The Eta Aquariid meteor shower will peak overnight from May 5-6, giving skywatchers a chance to spot fast-moving "shooting stars" created by debris from Halley's Comet.

The Eta Aquariids (also spelled Eta Aquarids) are active from April 19 to May 28 each year, with meteors appearing to radiate from the constellation Aquarius, specifically near the star Eta Aquarii, according to Time and Date. The star, which is 168 light-years away, is visible to the naked eye — however, that distant star really has nothing to do with the shower.

The shower is one of two annual meteor displays linked to the famous Halley's Comet, which takes about 76 years to orbit the sun. The last time it was in the inner solar system was in 1986, and it will return in 2061.

Halley's Comet is currently traveling through the outer reaches of the solar system, beyond the orbit of Neptune. But twice each year, Earth passes through the trail of dust and debris that the comet has previously left behind. That creates both the Eta Aquariids in April and May and the Orionid meteor shower from early October to early November.

As Earth moves through Halley's debris, tiny particles enter the atmosphere at around 40.7 miles per second (65.4 kilometers per second), according to the American Meteor Society, producing swift meteors and persistent glowing trails. Bright fireballs are possible, but rare. Eta Aquariid activity is strongest for about a week centered on the peak night.

From the Northern Hemisphere, the shower usually produces medium rates of around 10 to 30 meteors per hour. That's because the radiant, Eta Aquarii, stays relatively low on the eastern horizon. However, meteors may still appear as long "Earthgrazers" that skim low across the sky.

The Eta Aquariids are strongest when viewed from the Southern tropics, where the radiant rises higher in the sky before sunrise. Under ideal dark-sky conditions, up to 50 meteors per hour are possible.

For this year's meteor shower, moonlight will make it harder to spot meteors. On the peak night of May 5-6, the moon will be a waning gibbous that's 84% full, and its brightness could reduce rates to fewer than 10 meteors visible per hour, according to the American Meteor Society.

The best time to watch will be before dawn on May 6, when the radiant point is highest in the sky and the moon is lower, which improves visibility for fainter meteors. You'll want to watch the shower with your naked eyes, after letting them adjust to the dark — however, a good astrophotography camera is recommended if you want to try your hand at photographing a meteor shower.

A dramatic photo shows the extremely unlikely moment when a blazing fireball meteor photobombed a contender for the "Great Comet of 2026" as it shone in the night sky over a 500-year-old European castle.

Photographers Petr Horálek and Josef Kujal snapped the cosmic coincidence on April 18 in the skies over the ruins of the 15th-century Kunětická Hora Castle, in the central Czech Republic, at around 4:15 a.m. local time. They were initially attempting to capture the lengthy tail of Comet C/2025 R3 (PanSTARRS) when a bright streak of light flew across the sky in front of their target.

Reports from the European Fireball Network later confirmed that the streaking light was a fireball meteor that resulted from an asteroid exploding over Belarus shortly after entering Earth's atmosphere, Horálek told Live Science. It is currently unclear how large the space rock was, how fast it was traveling or how long it shone in the sky.

"What are the odds," Horálek wrote in an Instagram post. By combining his photos with Kujal's, Horálek created a time-lapse image to "show the whole lucky moment," he added.

The photo is even more incredible considering that this was the "last chance to capture the comet from mid-Europe," due to adverse weather conditions the following nights, Horálek wrote on his personal website. If the incident had occurred just 15 minutes later, light from the rising sun likely would have obscured the comet's tail, he added.

A similarly unlikely photo was captured last October, when the tail of Comet Lemmon appeared to be entwined with a smoke trail left by a "shooting star." However, in this case, the photographer was able to intentionally align the comet with the smoke trail, which lingered in the air after the meteor burned up, making the newest photo arguably more impressive.

The Great Comet of 2026?

Comet PanSTARRS is a long-period comet, meaning it likely takes more than 200 years to orbit the sun. It probably originates from the Oort cloud, a giant reservoir of comets and other icy objects near the edge of the solar system.

The comet passed its closest point to the sun, or perihelion, Sunday (April 19). It was clearly visible with a decent telescope or pair of stargazing binoculars beginning April 13. However, it has now largely disappeared from view.

The comet was first spotted in September 2025, and some experts later suggested that it could become the most easily visible comet of 2026. So far, this prediction has held true, especially after its main competitor — the sungrazer comet C/2026 A1 (MAPS) — ripped apart during its superclose approach to the sun earlier this month, before it got a chance to shine properly.

However, there is always a chance that a previously unknown comet could emerge to steal the show, much like the interstellar comet 3I/ATLAS, which was discovered last July and went on to become one of the biggest space news stories of the year.

"Fireball season"

Fireball meteors occur when falling space rocks suddenly split apart due to strain on their surfaces caused by friction with the atmosphere. This releases energy in the form of bright light, which can shine in many potential colors depending on the meteor's chemical composition.

Fireballs are most likely between February and April, also known as "fireball season," when the number of exploding space rocks can rise by between 10% and 30% compared with the rest of the year, according to NASA. This is likely due to Earth's position relative to the sun and the rest of the solar system. However, experts are still not entirely sure why.

This fireball season has been particularly eventful, especially March, when there were at least 10 major fireballs visible in the U.S. — the highest total for that month since 2012, according to AccuWeather.com. This included a cannonball-size meteor crashing through the roof of a house in Texas and a rare daytime explosion that triggered a powerful sonic boom over Ohio.

A bright fireball also exploded over Europe last month and showered a German town with meteorites, one of which also punched a football-size hole through the roof of a house. And just last week, on April 13, a bright-green fireball exploded over the North Sea and was spectacularly snapped streaking above Lindisfarne Castle in northeast England.

A highly anticipated "sungrazer" comet is no more. Many experts expected the comet to shine so brightly that it could be seen in the daytime sky. Instead, the unfortunate object was ripped apart by a superclose "death dive" with our home star, which briefly transformed it into a "headless wonder" — a comet with no body, just a ghostly tail — stunning footage reveals.

The comet, dubbed C/2026 A1 (MAPS), was a member of the Kreutz sungrazers — a group of comets, likely leftover fragments from a massive exploded comet, that pass extremely close around the sun. Scientists discovered the comet in January and initially believed it was around 1.5 miles (2.4 kilometers) wide, but subsequent photos captured by the James Webb Space Telescope revealed that it was only around 0.25 miles (0.4 km) across.

For months, experts have been guessing how bright comet MAPS might become if it survived its solar slingshot. Most agreed that it would put on a spectacular show, like other previous sungrazer comets, such as comet Lovejoy, which lit up the night sky in 2011. Others even speculated that it could become so bright that it would become visible to the naked eye during the day.

On Saturday (April 4), comet MAPS reached its closest point to the sun, or perihelion, where it dipped into the sun's outer atmosphere, or corona, at a distance of just 100,000 miles (160,000 km) from the solar surface — around half the distance between Earth and the moon. The close encounter was not visible to astrophotographers, thanks to the comet's close proximity to our home star. But several space-based observatories captured the solar flyby.

It quickly became clear that comet MAPS did not survive its solar slingshot. Time-lapse images captured by the Solar and Heliospheric Observatory (SOHO) show the bright comet streaking toward the sun and then emerging from the obscured solar disk as a plume of dust and gas — essentially, nothing but a tail.

The comet was likely destroyed by the intense thermal stress placed on its icy shell, or nucleus, as well as the high gravitational forces on the comet as it traveled at around 1 million mph (1.6 million km/h), according to Spaceweather.com.

"The comet went in, but only a cloud of debris came out," Spaceweather.com representatives wrote about the SOHO video footage. "RIP, comet MAPS."

The debris trails left over from comet MAPS, known as striae, briefly shone as a headless wonder. However, the debris quickly scattered, and there is now nothing left to see of comet MAPS, Live Science's sister site Space.com reported.

Luckily, comet MAPS is not the only highly anticipated comet that could be visible in April.

Later this month, another comet, C/2025 R3 (PanSTARRS), will shine brightly as it reaches its perihelion on April 19. But unlike comet MAPS, this object will pass much farther from the sun — around 46.4 million miles (74.6 million km) — making it a much more reliable target for skywatchers armed with a decent telescope or a pair of stargazing binoculars. The best time to see it will be a few days before its close approach to the sun, when the new moon guarantees a dark sky.

Several experts previously predicted that comet PanSTARRS could be the "Great Comet of 2026." And given the death of comet MAPS, this suggestion now seems more likely to be correct.

An incoming comet could provide one of the year's most exciting skywatching events, but only for early risers.

The comet, named C/2025 R3 (PanSTARRS), is currently brightening in the night sky, getting comet hunters excited for its closest approaches to Earth and the sun. The spectacle comes shortly after the unrelated Comet C/2026 A1 (MAPS) was vaporized when it flew just 100,700 miles (162,000 kilometers) from the sun, depriving skywatchers of the chance to see it at its best.

