteroids, and interstellar objects in the act

These alerts will enable scientists to collaborate to an unprecedented degree, the NSF noted, because Rubin will spot information quickly for follow-up by other telescopes on the ground or in space. Rubin's alerts may also shed light on ongoing astronomical mysteries that require quick wayfinding to gather more information.

"Scientists will have a greater ability to catch supernovae in their earliest moments, discover and track asteroids to assess potential threats to Earth, and spot rare interstellar objects as they race through the solar system," NSF representatives wrote in the statement. "Scientists can then use these data to better understand the nature of dark matter, dark energy, and other unknown aspects of the universe."

Rubin's alert system is starting up shortly before the observatory begins a 10-year program, known as the Legacy Survey of Space and Time (LSST), later this year. Rubin will do nightly sky scans to generate an image of the entire Southern Hemisphere sky every few nights, using the largest-ever digital camera to spot any changes in the view overhead.

"What’s revolutionary about Rubin is its ability to capture both rapid changes and long-term evolution in the sky," Rosaria Bonito, researcher at the Italian National Institute for Astrophysics in Italy and co-chair of the Rubin LSST Transients and Variable Stars science collaboration, said in the statement.

The observatory's debut images, released in June 2025, revealed more than 10 million galaxies in and around the Virgo Cluster — many of them never studied before — as well as 2,000 previously undiscovered asteroids, spotted after just a few nights of observations.

The first year of the LSST program alone is expected to image more night-sky objects than those of all other optical observatories combined throughout human history, according to the NSF. Every night's LSST observations will produce 10 terabytes of data, which also required background engineering in image processing, databases and data distribution to achieve the milestone.

The observatory's alerts are all available to read for free on the public alert broker website ANTARES.

Editor's note: This article was updated on Feb. 26 at 2:50 p.m. to add additional images and quotes.

The building-size asteroid 2024 YR4 has a small chance of striking the moon in 2032 — and a new study predicts it could also put on a spectacular show for skywatchers by creating thousands of impact flashes as well as extreme meteor storms.

The space rock — which is about 200 feet (60 meters) wide, or about as big as a 15-story building — was discovered on Dec. 27, 2024. It briefly gained notoriety in February 2025, when astronomers calculated that it had the highest-ever probability of colliding with Earth of asteroids that size or larger. Although this likelihood reached as high as 3.1%, more detailed estimates of the asteroid's trajectory negated any chances that the rock would collide with Earth during its near pass on Dec. 22, 2032.

However, there's still a 4.3% chance that 2024 YR4 may strike the moon instead, according to NASA. A 2025 study noted that such an impact would release the energy equivalent of 6.5 million tons of TNT, making it the biggest lunar impact recorded in modern times.

The possibility of this impact intrigued Yifei Jiao, a postdoctoral researcher at the University of California, Santa Cruz. He and his colleagues realized that this was "a rare 'natural experiment': a forecastable small-body impact whose signatures could be scientifically rich and operationally relevant," he told Live Science by email. As a result, the researchers wanted to assess all plausible outcomes, he said.

10,000 collisions

To do this, the scientists created computer models of the solar system that included the asteroid, all of the planets, Earth's moon and the sun — and simulated 2024 YR4's path as it whizzed through the inner solar system.

By tweaking the space rock's trajectory, the team created 10,000 such simulations, with which they charted the likeliest collision areas on the moon. Drawing on a different set of finer-scale simulations, the researchers also simulated the actual impact process over a 500-second time interval. The team modeled the range of possible scenarios for the impact debris, tracking the paths of the objects that escaped the moon's gravity.

The results of their simulations, which are available on the arXiv preprint server and haven't been peer-reviewed yet, suggest that the asteroid will likely impact the moon somewhere along a roughly 1,900-mile-long (3,000 kilometers) stretch. The predicted impact corridor lies just north of the moon's Tycho crater. That would be along the moon's lower half if you were observing from Earth's Northern Hemisphere (and the opposite from the Southern Hemisphere), according to The Planetary Society.

A blast bright as Venus

More spectacularly, the impact would produce a starlike flash between magnitudes -2.5 and -3 — about as bright as Venus in the night sky. The flash would last between 200 and 300 seconds (three to five minutes), although it would definitely be visible for at least 10 seconds "when the flash is bright enough above background conditions to be reliably noticed," first author Yifan He, a researcher at Tsinghua University in China, told Live Science in an email.

If the collision were to occur, the predicted impact time would be 10:19 a.m. EST (15:19 UTC) — so the flash would be visible in parts of the world where the moon had risen. This would make East Asia, Oceania, Hawaii and western North America great places for viewing it.

But there's a catch: On the predicted day of impact, 70% of the moon will be illuminated. The impact flash would be visible to naked-eye observers only if the asteroid were to strike in the moon's unlit region. He and Yixuan Wu, a researcher at Tsinghua University and the study's second author, estimate that the chance of that happening — if asteroid 2024 YR4 collides with the moon — is merely 2.85%.

Still, regardless of the impact location, the flash would be detectable by amateur telescopes. Other spectacles would be likely — an impact would lift many lunar rocks that would then rain back onto the moon's surface, causing potentially several thousand flashes. However, the flashes from these secondary impacts would not be as bright as the main one, and will probably be more difficult to see without any instruments.

Additionally, the study predicts that the impact would fling up to 220 million pounds (100 million kilograms) of lunar rocks toward Earth. These would create what Wu calls “super meteor storms”, extreme meteor showers that would be prominent between two and 100 days after the impact. 2024 YR4's lunar impact is still fairly uncertain, but Wu is excited about the future. “If this scenario plays out, it will be a milestone for planetary science, turning the Earth-Moon system into a grand stage for validating our understanding of asteroid impacts,” she told Live Science in an email.

Scientists analyzing the first images from the Vera C. Rubin Observatory have discovered the fastest-spinning asteroid in its size class yet.

The record-breaking space rock, called 2025 MN45, is larger than most skyscrapers on Earth at about 2,300 feet (710 meters) wide. The massive rock completes a rotation in about 113 seconds — making it the fastest-spinning known asteroid over 1,640 feet (500 meters) in diameter.

The research, published in The Astrophysical Journal Letters Wednesday (Jan. 7), is part of an asteroid survey aimed at improving our understanding of how these small bodies formed and evolved.

The study is the first peer-reviewed paper from the Rubin Observatory's LSST Camera — the largest digital camera in the world — which will repeatedly scan the Southern Hemisphere's night sky over 10 years to create an unprecedented time-lapse movie of the universe.

Rocks that roll

Asteroids are essentially large space rocks, and many are remnants of how our solar system appeared early in its 4.5 billion-year-old history, before the evolution of planets and moons. Therefore, by studying asteroids, scientists can figure out how our solar system changed over the eons.

Scientists found 2025 MN45 using the preliminary data release from the Rubin Observatory, which has already revealed thousands of previously unknown asteroids around the solar system after just seven nights of observations. (The 10-year LSST survey has yet to formally begin, but is expected to start in the next few months.)

The asteroid's remarkably fast spin excited the team, as it provides clues about the ancient rock’s composition.

"Clearly, this asteroid must be made of material that has very high strength in order to keep it in one piece," Sarah Greenstreet, an assistant astronomer at the National Science Foundation's National Optical-Infrared Astronomy Research Laboratory, said in a statement. "It would need a cohesive strength similar to that of solid rock."

"This is somewhat surprising," added Greenstreet, who also leads a Rubin working group about near-Earth objects and interstellar objects, "since most asteroids are believed to be what we call 'rubble pile' asteroids, which means they are made of many, many small pieces of rock and debris that coalesced under gravity during solar system formation or subsequent collisions."

Thousands more to come

In general, fast-spinning asteroids could have reached that state after a collision with another space rock, the study team said. It is also possible that 2025 MN45 is a remnant of a much larger asteroid that was shattered by a cosmic crash.

Most asteroids in the solar system are in the main asteroid belt between Mars and Jupiter. But most fast-spinning asteroids that astronomers have observed are much closer to Earth, simply because they are easier to see, the study authors noted. 2025 MN45 is a main-belt object, where most asteroids (as they are loose piles of rubble) must take at least 2.2 hours to rotate in order to avoid fragmentation. Anything that rotates faster than that "must be structurally strong," they wrote.

That said, 2025 MN45 is not the only fast spinner in the main asteroid belt. In addition to 2025 MN45, Rubin's first dataset includes 16 "super-fast" rotators, each of which has a rotational period of between 13 minutes and 2.2 hours, as well as two "ultra-fast" rotators with spins of less than two minutes each. All of these asteroids are also longer than 100 yards (90 m), and all but one of the newfound asteroids lives in the main belt.

The commissioning data from Rubin, which was released last June, underwent a deeper look in the new paper, which was also discussed Wednesday at a news conference at the 247th meeting of the American Astronomical Society in Phoenix.

The huge set of observations has about 1,900 never-before-seen asteroids, according to the statement. There will be many more to come when Rubin formally begins its 10-year survey of the sky in the coming months.

Astronomers hoping to observe a planet around a nearby star have witnessed a much rarer "unprecedented celestial event," the team said: The violent aftermath of not one, but two collisions between the rocky building blocks of planets.

Over the past two decades, astronomers witnessed two separate catastrophic collisions around the star Fomalhaut, located just 25 light-years away in the constellation Piscis Austrinus. The detections occurred after planetesimals (rocky pieces of unformed planets) measuring much larger than the dinosaur-killing asteroid smashed each other into massive clouds of glittering debris.

The Fomalhaut system is no stranger to such crashes. It's famously known as the "Eye of Sauron" due to its resemblance to the fiery, all-seeing eye from J.R.R. Tolkien's Lord of The Rings franchise. The likeness comes from the spectacular dust belt that surrounds Fomalhaut at a distance of 133 astronomical units (AU), with one AU being equal to 93 million miles (150 million km) — the average distance between the sun and Earth.

Formed from countless rocky, icy collisions, this belt of dust and debris provides a dustier analog of our early solar system as it appeared more than 4 billion years ago, the team said — offering a glimpse of our neighborhood's chaotic infancy, when planets were being created, destroyed, and reassembled.

False planet syndrome

A new study, conducted by an international team of researchers and led by Paul Kalas, an astronomer at the University of California, Berkeley, described these two collision events in destructive detail to help solve a planetary mystery.

In the early 2000s, astronomers observing the Fomalhaut system spotted a large, luminous object that many assumed to be a dust-covered exoplanet reflecting light. They designated this exoplanet candidate Fomalhaut b.

Yet when this supposed planet blinked out of existence and another bright point of light appeared nearby, all in the span of approximately 20 years, researchers realized they weren't viewing planets, but the shining debris clouds formed by what they call a "cosmic fender bender."

Fomalhaut forensics: a history of catastrophic crashes

The two collision events, now known as Fomalhaut cs1 and Fomalhaut cs2, appear to be incredibly serendipitous. Theory suggests that collisions of this size should only happen once every 100,000 years or so, but the Fomalhaut system surprised scientists with two such smash-ups in just 20 years.

Indeed, based on this timeline, the study infers that 22 million similar events may have occurred during the Fomalhaut system's relatively young, 440-million-year-old life so far. Even if one could rewind only the past 3,000 years or so, "Fomalhaut's planetary system would be sparkling with these collisions," Kalas explained in a statement.

Reverse engineering the collisions based on factors like the mass of the debris clouds and the size of the dust grains suggests that Fomalhaut cs1 and cs2 were the result of colliding planetesimals around 37 miles (60 km) in diameter, or around four to six times the size of the asteroid that devastated the non-avian dinosaurs 66 million years ago.

It's an alien event with a relatable twist: "These larger bodies are like the larger bodies that comprise our own asteroid and Kuiper belts," study co-author Jason Wang, an astronomer at Northwestern University, told Live Science via email.

And there are a lot of these bodies. Based on their reconstruction of the event, the researchers suggest that the Fomalhaut system may host 1.8 Earth masses of these primordial planetesimals. This may amount to about 300 million such bodies, according to a separate statement.

Furthermore, the system holds another 1.8 Earth masses in smaller bodies measuring less than 0.186 miles (0.3 kilometers) across. These relative runts constantly replenish the tiny dust grains, many just a few 10,000ths of an inch in size, that swirl and shimmer in Fomalhaut's dust belt. Without this rocky reservoir, the dust belt would disappear as its grains are blown out of the system by stellar wind or engulfed by its star.

The planet that never was, still may be

Even though Fomalhaut b no longer exists — as a planet, at least — this "planet that never was" may actually still be hiding within the system.

Researchers calculated that, given the specific conditions, there's about a 10% chance that Fomalhaut cs1 and cs2 are not random collisions. Their similar timing and location may point to a hidden influence, such as the ghostly gravitational pull of an unseen exoplanet.

"For example, something — like planets — should be responsible for carving out the planetesimals into a dust belt that we see," Wang told LiveScience. "Additionally, we speculate that the proximity in location of the cs1 and cs2 impact sites may be driven by a planet that preferentially causes planetesimals to collide there."

Playing planetary peek-a-boo

This exoplanetary confusion highlights an important consideration for planet-hunters, and for next-generation facilities like NASA's Habitable Worlds Observatory that are designed to directly image habitable-zone exoplanets in the nearby universe: "Fomalhaut cs2 looks exactly like an extrasolar planet reflecting starlight," explained Kalas.

As a result, this unique study not only informs our ideas about planetary formation, such as collision rates and debris belt mechanics, but can also help astronomers more precisely identify planetary bodies from among all the other shining celestial objects with which the universe continually dazzles us.

At this point in history, astronomers and engineers who grew up watching Deep Impact and Armageddon, two movies about the destructive power of asteroid impacts, are likely in relatively high ranking positions at space agencies. Don't Look Up also provided a more modern, though more pessimistic (or, unfortunately, realistic?), look at what might potentially happen if a "killer" asteroid is found on approach to Earth. So far, life hasn't imitated art when it comes to potentially one of the most catastrophic events in human history, but most space enthusiasts agree that it's worth preparing for when it will. A new paper, available in pre-print on arXiv, from Maxime Devogèle of ESA's Near Earth Object (NEO) Coordination Centre and his colleagues analyzes a dry run that happened around a year ago with the discovery of asteroid 2024 YR4.

The paper walks through the process of discovery, classification, escalation, scientific response, and eventually de-escalation that the asteroid went through in a matter of months. While the asteroid early-warning system largely worked as intended, reviewing this first-ever scenario for this particular type of asteroid is worthwhile, as it surely won't be the last one.

2024 YR4 was in the headlines starting in early January of 2025, though it was discovered on December 27th by the ATLAS survey. Over the course of the next month, additional observations actually increased the chance of an impact, unlike 99.9% of other newly discovered asteroids.

One of the key aspects of the paper is its discussion of the Torino scale. Originally developed in 1995 by Dr. Richard Binzel of MIT, and later updated in June 1999 at a conference in Torino (Turin) Italy, this scale is explicitly designed to classify asteroid impact threats into one of eleven categories. Importantly, each category is based on a risk assessment of both it's probability of impact and also the potential damage it can cause. The categories are:

• Scale 0 (White) - No Hazard - The asteroid with either miss us or burn up in the atmosphere
• Scale 1 (Green) - Normal - Where most asteroids are classified when they are first discovered. Impact is "extremely unlikely", and they are typically downgraded to Scale 0 within a few days.
• Scale 2 (Yellow) - Meriting Attention - Typically involves a "close" but not threatening pass, but very unlikely impact. This is relatively rare
• Scale 3 (Orange) - Concerning - These have a greater than 1% chance of hitting Earth and causing "localized" destruction. A good analog would be the Tuskunga event in the early 20th century. This is the rating 2024 YR4 eventually grew to.
• Scale 4 (Orange) - Threatening - Still a greater than 1% chance, but with "regional" devastation rather than localized.
• Scale 5-7 (Red) - Threatening - A "credible threat" of regional to global devastation. No asteroid has ever been categorized this high.
• Scale 8-10 (Red) - Certain Collision - At this level, astronomers are sure the asteroid will hit us - each scale number simply increases the potential destruction caused when it does.

On January 27th of 2025, 2024 YR4 was officially listed as a 3 on the Torino scale, eventually winding up with a 3.1% percent impact chance on February 18th, and making it the first ever asteroid to reach that level of the scale. It's important to note that, technically this wasn't the highest ever rank on the scale - that distinction goes to asteroid Apophis, which famously reached a Level 4 on the Torino scale in 2004. In fact, Apophis could never have been classified as a 3 on the Torino scale, because its larger size would have caused regional rather than localized devastation - but, it's also important to note that the threat level was downgraded much more quickly than that of 2024 YR4.

Even the Scale 3 rating was enough to cause the first ever official notification of the International Asteroid Warning Network - which didn't exist when Apophis was discovered in 2004, having come into existence in 2014 after the Chelyabinsk asteroid explosion in 2013. After hitting that high on the scale, the discussion about 2024 YR4 moved from pure scientific fact-finding to wider consideration of a threat to potentially large parts of humanity.

The system worked exactly as intended - it got attention. Certainly plenty from the public, and even some policy makers. But perhaps more importantly it got the attention of more astronomers. The increased interest brought with it additional resources, including, critically "Director's Discretionary Time" on some of the world's most powerful telescopes.

As these telescopes, which included the Catalina Sky Survey, the Gran Telescopio Canarias, and the Very Large Telescope began to turn their optics towards the potential threat, it began to look far less imposing. By early March, these behemoths had characterized many of the asteroid's critical features, such as its rotation and taxonomy. It spun much faster than typical "rubble pile" asteroids, with a rotational period of only 19.5 minutes. And it was classified as either a Sq-type or K-type asteroid, though there is still some residual debate on this point, as its albedo seemed different depending on what observational platform was used.

That final clarification will be a critical feature, as, though the threat of an impact to Earth decreased, the threat of an impact to the Moon has actually increased over the course of the observations earlier this year. As of now, 2024 YR4 has a ~4% chance of hitting the Moon in 2032, which could cause widespread destruction amongst satellites orbiting Earth from its debris cloud. Therefore, the planetary defense community's job isn't yet done - but it seems to be operating exactly as intended so far. Someday it will truly be needed to kick the international response to a threatening asteroid into gear - and hopefully the response turns out to be better than that depicted in the movies.

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

Astronomers have discovered a 2,300-foot-wide (700 meters) asteroid hidden in the sun's glare, and it’s whizzing through our solar system at a near record-breaking pace.

The skyscraper-size asteroid, named 2025 SC79, loops around the sun once every 128 days, giving it the second-fastest asteroid orbit in the solar system. It is also only the second known space object that orbits entirely inside of Venus' orbit, occasionally even crossing the orbit of Mercury.

Scott Sheppard, an astronomer at the Carnegie Science research institute in Washington, D.C., first spotted 2025 SC79 on Sep. 27. The asteroid was obscured by the sun's glare, making it exceptionally difficult to observe, according to a statement released by Carnegie Science. Spotting hidden asteroids like 2025 SC79 is important to ensure that no potentially hazardous space rock sneaks up on our planet without us noticing.