Observations in early April had Comet PanSTARRS at around magnitude 6, right on the cusp of naked-eye visibility in a very dark sky. Although nothing is guaranteed, light-curve data from the Comet Observation database indicates that the comet could brighten to approximately magnitude 4 in the coming weeks, making it much more likely to be visible to the naked eye.

However, comet brightness is highly unpredictable. While current projections are encouraging and PanSTARRS is far less likely to break up than Comet MAPS was, its actual visibility will depend on how the comet behaves as it nears the sun. What seems almost certain is that it will, at the very least, be visible with a pair of stargazing binoculars, which is a rare opportunity.

The comet will reach perihelion (its closest point to the sun) on April 20, when it will pass within 47.4 million miles (76.3 million km). This close approach often increases a comet's activity and brightness, as ice on the comet sublimates into gas that glows as it soaks up solar radiation. The comet will then make its closest approach to Earth on April 27, at about 44 million miles (70.8 million km) distant.

The best time to observe Comet PanSTARRS from the Northern Hemisphere will be in mid-April. From around April 13 to April 15, the comet will appear near the Great Square of Pegasus, which will be just above the eastern horizon an hour before sunrise, before moving into Pisces. A new moon on April 17 will provide dark skies leading into perihelion, which will improve viewing conditions. However, by April 27, the comet may be partially lost in the sun's glare, despite reaching peak brightness.

Whether it becomes a truly spectacular object remains uncertain, but current signs suggest that Comet PanSTARRS is one to watch this month. Learn more in our April stargazing guide.

A rare "sungrazer" comet is about to pass very close to our star and could become visible in daylight — or it could completely disintegrate before our eyes. Either way, there could be something special to see in the night sky, with a large tail potentially visible late this week.

Comet C/2026 A1 (MAPS) was discovered Jan. 13 by French astronomers at the AMACS1 Observatory in Chile. Although the comet was initially thought to have a nucleus measuring around 1.5 miles (2.4 kilometers) wide, astronomers later reduced the estimate to under 0.25 miles (0.4 km) based on James Webb Space Telescope observations taken in February.

C/2026 A1 (MAPS) belongs to a special family of comets called Kreutz "sungrazers," so called because they get very close to the sun, lighting up brightly but often breaking into smaller pieces. There are around 3,500 members of the Kreutz family, all of which are thought to be fragments of a single giant comet that got too close to the sun about 1,700 years ago, according to Live Science's sister site Space.com.

C/2026 A1 (MAPS) is expected to get within 98,000 miles (158,000 km) of the sun's surface and pass through the lower regions of the sun's outer atmosphere, or corona, at 9:30 a.m. EDT (13:30 UTC) Saturday (April 4), according to the British Astronomical Association (BAA). According to the European Space Agency, many Kreutz sungrazers evaporate, but if they survive, they could put on a spectacular show.

Because C/2026 A1 (MAPS) is traveling into the sun's glare, it will be difficult to see before April 4. If it survives its close encounter with the sun — even if it fragments — it could become visible for a short time after sunset in the evenings that follow. Unless it breaks apart before it gets close to the sun, there will be a possibility of seeing a potentially large and bright tail in the western evening sky starting around April 9, according to the BAA.

If that occurs, Comet C/2026 A1 (MAPS) will be the first of two comets visible in April, with the likely dimmer but more predictable C/2025 R3 (PanSTARRS) set to become an easy binocular target close to April 20.

For the first time ever, an astronomer has witnessed a comet changing the speed and direction of its own spin, thanks to newly analyzed Hubble Space Telescope photos. The unexpected reversal was triggered by "outgassing" jets that shot an icy mix of gas and dust into the solar system, according to a new study.

The comet, dubbed 41P Tuttle-Giacobini-Kresák (41P for short), was discovered by American astronomer Horace Parnell Tuttle in 1858, before being rediscovered by French astronomer Michel Giacobini in 1907 and again by Slovak scientist L'ubor Kresák in 1951 (hence its lengthy name). Comet 41P likely originates from the Kuiper Belt — the ring of asteroids, comets and dwarf planets beyond the orbit of Neptune — and likely spent the majority of its long life circling the sun on a timescale of decades to centuries.

But around 1,500 years ago, 41P was tugged off its usual course by a close interaction with Jupiter. Now, it is locked in a much tighter orbit, circling our home star every 5.4 years. As the comet reaches its closest point to the sun, known as perihelion, it also passes by Earth and becomes clearly visible with a telescope. Its last flyby of the sun occurred in 2022, but it was also studied extensively in 2001, 2006, 2011 and 2017.

During the 2017 flyby, astronomers noticed that 41P's rate of rotation slowed significantly as the comet shot past Earth ‪—‬ which scientists had previously attributed to a standard outgassing event. Hubble also captured extensive photos of the flyby. However, these images were filed away and had not been studied properly.

Now, in the new study published March 26 in The Astronomical Journal, an astronomer has analyzed the Hubble images from 2017 and discovered that the sudden slowdown was followed by a previously unrecognized acceleration event.

By comparing the Hubble images to data collected by ground-based telescopes, study author David Jewitt, an astronomer at UCLA, estimated the changes in 41P's rotation throughout 2017. He found that by May of that year, the comet's spin had slowed to around one rotation every 46 to 60 hours, which was around three times slower than it was spinning in March 2017. But by December 2017, the comet was completing a rotation once every 14 hours, which was a much quicker return to form than previously realized, according to Live Science's sister site Space.com.

But if outgassing had slowed the comet's spin, how could it speed it up again so quickly? The only thing that makes sense, Jewitt argues, is if the direction of the comet's spin was completely reversed.

"It's like pushing a merry-go-round," he said in a statement. "If it's turning in one direction, and then you push against that, you can slow it and reverse it."

With the Hubble data, Jewitt also constrained the true size of 41P's nucleus, which is approximately 0.6 miles (1 kilometer) across — around three times wider than Paris' Eiffel Tower is tall. That might sound impressive, but it is actually quite small for a comet. And its diminutive size may prove key in explaining its unusual behavior.

Passing gas

Almost all known comets have been observed "outgassing" at some point in their lifetimes. This phenomenon occurs when ice, gas and dust from the comet's interior shoots out of small cracks that appear in its nucleus — normally due to an increased proximity to the sun, which allows solar radiation to sublimate the comet's innards and crack its icy shell.

In recent years, we have seen several stunning examples of outgassing in action, including the demonic horns of the explosive "devil comet" 12P/Pons-Brooks, which slingshotted around the sun in 2024, and the multiple jets and "anti-tail" of the interstellar object 3I/ATLAS, which was spotted shooting through the solar system last year.

Scientists previously knew that outgassing could alter the spin of a comet, but most of these objects are too large for an outflowing jet to make much of a difference before it fades away. However, 41P's relatively small size likely enabled the comet's jets to make a greater impact.

"Jets of gas streaming off the surface can act like small thrusters," Jewitt said in the statement. "If those jets are unevenly distributed, they can dramatically change how a comet, especially a small one, rotates."

Experts are unsure if 41P's extreme outgassing event was caused by multiple jets or a single massive outflow. But if repeated events occur over the comet's next few perihelia, the icy ball could end up ripping itself apart, similar to Comet C/2025 K1 (ATLAS), which spectacularly broke apart in late 2025.

"I expect this nucleus [41P] will very quickly self-destruct," Jewitt said.

Interstellar comet 3I/ATLAS is up to 12 billion years old and unlike anything found in our solar system, new James Webb Space Telescope (JWST) observations suggest.

Comet 3I/ATLAS became a celestial celebrity last year after the interstellar visitor was discovered hurtling through our cosmic neighborhood. Not long after, online speculation suggested that the space rock could be an alien spacecraft. However, most astronomers are confident that 3I/ATLAS is a comet from an unknown star system.

Now, new preliminary findings from a study posted to the preprint server Research Square, which are still under peer review, suggest the comet formed in a cold and distant region of the Milky Way around 10 billion to 12 billion years ago. That would make comet 3I/ATLAS more than twice as old as Earth (4.5 billion years old) and our solar system (4.6 billion years old), and at its upper range, not far off the ages of our Milky Way galaxy and the universe itself (about 13.6 and 13.8 billion years old).

Researchers already knew from the comet's speed and trajectory that it was potentially the oldest comet ever seen. Previous estimates put the comet's age at somewhere between 3 billion and 11 billion years old. The new findings further narrowed down the comet's age and origin by looking at isotope measurements taken by JWST when the comet flew past Earth in December 2025.

"They show that 3I/ATLAS isotopic composition is very different from solar system comets and suggest that it likely formed 10-12 billion years ago," Romain Maggiolo, a research scientist at the Royal Belgian Institute for Space Aeronomy who was not involved in the study, told Live Science in an email. "In other words, 3I/ATLAS formed in a stellar environment different from ours, not only somewhere else in space, but also at a much earlier time in the history of the Milky Way."

Comet 3I/ATLAS is only the third interstellar object ever recorded in our solar system. The space rock, which Hubble Space Telescope observations suggest is somewhere between 1,400 feet (440 meters) and 3.5 miles (5.6 kilometers) wide, zoomed into our solar system at around 137,000 mph(221,000 km/h) last year before slingshotting around the sun.

After reaching its closest point to our star, known as perihelion, on Oct. 29, 2025, the comet then made its closest approach to Earth on Dec. 19, when it came within about 168 million miles (270 million km) of our planet. JWST made the observations that have been analyzed in the new study a few days later on Dec. 22.

A relic from the ancient universe

Comets heat up as they fly closer to stars, which causes ice on their surfaces to sublimate into gas. By studying the composition of this gas, researchers can start to figure out what they're made of and the conditions in which they formed.

The authors of the new preprint looked at the ratio of isotopes, or versions of elements, in material outgassed by 3I/ATLAS. They found that the comet's water is more enriched in deuterium, a heavier hydrogen isotope, than any previously studied comet, while its ratio of carbon isotopes also exceeded levels normally seen in our solar system.

The results offer clues to what conditions may have been like in whatever ancient planetary systems forged the comet in the early years of the Milky Way.

"If 3I/ATLAS is indeed as old as this study suggests, the large amounts of volatile molecules it contains indicate that rich prebiotic chemistry may already have been occurring in star-forming regions very early in the history of our Galaxy," Maggiolo said.

The results also indicate that the comet formed in a cold environment that was around 30 kelvins (minus 406 degrees Fahrenheit, or minus 243 degrees Celsius), likely in a dense and well-shielded protoplanetary disk, according to the study.

While the study is still in the preprint stage, Maggiolo, who has studied comet 3I/ATLAS as part of his own research, didn't have any major concerns about it. The new measurements help researchers "better understand this interstellar messenger," he said.

Josep Trigo-Rodríguez, the research principal investigator of the Asteroids, Comets and Meteorites research group at the Institute of Space Sciences (CSIC/IEEC) in Spain who has previously identified erupting "ice volcanoes" on comet 3I/ATLAS, described the new findings as a good compilation of scientific results, using different techniques from well-recognized experts.

"This manuscript exemplifies that interstellar comets are unique bodies that are able to sample remote regions of our Milky Way galaxy," Trigo-Rodríguez told Live Science in an email.

There's a good chance that researchers will never know which star system birthed comet 3I/ATLAS. The comet has likely been traveling through space for billions of years and has come a very long way in that time. Maggiolo's own research has found evidence that the object is extremely irradiated, with all that time in space exposing it to cosmic rays that could have fundamentally altered its chemical composition, making its origins more difficult to decipher.

"The isotopic composition of the material outgassed by 3I/ATLAS provides a crucial new piece of the puzzle," Maggiolo said. "But the puzzle is far from being complete!"

Finding those puzzle pieces is a race against time for astronomers, as comet 3I/ATLAS is now hurtling out of the solar system. It's currently passing Jupiter, where it is expected to make its closest approach on Sunday (March 15). The comet will come within about 33 million miles (54 million km) of the gas giant — much closer than it got to Earth.

The interstellar traveller will then continue its journey away from us, crossing Saturn's orbit in July, Uranus' orbit in April 2027 and Neptune's orbit in March 2028. You can track the comet using NASA's Eyes on the Solar System simulation of the comet's trajectory.

The arrival of 3I/ATLAS in our solar system spawned multiple proposals for a rendezvous mission to study it up close. As the third interstellar object (ISO) ever detected, the wealth of information direct studies could provide would be groundbreaking in many respects. However, the mission architecture for intercepting an interstellar comet poses numerous significant challenges for mission designers and planners. Chief among them is the technological readiness level (TRL) of the proposed propulsion systems, ranging from conventional rockets to directed-energy propulsion (DEP).

So far, mission proposals have focused on chemical rockets launched from Earth, like NASA's Janus mission and the ESA's Comet Interceptor, or on existing missions like the Juno probe adjusting their trajectories to rendezvous with it. In a recent paper, researchers from the Initiative for Interstellar Studies (i4is) propose foregoing a direct transfer mission that would launch from Earth today. Instead, they demonstrate how a mission launching in 2035 could intercept 3I/ATLAS using an indirect Solar Oberth maneuver.

Adam Hibberd, a software and research engineer in Astronautics with the i4is and the owner/director of Hibberd Astronautics Ltd., led the study. He was joined by T. Marshall Eubanks, the Chief Scientist at Space Initiatives Inc. and the CEO of Asteroid Initiatives LLC., and Andreas Hein, an Associate Professor of Aerospace Engineering at the University of Luxembourg and the Chief Scientist at the Interdisciplinary Centre for Security, Reliability and Trust. Their paper has accepted for publication in the Journal of the British Interplanetary Society (JBIS).

The main challenges for a direct mission to rendezvous with 3I/ATLAS stem from the target object's celestial mechanics, its high heliocentric speed, and the late initial detection. The first issue effectively rules out a rendezvous mission that relies on an onboard propulsion system to match the comet's velocity, thereby enabling a prolonged close-up study of the body. As a result, a flyby mission is the preferred option. However, the second and third considerations rule out a direct mission because the optimal launch date had already passed before it was detected. As Hibberd summarized these for Universe Today via email:

"For the direct mission, the object 3I/ATLAS was detected too late, when it had already travelled inside the orbit of Jupiter, and with a velocity in excess of 60 km/s. It turns out, this was after the optimal launch date for a direct mission to intercept it. One paper found that there would even have been difficulties for a ‘Comet Interceptor’ spacecraft had it been already loitering at the sun/Earth L2 point when 3I/ATLAS was discovered."

This is where Hibberd employed the Optimum Interplanetary Trajectory Software (OITS), which he designed, to assess the feasibility of direct and indirect missions to intercept ISOs. This software has a proven track record for solving missions with Solar Oberths, which includes a previous i4is study for a mission (Project Lyra) that would intercept the first ISO ever detected, 'Oumuamua. Integral to Project Lyra and other missions utilizes OITS is the use of gravitational assists (GAs) and/or Oberth Maneuvers.

The former involves a slingshot maneuver that leverages a planet's (or moon's) gravity to increase speed. The latter consists of a spacecraft under the gravitational influence of a massive body (the sun), waiting to reach its closest pass (perihelion), then applying thrust to achieve a high heliocentric speed. The spacecraft can either achieve escape velocity from the solar system this way, or pick up enough speed to rendezvous with an ISO that has already traveled a huge distance by this time. Said Hibberd:

"For the direct mission, the object 3I/ATLAS was detected too late, when it had already travelled inside the orbit of Jupiter, and with a velocity in excess of 60 km/s. It turns out, this was after the optimal launch date for a direct mission to intercept it. One paper found that there would even have been difficulties for a 'Comet Interceptor' spacecraft had it been already loitering at the Sun/Earth L2 point when 3I/ATLAS was discovered."

The Solar Oberth option is designed for when an interstellar object has passed through its perihelion (closest approach to the sun) and is receding rapidly away from the sun. It recognizes the fact that a humongous speed needs to be generated by a spacecraft to catch such an object and exploits the so-called ‘Oberth Effect’ in order to generate this speed. When a spacecraft approaches the sun, the sun’s gravitational attraction increases its velocity until the perihelion is reached, then the spacecraft burns its solid-propellant engines at this optimal point, to maximize the ‘slingshot effect’, and to accelerate the probe expeditiously to the target object, in this case 3I/ATLAS.

Based on their OITS simulations, the team found that an intercept could be achieved via a Solar Oberth maneuver, but the launch would have to occur in 2035 to achieve optimal alignment between Earth, Jupiter and 3I/ATLAS. The flight duration would be 50 years (though Hibberd notes that this could be reduced marginally). "2035 is optimal because the alignments of the celestial bodies involved (i.e. the Earth, Jupiter, sun, and 3I/ATLAS) are the most propitious to reach 3I/ATLAS with a minimum Solar Oberth propulsion requirement from the probe, a minimum performance requirement for the launch vehicle, and a minimum flight time to the target," he said.

While such a mission would take a long time to intercept an ISO, the scientific returns would be nothing short of revolutionary. Asteroids and comets are essentially material leftover from the formation of planetary systems. As such, the study of ISOs would reveal things about other star systems without having to send missions to them, which could take centuries or longer. While DEP is being investigated as a possible solution, a la Swarming Proxima Centauri (another i4is project), the TRL of this concept is likely many decades away.

In the meantime, a spacecraft developed with current technology that relies on a Solar Oberth maneuver could reach an ISO and provide a detailed analysis in the same time frame. Even if we never send missions to nearby stars to observe what is there, an ISO interceptor could tell us all we need to know about systems beyond ours.

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

A mysterious volcanic comet has transformed into a giant, "fossil-like" spiral of light after one of its most violent outbursts in years, new photos reveal. The stunning spectacle is a reminder of how puzzling this particular planetary remnant really is.

The unusual comet, known as 29P/Schwassmann-Wachmann (29P), is a hefty ice ball spanning around 37 miles (60 kilometers) — roughly three times the length of Manhattan. It is part of a rare group of around 500 objects dubbed "centaurs," which spend their entire lives circling the inner solar system. The comet also belongs to an even more exclusive club known as cryovolcanic comets, which occasionally spew gas and ice across our cosmic neighborhood.