"The most dangerous asteroids are the most difficult to detect," Sheppard said in the statement. "Most asteroid research finds these objects in the dark of night, where they are easiest to spot. But asteroids that lurk near the Sun can only be observed during twilight — when the Sun is just about to rise or set. If these 'twilight' asteroids approach Earth, they could pose serious impact hazards."

Asteroids like 2025 SC79 are definitely worth keeping an eye on. To put its 2,300-foot diameter in context, the so-called "city-killer" asteroid 2024 YR4 discovered earlier this year is only around 180 feet (55 meters) wide, and that has the potential to release 500 times more energy than the atomic bomb that destroyed Hiroshima if it were to hit Earth (don't worry, it almost certainly won't).

Sheppard discovered 2025 SC79 using the Dark Energy Camera on the National Science Foundation's (NSF) Blanco 4-meter telescope. The asteroid's existence was then confirmed with observations from the NSF's Gemini telescope and Carnegie Science's Magellan telescopes, according to the statement.

This is the second super speedy asteroid spotted by Sheppard and his colleagues in recent years, having also discovered the fastest known asteroid in 2021. That object, named 2021 PH27, orbits the sun in 113 days, making it just 15 days quicker than 2025 SC79. The only object in the solar system with a faster orbital period is the planet Mercury, which completes an orbit of the sun in 88 days.

2025 SC79's orbit has now taken it behind the sun, so it won't be visible for several months. Researchers will attempt further observations in the future to learn more about the object, which is ultimately another piece of the galactic puzzle that helps astronomers understand how our solar system and its potential asteroid-shaped threats evolved.

"Many of the Solar System's asteroids inhabit one of two belts of space rocks, but perturbations can send objects careening into closer orbits where they can be more challenging to spot," Sheppard said. "Understanding how they arrived at these locations can help us protect our planet and also help us learn more about Solar System history."

NASA's plans to fly a spaceship alongside a potentially hazardous asteroid in 2029 will continue — for the next year, at least.

After threats of mission cancellation, the OSIRIS-APEX spacecraft received a last-minute $20 million allocation in the House budget bill to continue basic operations for the next fiscal year. The fates of 18 other NASA missions slated to stop operations on Oct. 1, however, remain unclear due to the ongoing government shutdown.

"We were incredibly relieved and grateful," Dani Mendoza DellaGiustina, principal investigator of OSIRIS-APEX at the University of Arizona, told Live Science in an email. The news was first announced Oct. 7 at a meeting of the National Academies' Committee on Astrobiology and Planetary Sciences, Ars Technica reported.

OSIRIS-APEX stands for "Origins, Spectral Interpretation, Resource Identification and Security — Apophis Explorer". The mission is slated to observe the quarter-mile-wide (400-meter) asteroid Apophis, which was once believed to pose a minor threat to Earth during an upcoming close encounter in 2029.

More observations fortunately showed that Apophis — which is named after an ancient Egyptian god associated with chaos — will instead fly safely by Earth. It will come very close, however: its trajectory will bring it inside the orbit of geostationary satellites, roughly 22,000 miles (36,000 km) away, potentially making it visible to the naked eye. But as Apophis crosses our planet's pathway periodically, there's still a risk of a direct impact in the distant future.

OSIRIS-APEX uses the OSIRIS-REx spacecraft that snatched a small sample of the asteroid Bennu in 2020, and brought the precious dust to Earth in a separate return capsule, providing critical information about our early solar system. The core spacecraft remains healthy, and both DellaGiustina and NASA have emphasized it will be cheaper to use an existing space mission to observe Apophis than to launch something new.

"Apophis is one of the most compelling near-Earth asteroids we've ever discovered," DellaGiustina said. "By studying Apophis during and after its Earth encounter, we have a unique opportunity to understand how close planetary flybys reshape small bodies: from seismic shaking and surface landslides, to changes in rotation and orbit."

Nevertheless, in May the Trump administration placed OSIRIS-APEX on a list of 19 NASA missions that they intended to cancel, as part of sweeping cutbacks that would see the agency's budget slashed by nearly 25%, from $24.8 billion to $18.8 billion. The fate of the other 18 missions remains uncertain; the U.S. government has been in shutdown since Oct. 1 after lawmakers in Washington, D.C. failed to agree on this year's fiscal budget.

While OSIRIS-APEX's 2026-27 operations are secure, Congress requires a review of NASA funding every year. This means the mission, along with other NASA projects, will be reconsidered for funding in the next fiscal year.

DellaGiustina said she is hopeful the funding will continue. The mission was "explicitly named," she said, in the House and Senate versions of the fiscal 2026 NASA budget, thanks to support from the Arizona congressional delegation, particularly Sen. Mark Kelly (D) — a former NASA astronaut — and Rep. Juan Ciscomani (R), a graduate of the University of Arizona (the institution that leads OSIRIS-APEX, and which also led OSIRIS-REx).

"Congress recognized the value of keeping our healthy spacecraft and instruments operational as we cruise toward Apophis," DellaGiustina said. "It doesn't guarantee funding in future years, but it keeps us moving forward and gives us a fighting chance to carry out this once-in-a-lifetime encounter."

Future science at risk

While the funding came as a relief to the team, it's not all good news. The science team did not receive any funding for active research this year, which means that mission managers — and the early-career researchers they mentor, such as students — cannot do analysis, planning or mission science.

DellaGiustina said it was "disheartening to have to pause their participation for a year or more." In 2022, the last senior review of the NASA mission — a community effort undertaken roughly every three years to evaluate the benefits of scientific research — explicitly said that mentorship within the team would be beneficial for the space community.

"This long-duration mission presented an effective professional development plan, which would transition junior scientists into more senior roles as the mission progresses," the senior review stated, adding that most of OSIRIS-APEX's senior leadership — including DellaGiustina herself — came up through the ranks from previous, junior roles on OSIRIS-REx.

The two missions, meanwhile, continue to produce science papers each year; their scientific productivity got praise from the senior review team, which in 2022 flagged at least 137 papers produced "that reveal significant discoveries and insights into the structure and evolution of a small asteroid."

Many other papers have been published in the last three years, and more are coming up soon concerning Bennu's composition and origin, DellaGiustina said. Notably, a Nature paper in January showed that the parent body from which Bennu came had a sort of brine running through it, which included carbonates — the building blocks of life. "The parent body may have been similar to an ocean world," DellaGiustina said.

The asteroid Psyche may have once had vents that spewed molten metal — but only if it is chemically similar to rare, metal-rich meteorites, a new study suggests. The study, which was published online July 31 in the Journal of Geophysical Research: Planets, could explain why the space rock has an unusual metallic cloak.

Potato-shaped asteroid Psyche, a member of the main asteroid belt between Mars and Jupiter, is unique in being super-shiny. Radar measurements indicate that, on average, its surface reflects nearly a third of the sunlight shining on it, making it at least twice as reflective as most asteroids.

Because of its reflectivity, scientists have posited that Psyche isn’t just mostly metal but may actually be the exposed iron-rich heart of a planetary building block. Samuel Courville, a planetary scientist at Arizona State University, described Psyche to Live Science in an email as "a relic from the dawn of the solar system." Some have estimated the value of its metals to be a staggering $100,000 quadrillion.

However, this shininess may be mostly skin-deep. In 2020, calculations involving updated estimates of Psyche’s mass and volume suggested that the asteroid’s density wasbetween 231 lbs per cubic foot (3,700 kilograms per cubic meter) and 256 lbs/cubic foot (4,100 kg/cubic meter). While denser than most asteroids, it’s only about half the density expected if Psyche were made entirely of iron and nickel. This, along with surface heat emission data, indicated that while Psyche's bulk is largely non-metallic, the asteroid probably possesses a metal-rich cloak.

Scientists still aren’t sure how Psyche acquired this coat. Although many phenomena could be responsible, the most favored at present is ferrovolcanism. "Ferrovolcanism is like normal volcanism except instead of molten rock, the 'lava' is molten metal," Courville, who wasn’t involved in the new study, said.

First suggested in 2019, the idea is that during Psyche’s infancy, its metallic core solidified from outside in, with the molten inner core becoming progressively richer in lighter elements. The difference in density between the core's solid exterior and molten interior would have created enough pressure for the latter to pierce into the overlying mantle and the asteroid’s surface, creating vents that spewed molten metal.

But ferrovolcanism can only work with specific chemical compositions, since it greatly depends on how much pressure builds up in the inner core. Data from meteorites — space rocks that fall on Earth’s surface — help constrain the range of these chemical combinations.

To determine the chemistry that could have spawned Psyche’s iron-spewing vents, the authors of the new study — Jaap Jorritsma, a Ph.D. student at Delft University of Technology and Win van Westrenen, a professor of earth sciences at Vrije University in Amsterdam — created computer models of the asteroid.

They considered the asteroid to have a chemical makeup similar to one of three types of meteorites: EH-chondrites (rare, stony meteorites lacking iron), H-chondrites (commonplace, stony meteorites with moderate amounts of iron) and mesosiderites (rare, iron-rich meteorites). The researchers then ran simulations to figure out which chemical composition was most favorable for ferrovolcanism to occur.

The researchers found that Psyche’s bulk must be rich in metals like iron, as low iron content would lead to tiny cores in which the internal pressure generated is insufficient to push out magma. This meant that Psyche was most likely to have had ferrovolcanism if it contained large amounts of mesosiderite. H-chondrites could lead to the spewing of molten metal too, but only if they had a relatively high density. In contrast, EH-chondrites only produced tiny cores that lacked iron-rich exteriors, making them unlikely to constitute part of Psyche.

The researchers expect NASA’s ongoing Psyche mission will provide evidence supporting their findings. Scheduled to arrive at Psyche by July 2029, the spacecraft will spend two years photographing the asteroid and collecting spectroscopic data. Courville said that these snapshots will reveal if surface metal is in large outcrops or flows, which would indicate that ferrovolcanism had occurred in the space rock's past.

A small asteroid zoomed past Earth closer than most satellites last week — and astronomers didn't notice it until hours later.

The surprise asteroid encounter occurred at 8:47 p.m. EDT on Tuesday, Sept. 30 (Wednesday, Oct. 1 at 0047 GMT) when the roughly giraffe-size space rock flew over Antarctica at just 265 miles (428 kilometers) above Earth's surface, according to newly released data from the European Space Agency (ESA). Astronomers first spotted the sneaky space rock — now officially named 2025 TF — a few hours later, using observations from the Catalina Sky Survey, a NASA-funded mission to track near-Earth objects.

Measuring an estimated 3.3 to 9.8 feet wide (1 to 3 meters), the asteroid posed no serious threat to Earth, ESA added, and likely would have burned up as a bright fireball had it reached Earth's atmosphere. However, even small asteroids can cause big problems for spacecraft — and this one happened to whip by at around the same altitude where the International Space Station usually orbits. Fortunately, no spacecraft were in the space rock's path.

Space agencies like NASA and ESA track thousands of known near-Earth objects, carefully monitoring which ones pose the greatest risk of colliding with Earth. (Currently, no known objects pose a significant threat to our planet for at least 100 years). For an asteroid to be considered "potentially hazardous," it must measure at least 460 feet (140 m) in diameter, and follow an orbit that comes within 4.65 million miles (7.48 million km) of Earth — or roughly 20 times the average distance between Earth and the moon. Asteroid 2025 TF falls far short of that size threshold, which may also explain why it evaded detection until after it had passed.

Astronomers at ESA's Planetary Defence Office observed the asteroid shortly after it was discovered, ESA officials reported. NASA, which has paused all public communications during the ongoing U.S. government shutdown, did not make any announcements about the asteroid — however, an entry for the asteroid has been updated on NASA's Center for Near-Earth Object Studies website. The tiny space rock is not expected to fly by our planet again until April of 2087, according to NASA.

Earth may have dodged a "fireball" with this near-miss asteroid encounter, but skywatchers can expect more fiery lights this week. The Draconid meteor shower peaks on Wednesday (Oct. 8) — and while the display of shooting stars will be somewhat dampened by the light of the full Harvest Moon, the appearance of bright fireball meteors is possible. No asteroids play a part in this annual sky show; the Draconids come from icy debris left by the comet 21P/Giacobini-Zinner, which blazes through the inner solar system every 6.5 years.

The asteroid belt is found orbiting between Mars and Jupiter and is a vast collection of rocks that is thought to be a planet that never formed. When our Solar System formed 4.6 billion years ago, the material in this region should have coalesced into a planet, however, Jupiter's gravitational influence prevented this from happening, stirring up the region so that collisions became destructive rather than constructive. What remains today contains only about 3% of the Moon's mass scattered across millions of kilometres.

Jupiter's influence didn't stop there. Gravitational resonances, areas in space where the orbital periods of asteroids create regular interactions with Jupiter, Saturn, and even Mars, destabilise asteroid orbits, flinging fragments either toward the inner Solar System, where Earth resides, or outward toward Jupiter's orbit. Asteroid fragments that don't escape are ground down by mutual collisions into meteoritic dust.

A team of astronomers led by Julio Fernández from the Universidad de la República in Uruguay has calculated precisely how fast this depletion of asteroid belt material is progressing. They found that the asteroid belt is currently losing approximately 0.0088% of the portion of the asteroid belt that's still participating in the ongoing collisions. That might sound like a small number but it represents a significant flow of material when considered over the immense timescales of Solar System evolution.

What makes this result particularly interesting is how that lost mass splits up between different fates. About 20% escapes as asteroids and meteoroids that occasionally cross Earth's orbit and sometimes make rather dramatic entrances into our atmosphere as meteors. The remaining 80% is ground down through mutual collisions into meteoritic dust that feeds the faint glow that is the zodiacal dust that is visible in the night sky after sunset or before sunrise. The more familiar asteroids like Ceres, Vesta, and Pallas were excluded from the study since they have survived sufficiently long to no longer be participating in the ongoing depletion of material.

Understanding the asteroid belt's mass loss is important and has a direct implication for Earth's evolution. The large bodies that escape the belt don't simply vanish into space, some eventually find their way to the inner Solar System, where they become potential impactors. The research suggests that if the current mass loss rate is extrapolated backward in time, the asteroid belt could have been about 50% more massive around 3.5 billion years ago, with a mass loss rate about twice as high. This correlates remarkably well with geological evidence from the Moon and Earth showing a declining bombardment rate over the past few billion years.

The asteroid belt, is often considered to be a permanent feature of our Solar System, but this research reveals it as a dynamic structure that's been gradually losing material for billions of years. The glass spherule layers found in Earth's rock strata reveal a more violent past when a more massive asteroid belt sent far more chunks of rock our way. Today, that bombardment has settled into a steady trickle as the belt continues its slow decline. Understanding this process not only helps us piece together the impact history that shaped Earth's surface but it also provides crucial data for modeling the future risk from near Earth objects.

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

On Sept. 26, 2022, at 7:14 p.m. EDT, NASA smashed a pint-sized spacecraft into an asteroid — and changed the course of both the space rock and planetary defense forever.

The purpose of that mission, dubbed the Double Asteroid Redirection Test (DART), was to see whether an "impactor," or a heavy, fast craft, could deflect a dangerous asteroid from a potential collision course with Earth.

As early as 1968, students at MIT had proposed a thought experiment to commandeer NASA rockets to deflect an earthbound asteroid. But it wasn't till 1980, when geologist Luis Alvarez and colleagues found a global band of iridium in Earth's crust dating to the end of the Cretaceous period, that the potential stakes of such a strike became clear.

The layer of iridium, rare on Earth but common on asteroids, suggested that a massive space rock had struck our planet 66 million years ago, triggering a mass extinction event that wiped out the dinosaurs. In 1992, scientists found the "smoking gun:" the roughly 120-mile-wide (200 kilometers) Chicxulub crater off of Mexico's Yucatan peninsula.

In the 1980s and 1990s astronomers identified a bevy of potentially dangerous space rocks — sometimes only after they had passed worryingly close to Earth. So they began to seriously consider proposals to neutralize asteroids: by nuking them , shooting lasers at them, shoving them off course with steam clouds, or smashing something big into them. (The “smashing” scenario is now known as the kinetic impactor method.)

Then in 2013, a meteor the size of a semitrailer breached the atmosphere over Chelyabinsk, Russia. Exploding with 30 times the energy of the Hiroshima blast, it blew out the windows on more than 7,000 buildings and caused instant ultraviolet burns and injuries to 1,600 people on the ground. No one saw it coming.

Chelyabinsk "was a cosmic wake-up call," then NASA Planetary Defense Officer Lindley Johnson said about the event.

In 2017, NASA approved funding for a project to test a kinetic impactor against Dimorphos, a moonlet that orbited the larger asteroid Didymos. The duo posed little threat to Earth, but because they skim relatively close to our planet, they presented a good test bed for the kinetic impactor method.

Over the next few years, scientists with NASA and Johns Hopkins' Applied Physics Laboratory built a 6.2-foot-long (1.9 meters), 1,280 pound (580 kilograms) spacecraft whose sole purpose was to slam into Dimorphos.

DART launched on Nov. 23, 2021, and smashed into the moonlet's rocky heart, just shy of center, on Sept. 26, 2022, using a special onboard camera to record its last moments. A tiny cube camera had split off from the main rocket days earlier, and lingered to record the chaotic aftermath of the collision.

DART shortened Dimorphos' orbit by 32 minutes, more than astronomers expected and far more than the 73 seconds needed for the project to be considered a success. The impact also created a swarm of boulders, Hubble revealed.

Follow-up studies have raised concerns about the unintended consequences of future deflection missions. One found that rogue boulders from the rubble pile could hit Earth and trigger a spectacular meteor shower in 30 years, while another study predicted that boulders could crash into Mars.

And earlier this year, scientists determined that the boulders aren't behaving as expected, traveling faster and in non-random configurations that hint at physics not yet accounted for. The findings suggest we still have more to learn before we can rely on such technology to save us from a true killer space rock.

"If an asteroid was tumbling toward us, and we knew we had to move it a specific amount to prevent it from hitting Earth, then all these subtleties become very, very important," Jessica Sunshine, a University of Maryland scientist who worked on DART, said at the time. "You can think of it as a cosmic pool game. We might miss the pocket if we don’t consider all the variables."

DART remains the first and only planetary defense mission to be tested on a real space rock. But China has announced that its space agency will mount its own DART-like mission to strike the roughly 100-foot-wide (30 meters) asteroid 2015 XF261, with the launch window opening as soon as 2027.

Scientists are considering the possibility of launching a nuclear weapon at an asteroid that could potentially hit the moon in 2032 — but they say more research is needed before taking this forward as an option.

The investigation concerns asteroid 2024 YR4, which reached notoriety shortly after its discovery in December 2024 when scientists (working with limited observations) revealed it had a relatively high chance of impacting Earth in 2032, peaking at 3.1%.

This got media attention as the 180-foot (55 meters) asteroid is large enough to wipe out a city. However, the odds of disaster quickly dropped when subsequent observations showed the asteroid was very unlikely to come near Earth. Its impact probability fell to less than 1 in 360 (0.28%) as of February 2025.

That's good news for our planet, but the updated tracking also shows the asteroid has a fairly good chance of crashing into the moon — about 4%. A crash of an object that size, and relatively close to Earth, would almost certainly have some effect on us.

Threats to astronauts, spacecraft

If an asteroid the size of 2024 YR4 crashed into the moon, it would produce lunar "ejecta," kicking up the regolith — the top layer of dust and small rocks on the surface — which would substantially increase micrometeoroid debris in low Earth orbit.

The flux could be up to 1,000 times "above background levels … possibly threatening astronauts and spacecraft" as little space rocks can puncture spacecraft, spacesuits and similar, the researchers wrote in the new study, which was posted Sept. 15 on the preprint server Arxiv and has not yet been peer-reviewed.

While that's a threat for satellites and the International Space Station (if it does not deorbit in 2031 as planned), any attempt to divert the asteroid could create an even higher risk, the authors warned. There remains great uncertainty about the asteroid's exact mass, which means any attempt to nudge it off course would also be far from certain. An ill-planned deflection mission could accidentally push the asteroid toward Earth, the researchers wrote.

Scientists do have diverting experience to draw upon: NASA's DART mission deflected an asteroid moonlet's path in 2022. DART sent a kinetic impactor into the moonlet, called Dimorphos, which slightly altered the little space rock's path around its parent asteroid, Didymos. But the researchers behind the new study concluded that any attempt at deflecting 2024 YR4 would "appear impractical" because of constraints such as not knowing the object's mass — and having a very limited window to study the object further before its close flyby in 2032.

Just nuke it

The researchers instead consider the idea of breaking up the asteroid. A DART-style spacecraft could be sent to not move the asteroid but to punch it into pieces, they suggest. This is an untested concept, but NASA has several years to think about it given the launch window for such a mission is between April 2030 and April 2032.

Failing that, NASA could send a nuclear mission, detonating a rocket-propelled nuke on or near the asteroid before its approach. This method is also untested but theoretically possible. There would be slightly less time to get that mission ready, but that could launch between late 2029 and late 2031, according to the researchers.

The paper emphasizes that there's still a 96% chance that the asteroid breezes by the moon with no issues, but the researchers say this situation as an opportunity to further research asteroid-smashing spacecraft.

They call on other researchers to provide estimated build times for spacecraft, and to create more designs — just in case a more serious threat comes by our planetary neighborhood.

Around 66 million years ago, the reign of the dinosaurs came to a fiery end. An asteroid about 7 miles (12 kilometers) wide, flying at 27,000 mph (43,000 km/h), slammed directly into Earth. The impact triggered a cascade of deadly events that led to the fifth mass extinction that eliminated dinosaurs, with the exception of some birds.

But what happened to the Mount Everest-size asteroid?

When it smashed into Earth "with the energy of about 8 billion times a World War II-era nuclear bomb, the asteroid basically vaporizes," Sean Gulick, research professor and co-director of the Center for Planetary Systems Habitability at the University of Texas at Austin, told Live Science. The asteroid became "a fine dust that ends up in the upper atmosphere and rains down" over the entire planet.

Decades of asteroid dust rained down to form what is now known as the iridium anomaly, a thin layer of rock that has 80 times more iridium than anywhere else in Earth's crust, Gulick said. While iridium is highly concentrated in asteroids, it's almost nonexistent in Earth's outer shell — a key piece of evidence linking the 66 million-year-old layer to the dinosaur-killing asteroid.

Perhaps the only chunk of the asteroid known to exist is a sesame-seed-size fragment found by Frank Kyte, a geochemist at UCLA. The rock bit was discovered in a core sample drilled off Hawaii, Kyte reported in the journal Nature in 1998. More tiny shards were allegedly discovered in 2022, but that claim was not backed by peer review.

"We would have to get pretty lucky to find a larger chunk," Gulick said. But if we did, scientists could learn more about the "process of shock" experienced by the asteroid itself and make even more precise estimates about the pressures and temperatures it experienced, for example.

The asteroid left behind a number of additional clues about its journey, including the huge crater it created when the giant rock collided with Earth. Roughly 110 miles (180 km) wide and about 12 miles (20 km) deep, the Chicxulub crater in what is now Mexico bears the massive scar of the asteroid. Named after a town near the center of the impact, the crater has been covered by rock and sediment that shifted over tens of millions of years and a major portion is hidden under the Gulf of Mexico. But still visible from the surface is an arc of sinkholes along part of its rim that formed in weakened limestone.

Related: What if a giant asteroid had not wiped out the dinosaurs?

The impact also generated a nearly mile-high tsunami that moved through the entire ocean, moving water as fast as 89 mph (143 km/h). The massive waves caused marks on the seafloor — called "megaripples" — that were as tall as five-story buildings and are preserved deep beneath Louisiana. A seismic survey revealed that the water that formed the ripples came from the direction of the Chicxulub crater.

Besides killing the unlucky creatures in the immediate area of the asteroid's landfall and subsequent tsunami, the impact triggered a series of other devastating effects, including deadly acid rain and a global firestorm. But perhaps most destructive was the massive cloud of debris that shrouded Earth, drastically cooling the planet, blocking sunlight and photosynthesis, and collapsing the food chain (although the length of this "nuclear winter" is debated). The asteroid and its aftermath are widely agreed to be the cause of the nonavian dinosaurs' extinction and ultimately wiped out about 75% of species on Earth.

"The energy release was like fighting total nuclear war, over and over again, 10,000 times," said Alan Hildebrand, a planetary scientist and associate professor at the University of Calgary. Hildebrand co-authored the paper that published the discovery of the Chicxulub crater in 1991, and that work provided major evidence linking the crater's connection to the death of the dinosaurs.

It's no surprise to Hildebrand that the asteroid wiped out the majority of life on Earth.

In Alberta, where he was during the time of the interview, Hildebrand marveled at the sheer power of the impact. The nearby layer from the Chicxilub impact is 0.4 to 0.8 inches (1 to 2 cm) thick, "and that material was blasted up here from the Yucatán Peninsula," he said.

What's inside Earth quiz: Test your knowledge of our planet's hidden layers

A skyscraper-size, "potentially hazardous" asteroid is set to make a close approach to Earth this week — and you can see it zoom past for yourself, either by using a backyard telescope or via a free online livestream.

The asteroid, which was discovered earlier this year, was initially predicted to have a slim chance of hitting our planet in 2089 — temporarily earning it a spot at the top of the European Space Agency’s (ESA’s) impact risk list. But, following new observations, it is no longer considered an imminent threat.

The space rock, dubbed 2025 FA22, is somewhere between 427 and 951 feet (130 and 290 meters) across, making it large enough to wipe out a major city were it to collide with Earth. It will reach its minimum distance to us in the early hours of Thursday (Sept. 18), coming within 520,000 miles (835,000 kilometers) of our planet — just over twice as far away from us as the moon — and will be traveling at around 24,000 mph (38,600 km/h).

2025 FA22 was initially discovered in March by the Pan-STARRS 2 telescope in Hawaii. The asteroid quickly made headlines when it was revealed that it has a 0.01% chance of hitting Earth when it returns for another close flyby on Sept. 23, 2089. (This story was somewhat overshadowed by fellow asteroid 2024 YR4, which was briefly predicted to have a much higher chance of impacting our planet in 2032 at around the same time 2025 FA22 was first spotted.)

Despite the low odds of a collision, space agencies took the threat of 2025 FA22 seriously, and the asteroid was briefly bumped to the top spot on ESA’s Risk List, which monitors all near-Earth objects predicted to have a non-zero chance of impacting our planet.

"However, high-priority follow-up observations soon allowed astronomers to refine the asteroid’s trajectory and rule out any impact risk," according to a new ESA statement. Asteroid 2025 FA22 was removed from ESA's Risk List entirely in May.

Related: NASA's most wanted: The 5 most dangerous asteroids to Earth

The now totally safe flyby of 2025 FA22 will be shared on a free livestream by the Virtual Telescope Project, which will track the object using a telescope in Manciano, Italy. The livestream will begin at around 23:00 p.m. EDT on Wednesday (Sept. 17).

During its close approach, the asteroid could reach an apparent magnitude of 13, which will make it just bright enough to spot with a decent backyard telescope or a pair of stargazing binoculars, according to IFLScience. You can find where it is in the night sky using TheSkyLive.com.

Researchers will be keeping a close eye on the asteroid from observatories across the globe, including NASA's Goldstone radar telescope in Barstow, California, which has the capability to reveal more about the space rock's true size and shape.

The International Asteroid Warning Network (IAWN) is also taking 2025 FA22's flyby as an opportunity to practise its emergency protocols by running a practice scenario under the pretence that the asteroid will still impact us in 2089. This mock test, named the 2025 FA22 IAWN Campaign, will involve measuring as many of the asteroids' characteristics as accurately as possible, in preparation for a hypothetical mission to deflect the space rock in the future.

"While 2025 FA22 poses no danger, practicing our ability to measure these properties is important, as they influence how an asteroid will react to any attempt to deflect it off of a collision course with Earth," ESA representatives wrote about the campaign.

In reality, 2025 FA22 will not get very close to us in 2089. The latest calculations from NASA's Jet Propulsion Laboratory suggest that it will only come within 3.7 million miles (6 million km) of Earth, more than seven times further away than its current flyby.

However, the asteroid will return for a super close approach in 2173, when it will reach a minimum distance of around 200,000 miles (320,000 km), bringing it closer to us than the moon.

Scientists in Japan now believe that liquid water once flowed through the heart of the near-Earth asteroid Ryugu, after researchers detected something unusual in the samples of the space rock that were returned to our planet five years ago.

The surprising findings also have potential implications for how Earth acquired its own water, the researchers say.

162173 Ryugu is a roughly 3,000-foot-wide (900 meter) asteroid that orbits the sun every 474 days on a trajectory that frequently overlaps with Earth's. It is unlikely to ever hit our planet, but it is still large enough and comes close enough to us to be considered "potentially hazardous" by NASA.

Ryugu was visited by Japan's Hayabusa2 mission between 2018 and 2019, which deployed a probe that landed on the spinning top-shape space rock and collected samples that were later returned to Earth in December 2020.

In a new study, published Sept. 10 in the journal Nature, researchers unearthed chemical irregularities within these samples, which they say can currently be explained only by the historic presence of flowing water within the asteroid.

"We found that Ryugu preserved a pristine record of water activity," study lead author Tsuyoshi Iizuka, a geochemist at the University of Tokyo in Japan, said in a statement. There is also "evidence that fluids moved through its rocks," he added. "It was a genuine surprise!"

Related: Key building block for life discovered on distant asteroid Ryugu — and it could explain how life on Earth began

The new findings emerged after the team analyzed the radioactive isotopes — rare versions of elements with an altered atomic mass — of lutetium (Lu) and hafnium (Hf) within the samples.

Lu-176 naturally decays into Hf-176 via beta decay, in which an element spits out charged subatomic particles, such as electrons or positrons, transforming them into something else. By working out the ratio of Lu-176 to Hf-176 and comparing it to the half life of Lu-176 — the time taken for half a sample of the isotope to naturally decay — the team aimed to work out how old the samples were.

But when they carried out their analysis, the researchers found that there was far too much Hf-176 in the samples. The researchers argue that the only thing that could properly explain this result was that ancient liquid water had washed away a majority of Lu-176 within the samples, which could have started happening shortly after Ryugu was born.

A watery past

"The most likely trigger [for the water] was an impact on a larger asteroid parent of Ryugu, which fractured the rock and melted buried ice, allowing liquid water to percolate through the body," Izuka said.

Recent analysis from the James Webb Space Telescope (JWST) had suggested that Ryugu's parent asteroid may have also spawned the asteroid Bennu, which was visited by NASA's OSIRIS-REx mission that later returned samples of the asteroid to Earth in September 2023. However, similar signs of flowing water have not been seen within Bennu's samples so far, creating uncertainty about the asteroids' respective origins.

Given that Ryugu likely had flowing water, the researchers also believe that its parent asteroid may have contained ice for at least a billion years after the solar system was formed, which is far longer than most asteroids were thought to be able to hold onto their water.

"This changes how we think about the long-term fate of water in asteroids," Izuka said. "The water hung around for a long time and was not exhausted so quickly as thought."

It is widely accepted that a majority of Earth's water likely came from impacts with asteroids, comets or other planetesimals in the early days of the solar system. The new findings hint that asteroids could have played a much larger role in this process than previously thought, potentially delivering up to three times more water to our planet than expected, the researchers claim.

The study team is now planning to analyze veins of phosphate within the samples, which could pin down a more accurate age for the water that flowed through Ryugu, and look more closely at the isotopes from asteroid Bennu to see if it too has signs of flowing water, according to Live Science's sister site Space.com.

When the potentially hazardous asteroid 99942 Apophis makes its breathtakingly close flyby of Earth on April 13, 2029, more than 2 billion people across Africa and Western Europe will be able to watch it drift across the night sky. Under clear skies, the space rock will appear as a faint star — about as bright as the stars in the Big Dipper and easily visible to the unaided eye — gliding steadily overhead.

Apophis' flyby will mark "the first time in space history that a potentially hazardous asteroid is visible to the naked eye," Richard Binzel, a professor of planetary sciences at MIT, said Monday (Sept. 8) during a keynote address at the Europlanet Science Congress in Helsinki, Finland. Astronomers estimate that a close approach by an asteroid this large — 1,100 feet (340 meters) across, or roughly the height of the Eiffel Tower — occurs only once every 7,500 years.

For the public, it will be a dazzling, once-in-a-lifetime spectacle. For scientists, it promises something even rarer: a once-in-a-millennium natural experiment to watch in real time how Earth's gravity reshapes a massive asteroid. "We don't know," Binzel said, "and we won't know until we look."

Binzel, a pioneer in asteroid hazard research and the inventor of the Torino Impact Hazard Scale that's used to rate impact risks of asteroids and comets, underscored one point above all: "If you take nothing else away from this talk, I want you to take away three things," he said during his presentation. "Apophis will safely pass the Earth; Apophis will safely pass the Earth; Apophis will safely pass the Earth."

Related: NASA's most wanted: The 5 most dangerous asteroids to Earth

When Apophis was first discovered in 2004, however, the picture was far less certain. Early calculations suggested a 2.7% chance of impact on April 13, 2029, placing it at Level 4 on the Torino scale — the highest rating ever given to a near-Earth object. Scientists named the asteroid 99942 Apophis, after the Egyptian god of the underworld, earning it the nickname the "god of chaos" asteroid.

Over the next two decades, continuous tracking and radar observations narrowed Apophis' orbit from hundreds of miles of uncertainty to just a few. By 2021, Apophis was formally removed from all risk lists, and scientists estimated it posed no threat for at least the next 100 years. In September last year, however, a study noted there is still a tiny possibility that an unknown asteroid could nudge it onto a collision path before its close Earth flyby in 2029. The odds are over one in a billion, and while scientists won't be able to fully rule out this scenario for another three years, astronomers remain confident Apophis poses no danger for the next century.

"It's been a lot of work by a lot of people to make sure we can say totally and confidently that Apophis will safely pass the Earth — absolutely no doubt," Binzel said.

"Earth won't care, but Apophis will"

While Earth itself will barely notice the encounter, Apophis will not leave unchanged. As it passes just over 18,600 miles (30,000 kilometers) above the planet's surface — closer than geostationary satellites — its Aten-class orbit, which lies mostly inside Earth's path around the sun and is thus often hidden in our star's bright glare, will be reshaped into a wider Apollo-class trajectory. Its rotation may also shift, which might send the asteroid into a fresh tumbling state, Binzel said.

"The Earth won't care, but Apophis will care, because Apophis' orbit will change," he said. "It's all about the encounter physics."

To capture those changes firsthand, NASA has reassigned its OSIRIS-REx spacecraft, fresh from its mission to the asteroid Bennu, to a new role as OSIRIS-APEX. The probe will rendezvous with Apophis before the flyby, mapping its surface, monitoring its spin, and measuring how Earth's gravity alters the asteroid during its close pass. Among the most tantalizing goals, Binzel said, is the chance to measure seismic vibrations inside Apophis.

"In 60 years of planetary science, we've only measured seismicity for two objects: the moon and Mars," he said. "This would be the opportunity for another leap forward in seismic measurements and interpretation of interior properties."

That leap could come from the Rapid Apophis Mission for Space Safety (RAMSES). The European Space Agency (ESA) mission, if approved at ESA's Ministerial Council in November, would launch in spring 2028 and arrive at the asteroid by February 2029. The mission's goal would be to observe Apophis before, during and after its flyby of Earth, Monica Lazzarin, a professor of physics and astronomy at the University of Padua in Italy and a member of the RAMSES science team, said at the conference.

Hovering as close as 3 miles (5 km) from the asteroid during its April 12-14, 2029, encounter, RAMSES would map Apophis' orbit, search for dust clouds raised by tidal forces, and possibly deploy a small satellite called a cubesat to touch the surface and detect seismic waves, Lazzarin said.

Beyond science, Apophis is a proving ground for planetary defense, scientists say, as it will aid humanity's effort to understand and prepare for the rare-but-real risk of an asteroid impact. While Apophis itself poses no danger, it belongs to the class of near-Earth asteroids that could one day threaten our planet. By studying how Earth's tidal forces reshape Apophis, scientists can refine the models that would be critical for deflecting a hazardous asteroid.

"Apophis is not a planetary defense emergency," Tom Statler, a planetary scientist at NASA headquarters in Washington, D.C., added during a Q&A session at the conference. "It is an opportunity, and an unprecedented one."

"Asteroids are not something to be scared of," he added. "They're something to understand — and that's what we're doing."

A bus-size asteroid, first spotted just over a week ago, will zoom past Earth today (Sept. 3). The space rock will not get this close to us again until Sept. 4, 2125 — almost 100 years to the day.

The asteroid, dubbed 2025 QV5, was first spotted on Aug. 24. It is approximately 35 feet (11 meters) across, or around the same width as a school bus is long, and is hurtling toward us at more than 13,900 mph (22,400 km/h), according to NASA's Jet Propulsion Laboratory (JPL) Asteroid Watch.

The space rock will make a close approach to Earth on Wednesday, passing within 500,000 miles (805,000 kilometers) of our planet — or around twice as far away from us as the moon, according to JPL's Small-Body Database Lookup.

2025 QV5 has a roughly circular orbit around the sun, circling our home star every 359.4 days. During this time, it drifts between the orbits of Earth and Venus as it is subtly pulled from side to side between the two planets. As a result, it is unlikely to ever hit us. And even if it did, it is too small to be considered "potentially hazardous" and most of its material would likely burn up in the atmosphere.

Nevertheless, scientists are still keen to learn as much as they can about the space rock, and it has been listed as a target for NASA's Goldstone radar telescope in Barstow, California — which specializes in tracking and imaging near-Earth asteroids — over the coming days.

Related: NASA's most wanted: The 5 most dangerous asteroids to Earth

2025 QV5 will make several more "close approaches" to Earth over the next century, including flybys in 2026 and 2027. However, these flybys will occur at much greater distances from our planet. Next year, for example, the asteroid will only come within 3.3 million miles (5.3 million km) of us and will be three times further away again when it passes by in 2027.