A cryovolcanic comet blows its top when its icy shell, or nucleus, soaks up too much solar radiation. This extra radiation superheats the mix of frozen gas and dust — called cryomagma — in the comet's interior and causes the icy mix to sublimate. The resulting gas causes a pressure buildup in the comet's center, which eventually forces open a crack in the nucleus, allowing it to spray its icy guts into space. When this happens, the fuzzy cloud of material surrounding the comet, known as its coma, expands significantly, allowing it to reflect more sunlight and making it shine much more brightly in the night sky.

On Feb. 10, Comet 29P experienced a sudden brightening event, roughly equivalent to a 100-fold increase in its luminosity, signaling that it had undergone a major eruptive event, according to Spaceweather.com.

This outburst is one of the comet's "top five" eruptions of the past two and a half decades, experts told Spaceweather.com, and it's the most powerful event since a quadruple eruption in October 2024, which caused Comet 29P to shine 300 times brighter than normal.

However, in the days following the explosive outburst, researchers began to notice something unusual about 29P's expanding coma: The reflective cloud was not evenly distributed around the comet as it typically would be. Instead, the cloud appeared to have stretched out into a rare spiral shape.

Amateur astronomer and astrophotographer Eliot Herman snapped the lopsided coma from the Rio Hurtado valley in Chile (see above) and said it resembled a fossil of an extinct shelled cephalopod known as an ammonoid. Fellow photographer Anthony Kroes, who also captured a stunning shot of the spiral from Wisconsin, remarked on its "snail-shell appearance."

The unusual shape likely results from an internal rotation of the comet's interior relative to its nucleus, which causes cryomagma to unevenly spew out of a newly formed vent on its icy surface, according to Spaceweather.com.

This is very similar to the "devil comet," 12P/Pons-Brooks, which appeared to grow demonic horns during the initial eruptions of its solar flyby in late 2023, likely due to a notch on its surface that partially blocked the outflow of cryomagma, experts said at the time.

The interstellar comet 3I/ATLAS, which made headlines as it zoomed through the inner solar system last year, also displayed evidence of cryovolcanism and likely leaked cryomagma through multiple jets.

Unexplained outbursts

Most cryovolcanic comets, like 12P/Pons-Brooks and the recently discovered Comet SWAN, are long-period comets that dwell in the outer solar system and drift toward the sun every few hundred or thousand years. They erupt only as they near our home star — and soak up additional radiation — before ceasing activity and quietly returning to the edge of our cosmic neighborhood.

However, Comet 29P orbits the sun in a roughly circular trajectory, meaning it's pretty much always the same distance from the sun. It is located between Jupiter and Saturn — around six times farther from our home star than Earth is — so it does not receive much sunlight.

Still, Comet 29P experiences an average of 20 eruptions per year. Most of these are small, but occasionally, a much bigger outburst — like the one we have just seen — comes along, releasing up to 1 million tons of cryomagma into space.

This has been frustrating for researchers because they have no clear idea of what triggers these larger outbursts, when the comet's conditions appear to remain fairly stable.

In April 2023, researchers predicted one of these major eruptions in advance, thanks to a mini dimming event just before the comet blew its top. However, they were still unsure why it happened.

How to see 29P/Schwassmann-Wachmann

Comet 29P has passed its peak brightness. However, it has remained unusually luminous thanks to a second, smaller outburst Sunday (Feb. 15), which pumped a fresh batch of cryomagma into the comet's coma, according to Spaceweather.com. (It is currently unclear if the reinvigorated coma will also expand into a spiral.)

You should still be able to see the comet with a decent telescope or pair of stargazing binoculars. It is currently located in the constellation Leo, according to TheSkyLive.com.

Major eruptions like this are often followed by multiple smaller eruptions, or "aftershocks," meaning we could see more outbursts in the coming days or weeks, Richard Miles, an astronomer with the British Astronomical Association who has studied Comet 29P, told Spaceweather.com.

If you decide to head out under the stars, you may also want to keep an eye out for Comet C/2024 E1 (Wierzchoś), which is shining brightly after passing its closest point to Earth on Tuesday (Feb. 17). Researchers predict that this ice ball may soon be kicked out of the solar system forever, similar to 3I/ATLAS, so this may be your only chance to see it.

In April, we will be treated to two more exciting comets: the newly discovered "sungrazer" comet C/2026 A1 (MAPS), which could shine bright enough to be seen with the naked eye during the daytime, and the long-period comet C/2025 R3 (PanSTARRS), which could also become visible without a telescope at night.

A striking "green comet" about the size of a small city is lighting up the night sky as it nears Earth next week. Experts predict the hefty iceball may soon be permanently ejected from the solar system, dooming it to drift through interstellar space — like the "alien" comet 3I/ATLAS.

The new comet, dubbed C/2024 E1 (Wierzchoś), was discovered in March 2024 by Polish astronomer Kacper Wierzchoś, who spotted the icy object sailing toward us with a 4.9-foot (1.5 meter) telescope at the Mount Lemmon Observatory in Arizona. The comet has since been observed by the James Webb Space Telescope (JWST), which detected large amounts of carbon dioxide in its coma — the cloud of gas and dust that surrounds the comet's icy shell.

An initial analysis of JWST data suggested that Comet Wierzchoś' nucleus has a diameter of around 8.5 miles (13.7 kilometers), which is roughly two-thirds the length of Manhattan and around four times the island's width. However, a more recent study, which has not yet been peer-reviewed, hints that this may be an overestimate.

Comet Wierzchoś originates from the Oort cloud — the expansive reservoir of comets and other icy objects lurking near the outer edge of the solar system — and is hyperbolic, meaning that it has an open and flattened trajectory, and does not repeatedly orbit the sun. This is likely the first time it has ever ventured into the inner solar system, the researchers suspect.

Some researchers believe that it has been slowly falling toward the sun for between 1 million and 3 million years, although it is hard to tell for sure. But most experts agree that the gravitational kick from its current solar slingshot will fire it out of our cosmic neighborhood forever and into interstellar space, according to Spaceweather.com.

The eccentric iceball recently passed its closest point to our home star, known as perihelion, on Jan. 20, reaching a minimum distance of around 52 million miles (84 million km) from the solar surface, Live Science's sister site Space.com previously reported.

It will soon make its closest approach to Earth, on Tuesday (Feb. 17), when it will be around 94 million miles (151 million km) from our planet — roughly the same distance away as the sun.

Going, going, gone

According to the researchers, it could take several decades or even centuries for Comet Wierzchoś to officially leave the solar system. But once it has, it will spend millions if not billions of years drifting through the Milky Way, sporadically passing through other alien star systems on its way.

This is exactly what happened to the interstellar comet 3I/ATLAS, which made headlines last year as it shot through the inner solar system, having been kicked out by its home star likely long before the sun was born.

3I/ATLAS was first spotted in July and reached perihelion in late October, before swinging past Earth in mid-December. During this period, it displayed many unusual characteristics, which led some scientists to controversially propose that it may be an alien spacecraft — despite overwhelming evidence that it is a natural comet.

It is now on its way back out of the solar system and will likely pass through many other star systems, much like Comet Wierzchoś eventually will.

How to see C/2024 E1 (Wierzchoś)

Since Comet Wierzchoś passed perihelion, it has become significantly brighter and grown a long tail of gas and dust, allowing astrophotographers to snap spectacular shots of it speeding across the night sky. Austrian astrophotographer Gerald Rhemann captured one of the best photos of the iceball on Jan. 26 from a night sky reserve in Namibia (see above).

Many of these photos, including Rhemann's, show the comet's coma glowing green. This rare hue is likely tied to its high carbon content, as seen in previous comets, although the exact cause of its coloration has not been reported on by researchers.

The emerald iceball will not become bright enough to be visible to the naked eye. However, it can be easily spotted with a decent telescope or pair of stargazing binoculars.

From the Northern Hemisphere, it will remain observable over the next few weeks and can be best spotted above the southwestern horizon after sunset, as it passes through the constellation Sculptor, according to EarthSky.com. However, it will be easier to spot from the Southern Hemisphere.

For more information on exactly when and how to see the comet for yourself, you can visit TheSkyLive.com.

Close encounters of the cometary kind

2026 is shaping up to be another bumper year for comet enthusiasts, following on from the excitement of 3I/ATLAS, as well as other comets like Lemmon and SWAN, last year.

In recent weeks, astronomers have spotted a new "sungrazer" comet, dubbed C/2026 A1 (MAPS), which could potentially become bright enough to be seen with the naked eye during the daytime in early April — if it survives its extremely close slingshot around the sun.

Another hefty iceball, dubbed C/2025 R3 (PanSTARRS), could also become visible without a telescope as it nears its closest points to both the sun and Earth in late April.

With the help of the newly operational Vera C. Rubin Observatory, some researchers are also hoping that we may soon find many more hidden objects — potentially including the solar system's next interstellar visitor.

The interstellar comet 3I/ATLAS shed the building blocks of life as it flew past Earth last year, according to new data from NASA's SPHEREx space telescope.

From its position in orbit, SPHEREx watched the rare interstellar visitor swing around the sun and make its closest approach to Earth in December, before the comet began its long journey back out of our solar system.

The organic molecules seen emanating from the comet include methanol, cyanide and methane. These molecules are fundamental for biological processes on Earth, but can also be the product of non-biological processes, according to a statement released by NASA. In other words, organic doesn't mean aliens.

The SPHEREx researchers published their findings in the February issue of the Research Notes of the AAS (American Astronomical Society), which presents work in progress that has yet to be peer reviewed.

Comet 3I/ATLAS became a celestial celebrity in 2025, being only the third interstellar visitor ever detected and potentially the oldest comet ever seen. The comet's origins have been the subject of considerable speculation, with repeated suggestions that it could be an alien spacecraft. However, nearly all astronomers are confident that 3I/ATLAS is a natural comet from another star system, and the new findings don't change that.

Comets heat up as they fly closer to stars, causing ice on their surfaces to sublimate into gas. These newly unleashed gases can erupt from the comet's surface in jets, wrap around the comet's body in a cloud called a coma, and sweep away behind the comet to form a long tail. Researchers are able to detect and study these gases, and thereby explore a comet's makeup.

"Comet 3I/ATLAS was full-on erupting into space in December 2025, after its close flyby of the Sun, causing it to significantly brighten," study lead author Carey Lisse, an astronomer at Johns Hopkins Applied Physics Laboratory in Maryland, said in the NASA statement. "Even water ice was quickly sublimating into gas in interplanetary space. And since comets consist of about one-third bulk water ice, it was releasing an abundance of new, carbon-rich material that had remained locked in ice deep below the surface."

"We are now seeing the usual range of early solar system materials, including organic molecules, soot, and rock dust, that are typically emitted by a comet," Lisse added.

Though these organic molecules may be typical for a comet, they could still be remarkable in their own way. One popular theory holds that comets may spread the seeds of life to bodies across the cosmos, potentially including Earth.

Astronomers first detected comet 3I/ATLAS in July, 2025, when they spotted an unknown object whizzing along at around 137,000 mph (221,000 km/h) within the orbit of Jupiter. Researchers think it has been travelling through space for billions of years, gaining momentum from a gravitational slingshot effect as it whips by other stars and nebulae. After swinging past the sun, reaching the closest point to our star (perihelion) at the end of October, the comet came within about 168 million miles (270 million kilometers) of our planet in December.

SPHEREx (short for the Spectro-Photometer for the History of the Universe, Epoch of Reionization, and Ices Explorer) launched into low-Earth orbit in March, 2025, and just happened to get a decent view of the comet from Dec. 8 to 15.

The space telescope is designed to scan the entire night sky using 102 separate infrared color sensors, which will help researchers better understand the universe, including the gases around comets, and search for the ingredients of life. Getting a view of an interstellar visitor so soon after launch wasn't on SPHEREx's itinerary, so the timing of the comet 3I/ATLAS flyby was a lucky break for researchers.

"Our unique space telescope is gathering unprecedented data from across the universe," deputy study lead author Yoonsoo Bach, a researcher at the Korea Astronomy and Space Science Institute, said in the statement. "But in this case, our galaxy delivered a piece of a faraway star system to us only a few months after launch, and SPHEREx was ready to observe it. Science is sometimes like that: You're in the right place at the right time."

3I/ATLAS is currently soaring toward a close approach with Jupiter, where NASA's Juno spacecraft will get one last chance to study it up close before the comet leaves our solar system forever.

Earth's core contains up to 45 times more hydrogen than the oceans do, making it the largest hydrogen reservoir on the planet, a new study suggests.

Researchers found that this vast amount of hydrogen entered the core during its formation around 4.5 billion years ago, and did not arrive via comets that pummeled Earth once the core was established. The finding could settle the debate about when and how hydrogen was delivered to our planet.

"That hydrogen on Earth, including hydrogen in the core, was delivered during planet formation is an established hypothesis," study lead author Dongyang Huang, an assistant professor in the School of Earth and Space Sciences at Peking University in China, told Live Science in an email. "What differentiates the community is when hydrogen was delivered along Earth's formation."

This debate has continued because hydrogen deep inside Earth is extremely difficult to quantify. Hydrogen is the smallest and lightest element in the universe, so most techniques do not have the resolution to properly detect it in high-pressure and high-temperature environments such as Earth's core.

But estimating how much hydrogen is locked inside the core is a key to understanding how the hydrogen got there in the first place, Huang said.

Previous research used a technique called X-ray diffraction to estimate the amount of hydrogen in Earth's core. This method quantifies the minerals and other substances in a material by analyzing how that material scatters X-rays. Because Earth's core is made almost entirely of iron, scientists added hydrogen to a sample of iron in the lab and measured the expansion of the iron's crystal structure to calculate how much hydrogen could be trapped inside the core.

The downside of X-ray diffraction in this case is that it makes a couple of crucial assumptions, Huang said. First, it assumes researchers have an accurate understanding of iron crystal structures and how they react under certain conditions. Second, it supposes that silicon and oxygen, both present in the core, do not deform the crystal structure when they dissolve into iron — which, it turns out, they do.

For the new study, Huang and his colleagues employed an alternative method known as atom probe tomography. This technique can "provide 3D nanoscale compositional mapping of all the elements in the periodic table" and is "ideal for high-pressure samples," Huang said.

The researchers simulated the conditions that likely existed when Earth's core was forming. To begin, they coated a tiny sample of iron metal with hydrous silicate glass to model the core covered in magma. Then, they placed this object inside a diamond anvil cell — a device in which two diamond crystals squeeze together to generate extreme pressure similar to that found in Earth's core. To create high-temperature conditions, the scientists used lasers that heated the object to about 8,730 degrees Fahrenheit (4,830 degrees Celsius).

The researchers used atom probe tomography in this context. They discovered that hydrogen, oxygen and silicon dissolve into iron crystal structures simultaneously under extreme conditions, thus altering the crystals in previously unknown ways.

Crucially, equal amounts of hydrogen and silicon entered the "core" from the "magma" in the experiment, which helped the researchers estimate that hydrogen makes up 0.07% to 0.36% of Earth's core by weight.

The results, published Tuesday (Feb. 10) in the journal Nature Communications, suggest Earth's core contains nine to 45 times as much hydrogen as the planet's oceans. If comets had delivered hydrogen to Earth after the core had finished forming, hydrogen would mostly occur in Earth's shallower layers. But the finding that the core is Earth's biggest hydrogen reservoir indicates that hydrogen was delivered before the core was fully formed, Huang said.

"This is the first time that the mechanism of how hydrogen enters the core was identified," he said.

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

Astronomers have discovered an exciting new "sungrazing" comet that will have a perilously close encounter with our home star in less than two months. Some experts predict the hefty ice ball could become bright enough to be visible to the naked eye, even in daylight — but only if the comet survives its deadly solar slingshot.

The newfound comet, dubbed C/2026 A1 (MAPS), was discovered Jan. 13 by a team of French astronomers at the AMACS1 Observatory in Chile's Atacama Desert. It is likely around 1.5 miles (2.4 kilometers) wide and, when it was first spotted, was just over twice as far from the sun as Earth is, according to Sky & Telescope magazine.

C/2026 A1 belongs to the Kreutz family of "sungrazing" comets — a group of at least 3,500 comets with orbits that take them within 850,000 miles (1.4 million km) of our home star. The Kreutz sungrazers are suspected to be fragments of a single massive comet that was ripped apart by the sun around 1,700 years ago, according to Live Science's sister site Space.com.

The icy ball of rock and gas will reach its closest point to the sun, called perihelion, on April 4, when it will come within around 500,000 miles (800,000 km) of our home star — or roughly 70 times closer to the sun than Mercury is. At such proximity, the comet will whip around the sun at more than 2 million mph (3.2 million km/h), causing it to experience intense gravitational pressure, high temperatures, and a hefty dose of solar radiation.

This immense strain may end up ripping the comet apart, which happens to most other sungrazing comets. But if it survives its perilous perihelion, C/2026 A1 will be so changed by the event that it will shine like an incredibly bright star — potentially even during the daytime.

How bright will it get?

C/2026 A1 comes from a particularly noteworthy subgroup of Kreutz sungrazers that are thought to be fragments of the "Great Comet of 1106," which was itself a remnant of the family's massive progenitor. Previous alumni of this subgroup include Comet Ikeya-Seki, which shined brighter than the full moon in 1965, and Comet Lovejoy, which became a "headless wonder" after being largely ripped apart in 2011.

As these comets made their own solar flybys, they became uncommonly bright, largely due to the significant amounts of gas that were released as they soaked up solar radiation. This has also caused several sungrazers to grow spectacular "broom-like" tails as they neared the sun, which could also happen to C/2026 A1, according to Sky & Telescope.