The next time that the space rock will get anywhere near this close again is on Sept. 4, 2125 — approximately 100 years, 1 day and 2 hours after its current flyby — when it will reach a distance of around 830,000 miles (1.3 million km) from Earth, according to current calculations from the Small-Body Database Lookup.

However, the future date and distance of this cosmic coincidence are not fixed in place.

As researchers collect more data on the movements of 2025 QV5, they may refine a more accurate orbital trajectory for the object, which will change when it is likely to return. For example, the odds of the potential "city killer" asteroid 2024 YR4 hitting Earth in 2032, which made headlines earlier this year, frequently changed before eventually dropping to zero as researchers collated more observations of the space rock.

Asteroids can also be knocked off course by gravitational interactions with other objects, such as planets and larger space rocks. If 2025 QV5 were to drift past an undiscovered asteroid between Earth and Venus over the next 100 years, we may not even know it has been redirected until it fails to show up on its expected trajectory in the future.

The near-Earth asteroid Bennu contains stardust that is older than our solar system, as well as organic materials and ices from interstellar space, three fresh studies of the asteroid's sample materials show.

Scientists all over the world have been poring over samples of Bennu ever since material from the asteroid was brought to Earth in 2023, courtesy of NASA's OSIRIS-REx mission, which flew alongside the asteroid before briefly landing on it and scooping up samples in 2020.

The findings provide a glimpse at the conditions in the cosmos before our solar system arose 4.6 billion years ago and reveal more about the parent body that generated the 1,600-foot-wide (nearly 500 meters) asteroid.

A violent past

The first of the three papers, published Aug. 22 in the journal Nature Astronomy, suggests Bennu's ancestor broke apart in a violent collision, after a complicated history. That older body contained materials from a number of distinct environments: close to the sun, far from the sun but still within our solar system, and beyond our solar system in interstellar space.

Scientists spotted these locations by looking at isotopes, or element types, in the sample of Bennu's dust. Isotopes that originated in the solar system had a different makeup than those that came from interstellar stardust, for example.

"All of these constituents were transported great distances to the region that Bennu's parent asteroid formed," Ann Nguyen, co-lead author of the paper and a planetary scientist at NASA's Johnson Space Center in Houston, said in a NASA statement.

Related: James Webb telescope reveals that asteroids Bennu and Ryugu may be parts of the same gigantic space rock

Scientists suggest the parent asteroid formed in the outer solar system, likely beyond Jupiter and Saturn. But then came a cataclysmic event: "We think this parent body was struck by an incoming asteroid and smashed apart," co-lead author Jessica Barnes, an associate professor at the University of Arizona's Lunar and Planetary Laboratory, said in a statement from the University of Arizona.

After the initial impact, "the fragments re-assembled, and this might have repeated several times," Barnes added. Eventually, some of the surviving materials coalesced into Bennu.

Bennu vs. Ryugu

The second paper, published Aug. 22 in the journal Nature Geoscience, compared Bennu with primitive meteorites, as well as with asteroid Ryugu, from which samples were collected by the Japan Aerospace Exploration Agency's Hayabusa2 mission.

The parent asteroids for Ryugu, Bennu and the meteorites likely arose in a "similar, distant region of the early solar system," NASA officials wrote in the statement from the space agency. But Bennu differs from the other sampled bodies in some ways, suggesting that "this region changed over time, or did not mix as well as some scientists have thought," they said.

Specifically, Bennu's materials from the parent asteroid changed dramatically as they came into contact with water, the second study showed.

"Bennu's parent asteroid accumulated ice and dust," Tom Zega, co-leader of the second paper and a professor of planetary sciences at the University of Arizona, said in the NASA statement. "Eventually that ice melted, and the resulting liquid reacted with the dust to form what we see today: a sample that is 80% minerals that contain water."

"We think the parent asteroid accumulated a lot of icy material from the outer solar system," Zega added, "and then all it needed was a little bit of heat to melt the ice and cause liquids to react with solids."

Micrometeorites

The third paper, published Aug. 22 in the journal Nature Geoscience, traced ample evidence of micrometeorites striking Bennu. These tiny rocks left behind microscopic craters and "impact melts" — bits of rock that used to be molten — on the surfaces of the sample. Researchers also saw traces of the solar wind — the constant stream of particles coming from the sun — represented in the samples.

"The surface weathering at Bennu is happening a lot faster than conventional wisdom would have it, and the impact melt mechanism appears to dominate, contrary to what we originally thought," said co-author Lindsay Keller, a planetary scientist at NASA's Johnson Space Center.

Additionally, while Bennu itself does not host life, the study could help scientists learn how life arose on our planet, said Michelle Thompson, second lead author of the paper and an associate professor at Purdue University who specializes in space weathering.

"Asteroids are relics of the early solar system. They're like time capsules," Thompson said in a statement from Purdue. "We can use them to examine the origin of our solar system, and to open a window to the origin of life on Earth."

Two of the solar system's most famous asteroids, Bennu and Ryugu, may be fragments of a single massive "parent" asteroid that was smashed to pieces billions of years ago, new data from the James Webb Space Telescope (JWST) reveals.

If true, the sibling space rocks — which have both recently been visited by spacecraft that successfully returned samples of them to Earth — could shed light on how asteroid families are created and dispersed throughout our cosmic neighborhood.

Bennu is a roughly 1,650-foot-wide (500 meters) asteroid recently visited by NASA's OSIRIS-REx mission, which touched down on the space rock in 2022 and collected samples that were returned to Earth in September 2023, and have since yielded several promising discoveries. Ryugu, meanwhile, spans around 2,950 feet (900 m) and was visited by Japan's Hayabusa2 probe in 2019, which delivered samples of the asteroid to our planet in December 2020.

Both space rocks are shaped like spinning tops and are considered "potentially hazardous asteroids" due to their size and relative proximity to Earth. Neither poses a perceivable threat to our planet for at least the next century — although NASA is keeping a close eye on Bennu, due to the slim chance it could collide with us in 2182.

There are several different ideas about where the two asteroids originate from, but one leading theory is that the pair belongs to the Polana asteroid family, which was created when a massive asteroid broke apart in the early solar system. The largest remaining chunk of this ancient asteroid is 142 Polana, a gigantic space rock spanning more than 34 miles (55 kilometers) wide that is located in the main asteroid belt between Mars and Jupiter.

In a new study, published Aug. 18 in The Planetary Science Journal, researchers compared spectroscopy data of 142 Polana, collected by JWST, with the samples of Bennu and Ryugu brought back to Earth. The researchers found that all three space rocks bear a striking resemblance to one another, suggesting they all originated from the same parent asteroid. However, it is still not 100% certain if this is the case.

Related: 'City killer' asteroid 2024 YR4 could shower Earth with 'bullet-like' meteors if it hits the moon in 2032

"Very early in the formation of the solar system, we believe large asteroids collided and broke into pieces to form an 'asteroid family' with Polana as the largest remaining body," study lead author Anicia Arredondo, a planetary scientist at Southwest Research Institute (SwRI) in Texas, said in a statement. The findings "suggest that remnants of that collision not only created Polana, but also Bennu and Ryugu as well," she added.

All three asteroids share the same core composition of elements and minerals, such as carbon and magnetite, a rare form of iron oxide. However, there are some subtle differences in the concentrations of these substances between 142 Polana and the samples of Bennu and Ryugu, meaning a definite conclusion cannot be reached yet.

The study team believes that these discrepancies are likely caused by the asteroids' respective outer surfaces, which have each been slightly altered since they broke apart.

"Bennu and Ryugu are now much closer to the sun than Polana, so their surfaces may be more affected by solar radiation and solar particles," study co-author Tracy Becker, a SwRI planetary scientist, said in the statement. "Likewise, Polana is possibly older than Bennu and Ryugu and thus would have been exposed to micrometeoroid impacts for a longer period," she added. "That could also change aspects of its surface, including its composition."

Despite the differences, the researchers say that a shared parent asteroid is the best possible explanation for the space rocks' origins.

"They are similar enough that we feel confident that all three asteroids could have come from the same parent body, " Arredondo said.

Three years ago, NASA made history by deliberately smashing a spacecraft into a large asteroid, altering its course and demonstrating humankind’s ability to protect our planet from "potentially hazardous" space rocks in the future.

But a new analysis hints that the debris from this monumental collision is not behaving as expected, raising doubts about the success of future asteroid-deflecting missions.

On Sept. 26, 2022, NASA's Double Asteroid Redirection Test (DART) spacecraft purposefully collided with the asteroid Dimorphos, crashing directly into the middle of the space rock at around 15,000 mph (24,000 km/h). The mission was a smashing success: Not only did DART alter Dimorphos' trajectory — shortening its trip around its partner asteroid Didymos by around 30 minutes — it also completely changed the shape of the asteroid.

The collision, which occurred more than 7 million miles (11 million kilometers) from Earth, demonstrated that this type of action, known as the "kinetic impactor" method, was a conceivably viable option for protecting our planet from potentially hazardous asteroids.

However, a new study, published July 4 in The Planetary Science Journal, has revealed a hidden complication: Dozens of large "boulders," which were knocked loose from the asteroid by the spacecraft are apparently traveling with greater momentum than predicted and have configured into surprisingly non-random patterns.

Related: Could scientists stop a 'planet killer' asteroid from hitting Earth?

The researchers analyzed images from the European Space Agency's (ESA) Light Italian Cubesat for Imaging of Asteroids (LICIACube), which flew alongside DART to monitor the collision. This allowed them to track 104 boulders — each between 0.7 and 11.8 feet (0.2 to 3.6 meters) across — as they shot away from the asteroid.

The big takeaway was that these boulders had around three times more momentum than predicted, likely as the result of "an additional kick" the boulders received as they were pushed away from the asteroid's surface, study lead author Tony Farnham, an astronomer at the University of Maryland, said in a statement. "That additional factor changes the physics we need to consider when planning these types of missions," he added.

The team also noted that the boulders were arranged into unexpected patterns: "We saw that the boulders weren't scattered randomly in space," Farnham said. "Instead, they were clustered in two pretty distinct groups, with an absence of material elsewhere, which means that something unknown is at work here."

The researchers want to learn more about what happened so that we have all the necessary information at hand if and when we need to make decisions about using a kinetic impactor to protect our planet from an incoming space rock in the future.

"If an asteroid was tumbling toward us, and we knew we had to move it a specific amount to prevent it from hitting Earth, then all these subtleties become very, very important," study co-author Jessica Sunshine, an astronomer at the University of Maryland, said in the statement. "You can think of it as a cosmic pool game," she added. "We might miss the pocket if we don't consider all the variables."

Unpredictable fragments

This is not the first time scientists have noticed something unexpected about the fallout from the DART mission.

In April 2024, researchers noted that some of the largest boulders might have been set on a collision course with Mars and could smash into the Red Planet in around 6,000 years, potentially endangering any future human colonies that may live there.

In August last year, simulations using LICIACube data also suggested that some of the smaller fragments from the asteroid could hit Earth in around 30 years, potentially triggering a spectacular meteor shower without posing a real threat to our planet.

However, despite all these uncertainties, the kinetic impactor method is still the most viable option to protect ourselves from any real threat of being hit by an asteroid.

This topic was discussed earlier this year when the "city killer" asteroid 2024 YR4 was temporarily believed to have a roughly 3% chance of hitting Earth in 2032. The odds of a collision are now zero, but experts are keen to keep the conversation going, especially as the severe cuts to NASA's budget proposed by the Trump administration could limit our ability to spot dangerous space rocks.

Researchers will get a better idea of what is happening with the Dimorphos debris next year, when ESA's Hera spacecraft arrives at the asteroid to properly study the fallout from the DART collision.

Update: On Wednesday (July 2), NASA confirmed that A11pl3Z is an interstellar object and gave it a new official name — 3I/ATLAS. The agency also revealed that the object is a comet, not an asteroid, and updated other information about its trajectory through the solar system. You can see the interstellar interloper for yourself in a live stream by the Virtual Telescope Project on Thursday (July 3).

Astronomers have spotted what they think might be an "interstellar object" hurtling through the solar system — and it's headed toward us. The visiting space object, potentially the third of its kind ever seen, will make its closest approach to the sun in around four months, before eventually leaving our cosmic neighborhood forever.

The newly discovered object, currently dubbed A11pl3Z, was first spotted in data collected between June 25 and June 29 by the Asteroid Terrestrial-impact Last Alert System (ATLAS), which automatically scans the night sky using telescopes in Hawaii and South Africa. The mystery object was confirmed by both NASA's Center for Near Earth Object Studies and the International Astronomical Union's Minor Planet Center on Tuesday (July 1), according to EarthSky.org.

A11pl3Z is most likely a large asteroid, or maybe a comet, potentially spanning up to 12 miles (20 kilometers). It is traveling toward the inner solar system at around 152,000 mph (245,000 km/h) and is approaching us from the part of the night sky where the bar of the Milky Way is located.

Based on A11pl3Z's speed and trajectory, experts think it originated from beyond the sun's gravitational influence and has enough momentum to shoot straight through our cosmic neighborhood without slowing down. However, more observations are needed to tell for sure.

Until now, only two confirmed interstellar visitors have ever been spotted: Comet 2I/Borisov, which was seen sailing through the solar system in 2019; and 'Oumuamua, a cigar-shaped object that made headlines in 2017 when some astronomers argued it was potentially an alien probe, before experts showed it was most likely a hydrogen-spewing space rock.

But scientists have long suspected that many more interstellar interlopers likely pass through our cosmic neighborhood without ever being detected.

Related: 1 million 'interstellar objects' — each larger than the Statue of Liberty — may lurk in the outer solar system

A11pl3Z is currently around 3.8 times as far from the sun as Earth is. Its first close approach to a planet will be on Oct. 3, when it comes relatively close to Mars. Shortly afterward, it will reach its closest point to the sun, or perihelion, on Oct. 23, coming within two Earth-sun distances of our home star, according to Universe Today.

Earth will be on the opposite side of the sun as A11pl3Z during the object's solar flyby, so it will pose no risk to our planet. The object will likely make its closest approach to Earth in December, on its journey back out of the solar system.

Researchers will continue to study the object in the coming weeks and months to learn more about its size, shape and origins. And, compared with when the previous interstellar objects passed by, we now have better ways of tracking and imaging the mysterious space rock.

For example, the Vera C. Rubin Observatory — the world's most powerful optical telescope, which recently released its first images — will likely be fully operational by the time A11pl3Z is closest to us, and the telescope is exceptionally good at spotting moving objects, like asteroids.

Some researchers have also proposed using NASA's Mars rovers to photograph the object as it flies close to the Red Planet.

Avi Loeb, an astronomer at Harvard University who first proposed that 'Oumuamua might be an alien probe, has additionally suggested using the James Webb Space Telescope to search for signs of "non-gravitational acceleration" — indicating, perhaps, some kind of artificial propulsion system — in A11pl3Z, via a post on Medium.

It was weirdly emotional on Monday, June 23, as several grainy white specks streaked across my computer screen while ambient rhythms buzzed in the background. Those specks were part of a film that played during the Vera C. Rubin Observatory's highly anticipated first image release conference — and they each represented an asteroid that had just been discovered. It felt like witnessing something hugely profound, and there are two reasons why.

First of all, to put it simply, with just a few nights of data, the Rubin Observatory team was able to identify 2,104 never-before-seen asteroids in our solar system — seven of which are categorized as near-Earth objects. (No, none are expected to strike our planet. Don't worry). For context, there are approximately a million known asteroids in our cosmic neighborhood; over the next few years, Rubin could very well hike that figure up to five million.

"This is five times more than all the astronomers in the world discovered during the last 200 years since the discovery of the first asteroid," Željko Ivezić, Deputy Director of Rubin's Legacy Survey of Space and Time, said during the conference. "We can outdo two centuries of effort in just a couple of years."

This is astonishing in itself — talk about an exemplary first impression — but there's still that second thing that makes Rubin's new asteroid data incredible.

They can be formatted as movies.

Welcome to Hollywood, asteroids

For some context about Rubin, this observatory is our brilliant new ground-based eye on the universe, and is located at the El Peñón peak of Cerro Pachón in Chile. It has the ability to image giant swaths of the sky using the world's largest digital camera — and when I say giant, I mean giant.

Related: 6 incredible objects hidden in Vera C. Rubin Observatory's mind-boggling first image

One of its first presented images, for instance, features a bunch of glowing, hazy galaxies of all shapes and sizes. It's difficult not to daydream when looking at a couple of lovely lavender spirals that represent realms comparable to our entire Milky Way.

But what you see below in this image is only 2% of the full Rubin view:

The plan is for Rubin to capture such massive, high-resolution images of the southern sky once every three nights for at least the next 10 years. You can therefore consider it to be a super-fast, super-efficient and super-thorough cosmic imager. Indeed, those qualities are perfect for spotting some of the smallest details trailing through the space around our planet: asteroids.

"We make movies of the night sky to see two things: objects that move and objects that change brightness," Ivezić said. "Objects that move come in two flavors. Stars in our galaxy move, and they move slowly. Much faster objects are asteroids."

Zooming into a tiny portion of one of Rubin's images, Ivezić pointed out that there are actually invisible photobombers present. He was talking about the asteroid streaks Rubin's software so kindly removed from the main attraction (I mean, look at that spiral). However, the fact that those asteroids can be removed from an image means they can be precisely isolated to begin with, making it possible to really focus on them if you want to — something that isn't always possible with zippy, fleeting space objects.

In fact, it's tremendously difficult to record an asteroid at all.

"Asteroids, they disappear after you get one picture of them," Ivezić said, calling Rubin's ability to image small objects orbiting the sun "unprecedented."

In the Rubin image Ivezić called out to showcase the observatory's asteroid-tracking capabilities, the asteroid streaks are seen in different colors. This is because each corresponds to one exposure used to create the final image. You can think of it as different images stitched together to create a final view of the asteroids' trajectories. And to take things a step further, if you slap a few of these datasets together, you can indicate asteroid motion against the more static background of stars and galaxies — like a movie.

This feature of Rubin should be huge not only because it'd allow scientists to better study asteroid movements and discover new near-Earth objects, but also for humanity's efforts in planetary defense.

Another tool to protect Earth

Over the last couple of years, scientists have really started to question how we can protect our planet if an asteroid were headed our way.

NASA's wildly successful DART (Double Asteroid Redirection Test) mission — which sent a spacecraft on a death mission to crash into an asteroid and see if the object's trajectory can be changed — was arguably the feat that brought planetary defense to the public eye. It'd also be remiss not to mention all the recent anxiety surrounding Asteroid 2024 YR4, which was potent enough to even penetrate the jokes of a random comedy show in New York City I went to around the time it was making headlines. 2024 YR4 briefly had a head-turning likelihood of hitting our planet before that likelihood shot down to nil.

There was even a hearing about asteroid safety in May, held by the U.S. House Committee on Space, Science and Technology, during which U.S. Representatives expressed their concern that asteroid defense may be impacted by President Trump's major science funding cuts.

All of this is to say that I imagine a state-of-the-art asteroid detector is very welcome in the scientific community right now.