It is too early to accurately predict how bright C/2026 A1 will become. However, some researchers speculate that it could get several times brighter than the full moon, which would make it visible to the naked eye in the daytime sky, according to an article in The Conversation. But this will happen only if it survives perihelion; if not, it won't get anywhere near its max brightness.

Most sungrazing comets are small and are discovered mere days before they reach perihelion. Usually, they also get ripped apart by the encounter. For example, during the total solar eclipse of April 2024, researchers discovered a tiny sungrazer just hours before it disappeared forever.

How to see C/2026 A1 (MAPS)

If C/2026 A1 survives its deadly dance with the sun, it will likely reach its max brightness a few days later as it nears its closest point to Earth later in the month.

Observers in the Southern Hemisphere will get the best views of the comet, according to Sky & Telescope. However, people in the global north will still be able to see the object low above the southwestern horizon just before sunset.

But even if the comet falls apart, it will still be visible from late March with a decent telescope or pair of stargazing binoculars.

Later in April, another potentially spectacular comet, C/2025 R3 (PanSTARRS), could also become visible to the naked eye as it nears its own perihelion on April 20. This ice ball was previously (and perhaps prematurely) dubbed the "Great Comet of 2026."

Time will tell if C/2026 A1 can wrestle that title for itself.

Just as the mythological Icarus melted his feathers and wax wings when he flew too close to the sun, comets often suffer the consequences of orbiting too close to our star. That was definitely the case for Comet C/2025 K1 (ATLAS), which was caught breaking apart by the Gemini North telescope on Mauna Kea, Hawaii, late last year.

First discovered in May 2025 by the Asteroid Terrestrial-impact Last Alert System (ATLAS), Comet K1 was best seen from the Southern Hemisphere.

As it approached its closest point to the sun on Oct. 8, 2025, at just 31 million miles (50 million kilometers), hopes were not high for the ball of ice and dust to survive; comets that endure a close approach to the sun often brighten significantly afterward, as their component ices sublimate into gas. Surprisingly, Comet K1 emerged from behind the sun intact, but it never brightened enough to be seen with the naked eye.

In early November, the comet's nucleus began to break up. This is not unusual for comets; extreme solar heating causes the nucleus to release jets of gas and dust — called outgassing — which combines with gravitational forces from the sun to weaken the comet's structure. Most comets either survive or never emerge from behind the sun, but Comet K1 did — and in just the right place for telescopes across the world to image its spectacular breakup.

A zoomable version of Gemini North"s image clearly shows three fragments.

Another high-stakes encounter with the sun may soon follow the dramatic disintegration of Comet K1. Comet C/2026 A1 (MAPS), a "Kreutz sungrazer comet" discovered Jan. 13, is now hurtling toward the sun and will make a perilously close pass on April 4, when it gets within 465,000 miles (748,000 kilometers) of the sun's surface.

If it survives that dangerous encounter, some astronomers predict the comet could reach magnitude -4, about the same brightness as Venus. That would be a spectacular sight, but like Comet K1, Comet A1 will have to face searing heat and intense gravity and could either blaze brilliantly or succumb to the sun's fury.

For more sublime space images, check out our Space Photo of the Week archives.

We may be less than two weeks into 2026, but a new comet is already leading the charge to become the "Great Comet" of the year. The highly anticipated ice ball, which could potentially be seen with the naked eye, will reach its closest point to us less than four months from now.

Scientists discovered the incoming comet, dubbed C/2025 R3 (PanSTARRS), on Sept. 8, 2025, in images captured by the Panoramic Survey Telescope and Rapid Response System (Pan-STARRS) — a pair of 5.9-foot (1.8 meters) reflector telescopes located on the summit of Hawaii's Haleakalā volcano. It is currently around 216 million miles (348 million kilometers) from Earth, around halfway between the orbits of Jupiter and Mars, according to TheSkyLive.com.

C/2025 R3 is a long-period comet, meaning it likely takes more than 1,000 years to orbit the sun, and probably originates from the Oort cloud — a giant reservoir of comets and other icy objects near the edge of the solar system. Astronomers have yet to narrow down the comet's orbital pathway, so they do not know how long the ice ball takes to circle our home star. But similar discoveries in recent years have revealed comets that have not passed by Earth for tens of thousands of years.

C/2025 R3 is currently speeding toward the sun and will reach perihelion — its closest point to our home star — on April 20. It will come within 47.4 million miles (76.3 million km) of the sun, which is somewhere between the orbits of Mercury and Venus.

Just one week later, on April 27, the comet will make its closest approach to Earth, coming within 44 million miles (70.8 million km) of our planet, which is more than 180 times farther from us than the moon is.

Astronomers don't yet know how brightly the comet will shine during its solar flyby, Live Science's sister site Space.com recently reported. Some researchers have predicted that it will reach an apparent magnitude of 8, meaning it would be visible only via a decent telescope or pair of stargazing binoculars. But others estimate that it could reach magnitude 2.5, which would make it clearly visible to the naked eye. (Apparent magnitude is measured on a reverse logarithmic scale, meaning a lower number equates to a greater brightness.)

When to see comet C/2025 R3

The best chance to see C/2025 R3 will likely be just before perihelion, around April 17, when a new moon will darken the night sky, making it easier to spot objects on the cusp of naked-eye visibility. But by its closest approach to Earth, the comet may become obscured by the sun, making it harder to spot. Viewers in the Southern Hemisphere may also get a good look at the comet in early May.

Whether the comet becomes visible to the naked eye may depend on a phenomenon known as forward scattering, which occurs when a comet is positioned directly between Earth and the sun, as C/2025 R3 will be. If this happens, the comet's tail will likely scatter more sunlight, thereby increasing its brightness, according to Space.com.

A comet's brightness also depends on how it reacts to increased solar radiation: When a comet gets closer to the sun, it soaks up more sunlight, causing it to release trapped ice and gases, which reflect sunlight toward Earth. But it is too early to predict exactly how this will affect C/2025 R3.

During its perihelion and flyby of Earth, C/2025 R3 will be located in the constellation Pisces, just beneath the Great Square of Pegasus, according to Space.com.

The next "Great Comet"?

Several stunning comets have passed by Earth in recent years, including the explosive "devil comet" 12P/Pons-Brooks and the "once-in-a-lifetime" Comet Tsuchinshan-ATLAS, which passed by in 2024, as well as the superbright comets Lemmon and SWAN, which simultaneously lit up our skies last year.

In 2025, astronomers also discovered the interstellar comet 3I/ATLAS, which dominated headlines due to wild and unfounded rumors that it was an alien spaceship. It reached its closest point to Earth in December but is now rapidly moving away from us, and will soon disappear forever.

At present, there are not many noteworthy comets predicted to pass by us this year, which has led many to speculate that C/2025 R3 will be 2026's "Great Comet" — a superlative title often used to describe the brightest comet of a given year.

However, there is always a chance that an even better and brighter comet will soon be discovered and make a similar spectacular flyby later in the year.

Comet 3I/ATLAS whizzed past Earth last night as astronomers worldwide continue to gather data on the interstellar visitor.

The comet made its closest approach at around 1 a.m. EST on Friday (Dec. 19), coming within about 168 million miles (270 million kilometers) of our planet.

When you consider the vastness of space, 168 million miles is a relatively short distance, but even at the comet's nearest point to us, 3I/ATLAS was still almost twice as far away as the sun.

Comet 3I/ATLAS is up to a few miles wide and didn't get close enough to be visible to the naked eye. However, skywatchers observed it using telescopes.

And last night was far from our last chance to see the comet. It will remain observable in the pre-dawn sky with a small telescope until spring, according to NASA. If you don't have a telescope, then the best way to see comet 3I/ATLAS is online.

The Virtual Telescope Project in Italy is hosting a livestream of the comet passing Earth at 11 p.m. EST on Friday. The livestream, which was scheduled for last night but postponed due to rain, will feature real-time images of the comet as it zooms toward Jupiter.

Comet 3I/ATLAS is worth checking out because it's a rare example of an interstellar object from outside of our solar system. This is only the third interstellar visitor ever detected and could be the oldest comet ever seen.

The comet's origins have been the subject of considerable speculation, most notoriously the repeated suggestions that it could be an alien spacecraft. However, nearly all astronomers are confident that 3I/ATLAS is a comet from another star system.

Researchers discovered comet 3I/ATLAS in July, when they spotted an unknown object racing along at around 137,000 mph (221,000 km/h) within the orbit of Jupiter. Having swung past the sun, reaching the closest point to our star (perihelion) at the end of October, the comet is now making its way out of our solar system.

What's next for comet 3I/ATLAS?

Comet 3I/ATLAS will pass Jupiter next, where it is expected to make its closest approach on March 15, 2026, according to NASA. The comet will get much closer to Jupiter than it did to Earth, coming within about 33 million miles (54 million km) of the gas giant. Spacecraft stationed at Jupiter, like Juno, might be able to observe the comet as it approaches.