To really illustrate the ultimate promise of Rubin's asteroid adventures, Ivezić brought up a simulation of all asteroids expected to orbit our sun.

"This blue donut is a simulation of all asteroids we expect there," he said. "All of these new discoveries are found in this one narrow slice of this big donut. In two or three years, after we start LSST later this year, we will sweep around and discover all of the millions of asteroids."

This article was originally published on Space.com.

New simulations reveal that the infamous "city killer" asteroid 2024 YR4 could shower Earth with "bullet-like" debris if it hits the moon in seven years' time, potentially triggering an eye-catching meteor shower — and endangering the satellites that orbit our planet.

2024 YR4 is a potentially hazardous asteroid measuring roughly 200 feet (60 meters) across, making it large enough to wipe out a large urban area if it were to hit Earth head-on. It was first discovered in December 2024 but made headlines earlier this year when scientists first predicted that there was a chance it could smash into Earth on Dec. 22, 2032. The odds of a collision peaked at 3.1% in February, which was enough to prompt NASA to study it extensively. However, subsequent analysis revealed there is zero chance of it impacting our planet.

But in April, researchers realized that, while Earth is no longer in the firing line, the space rock could still hit the moon. The odds of such a collision have grown slowly but steadily, and most recently jumped to 4.3% earlier this month. Experts will likely know the final likelihood by 2028, when the asteroid will make its next close approach to our planet.

In a new study, uploaded June 12 to the preprint server arXiv, researchers ran computer simulations to model what a lunar impact might look like. The team estimated that up to 220 million pounds (100 million kilograms) of material could be ejected from the lunar surface. If 2024 YR4 hits the Earth-facing side of the moon — which is roughly a 50/50 chance — up to 10% of this debris could be pulled in by Earth's gravity over the following days, the scientists wrote.

2024 YR4 would be the largest space rock to hit the moon in "at least 5,000 years," study lead author Paul Wiegert, an expert in solar system dynamics at Western University in Ontario, Canada, who has also extensively studied the "God of Chaos" asteroid Apophis that will zip past Earth in 2029, told French news site AFP. The impact would be "comparable to a large nuclear explosion in terms of the amount of energy released," he added.

Related: 'Just the tip of the iceberg': Why risky asteroids like 2024 YR4 will pester Earth for decades to come

It is important to note that the new simulations (visible below) were created before the odds of a lunar impact rose from 3.8% to 4.3% on June 16, which slightly raises the chances of this scenario playing out. But it is still far from a certainty. The findings from the new study have also not yet been peer-reviewed.

It is unlikely that any of the potential debris fragments will pose a risk to people on the planet's surface. Instead, we may be treated to a "spectacular" meteor shower as wayward fragments of rock burn up in Earth's atmosphere, which could last for several days and be seen by people across the globe, Weigert said.

But while we will almost certainly be safe on the ground from any potential lunar meteor shower, our space-based infrastructure could be under threat. The amount of debris that could potentially be pulled close to Earth makes it around 1,000 times more likely that our satellites could be struck by a meteor. And by 2032, the number of spacecraft orbiting our planet is expected to rise significantly.

"A centimeter-sized rock traveling at tens of thousands of meters per second is a lot like a bullet," Weigert said. Such an object could easily take out a satellite or cause critical damage to human-inhabited space stations, such as China's Tiangong station. (The International Space Station is scheduled to be decommissioned by 2030.)

If the odds of a lunar impact increase further in the coming years, government agencies may make the decision to try and divert the asteroid's course to protect Earth's space assets. The asteroid would be a "good target" for testing our planetary defence capabilities, Weigert said. "I'm sure it will be considered."

NASA already demonstrated its ability to redirect dangerous asteroids back in 2022, when it diverted the trajectory of the asteroid Dimorphos by slamming the DART probe into it. 2024 YR4 is only around half the size of that particular space rock.

However, if we wait too long, it may become "dangerous" to try and alter the space rock's trajectory because a wrong move could put it onto a potentially catastrophic collision course with Earth, Weigert said.

Some experts are also worried that the proposed cuts to NASA's budget by the Trump administration could make it harder to track dangerous asteroids, such as 2024 YR4, in the future.

After decades of preparation, the Vera C. Rubin Observatory released its first images to the world in a live stream on Monday (June 23). The photos, taken by the world's largest digital camera, are highly-detailed and show relatively large areas of the sky.

In a televised news conference, scientists from the observatory revealed new details about the images that far surpass the "sneak peek" images released earlier in the day. In fact, an awe-inspiring spiral galaxy image shared prior to the press conference on Monday only shows about 2% of the space cataloged in Rubin's first photo of the night sky, project scientists revealed.

The full image includes 10 million galaxies in and around the Virgo Cluster, many of which have never been seen before, Zeljko Ivezic, Project Scientist at Rubin and Deputy Director of the observatory's Large Synoptic Survey Telescope (LSST) construction project, said during the live stream.

The complete image is a whopping 3200 megapixels, which would need to be displayed on 400 ultra-high-definition TV screens for human eyes to resolve it — enough monitors to blanket an entire basketball court — Ivezic explained.

You can find all of the first-look images on the observatory's website, including a searchable and zoomable version of the full 3200-megapixel image.

"Staggering amount of data"

In the observatory's first year of operation, it will gather more data than all other existing optical observatories combined, according to a statement from the observatory.

This data will be freely available to scientists in hopes that it will lead to critical new discoveries about the universe, including the locations of previously unseen asteroids, insights into the properties of dark matter and dark energy — two invisible entities that make up a majority of the universe but remain poorly understood — and more.

Related: Vera C. Rubin Observatory: The groundbreaking mission to make a 10-year, time-lapse movie of the universe

"I trust that the stunning images and staggering amount of data the observatory will produce will support exceptional scientific efforts around the world," said Michael Kratsios, director of the White House Office of Science and Technology Policy, in the conference.

During its planned 10 years of operation, Rubin will produce about 20 terabytes of data per night by taking high-resolution photographs of the night sky at 30-second intervals, according to the statement. By the end of its run, the observatory will have captured an estimated 40 billion celestial objects and taken trillions of measurements.

The Rubin team hopes that this data will advance understanding of mysterious cosmic phenomena. "Starting today, our ability to understand dark matter, dark energy and planetary defense will grow even faster than ever before," Brian Stone, chief of staff of the National Science Foundation, which operates the Observatory along with the U.S. Department of Energy, said in the conference.

A movie of the night sky

Once fully operational later this year, Rubin will continuously take photos of the night sky to capture every possible movement of the celestial objects it can see. It will collect about 1,000 images per night, covering the Southern sky every three or four nights. These images will then be stitched together to create an extremely detailed time-lapse movie of the universe.

The time-lapse will reveal the nightly movements of asteroids, comets, stars, supernovas, galaxies and possibly other cosmic phenomena that are as yet unknown, the statement noted.

In its first few nights of observations, for example, the Rubin Observatory pinpointed the locations of more than 2,000 previously unknown asteroids moving through our solar system. By the end of its mission, the observatory is expected to discover some 5 million new asteroids — about five times the number of all known asteroids discovered in the last 200 years, researchers said in the conference.

"The movie has started, the camera is running and we're going to see our cosmos unfold before us," said Chris Wright, Secretary for the Department of Energy, in the conference.

Constellations quiz: Can you name all the animals, objects and mythological figures hiding in the night sky?

The James Webb Space Telescope (JWST) has taken its final look at the potentially hazardous asteroid 2024 YR4, at least until the potentially hazardous space rock darkens Earth's cosmic doorstep again in 2028. The latest observations reveal that, while Earth faces no risk of impact from the asteroid for the foreseeable future, the moon might not be so lucky.

The new observations, taken with JWST's Near-Infrared Camera in May, allowed scientists to calculate the space rock's trajectory with the greatest precision yet, according to a NASA statement. The new predictions suggest there's a 4.3% chance that asteroid 2024 YR4 will collide with the moon on Dec. 22, 2032 — up from the 3.8% odds of a lunar impact reported after JWST initially imaged the space rock in March.

"As data comes in, it is normal for the impact probability to evolve," NASA representatives wrote in the statement. "NASA expects to make further observations when the asteroid's orbit around the Sun brings it back into the vicinity of Earth in 2028. "

Asteroid 2024 YR4 is a building-size space rock measuring between 174 and 220 feet (53 to 67 meters) in diameter — about as wide as the Leaning Tower of Pisa is tall. If an asteroid this size were to impact Earth, it could wipe out a city with the equivalent force of 500 Hiroshima bombs, Live Science previously reported. (Again, there is no risk of an Earth impact anytime in the foreseeable future.)

The asteroid was first discovered in December 2024, when astronomers realized that its orbit around the sun routinely crosses Earth's. Early projections of its trajectory revealed a potential collision course with Earth in 2032, with the odds of an impact peaking at 3.1% in February.

Further observations with JWST and ground-based telescopes soon helped scientists hone the rock's trajectory, bringing the odds of an Earth impact down to zero.

Related: NASA's most wanted: The 5 most dangerous asteroids to Earth

At the same time, the chances of the meaty space rock striking the moon have steadily climbed. Given the rock's size, a collision with the moon would create a new crater but would not be devastating to Earth's satellite. In fact, some scientists are welcoming it as a valuable exercise in asteroid impact prediction.

"We've got our fingers crossed for a moon impact," Alan Fitzsimmons, a physics and math professor at Queen's University Belfast in the U.K. who was not involved in the JWST observations, told New Scientist in March. "It would have no effect on Earth, but would allow us to study the formation of a lunar crater by a known asteroid for the very first time."

The asteroid is currently blazing toward the outer solar system, beyond the view of Earth-based telescopes. Astronomers took advantage of JWST's emergency stockpile of discretionary observation time to view the asteroid twice — first in April and then in May. NASA has not yet confirmed whether JWST will be one of the telescopes to observe the asteroid again when it makes its next approach to Earth and the moon in 2028.

A hidden swarm of "city killer" space rocks, known as co-orbital asteroids, is likely hiding around Venus and could pose an "invisible threat" to Earth over the coming millennia if the asteroids are not found, new simulations suggest. However, there is no immediate danger to our planet, researchers told Live Science.

Co-orbital asteroids are space rocks that orbit the sun alongside a planet or other large body without truly orbiting the larger object. There are currently 20 known co-orbitals around Venus — ranging from "Trojan asteroids," which are fixed either in front of or behind a planet in its orbital plane, to a closely circling "quasimoon," known as Zoozve — all of which likely originated from the solar system's main asteroid belt between Mars and Jupiter. Dozens of similar co-orbitals also tag along with Earth, and more are being discovered all the time.

All of the Venusian space rocks are likely wider than 460 feet (140 meters) — large enough to be considered "city killers," meaning they could potentially wipe out a heavily populated area if they impacted our planet.

Although the co-orbitals pose no threat to us from afar, a close approach to Earth could cause them to be pulled away from their gravitational anchor — and thus put them on a collision course with our planet. Venus is one of our closest neighbors and comes closer to Earth than any other planet — within around 25 million miles (40 million km) at its nearest point — making its trailing asteroids a credible threat to our world.

Related: Undiscovered extra moons may orbit Earth. Could they help us become an interplanetary species?

Researchers think there are more hidden space rocks lurking around Venus. All but one of the planet's known co-orbitals have eccentricities greater than 0.38, meaning they have very elongated trajectories around the planet. This suggests there is an observational bias, likely because objects with lower eccentricities are probably being obscured by the sun's glare.

Co-orbitals can also move around relative to Venus, which can change their chances of colliding with Earth in the future. Previous research has shown that this likely happens to the space rocks once roughly every 12,000 years — known as a co-orbital cycle.

In a new study, which was uploaded May 21 to the preprint server arXiv and is currently undergoing peer review, researchers carried out a series of computer simulations to gauge whether hidden asteroids with lower eccentricities could threaten Earth. To do this, the researchers "cloned" known co-orbitals with eccentricities below 0.38 and simulated how they might behave over a 36,000-year period (three co-orbital cycles).

The simulations revealed that some of the newly added co-orbitals could pose a threat to Earth during this period. However, the study offers no indication of how likely a future collision really is, because it is "hard to predict" how many co-orbitals there really are, study lead author Valerio Carruba, an astronomer at São Paulo State University in Brazil, told Live Science in an email. "How many exactly is an open question."

"Exciting" asteroids

Since the new study was first uploaded, several media outlets have overhyped the risk of an imminent collision, with several tabloids claiming Earth could be hit by Venusian asteroids "within weeks." But there is nothing in the study to support those claims.

"None of the current co-orbital objects will impact Earth soon," Carruba clarified.

Carruba has been disappointed by some of the reporting surrounding the new study, but is glad the topic is being covered. "There has been some sensationalism about this research, and our work has been cited with some liberties," he said. "But we hope that this attention could raise interest in a very exciting class of asteroids, which should be more carefully monitored."

Related: 'Planet killer' asteroids are hiding in the sun's glare. Can we stop them in time?

The researchers also highlighted the recent discovery of the city killer asteroid 2024 YR4, which was initially predicted to have a 2.3% chance of colliding with Earth in 2032, before the odds were later downgraded to zero. This was an important reminder of the importance of detecting and monitoring potentially hazardous asteroids, they wrote.

New observational tools — such as the Vera C. Rubin Observatory in Chile, which will capture its first light later this year — will improve scientists' ability to spot dangerous space rocks, including Venus' co-orbitals, in the coming decades. However, it may also be prudent to send a telescope to Venus' orbit to specifically hunt for these objects, the researchers wrote.

"I believe that we should not underestimate their potential danger, but I would not lose sleep over this issue," Carruba said. "Soon, our understanding of this population will improve."

On Thursday (May 15), the U.S. House Committee on Space, Science and Technology convened with scientists to discuss a rather exciting topic: What can NASA do if we identify a dangerous asteroid on a collision course with Earth? It was an especially prudent subject given all the recent fuss about asteroid 2024 YR4, which had a notable chance of hitting our planet before scientists refined its position and deemed it harmless.

Most of Thursday's conversation surrounded the agency's highly anticipated Near-Earth Object (NEO) Surveyor mission, which should greatly improve hazardous asteroid detection capabilities as a whole. However, there were also many efforts to address the elephant in the room: the Trump administration's recently announced intention to slash NASA's top-line funding by 24% for the upcoming fiscal year. The proposed cut to the agency's science programs — which includes its planetary defense work — is even deeper, at 47%.

Outlined in the White House's "skinny budget proposal," as it's called, the top-line reduction would be the "largest single-year cut to NASA in American history."

"If enacted, the Trump administration's skinny budget proposal risks putting NASA on a path to irrelevance," Rep. Valerie Foushee (D-North Carolina) said during the hearing. "It threatens our economic and national security, surrenders U.S. leadership and space to our adversaries, and jeopardizes our competitiveness and standing on the world stage. That's a strategic posture I simply cannot accept."

What is NEO Surveyor?

The NEO Surveyor mission is the first space telescope that'll be dedicated to locating asteroids that could threaten Earth, NASA says. It's the agency's next big step in upping the nation's planetary defense game, which was really brought to the forefront for the public in 2022 with the DART mission.

Related: 'Planet killer' asteroids are hiding in the sun's glare. Can we stop them in time?

DART, which stands for Double Asteroid Redirection Test, sent a spacecraft to smash into an asteroid called Dimorpohos. Dimorphos orbits a larger asteroid, called Didymos. Neither threatened us, to be clear, as this was just a proof-of-concept mission. The goal was to see whether this impact would adjust Dimorphos' trajectory around Didymos; if so, it would suggest that a spacecraft can one day be sent to an actually threatening asteroid to knock it off a potential collision course with Earth. DART worked beautifully, but it could use a little help.

NEO Surveyor is more of a prophylactic measure for planetary defense. It'll be the thing that spots the asteroid we may want to smash a future DART craft into.

"We do not know of any sizable object that has a significant risk of impacting Earth in the next 100 years — however, there are a lot more to be found," Nicola Fox, the associate administrator for NASA's Science Mission Directorate, said during the hearing.

"The mission will improve NASA's ability to discover and then define the sizes and the orbits of the NEOs to understand the hazard they actually pose to us," she added. "Finding those potentially hazardous asteroids remains a top priority for NASA's planetary defense program."

One of the most promising aspects of NEO Surveyor is the fact that it'll be able to pinpoint NEOs by way of infrared detection. Infrared wavelengths aren't visible to human eyes and most human technology; they're usually thought of as heat signatures. Firefighters, for instance, can use infrared wavelengths to understand fire distribution in a burning building.

This detection strategy should yield a higher target hit rate when compared to traditional methods, which are usually based on whether sunlight reflects off an NEO. In fact, an issue with relying purely on sunlight for NEO hunting was illustrated with the Chelyabinsk asteroid that exploded over Russia in 2013, which damaged many buildings and injured over 1,000 people.

"The blast released energy equivalent to about 440 kilotons of TNT, more than 30 times the force of the Hiroshima bomb, shattering windows, injuring thousands and causing millions of dollars in property damage in Russia. Because the asteroid approached from the direction of the sun, it was undetectable by ground-based telescopes and went untracked," Rep. Brian Babin (R-Texas), who currently serves as the chairman of the House Committee on Space, Science and Technology, said during the hearing.

Though NEO Surveyor still won't be able to detect a possibly hazardous asteroid coming straight from the direction of the sun, it'll enable observations of NEOs super-close to our star, Fox said.

"It'll help us find the objects, including the dark fraction of the population, which we think is sort of roughly 35 to 40% or so of the population," Amy Mainzer, principal investigator for the NEO Surveyor mission and a professor at the University of California, Los Angeles, said during the hearing. "It will also help us measure the sizes, because we can quickly convert the infrared fluxes into a diameter as soon as we get an orbit from the Minor Planet Center … That's such an important component to the impact energy."

"We track the orbits of all 38,000 currently known NEOs, including the more than two and a half thousand potentially hazardous ones, and an impact by any one of those would be devastating," Matthew Payne, director of the Minor Planet Center, said during the hearing.

Fox said that NEO Surveyor should be ready to launch by 2028, perhaps sooner, but that is of course assuming the mission gets the funding it needs.

What happens next?

"Passback documents" — a sort of preview of the White House's 2026 budget request— suggested that the proposed cuts could lead to the closure of NASA's Goddard Space Flight Center in Maryland. The prospect of shutting down such a key agency research facility worries scientists, and it came up during the hearing.

Fox was asked, theoretically, what would happen if NASA's Ames Research Center in Silicon Valley, which plays a vital role in planetary defense, were to be shut down.

"If [NASA Ames] were no longer able to do the the the assessment, what we would lose is really the ability to give our sort of early expert advice to [the Federal Emergency Management Agency], which is then responsible for deciding where the perimeter is and what the response is to protect as much human life as possible," Fox said.

Payne said that, at present, the Minor Planet Center hasn't been affected by the proposed cuts; Mainzer said she's uncertain how the cuts might affect NEO Surveyor's operations. She also emphasized how expensive it can be to train scientists like herself to lead such an important mission.

"We really do have to have the investment and the time that it takes to learn the science, to be able to do it well," Mainzer said.

Fox echoed the uncertainty, responding to nearly all questions concerning Trump's skinny budget with the answer that she needs to see the finalized budget before coming to conclusions. "We await the full president's budget so we can see the priorities in the direction on which missions may be supported or not supported," she said.

"It's clear that planetary defense leverages many of our federal [science and technology] agencies. Now, whether that federal agency continues — whether that expertise continues — I think, is now in question," Rep. Zoe Lofgren (D-California) said during the hearing. Other Trump-instigated orders, like widespread layoffs of probationary employees and deferred resignation programs, are creating a "brain drain," she added.

Recent executive orders, for instance, have seen the rapid federal layoffs of over 800 workers at the National Oceanic and Atmospheric Administration (NOAA) who monitor natural disasters such as hurricanes and forecast daily weather patterns. The deferred resignation program is a sort of roundabout way of laying off employees, offering them payment through a certain month if they leave of their own accord.

"A very reasonable question is whether NASA should, in fact, be spending more money on asteroid monitoring and defense given the catastrophic risk to our country and civilization," Rep. George Whitesides (D-California), who used to work at NASA in a leadership position, said during the hearing. "As several members have mentioned already, our leadership in this area, like so many areas of space and Earth science, are under threat now from the proposed cuts to NASA's budget, as well as the budgets of other science agencies."

"We're talking about impacts that can actually wipe out an entire region, lay waste to a country or devastate the planet. And, you know, this is something that we can do something about. Actually, this is a natural disaster that is 100% preventable if we do our homework," Payne said.

Of note, Rep. Foushee asked both Payne and Mainzer how much NEO tracking could improve if artificial intelligence could be implemented in the workflow. Both agreed that training systems with AI would lead to more accurate and more rapid results, but when Foushee inquired how much funding would be necessary to realistically perform such AI implementation, the question was deferred to Fox. "Adequate funding is certainly a major thing," Fox said.

Exactly how our planetary defense strategies may be affected hinges on the details of Trump's budget, which have not yet been released. (And Congress still has to enact a budget, which remains a proposal until that happens.) If the White House indeed cuts back on funding for these efforts, Fox said NASA may be able to rely on global partners for hazardous NEO tracking.

"If we can't all unite on a large chunk hurtling towards the planet, what are we going to unite on?" Fox said.

This article was originally published on Space.com.

NASA's Lucy spacecraft has captured its first high-resolution images of an asteroid, revealing a bizarrely shaped 150-million-year-old space rock.

The asteroid Donaldjohanson formed when two smaller objects smashed into each other. Donaldjohanson is narrow in the middle with two lobes on either side, like a misshapen peanut with one kernel larger than the other.

Lucy flew as close as 600 miles (960 kilometers) — about the width of Montana — from Donaldjohanson on Sunday (April 20), capturing the first detailed images of the asteroid. Researchers hope that studying Donaldjohanson will help shed light on how our solar system's planets formed.

"Asteroid Donaldjohanson has strikingly complicated geology," Hal Levison, the principal investigator for Lucy at the Southwest Research Institute in Colorado, said in a statement from NASA. "As we study the complex structures in detail, they will reveal important information about the building blocks and collisional processes that formed the planets in our Solar System."

Related: 'City-killer' asteroid that might hit moon has 'unexpected' shape, astronomers say

The Lucy mission launched in 2021 and is on its way to study ancient asteroids orbiting the sun in the main asteroid belt, around 445 million miles (715 million km) from Earth. Lucy's main targets are the Trojan asteroids, which are billions of years old — far older than Donaldjohanson — and orbit in two groups on either side of Jupiter.

The Trojan asteroids are likely made from the same ancient material that formed planets like Jupiter, Neptune and Saturn, and thus have the potential to provide scientists with a window into the formation of our solar system.

Donaldjohanson is a medium-sized asteroid in the main asteroid belt between Mars and Jupiter, orbiting the sun from a distance that ranges between around 180 million and 260 million miles (290 million and 420 million km), according to Space Reference.

Researchers estimated that Donaldjohanson is around 5 miles (8 km) long and 2 miles (3.5 km) wide at its widest point. That makes the peanut-shaped rock peanut-sized compared with some of the Trojan asteroids Lucy aims to study. Lucy's first Trojan target, Eurybates, is estimated to be around 40 miles (64 km) wide.

Donaldjohanson is an appropriate stop-off for Lucy: The asteroid is named after American paleoanthropologist Donald Johanson, who discovered the Australopithecus fossil "Lucy" — the remains of an extinct human relative — with his graduate student Tom Gray in 1974. NASA named the Lucy mission after that fossil because, in the same way that the fossil provided insights into the evolution of humans, researchers hope that this mission will achieve the same for the origins of planets.

Lucy captured the new images using the Lucy Long-Range Reconnaissance Imager, although not all of the asteroid is visible in the images because Donaldjohanson is larger than Lucy's field of view. Researchers will learn more about the asteroid's full shape as they receive more data from the spacecraft, according to the statement.

Lucy first tested its systems with a flyby of the asteroid Dinkinesh in 2023. However, a NASA spokesperson described the recent encounter with Donaldjohanson as a "full dress rehearsal" ahead of the spacecraft's visit to the first Trojan asteroid in 2027.

"These early images of Donaldjohanson are again showing the tremendous capabilities of the Lucy spacecraft as an engine of discovery," Tom Statler, a program scientist for the Lucy mission at NASA, said in the statement. "The potential to really open a new window into the history of our solar system when Lucy gets to the Trojan asteroids is immense."

Scientists have revealed the unusual shape of a large asteroid with the potential to smack into the moon in the year 2032, according to new research.

Asteroid 2024 YR4 sparked a flurry of interest earlier this year after NASA determined there was a chance it could hit Earth. The risk of an Earth impact has since dropped to zero, but there's still a slim chance 2024 YR4 could hit the moon in 2032 — 3.8% likelihood as of early April.

A team of astronomers recently studied the asteroid in more detail using the Gemini South telescope in Chile. The researchers found that 2024 YR4 likely came from the asteroid belt between Mars and Jupiter and has an unusually flat, disk-like shape, similar to a hockey puck, according to a statement released by the National Science Foundation's National Optical-Infrared Astronomy Research Laboratory (NOIRLab).

"This find was rather unexpected since most asteroids are thought to be shaped like potatoes or toy tops rather than flat disks," study lead author Bryce Bolin, a research Scientist at Eureka Scientific, a California-based astrophysics and astronomy research corporation, said in the statement.

The researchers posted their findings to the preprint database arXiv, and will soon publish them in The Astrophysical Journal Letters.

Related: 'Just the tip of the iceberg': Why risky asteroids like 2024 YR4 will pester Earth for decades to come

Astronomers discovered the asteroid 2024 YR4 in December 2024, hence the "2024" in its name. In February, the likelihood of 2024 YRY hitting Earth in 2032 rose to 1 in 32, or 3.1%, which was the highest impact probability NASA had ever recorded for a space object of 2024 YR4's size or larger.

However, astronomers always expected the threat level to drop once they learned more about 2024 YRY's trajectory. Within days, the likelihood plummeted to effectively zero, and has a 0.00078% chance of hitting Earth in 2032 at the time of writing. However, there remains a risk for the moon — not that the asteroid would significantly damage the moon even if it does hit.

For the new study, researchers captured images of the space rock at different wavelengths of light. The team used 2024 YRY's pattern of light output over time, or lightcurve, to study the asteroid's shape, composition and orbital characteristics, according to the statement.

From the rock's reflective pattern, the researchers concluded that 2024 YR4 is likely an S-type asteroid, which means it is rich in silicates — a class of minerals that includes quartz. The team also determined that the asteroid is rotating very fast, about once every 20 minutes, and estimated its size to be 98 to 213 feet (30 to 65 meters) wide, according to the study.

Researchers have been trying to accurately calculate the size of 2024 YR4 since its discovery, and this latest approximation is similar to previous estimates. Recent data from the James Webb Space Telescope suggested it could be slightly larger, 174 to 220 feet (53 to 67 meters), Live Science previously reported.

2024 YR4 is one of the largest objects in recent history with the potential to strike the moon, according to the statement. Back when there was a rising likelihood of 2024 YR4 hitting Earth, it was dubbed a potential "city killer" because it was large enough to wipe out a major city.

While unlikely, a lunar impact would provide researchers with an unprecedented opportunity to study how the size of an asteroid relates to the size of the crater it creates, according to the statement.

On March 27, scientists bid farewell to the Gaia telescope, bringing to a close its groundbreaking 11-year mission of mapping the Milky Way and our cosmic neighborhood.

Though not as famous as some of its peers like the Hubble or James Webb space telescopes, Gaia has reshaped our understanding of our home galaxy, the Milky Way. Since 2014, the European Space Agency's (ESA) telescope has meticulously charted the cosmos, creating a vast catalog of nearly 2 billion stars, more than 4 million potential galaxies and around 150,000 asteroids, with moons possibly circling hundreds of them.

These observations have led to more than 13,000 scientific studies, with many more likely to follow in the coming years.

"Gaia's extensive data releases are a unique treasure trove for astrophysical research, and influence almost all disciplines in astronomy," Johannes Sahlmann, a physicist at the European Space Astronomy Centre in Spain and a project scientist for the Gaia mission, said in a statement.

After 11 years of operations — nearly double its expected lifetime — Gaia ran out of fuel, prompting its operators at ESA to power down and retire the spacecraft.

The best map of the Milky Way galaxy

Since it launched in December 2013, Gaia charted the cosmos from a vantage point about a million miles (1.6 million kilometers) from Earth, at a spot called Lagrange point 2 (L2), where the gravitational forces of Earth and the sun, and the orbital motion of a satellite balance each other.

Gaia's primary goal was to map the positions and movements of over a billion stars within the Milky Way, creating the largest, most precise 3D map of our galaxy. To do so, it was equipped with twin telescopes pointed in different directions to measure the distances between stars, while three onboard instruments collected data on the positions, velocities, colors as well as chemical compositions of celestial objects.

The exquisite map of our galaxy it assembled has enabled scientists to better understand the galaxy's spiral structure, estimate the shape and mass of the dark matter halo that surrounds the Milky Way, and solve the decades-old mystery of our galaxy's warped and wobbling disk — which is likely due to an ongoing collision with the smaller Sagittarius galaxy.

Additionally, the catalog has provided astronomers with new insights into the ancient nature of parts of our galaxy, suggesting that stars began forming in the Milky Way's disk less than 1 billion years after the Big Bang — far earlier than the previously accepted timeline of 3 billion years.

The telescope's observations have also led astronomers to discover previously hidden stellar streams. For example, in 2020, its database of stars revealed the presence and shape of the largest structure ever observed in our galaxy: a vast ensemble of interconnected stellar nurseries spanning 9,000 light-years, known as the Radcliffe Wave, which may have had a lasting impact on Earth's climate.

"Gaia has changed our impression of the Milky Way," Stefan Payne-Wardenaar, a scientific visualiser at the Heidelberg University in Germany, said in a previous statement.

The spacecraft has serendipitously captured thousands of starquakes — tiny motions on surfaces of stars that cause them to swell and shrink periodically — providing unique insights into the inner workings of stars, and spotted high-velocity stars both escaping our galaxy and, surprisingly, racing toward it. It also uncovered several cosmic "sleeping giants," or black holes — one of which is lurking extremely close to Earth.

Gaia's star catalog has also been used to clock the expansion rate of the universe, fueling the ongoing debate over why the expansion seems to be occurring faster than astronomers expected.

"It is impressive that these discoveries are based only on the first few years of Gaia data, and many were made in the last year alone," Anthony Brown, an associate professor of astronomy at the University of Leiden in Netherlands, said in the statement.

Saying goodbye to the 'discovery machine of the decade'

On March 27, ESA commanded Gaia to use its thrusters for the final time, pushing the spacecraft into a "retirement orbit" safely away from Earth and the scientifically important L2 orbit, which is also home to the James Webb Space Telescope, Euclid telescope and China's Chang'e 6 orbiter.

Last week the mission team deactivated the spacecraft's instruments, which were designed with multiple redundant systems to ensure it could reboot and resume operations after any failure. To prevent its computers from powering back on in the future, operators deliberately corrupted its onboard software, according to the ESA statement.

"We had to design a decommissioning strategy that involved systematically picking apart and disabling the layers of redundancy that have safeguarded Gaia for so long," Tiago Nogueira, Gaia spacecraft operator, said in the statement. "We don't want it to reactivate in the future and begin transmitting again if its solar panels find sunlight."

Team members wrote the names of all 1,500 contributors to the Gaia mission into the spacecraft's onboard memory, as well as personal farewell messages and poems.

The telescope may have gone dark, but scientists hope its discoveries will continue to shine brightly. So far, only a third of the mission's data has been analyzed, as processing the vast amount of information — Gaia is expected to have gathered more than 1 petabyte (1 million gigabytes) of data by the end of its mission — takes months. The next batch of science data is set to be released in 2026, covering a little over five years of observations, with the fifth and final release scheduled for 2030, which will encompass the full 10 years of data.

"Gaia has been the discovery machine of the decade, a trend that is set to continue," Brown said in the statement.

The powerful James Webb Space Telescope (JWST) has just completed the first of two planned observations of the infamous "city-killer" asteroid 2024 YR4, which will make a perilously close approach to Earth and the moon in December 2032.

Making use of emergency telescope time awarded to an international team of astronomers in February, JWST's first observation of the building-size asteroid reveals that 2024 YR4 may be slightly larger and rockier than previous ground-based telescope studies suggested.

According to a NASA statement released on April 2, the JWST observations suggest the asteroid measures between 174-220 feet (53-67 meters) in diameter, which is roughly the size of a 10-story building. This is a slightly higher range than the previous size estimate of 131-295 feet (40-90 meters).

Luckily, though, JWST also confirmed what NASA has known for weeks: 2024 YR4 is no longer a hazard, and there is zero chance that the asteroid will strike Earth in 2032. However, a direct collision with the moon is still possible. NASA calculates that the odds of the asteroid hitting the moon in 2032 have risen from a roughly 2% chance to a 3.8% chance of collision.

"While an Earth impact by 2024 YR4 on December 22, 2032 has now been ruled out, it continues to have a non-zero probability of impacting the Moon at this time," the researchers wrote in their preliminary report, which has not yet been peer-reviewed. A second round of JWST observations is planned for May 2025, before the asteroid disappears into the outer solar system for the next several years.

Related: NASA's most wanted: The 5 most dangerous asteroids to Earth

Tracking a "city-killer"

Astronomers first discovered asteroid 2024 YR4 in December 2024. Initial observations with ground-based telescopes indicated that the space rock had a diameter of about 180 feet (55 meters) — roughly as wide as the Leaning Tower of Pisa is tall.

Its orbital trajectory frequently crosses Earth's route around the sun, making a direct collision with our planet possible. If such a strike were to occur, it could wipe out an entire city with the equivalent force of 500 Hiroshima bombs.

While analyzing the asteroid's trajectory, researchers briefly estimated that 2024 YR4 had up to a 3.1% chance of crashing into Earth in 2032 — the highest probability ever recorded for an object of this asteroid's size. NASA eventually refined this prediction down to 0%. But, while uncertainty reigned, the European Space Agency (ESA) announced that several hours of JWST's emergency discretionary time would be used to study the potentially hazardous space rock's size and trajectory.

Key to these observations are JWST's infrared sensors, which can directly detect heat emitted by the asteroid and provide insight into both its size and composition. Ground-based telescopes that observe visible light can only see the sunlight reflected off of the asteroid's surface, leaving big questions about its true nature.

"In general, the brighter the asteroid, the larger it is, but this relationship strongly depends on how reflective the asteroid's surface is," ESA officials wrote in a Feb. 10 blog post. "2024 YR4 could be 40 m [130 feet] across and very reflective, or 90 m [295 feet] across and not very reflective … the hazard represented by a 40 m asteroid is very different from that of a 90 m asteroid."

JWST made its first observations of the asteroid on March 26, watching the asteroid rotate once every 20 minutes over a five-hour period. The researchers then converted the asteroid's brightness to mid-infrared wavelengths, taking into account the known distances and angles between the asteroid, the sun and JWST.

With these data, the team estimated that asteroid 2024 YR4 is slightly larger than was previously estimated, measuring about 200 feet (60 m) in diameter (this is roughly in the middle of NASA's estimated size range of 174-220 feet wide). The thermal analysis also suggests that the asteroid is cooler than is typical for objects of this size, hinting that it may be rockier than previously thought as well.

Front-row seats to a lunar impact?

But even if 2024 YR4 is a bit bigger and harder than we thought, it still poses no imminent threat to Earth, the JWST data confirm. But there does remain a roughly 3.8% chance that the asteroid will slam into the moon in 2032, according to NASA.

While a lunar impact may sound scary, the moon endures thousands of tiny meteor strikes every year and has the cratered scars to prove it has survived much larger impacts. But seeing a known asteroid, with a known size and trajectory, gouge open a new crater in real time would be a world-first opportunity for lunar researchers.

"We've got our fingers crossed for a moon impact," Alan Fitzsimmons, a physics and math professor at Queen's University Belfast in the U.K. who was not involved in the JWST observations, told New Scientist. "It would have no effect on Earth, but would allow us to study the formation of a lunar crater by a known asteroid for the very first time."

The second round of JWST observations, scheduled for May, will further help to refine the asteroid's orbital trajectory and its chances of hitting the moon.

Editor's note: This article was updated on April 3 with new facts and figures from NASA.

A "potentially hazardous" pyramid-size asteroid is about to zoom past Earth at around 48,000 mph (77,300 km/h) this week as it reaches its closest point to our planet in more than 100 years. But the hefty space rock poses zero risk of hitting us now or in the future, data shows.

On Wednesday (March 26), at around 7:30 a.m. ET, asteroid 2014 TN17 will come within 3.2 million miles (5.1 million kilometers) of Earth — or around 13 times further away than the moon, according to NASA's Jet Propulsion Laboratory (JPL). This is the closest approach predicted for the asteroid across almost 300 years of JPL simulations, which included calculations of all of its flybys between 1906 to 2200.

Researchers estimate that it is around 540 feet (165 meters) wide. That is slightly wider than the height of Egypt's Great Pyramid of Giza and makes it large enough to wipe out a city if it impacted our planet. NASA classifies 2014 TN17 as "potentially hazardous" because of its size and occasional proximity to Earth. However, that does not mean it is dangerous.

Related: NASA's most wanted: The 5 most dangerous asteroids to Earth

During the upcoming flyby, the asteroid will be too far away to be observed with a backyard telescope or stargazing binoculars. However, it is large enough for researchers to study it and the space rock is currently scheduled to be observed by NASA's Goldstone Solar System Radar (GSSR) system in California, which specializes in observing nearby solar system objects as they pass us by.

In recent years, the GSSR telescope has helped reveal the unusual "snowman" shape of one asteroid, detect changes in the orbital trajectories of another and discover a mini-moon orbiting a third. The upcoming observations could yield similarly interesting insights about 2014 TN17.

Close encounters

There are currently around 2,500 known potentially hazardous asteroids, according to the International Astronomical Union's Minor Planet Center. None of them are predicted to hit Earth anytime soon. However, there are a few that will get quite close.