The interstellar interloper will then cross Saturn's orbit in July 2026; Uranus' orbit in April 2027; and Neptune's orbit in March 2028. However, it won't get close to any of these planets. You can track comet 3I/ATLAS for yourself using NASA's Eyes on the Solar System simulation of the comet's trajectory.

Researchers will keep an eye on comet 3I/ATLAS while it remains in our cosmic neighborhood. After all, there's a lot they still don't know about its properties. For example, the size of the comet is uncertain. Hubble Space Telescope observations suggest that it's somewhere between 1,440 feet (440 meters) and 3.5 miles (5.6 km) wide.

Researchers also don't know which star system forged comet 3I/ATLAS, and they may never find out. The comet travelled a very long way and could have been hurtling through space for billions of years before visiting our solar system.

Editor's note, Dec. 19 at 10:00 a.m. ET: Comet 3I/ATLAS officially passed its closest point to Earth last night and is zooming away from us for good. However, due to rainy conditions in Italy, the Virtual Telescope Project live stream was postponed until 11 p.m. EST on Friday, Dec. 19 (0400 GMT on Dec. 20). Try to catch the free webcast here tonight. You can still see the comet through a decent backyard telescope, as well.

Comet 3I/ATLAS, the third interstellar object ever detected by astronomers, will make its closest approach to Earth overnight between Thursday and Friday (Dec. 18 to 19), when it gets to just 168 million miles (270 million kilometers) from our planet. It poses no threat to Earth.

The precise moment will come at 1 a.m. EST (0600 GMT) on Dec. 19, according to Space.com. Though still just under twice the distance from Earth as the sun — something that will preclude stunning photos from giant telescopes — it’s a unique opportunity to glimpse an object from another star system. Discovered in July 2025, it comes in the wake of 1I/'Oumuamua in 2017 and 2I/Borisov in 2019.

Comet 3I/ATLAS is now on its way away from the sun and out of the solar system, and by far the easiest way to see it before it departs will be online. Using its large telescopes in Manciano, Italy, the Virtual Telescope Project will host a free webcast on YouTube beginning at 11 p.m. EST on Dec. 18 (0400 GMT on Dec. 19). The webcast will also be available as a replay after the live event ends.

Another way to see comet 3I/ATLAS is with a GoTo or smart telescope. Any optical device with a motor can be trained on the object in the constellation Leo. The easiest method is via a smart telescope, such as the Seestar S50, Unistellar eVscope 2, Vaonis Vespera Pro or Celestron Origin; you should be able to find 3I/ATLAS in the app used to control any of these telescopes.

Any planetarium app — such as Sky Tonight, Sky Guide, Stellarium and SkySafari 7 Pro — will also have 3I/ATLAS in its database. That will be helpful to find it visually. Technically, it is visible in large astronomy binoculars, but at magnitude 11, it’s going to look “like a tiny, slightly out-of-focus star,” according to Sky at Night.

A better way to view the comet is with a medium-to-large telescope of about 12 inches, according to NASA, through which observers may spot a faint, fuzzy patch of greenish light close to the bright star Regulus in Leo and a fainter companion, called Rho Leonis.

In the meantime, astronomical telescopes on Earth and in space will continue to monitor it — some from much closer distances than we’ll get. Just today, NASA released new ultraviolet images of the comet taken with its Europa Clipper spacecraft from roughly 102 million miles (164 million km) away, closing the distance from Earth by about a third. Stay tuned for more NASA image releases after the close approach.

A NASA spacecraft designed to hunt for signs of extraterrestrial life has turned its lens toward comet 3I/ATLAS — but not for the reason you might think. The spacecraft just happened to be in the right place at the right time.

Zooming through the solar system at an estimated 153,000 mph (246,000 km/h), the beguiling interstellar comet will reach its closest point to Earth overnight tonight (Dec. 18-19). At its closest, 3I/ATLAS will swoop within about 168 million miles (270 million kilometers) of our planet.

It's close enough that amateur astronomers can spot it with a good backyard telescope, though skywatchers should temper their expectations of seeing much more than a speedy green dot. (See astrophotographer Andrew McCarthey's latest image for a preview.)

Meanwhile, the latest image from NASA — taken with the Europa Clipper spacecraft — cuts the distance to 3I/ATLAS by a third. Snapped on Nov. 6 from a distance of about 102 million miles (164 million km), the new image is the result of seven hours of observations with the craft's Europa Ultraviolet Spectrograph (Europa-UVS) instrument.

Seeing the unseen

Human eyes can't see UV light. But by splitting the observations into their constituent wavelengths and stacking them together, NASA scientists offer a hint of what 3I/ATLAS would look like beyond the visible spectrum. (See also the James Webb telescope's infrared observations and XMM-Newton's X-ray view.)

Clipper happened to be in a prime spot to observe 3I/ATLAS as both objects zoom toward Jupiter; the swift interstellar comet makes its closest approach to the gas giant in March 2026, while Clipper isn't due to arrive there until April 2030.

When it does reach the Jovian neighborhood, Clipper will begin its mission to hunt for signs of extraterrestrial life. The spacecraft's UV instruments will analyze the surface and atmosphere of Europa — one of Jupiter's giant, ice-encrusted moons — and look for geysers carrying chemical clues to the moon's interior. NASA models hint that a liquid water ocean lurks beneath the Europa's crust, which could contain alien life.

An evolving mystery

But the Clipper isn't looking for aliens in this case. (And there's no evidence that 3I/ATLAS is anything other than a natural comet.)

Using the same technology that will ultimately plumb the secrets of Jupiter's moon, Clipper's observations of 3I/ATLAS will be key in analyzing the elements spewing out of the comet and forming the makeshift atmosphere, or coma, around it.

There's no spectroscopic data from Clipper's new UV image yet, but NASA will share its findings as soon as they're available. We do know from prior observations that 3I/ATLAS is rich in carbon dioxide ice, and is releasing diatomic carbon (C₂) gas that gives it the greenish glow seen in recent optical light images.

Until more information rolls in, enjoy this rare close-up view of our solar system's most famous visitor from abroad.

As the interstellar comet 3I/ATLAS prepares for its closest approach to Earth on Dec. 19, it's being monitored not just by space agencies but also the United Nations.

The comet, which will come within roughly 167 million miles (270 million kilometers) of our planet, will be tracked by telescopes around the world so astronomers can pinpoint its location and make predictions about future objects like it.

The U.N.'s International Asteroid Warning Network (IAWN) is about halfway through its 3I/ATLAS observing campaign and expects to publish its findings in a peer-reviewed journal next year, James Bauer, a small-bodies node principal investigator at IAWN and a research professor in the University of Maryland's astronomy department, told Live Science. The network consists of more than 80 observatories and citizen scientists around the world doing active research on near-Earth objects, such as comets and asteroids.

NASA coordinates the IAWN and the network's observing campaigns, Bauer said, and 3I/ATLAS is the first interstellar object to be tracked since the campaigns began in 2017. (Notably, the potentially hazardous near-Earth asteroid Apophis was observed by IAWN in 2020 and 2021, and a new campaign is expected between 2027 and 2029 as the asteroid makes a safe-but-close approach to Earth.)

"The idea behind these campaigns is really to strengthen the technical capabilities for measuring sky positions, which we call astrometry, for asteroids and comets," Bauer said of IAWN's work. The investigators will be testing a new astrometry technique to track the pathway for 3I/ATLAS, which can be helpful for determining how to send a spacecraft to a similar comet in the future.

"We want the community to use the latest and greatest techniques," Bauer said. (Bauer also serves as principal investigator for the NASA Planetary Data System's small bodies node, which archives, catalogs and distributes scientific data related to comets, asteroids and interplanetary dust.)

Tracking 'a comet's comet'

IAWN had been planning an observing campaign like this since October 2024, so 3I/ATLAS was a late-but-fortuitous arrival when it was first spotted in late June. The interstellar comet's upcoming close approach coincides well with the team's planned observing schedule, and because 3I/ATLAS was visible in the network's observatories and of high interest, it seemed like a great fit, Bauer said.

There are challenges in accurately measuring a comet's position, he noted, such as the changing brightness and the variability in its coma, the cloud of gas and dust that extends around the comet’s nucleus and tail as it draws closer to the sun and heats up. These features can inflate the comet’s apparent size and make its location harder to pinpoint.

Luckily, although 3I/ATLAS originated outside the solar system, it's showing such classic comet behavior that it is almost a "comet's comet," Bauer said. For example, it includes components like water and carbon dioxide that are behaving similarly to normal solar system comets.

Community interest has been high. Citizen scientists, observatories large and small, and scientific organizations formed a record 171 campaign participants at the kickoff of IAWN's 3I/ATLAS campaign meeting in October. The mid-campaign teleconference, held Dec. 9 and days before Bauer's interview with Live Science, had 100 campaign participants.

"We've been answering questions from the community — for example, 'How to use the tool? What is the proper format for observing, or for reporting the observations?'" Bauer said.