One such space rock is the potential city-killer asteroid 2024 YR4, which made headlines earlier this year when the chances of it hitting our planet in 2032 rose as high as 3.1%. The odds of impact have since dropped to zero. However, there is still a slim chance that it may crash into the moon.

Another asteroid that will have a near-miss of Earth is the hefty "god of chaos" asteroid Apophis, which will come closer to our planet than some satellites in 2029. There is currently zero chance of it hitting us. Some researchers warn that this could change if its trajectory is altered by another asteroid en route — and we may not realize if this has happened for several years. However, this is very unlikely.

In 2022, NASA's Double Asteroid Redirection Test (DART) mission demonstrated our ability to deflect potentially devastating impacts by flying spacecraft into oncoming asteroids to alter their trajectory. However, this method would require advanced warning and lots of data on the target asteroid, which makes finding and tracking these potentially dangerous space rocks a priority.

A record-breaking asteroid with the potential to wipe out a city in 2032 is officially no longer a hazard, according to the latest NASA data.

Last week, NASA increased the likelihood of impact from asteroid 2024 YR4 to 1 in 32, or 3.1%, up from 1.2% at the beginning of February. 2024 YR4 is big enough to wipe out a major city, and with a 3.1% chance of impact, this asteroid had the highest impact probability NASA has ever recorded for a space object of 2024 YR4's size or larger. Humanity understandably took notice, but they needn't have worried.

The chances of impact soon fell as the space agency learned more about 2024 YR4's trajectory. By Friday (Feb. 21), 2024 YR4 had an impact probability of 1 in 360 or 0.28%, and the odds have continued to lengthen over the weekend.

At the time of writing on Monday (Feb. 24), the odds are 1 in 20,000, or 0.005%, according to NASA's Center for Near Earth Object Studies. The latest shift is significant because now that the odds have dropped below 1 in 1,000, NASA has downgraded the threat posed by 2024 YR4 to the lowest level possible (Level 0 on the Torino Impact Hazard Scale).

This latest reassignment was well predicted. Live Science previously reported that the most likely scenario has always been that 2024 YR4 will miss us on its closest approach to Earth on Dec. 22, 2032.

Related: 'Just the tip of the iceberg': Why risky asteroids like 2024 YR4 will pester Earth for decades to come

Astronomers discovered 2024 YR4 in December last year, hence the 2024 in its name. The asteroid is around 180 feet (55 meters) in diameter, so about as wide as the leaning tower of Pisa is tall. If 2024 YR4 were to hit Earth in 7 years time, it would release around 8 megatons of energy — upwards of 500 times more energy than the atomic bomb that destroyed Hiroshima.

Astronomers use the Torino scale to categorize the risk posed by asteroids and comets. When 2024 YR4's impact odds rose above 1% in January, the asteroid went to level 3 on the Torino scale, meaning it was capable of "localized destruction" and merited attention, according to the scale. 2024 YR4 dropped down to Level 1 (no unusual level of danger) towards the end of last week as the odds fell below 1%. Now, with the latest drop, 2024 YR4 falls to the bottom of the scale.

"Asteroid 2024 YR4 has now been reassigned to Torino Scale Level Zero (the level for "No Hazard") as additional tracking of its orbital path reduces its possibility of intersecting the Earth to below the 1-in-1000 threshold established for downgrading to Level 0," Richard Binzel, the inventor of the Torino scale and a professor of planetary sciences at MIT, told Live Science in an email.

The Torino scale is based on both the consequences of a potential impact — determined by the asteroid's size — and the likelihood of an impact. Binzel noted that odds of less than 1 in 1,000 is the Level 0 threshold for any object smaller than 100 m (330 feet), which is the case for the estimated 55-meter-wide 2024 YR4.

"The NASA JPL Center for Near-Earth Object Studies now lists the 2024 YR4 probability as 0.00005 (0.005 percent) or 1-in-20,000 for its passage by Earth in 2032," Binzel said. "That's Zero Folks!"

Following the space rock's demotion, there are currently no known asteroids with a threat level above zero.

Asteroid 2024 YR4 has gone from a potential 'city-killer' to an almost certain near-misser this week as the odds that this large space rock will hit Earth in 2032 rose and then plummeted in a matter of days. Here's what happened and why it matters.

2024 YR4 is around 180 feet (55 meters) wide, with the potential to release 500 times more energy than the atomic bomb that destroyed Hiroshima. A little concern was therefore understandable on Tuesday (Feb. 18), when the likelihood of YR4 hitting us crept up to 3.1% — the highest impact probability NASA has ever recorded for a space object of 2024 YR4's size or larger.

Fortunately, the record-high impact probability was short-lived, and the chances of a strike soon fell to 1.5% and, at the time of writing, dow to 0.28%. None of what played out came as a surprise to astronomers.

The most likely scenario for 2024 YR4 has always been that it will miss us on its closest approach to Earth in 7 years time. That's because, while astronomers have been aware of 2024 YR4 since last year, uncertainty about its orbital path has meant that they couldn't — and still can't — rule out the possibility of a strike. Slight variations in this level of uncertainty were reflected in the shifting odds, which ignited intrigue worldwide.

"Astronomers don't hide and can't hide their discoveries because the sky is open to everyone," Richard Binzel, the inventor of the Torino asteroid impact hazard scale and a professor of planetary sciences at MIT, told Live Science in an email. "So when we discover one of these future visitors that might someday be a close shave, the scientific method of slow careful measurements to get to the answer plays out in a public way."

Related: Potentially hazardous asteroids: How many dangerous space rocks lurk near Earth — and can we stop them?

How threatening is asteroid 2024 YR4?

To categorize the threat posed by asteroids and comets, researchers use Binzel's Torino Impact Hazard Scale. The Torino scale has 11 levels, ranging from Level 0 (no hazard) to Level 10 (global catastrophe).

2024 YR4 reached Level 3 in January 2025 after scientists determined it had a more than 1% chance of hitting Earth. Level 3 asteroids are capable of "localized destruction," which fits 2024 YR4's potential to take out a city.

However, even as 2024 YR4's odds rose to more than 3% — and fell back down to 1.5% — it stayed at Level 3. Binzel said that it's "perfectly natural" for 2024 YR4's odds of impact to "bounce around a bit." However, Level 3 means scientists expect the asteroid will end up with a 0% impact chance with further observations.

Darker skies gave astronomers better views of the asteroid in recent days, following a week of limited visibility around February's full moon. Clearer overnight observations between Feb. 19 and Feb. 20 allowed NASA to refine YR4's odds of impact to 1 in 360, or 0.28%, according to NASA's Planetary Defence blog.

Once the odds dropped below 1%, 2024 YR4 immediately became a Level 1 asteroid, categorized as having "no unusual level of danger" and "no cause for public attention or public concern." In other words, despite chatter surrounding shifting odds, the Torino scale has predicted what would happen all along.

"There's a learning process here, in that it has been pre-baked into the Torino Scale description for Level 3 the exact outcome that is unfolding," Binzel said. "For the moment YR4 has fallen to Level 1, and with further tracking we will see it fall to zero."

What happens if asteroid 2024 YR4's threat level rises?

Asteroids don't necessarily move up or down the Torino levels in order because they're assigned based on both the consequences of a potential impact and the likelihood of an impact.

2024 YR4 fit within the Level 3 criteria of potential "localized destruction" when it had a more than 1% chance of hitting Earth. Level 4 asteroids are larger and capable of more destruction, described as "regional devastation" — so a Level 3 asteroid can't become a Level 4 just with an increased likelihood of impact, according to the scale.

2024 YR4 is likely heading for Level 0 (no hazard). However, if the reassignment to Level 1 hadn't happened, and it turned out YR4 was actually on a collision course for Earth, then it would have leaped straight to the upper levels of the scale reserved for definite collisions, Binzel explained.

"If this asteroid were ever to jump to a higher level, it would go to Level 8, where a 'collision is certain, capable of localized destruction,'" Binzel said when 2024 YR4 was still at Level 3.

However, just like a Level 3 asteroid can't become a Level 4, 2024 YR4 can't get any higher than Level 8 because its size restricts how much damage it can do.

A Level 8 asteroid would be most destructive on land, but also possibly capable of causing a tsunami if it hit offshore. If 2024 YR4 was on course for Earth, it would probably hit somewhere along a "risk corridor" stretching across the eastern Pacific Ocean, northern South America, the Atlantic Ocean, Africa, the Arabian Sea and South Asia on Dec. 22, 2032, according to NASA.

Humanity could try to deflect a large incoming asteroid like YR4, for example by using the orbit of a spacecraft to pull it off course, or using a nuclear explosive to bash it off course, Live Science previously reported.

Binzel noted that decisions on any proactive measures to deflect are the responsibility of a group called the International Asteroid Warning Network (IAWN), which NASA coordinates.

How does 2024 YR4 compare to other space rocks?

2024 YR4 is a rare asteroid. It was the only large asteroid with an impact probability of more than 1% during the period before the odds shifted. A strike from 2024 YR4 would be something like a once-in-a-thousand-year event, based on a NASA asteroid hazard comparison chart.

Binzel compared 2024 YR4 to asteroid Apophis, which reached Level 4 on the Torino scale in 2004 before dropping to Level 0. Named after Apep, the ancient Egyptian god of chaos, Apophis is heading our way in 2029. Scientists are confident it will narrowly miss Earth, but humanity should get a nice view of the giant space rock when it passes in four years' time.

"As it turns out, a very close and safe passage by Apophis in 2029 will be a scientific bonanza and a fascinating view in the sky for billions of people," Binzel said.

Apophis is around 1,100 feet (335 m) long and would have jumped to Level 9 on the Torino scale if it had turned out to be on a collision course with Earth. Level 9 means unprecedented regional devastation on land or the threat of a major tsunami offshore. Only an even larger Level 10 asteroid would be more destructive, according to the scale.

"Level 10 is reserved for the kind of catastrophe that was a bad day for the dinosaurs," Binzel said.

"Tip of the iceberg"

Humanity is continuously improving its space rock detection methods. That means that, as rare as 2024 YR4 is, we are likely to detect more asteroids like it in the decades to come, according to Binzel.

"2024 YR4 is just the tip of the iceberg, as new asteroid discovery surveys are becoming more thorough than ever," Binzel said. "The Torino scale will have its work cut out for it."

Binzel noted that with improved asteroid discovery surveys, we will see many more cases where researchers can detect an asteroid, but don't have sufficient data on its orbital track to be certain of a miss for many decades after its discovery. However, Binzel doesn't see this as a cause for concern.

"Rather than making anyone anxious, by finding these objects that are already out there and by pinning down their orbits, we are becoming more secure in our knowledge that any sizable asteroid is not likely to take us by surprise as an unwelcome guest landing on us."

NASA has downgraded the threat level of potential city-killer asteroid 2024 YR4. It is now more likely to hit the moon than Earth, according to the latest data.

The space agency has been tweaking the odds of a potential strike from the 180-foot-wide (55 meters) YR4 all week. Those odds peaked at 1 in 32, or 3.1%, on Tuesday (Feb. 18), which was the highest impact probability NASA had ever recorded for a space object as big as YR4. However, the likelihood of a strike soon fell.

On Wednesday (Feb. 19), NASA more than halved the chances to 1 in 67, or 1.5%. Now, at the time of writing on Friday (Feb. 21), the odds are at 1 in 360, or 0.28%, according to NASA's Center for Near Earth Object Studies. The asteroid is also slightly more likely to hit the moon, with a lunar impact probability increasing to 1%, according to NASA's Planetary Defence blog.

The latest shift in odds is arguably the most significant so far because it lowers YR4's official threat level. Since YR4's impact odds rose above 1% in January, the asteroid has been at level 3 on the Torino Impact Hazard Scale. Level 3 means a space object is capable of "regional devastation" and alerts astronomers to take notice. However, now that the odds have dropped below 1%, YR4's threat level has dropped to level 1, which means there is no unusual level of danger, according to the scale.

Related: Potentially hazardous asteroids: How many dangerous space rocks lurk near Earth — and can we stop them?

The latest reduction in impact probability came after astronomers made overnight observations of YR4 between Feb. 19 and Feb. 20, according to NASA's Planetary Defence blog. The blog had previously noted that darker skies enabled astronomers to better observe the asteroid, following a week of limited visibility around a full moon.

The reduction in odds and change in threat level won't come as a surprise to astronomers. Even when YR4's impact odds were climbing, the change was due to uncertainty about the asteroid's orbital path, and researchers expected the odds to fall to zero with better data. A collision from an asteroid of this size would have been around a once-in-a-thousand-years event, based on a NASA asteroid hazard comparison chart.

"NASA's planetary defense teams will continue to monitor the asteroid to improve our predictions of the asteroid's trajectory," Molly Wasser, a spokesperson for NASA, wrote in the latest blog update on Feb. 20."

An asteroid big enough to destroy a city is now much less likely to collide with Earth in 2032, according to the latest NASA data.

In recent weeks, NASA had been steadily increasing the likelihood of a strike from asteroid 2024 YR4, with the odds peaking on Tuesday (Feb. 18) at 1 in 32, or a 3.1% chance. However, on Wednesday (Feb. 19), the space agency more than halved the chances to 1.5%.

The odds are likely to change again as astronomers learn more about YR4's trajectory, but they expect the likelihood to end up at 0% once the space rock's trajectory is confirmed.

YR4 has an estimated diameter of around 180 feet (55 meters) — that estimate has been fluctuating a bit, but the asteroid is about as wide as the leaning tower of Pisa is tall. YR4 has the potential to release around 8 megatons of energy in the event of a strike — upwards of 500 times more energy than the atomic bomb that destroyed Hiroshima in Japan. This means it's big enough to wipe out a major city but too small to end human civilization.

There's a tiny chance that YR4 will hit the moon instead of Earth, but it will almost certainly sail harmlessly past both when it makes its closest approach to Earth in 2032.

Related: Potentially hazardous asteroids: How many dangerous space rocks lurk near Earth — and can we stop them?

The Asteroid Terrestrial-impact Last Alert System (ATLAS) telescope in Chile recorded asteroid 2024 YR4 on Dec. 27, 2024, according to the NASA Center for Near Earth Object Studies. By January, scientists had determined that YR4 had a more than 1% chance of hitting Earth and thus warranted further attention from scientists.

With odds above 1%, YR4 also reached level 3 on the Torino Impact Hazard Scale. The scale enables scientists to categorize the risk posed by space rocks. Level 3 is reserved for asteroids and comets capable of localized destruction, but that are expected to be later reassigned to level 0 — meaning they pose no threat — once astronomers confirm they won't hit Earth.

An international team of scientists has been granted emergency use of the James Webb Space Telescope, humanity's most powerful space telescope, to further assess YR4's risk. As more observations come in over the next few months, astronomers should become more confident that YR4 poses no threat to Earth, and we will see the threat level drop to zero.

The probability that a major asteroid, big enough to wipe out an entire city, will hit Earth in 2032 has just increased to 1 in 32, or 3.1%, according to NASA.

On Feb. 7, NASA increased the likelihood that asteroid 2024 YR4 will hit Earth in seven years time from 1.2% to 2.3%. The odds of impact then climbed to 2.6%, and are now at 3.1%, according to the latest data on NASA's Center for Near Earth Object Studies website.

Asteroid 2024 YR4 has an estimated diameter of around 177 feet (54 meters), or about as wide as the leaning tower of Pisa is tall. But while it is too small to end human civilization, the asteroid could still wipe out a major city, releasing about 8 megatons of energy upon impact — more than 500 times the energy released by the atomic bomb that destroyed Hiroshima, Japan.

The good news is that there's still a 96.9% chance that the asteroid will miss Earth entirely, and as researchers learn more about its trajectory, the odds of a strike are likely to decrease to 0%, based on its current risk level in the NASA data. There's also a tiny 0.3% chance that YR4 will hit the moon instead of Earth, Live Science previously reported.

Related: Potentially hazardous asteroids: How many dangerous space rocks lurk near Earth — and can we stop them?

Scientists use a measurement called the Torino Scale to categorize the risk posed by nearby asteroids and comets. With a Torino Scale rating of 3 out of 10, YR4 is capable of localized destruction and passes the 1% impact probability threshold (meaning the risk of a potential impact is estimated to be greater than 1%).

Additional observations will give scientists a more precise estimate of the asteroid's orbit, which usually means they'll be more confident it won't hit Earth. Many other objects on NASA's asteroid risk list have ended up with an impact probability of 0% after more data became available.

A team of scientists was recently granted emergency use of the James Webb Space Telescope, the most powerful space telescope, to study YR4 in the coming months and assess its risk, as well as its true size.

YR4 is currently the only known large asteroid with a more than 1% chance of hitting Earth, according to NASA's planetary defense blog. In the unlikely event that YR4 does collide with Earth, it would probably hit somewhere along a "risk corridor" stretching across the eastern Pacific Ocean, northern South America, the Atlantic Ocean, Africa, the Arabian Sea, and South Asia, according to NASA.

Humanity's most powerful space telescope is setting its sights on the most dangerous known asteroid in the solar system.

According to a blog post from the European Space Agency (ESA), an international team of astronomers has been granted emergency use of the mighty James Webb Space Telescope (JWST) to observe the potentially hazardous asteroid 2024 YR4 in the coming months. The building-size space rock was discovered hurtling through our solar system by NASA's Asteroid Terrestrial-impact Last Alert System in December 2024 and currently sits atop the agency's asteroid watch list, with a roughly 1-in-43 chance (2.3%) of impacting our planet in December 2032.

Measuring a potential 'killer'

Astronomers estimate that the asteroid measures roughly 180 feet (55 meters) across, making it about as wide as the Leaning Tower of Pisa is tall. An impact from such a rock wouldn't trigger a mass extinction like the much larger, dino-snuffing Chicxulub impactor did 66 million years ago. But an asteroid that size could wreak regional havoc similar to the Tunguska impactor that flattened some 80 million trees in the Siberian wilderness in 1908, according to Live Science's sister site Space.com.

However, 2024 YR4's current size is just an estimate based on ground-telescope data. Stifled by Earth's atmosphere, these telescopes see only the sunlight reflected off of the asteroid's surface, which paints a limited picture of its actual size, according to ESA. The space rock could, in fact, be significantly larger than it seems.

Related: NASA's most wanted: The 5 most dangerous asteroids to Earth

"In general, the brighter the asteroid, the larger it is, but this relationship strongly depends on how reflective the asteroid's surface is," ESA officials wrote in the blog post, which was shared Monday (Feb. 10). "2024 YR4 could be 40 m [130 feet] across and very reflective, or 90 m [295 feet] across and not very reflective.

"It is very important that we improve our size estimate for 2024 YR4: the hazard represented by a 40 m asteroid is very different from that of a 90 m asteroid," ESA added.

JWST to the rescue

The upcoming JWST observations will significantly improve our understanding of the asteroid's size, according to ESA.

Rather than looking at reflected sunlight, JWST's infrared instruments will study the heat emitted by the asteroid itself, helping to constrain its true size and surface composition. The space-based JWST will also have a much clearer view of the asteroid compared with its ground-based counterparts, which must peer through the obscuring veil of our planet's atmosphere to observe near-Earth objects. (NASA and ESA's planned next generation of asteroid-hunting telescopes will also use infrared, for these reasons.)

JWST will first observe 2024 YR4 in March as the asteroid reaches its peak brightness, according to ESA. In May, the telescope will observe the asteroid again as it zooms far away from the sun — the final viewing opportunity for this space rock until its next close approach comes in 2028.

In total, the team behind the research will use about four hours of JWST's time, which is strictly budgeted through a competitive proposal process. The upcoming asteroid observations will come out of JWST's "director's discretionary time," a small stash of research hours reserved for time-sensitive observations that can't wait for the next year's proposal process. All data from the observations will be made publicly available upon release.

A telescope has revealed footage of an asteroid big enough to wipe out a city as it flies through the night sky — and there's a tiny chance it will come back to hit us in 2032.

The NASA-funded Asteroid Terrestrial-impact Last Alert System (ATLAS) telescope in Chile recorded asteroid 2024 YR4 on Dec. 27, 2024, according to the NASA Center for Near Earth Object Studies. The footage shows YR4 shooting through space after it made a close approach with Earth on Dec. 25.

YR4 has a tiny chance of hitting Earth in 2032, but the risk has increased since ATLAS captured the footage in December. Last week, NASA observations increased the likelihood of an impact to 1 in 43, or roughly 2.3%, up from the previous estimate of 1.2%.

The 1 in 43 odds are a little unnerving, given that YR4 is about 130 to 300 feet (40 to 90 meters) wide and capable of taking out a city. However, while the chances of YR4 striking Earth have increased, there's still a 97.7% chance that the asteroid will miss our planet entirely. In other words, the odds are still very much in our favor.

"While still an extremely low possibility, additional observations and analysis of asteroid 2024 YR4 indicate that its impact probability with Earth has increased to a 2.3% chance on Dec. 22, 2032," Molly Wasser, a spokesperson for NASA, posted on NASA's planetary defense blog on Friday (Feb. 7).

Additional observations will help scientists hone their measurements of the asteroid's orbit, likely reducing the chances of impact to 0%, as has happened with many other objects flagged on NASA's asteroid risk list in the past. However, it's also possible that the chances of impact could continue to rise, according to NASA.

Related: Here's what could happen if asteroid Bennu smashes into Earth in 157 years

YR4 currently has a risk rating of 3 out of 10 on the Torino Scale, which categorizes potential Earth impact events from asteroids and comets. Torino Scale 3 means that an object capable of causing localized destruction has a more than 1% chance of impact, but that likelihood will probably fall to 0% with new observations.

The risk of a strike from a newly identified asteroid can be higher at first due to uncertainty. Researchers initially identify certain characteristics of the asteroid's orbit with a higher degree of certainty than others, Live Science's sister site Space.com reported. However, as researchers make additional observations, they can narrow down an asteroid's trajectory to be certain it's not on a collision course for Earth.

If YR4 were to hit Earth, it would likely strike somewhere along what NASA calls a "risk corridor," which stretches across the eastern Pacific Ocean, northern South America, the Atlantic Ocean, Africa, the Arabian Sea, and South Asia.

Current estimates suggest that the asteroid would release about 8 megatons of energy on impact — about 500 times more powerful than the devastating atomic bomb dropped on Hiroshima in Japan.

In March, the James Webb Space Telescope will examine YR4 and better assess its size. Researchers will then continue to monitor the asteroid through April, after which it will be too faint to observe until 2028, according to NASA. YR4 is the only asteroid threatening us in the near future and if the odds of contact remains above 1%. scientists could attempt to deflect it from its course.

"Currently, no other known large asteroids have an impact probability above 1%," Wasser wrote on NASA's planetary defense blog on Jan. 29.

NASA scientists have just spotted a hunk of space rock that could smack into Earth in 2032. And while it's unlikely to wipe out humanity, it could take out a city.

The asteroid, dubbed 2024 YR4, was detected by NASA's Asteroid Terrestrial-impact Last Alert System on Dec. 27, 2024. According to the latest NASA estimates, it has about a 1-in-43 chance of impacting our planet in 2032.

But there's some good news for Earth: 2024 YR4 is only around 180 feet (55 meters) across, which means it is too small to end human civilization if it collided with Earth. But it could wipe out a major city. Scientists estimate that it would release about 8 megatons of energy upon impact — more than 500 times that of the atomic bomb that destroyed Hiroshima, Japan.

Although the asteroid is currently moving away from us, Earth will have several close shaves with the space rock in the next half century. Its next sideswipe will occur in late 2028, followed by six more close approaches between 2032 and 2074. Of these, the one with the highest chance of impact will be on Dec. 22, 2032, according to NASA. As the asteroid gets closer, scientists will have a much better sense of its trajectory and likelihood of hitting Earth.

All of these factors place 2024 YR4 at Level 3 on the Torino Impact Hazard Scale, the system scientists use to determine an asteroid's threat level. For objects at this level, "attention by public and by public officials is merited if the encounter is less than a decade away." However, most asteroids in this category are eventually downgraded to Level 0, which means "the likelihood of a collision is zero, or is so low as to be effectively zero."

Threats like this are the reason NASA and other space agencies are interested in developing techniques to redirect asteroids, as demonstrated by the Double Asteroid Redirection Test mission. The chances of a catastrophic asteroid impact are usually very low, so it is crucial to continue monitoring objects of interest, astronomers say. Even though 2024 YR4 probably won't trigger a mass extinction like the dino-killing space rock that slammed into what is now Mexico 66 million years ago, astronomers will keep a close eye on the asteroid as it circles back toward our planet.

Editor's note: This article was updated on Friday (Feb.7) after NASA increased the likelihood of a potential impact.

An enormous asteroid has just zoomed safely past Earth, but it isn't done with our planet yet.

This weekend, the mountain-size space rock will peak in brightness in a rare once-in-a-decade event that you can observe from home with basic stargazing binoculars — or in a free livestream.

Named (887) Alinda, the near-Earth asteroid measures an estimated 2.6 miles (4.2 kilometers) wide — roughly the width of Manhattan — according to NASA's Jet Propulsion Laboratory. On Wednesday (Jan. 8), the chunky space rock made its closest approach to Earth in decades, swooping to within 7.6 million miles (12.3 million km) of our planet, or about 32 times the average distance between Earth and the moon. Alinda isn't predicted to make another close approach to Earth until 2087.

While an asteroid this big could trigger a mass extinction event if it were to collide with Earth, its large size also makes it a great target for curious stargazers. On Sunday (Jan. 12), Alinda will peak in brightness at a magnitude of 9.4. That isn't bright enough to be seen with the naked eye, but it's bright enough to be visible through entry-level stargazing binoculars or a good backyard telescope, according to astronomer Gianluca Masi, who runs the Virtual Telescope Project in Italy.

The asteroid will be visible moving through the constellation Gemini, which appears in the Northern Hemisphere just after dark and remains visible all night long, according to skywatching reporter Jamie Carter.

Related: NASA's most wanted: The 5 most dangerous asteroids to Earth

If you don't have the gear, don't fret; Masi and the Virtual Telescope Project are hosting a free livestream of asteroid Alinda's bright flyby on Jan. 12 at 12:30 p.m. EST. You can watch it on the project's official YouTube page or in the video embedded below.

It's rare to see such a large object pass this close to Earth. According to Masi, events like this happen just once a decade, and Alinda is one of the five largest asteroids that will pass within 9.3 million miles (15 million km) of our planet from now until the year 2200.

Luckily, neither Alinda nor any other known asteroid poses a threat to Earth for at least the next century, according to NASA. However, space agencies take the threat of "planet killer" asteroids very seriously and are currently testing various planetary defense plans. NASA's recent Double Asteroid Redirection Test (DART) mission proved that it is possible to divert a large asteroid by crashing a spacecraft into it. However, the logistics of actually protecting Earth from a threatening asteroid would likely involve firing hundreds of rockets simultaneously, which would require years to decades of advance notice, Live Science previously reported. In the meantime, China plans to launch its own asteroid deflection mission by 2030.

If bright asteroids are not your space jam, then stay tuned for plenty of other exciting stargazing opportunities this month. On Monday (Jan. 13), the full Wolf Moon will rise next to Mars and appear to gobble up the Red Planet as Mars slips behind the moon for about four hours, before reemerging on the other side. Later, starting Jan. 21, a parade of six planets will be visible in Earth's skies, with Venus, Mars, Jupiter and Saturn all visible to the naked eye after dark and Uranus and Neptune visible with stargazing equipment. The planets will linger in the sky through February, with Mercury also joining the planetary procession in early March.

New James Webb Space Telescope (JWST) findings are giving scientists a fresh look at an "oddball" space rock that has features similar to both comets and asteroids.

Astronomers observing the hybrid, known as (2060) Chiron, detected frozen carbon dioxide and carbon monoxide in its icy nucleus, as well as carbon dioxide and methane in the surrounding gas cloud. The findings could help scientists better understand comets and centaurs — so named because they have properties of both asteroids and comets — and could offer a peek at the conditions in the early solar system.

Discovered in 1977, Chiron orbits the sun about once every 50 years, traveling in an oblong loop in the region between Jupiter and Neptune. In the new study, published Dec. 18 in the journal Astronomy and Astrophysics, researchers described their observation of the centaur on July 12, 2023 at a range of more than 18 times the distance from Earth to the sun.

Related: Comets played a 'major' role in making life on Earth possible, new study hints

The team found carbon dioxide and methane gases in Chiron's coma, the cloud of gas and dust around the nucleus. Though previous studies had detected carbon monoxide gas in the coma as well, the new JWST observations found carbon monoxide only in its frozen form on Chiron's surface. The finding suggests a complex scenario of gas emissions from different reservoirs on Chiron, the researchers wrote in the study. In general, carbon monoxide is more volatile, and therefore more likely than CO2 to sublimate, or transform directly from a solid on the surface to a gas released in the coma.

Detecting gas in our solar system

"These results are like nothing we've seen before," study co-author Charles Schambeau, a planetary scientist at the University of Central Florida (UCF), said in a statement. "Detecting gas comae around objects as far away from the sun as Chiron is very challenging, but JWST has made it accessible. These detections enhance our understanding of Chiron's interior composition and how that material produces the unique behaviors as we observe Chiron."

Astronomers also detected water ice and lightweight carbon-containing molecules like ethane and propane for the first time on a centaur. Chiron could have picked up simpler molecules like carbon dioxide and water left by the nebula that formed our solar system, study co-author Noemi Pinilla-Alonso, a planetary scientist at UCF and the University of Oviedo in Spain, said in the statement. Objects like Chiron haven’t changed much since the solar system first formed, she said, so observing how they interact on Chiron could help scientists better understand the early solar system. Molecules like ethane and propane, meanwhile, likely formed when light hit the surface and reacted with the methane and water ice there.

However, fully understanding the compositions of the nucleus and coma, and how they change during Chiron's orbit, will require additional data.

"We're going to follow up with Chiron," Pinilla-Alonso said in the statement. "It will come closer to us, and if we can study it at nearer distances and get better reads on the quantities and nature of the ices, silicates, and organics, we will be able to better understand how seasonal insolation variations and different illumination patterns can affect its behavior and its ice reservoir."

Astronomers analyzing archival images from the James Webb Space Telescope (JWST) have discovered an unexpectedly vast population of the smallest asteroids ever seen in the asteroid belt between Mars and Jupiter. The finding could lead to better tracking of the tiny but powerful space rocks that are likely to approach Earth.

The newfound asteroids range in size from that of a bus to several stadiums — tiny compared to the massive space rock that wiped out most dinosaurs, but they nevertheless pack a significant punch. Only a decade ago an asteroid just tens of meters in size took everyone by surprise when it exploded over Chelyabinsk, Russia, and released 30 times more energy than the atomic bomb detonated over Hiroshima in WWII.

These so-called "decameter" asteroids collide with Earth 10,000 times more frequently than their larger counterparts, but their small size makes it challenging for surveys to detect them well in advance.

In recent years, a team of astronomers including Julien de Wit, an associate professor of planetary science at MIT, has been testing a computationally-intensive method to identify passing asteroids in telescope images of faraway stars.

By applying this method to thousands of JWST images of the host star in about 40 light-years distant TRAPPIST-1 system, which is the best-studied planetary system beyond our own, the researchers found eight previously known and 138 new decameter asteroids in the main asteroid belt. Among them, six appear to have been gravitationally nudged by nearby planets into trajectories that will bring them close to Earth. An early, unedited release of the findings was published Dec. 9 in the journal Nature.

"We thought we would just detect a few new objects, but we detected so many more than expected — especially small ones," de Wit said in a statement. "It is a sign that we are probing a new population regime."

Fresh look at archival data

For the new study, de Wit and his colleagues compiled roughly 93 hours worth of JWST images of the TRAPPIST-1 system in order to enhance faint, fast-moving objects like asteroids above the background noise.

While such an approach rarely works for objects with unknown orbits, the team bypassed the limitation by using powerful graphics processing units (GPUs) to rapidly sift through large datasets, enabling a "fully blind search" across all possible directions to locate the newly-discovered asteroids, and then stacking those images.

Related: 'Spectacular' asteroid blazes over Siberia just hours after it was detected

"This is a totally new, unexplored space we are entering, thanks to modern technologies," study lead author Artem Burdanov, a research scientist in MIT's Earth, Atmospheric, and Planetary Sciences department, said in the statement. "It's a good example of what we can do as a field when we look at the data differently — sometimes there's a big payoff, and this is one of them."

The newfound asteroids, which are remnants of collisions among bigger, kilometer-sized space rocks, are the tiniest yet to be detected in the main asteroid belt. JWST has proven to be ideal for the discovery, researchers say, thanks to the telescope's sharp infrared eyes that detect the asteroids' thermal emissions. These infrared emissions are much brighter than the faint sunlight reflected off the asteroids’ surfaces — the type of visible light that traditional surveys typically rely on.

Upcoming JWST observations will focus on 15 to 20 faraway stars for at least 500 hours, which could lead to the discovery of thousands more decameter asteroids in our solar system, according to the new study.

And newer telescopes will also help uncover thousands of small asteroids in our solar system. Chief among them is the Vera C. Rubin Observatory in Chile — which, starting next year, will use the world's largest digital camera to photograph the southern sky every night for at least a decade, capturing images that each cover an area equivalent to 40 full moons. The high frequency and resolution are expected to detect up to 2.4 million asteroids — nearly double the current catalog — within its first six months.

"We now have a way of spotting these small asteroids when they are much farther away, so we can do more precise orbital tracking, which is key for planetary defense," said Burdanov.

The idea that comets delivered water to early Earth has fallen out of favor in the past decade, but a new look at data from the European Space Agency's (ESA) Rosetta mission to an iconic “rubber ducky” comet has reopened that possibility.

Water has a pretty simple chemical makeup: just three atoms (two hydrogen and one oxygen) in each molecule. It's also one of Earth's most abundant molecules, with our planet's oceans brimming with about a million trillion tons of the liquid.

How all of this water ended up on Earth, though, has remained a mystery. Some scientists think that although Earth's geological processes may have generated a tiny fraction of it, most water was likely deposited by comets or asteroids via repeated, cataclysmic collisions.

Figuring out which of these two groups was responsible involves a special chemical signature that arises because the hydrogen in water occurs in two distinct isotopes, or forms. Whereas most hydrogen atoms contain just one proton in their nucleus, a tiny fraction harbors an additional neutron. The chemical signature involves measuring the amount of this heavier hydrogen isotope, called deuterium, relative to its lighter, regular form — a quantity called the deuterium-to-hydrogen ratio, or D/H.

"The D/H in water tells us at what temperature the ice formed, and from that how far a comet formed from the Sun," Kathleen Mandt, a planetary scientist at NASA and corresponding author of a new study describing the reanalysis, told Live Science in an email. The lower the D/H value is, the farther from the sun the asteroid or comet was born.

Related: 'Crumb trails' of meteoroids could reveal potential 'planet-killer' comets years before they reach Earth

Research over the past few decades has shown that Earth's D/H ratio is similar to those of many asteroids and a handful of Jupiter-family comets — a group of comets that swing past the sun roughly every 20 years and whose paths are tweaked by Jupiter's gravity.

But the D/H value of the "rubber ducky" comet 67P/Churyumov-Gerasimenko, determined in a 2015 study, essentially ended the case for comets. Averaged over 150 measurements collected by ESA's Rosetta mission during the spacecraft's 2014 rendezvous with Comet 67P, the D/H value was roughly three times Earth's. The researchers interpreted this as evidence that comets were very unlikely to have delivered water to Earth.

The results were perplexing, Mandt said, because the D/H value was way higher than those of other Jupiter-family comets. Plus, "the comet should have a lot more CO [carbon monoxide] and N2 [nitrogen] than Rosetta measured because these ices also form at really cold temperatures," she added.

To understand Comet 67P's apparently high D/H ratio, Mandt and other astronomers from research institutes in the U.S., France and Switzerland decided to comb through the entire Rosetta dataset. Using an innovative statistical technique developed by Jacob Lustig-Yaeger from the Johns Hopkins Applied Physics Laboratory, the team identified signals coming only from deuterium-containing water molecules, allowing them to collate about 4,000 D/H measurements.

The researchers found that the D/H values varied wildly along the comet's long axis, with the highest being near the "nucleus" — the rocky part that resembles a rubber ducky — and decreasing along the tail.

Such variation likely occurs because of processes occurring within the comet, the researchers wrote in their study, published Nov. 13 in the journal Science Advances. As the comet approaches the sun, the comet's surface warms up, which releases gas along with ice-coated dust particles into the coma (the halo that develops around the nucleus). Previous, unrelated lab studies had shown that deuterium-containing ice tends to stick to dust grains more than to normal ice. The scientists realized that such dust grains, upon entering the coma, could account for the high D/H values recorded there.

However, the researchers noted that dust particles about 75 miles (120 kilometers) from the nucleus are essentially dried out, meaning they lack any deuterium-enriched ice that could generate spuriously high D/H values. Using only the data collected at this distance, the authors calculated that Comet 67P's actual D/H value was only 1.5 times that of Earth.

The revised D/H value means that "all Jupiter Family Comets that we have been able to measure have a D/H closer to the Earth's water D/H," Mandt said. This implies that comets played a major, rather than minor, role in irrigating Earth. Plus, she added, a lower D/H value suggests Comet 67P was born closer to the sun than scientists previously thought.

Asteroids are rocky objects that orbit the sun, and although the vast majority of asteroids are harmless, there are often close shaves with our planet. Live Science is here to put asteroid threats into perspective and answer all of your asteroid-related questions, from whether an asteroid could destroy Earth to why asteroids and comets are such weird shapes.

Whether it’s the fastest-orbiting asteroid in our solar system, a 600-foot asteroid detected near Earth or NASA proving humanity can deflect killer asteroids with rockets, our expert writers and editors are on point to separate the potentially hazardous from the mostly harmless. So, for everything you need to know about the sizeable stones that share our solar system check out the latest asteroid news, features and articles.

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