He said he's grateful for the community's time and interest, as it is helping astronomers refine their ability to report the positions of objects in the sky — including "vigilance" for other near-Earth asteroids and objects that come much closer to our planet.

New telescope images of the interstellar comet 3I/ATLAS confirm that the mysterious object has gotten brighter and greener since its close approach to the sun in late October. This increase in activity could portend new, bright outbursts of cometary material as 3I/ATLAS careens toward its closest encounter with Earth next week.

Taken on Nov. 26 with the Gemini North telescope atop Hawaii's dormant Mauna Kea volcano, the new images capture the comet in one of its most active phases yet. Recently heated by intense solar radiation, ice on the comet is sublimating and spewing into space along with tons of dust, forming a bright, cloudy atmosphere (a coma) around the comet's main body and a long, glowing tail behind it.

To capture this view, the team observed 3I/ATLAS using four filters (blue, red, orange and green), and found that gas in the comet's coma now emits a faint greenish hue, which wasn't the case several months ago.

Why is 3I/ATLAS going green?

Don't rush to blame little green men for the comet's new greenish glow. Among the gases spilling out of 3I/ATLAS is diatomic carbon (C₂) — a molecule of two carbon atoms that emits a greenish light, according to a statement from the National Science Foundation's NOIRLab, which operates the Gemini North telescope along with its twin Gemini South telescope in Chile.

Many solar system comets give off a similar green hue when activated by the sun, including last year's "Mother of Dragons" comet 12P/Pons-Brooks and the recently discovered Comet C/2025 F2 (SWAN).

However, it's noteworthy that 3I/ATLAS appeared distinctly redder when it was first observed by Gemini South in late August, months before its close flyby of the sun, according to NOIRLab. This is evidence that 3I/ATLAS is releasing new molecules into space as it heats up, offering fresh hints into its mysterious makeup.

Is another outburst coming?

As the comet approaches its closest point to Earth on Dec. 19 (coming within a comfortable 170 million miles, or 270 million kilometers, of our planet), we may be in for even more surprises.

"What remains unknown is how the comet will behave as it leaves the Sun's vicinity and cools down," NOIRLab representatives wrote in the statement. "Many comets have a delayed reaction in experiencing the Sun's heat due to the lag in time that it takes for heat to make its way through the interior of the comet. A delay can activate the evaporation of new chemicals or trigger a comet outburst."

3I/ATLAS is the third interstellar object ever discovered, after 1I/'Oumuamua and 2I/Borisov. The comet was detected in late June as it was speeding through our solar system at an estimated 130,000 mph (210,000 km/h), zooming by on a hyperbolic (U-shaped) orbit that will never bring it through our neighborhood again.

3I/ATLAS is probably the largest and, very likely, the oldest interstellar object seen so far. While it shows many intriguing features — including large, sun-facing jets and signs of being irradiated by its billions of years spent in interstellar space — the vast majority of astronomers and space agencies agree that it is a typical comet — and not an artificial piece of alien technology, as some viral claims have suggested.

Dozens of observatories and spacecraft around the solar system have been closely monitoring 3I/ATLAS to better understand its size, trajectory, composition and origins. Studying it in depth could reveal new details about the mysterious frontier of our galaxy and how some of the earliest star systems in the Milky Way formed.

The celebrity comet 3I/ATLAS is showing itself out of our solar system for good — but not before the cosmic paparazzi at Earth's space agencies snap some of the clearest photos of it yet.

Discovered in late June and confirmed to be the third known interstellar object in July, 3I/ATLAS has spent the past several months zooming through the inner solar system at an estimated 130,000 mph (210,000 km/h). The massive, jet-spewing snowball made its closest approaches to Mars and the sun in October. It is due for its closest encounter with Earth on Dec. 19, when it will be about 170 million miles (270 million kilometers) away — nearly twice the distance between our planet and the sun.

As the comet careens toward this astronomical milestone, spacecraft managed by NASA and the European Space Agency (ESA) are snagging as many close-up observations as possible. This week, both agencies shared new images of the comet — proving that its recent flyby of the sun has left it very bright and active as it spews large amounts of sublimated gas and dust into space.

Hubble doubles down

On Thursday (Dec. 4), NASA shared the latest image of 3I/ATLAS taken by the Hubble Space Telescope. The glowing white dot at the center of the image shows the comet's nucleus (its main body) and coma, the bright atmosphere of gas and dust that wraps around the comet before getting funneled into its tail. In the background, stars are stretched into long streaks as Hubble's camera stays fixed on the fast-moving comet.

Comets typically brighten as they approach the sun, when the ice within them heats up and sublimates. Solar radiation pushes this gas into a tail that stretches away from the sun. Meanwhile, the warmest, sun-facing side of the comet may erupt with jets of gas and dust angled toward our star. Both of these features are faintly visible in the new Hubble image.

NASA snapped this image on Nov. 30, when Hubble was about 178 million miles (286 million km) from the comet. This is considerably closer than when Hubble first imaged the comet in late July. Although that first view showed little more than a blue blur, it nevertheless allowed scientists to constrain 3I/ATLAS' size to somewhere between 1,400 feet (440 meters) and 3.5 miles (5.6 km) wide — likely the largest interstellar object seen to date.

New data from this image, including details of the coma's composition, has yet to be released but is likely on the way.

ESA juices up

Also on Thursday, ESA shared its latest view of the comet, taken by the Jupiter Icy Moons Explorer (Juice) orbiter on its way to study Jupiter's moons for signs of life. Juice snapped the image Nov. 2, just days after 3I/ATLAS' close approach to the sun.

Located even closer to its target than Hubble (only 41 million miles, or 66 million km, away), Juice shows us a comet brimming with activity.

"Not only do we clearly see the glowing halo of gas surrounding the comet known as its coma, we also see a hint of two tails," an ESA spokesperson wrote in a statement. "The comet's 'plasma tail' — made up of electrically charged gas, stretches out towards the top of the frame. We may also be able to see a fainter 'dust tail' — made up of tiny solid particles — stretching to the lower left of the frame."

Earth gets ready

Juice observed 3I/ATLAS with five scientific instruments on two days. But besides this teaser image, we don't yet know what those instruments saw; the full data set won't reach Earth until late February 2026, according to ESA. That's because Juice is currently using its main antenna as a heat shield to protect it during its close pass of the sun, and relying on its smaller, less efficient antenna to beam its observations back to us.

While there's little we can learn from NASA's and ESA's new images without the full complement of scientific data, it's a good reminder that human space exploration pays off in unexpected ways. Hubble and Juice number among a dozen spacecraft that have observed 3I/ATLAS from around the solar system, including Mars rovers, solar orbiters, asteroid trackers and space telescopes that were never intended to track comets.

And there's more to come: As 3I/ATLAS draws closer to Earth, the James Webb Space Telescope will take another look at it, while countless scientific observatories and amateur astronomers will have their chance to watch it as well. When you're dealing with a mysterious intruder from parts unknown, every observation matters.

In space, death can be a beautiful thing. That's certainly the case for the recently deceased "other" comet ATLAS, which is slowly breaking apart after meeting its explosive end earlier this month, stunning new images reveal.

C/2025 K1 (ATLAS) is a comet originating from the Oort Cloud beyond Neptune that was discovered in May by astronomers at the Asteroid Terrestrial-impact Last Alert System (ATLAS). It reached its closest point to the sun, or perihelion, on Oct. 8, coming within 31 million miles (50 million kilometers) of our home star. But the comet largely went under the radar until earlier this month, when it developed a rare golden glow in its coma and tail.

It has become known as the "other ATLAS," thanks to its shared surname with the interstellar comet 3I/ATLAS, which has been dominating headlines since it was first spotted shooting through the solar system in July. The two comets have no relation, other than being detected by the same telescope network around the same time.

On Nov. 13, astronomers noticed that C/2025 K1 had broken apart into several pieces. Austrian astrophotographer Michael Jäger has been keeping a close eye on C/2025 K1 since it began to fall apart, and he has now shared a stunning timelapse animation that shows the fragments of the comet slowly separating from one another.

"Following brightness surges in early November, we have been able to observe this comet splitting into three brighter fragments for the past two weeks," Jäger told Spaceweather.com. "The animation shows it on November 12, 14, 18, 19, and 20th."

The comet was not expected to survive its perihelion — astronomers predicted that the close proximity of its journey around the sun would place a huge amount of gravitational strain on the object. After its solar flyby, initial observations suggested that it had emerged unscathed. However, following a sudden brightening event, the comet then broke apart into three distinct pieces.

More recent photos have shown that a smaller fourth fragment also splintered from the comet, according to Spaceweather.com. However, this part of the comet is not visible in the new animation.

C/2025 K1 was one of just a handful of comets that have ever been seen with a golden hue (see below), which is likely the result of a surprising lack of carbon-bearing molecules, such as dicarbon, carbon monoxide and cyanide in its nucleus. In fact, only two other known comets have ever had fewer of these molecules, astronomer David Schleicher of Arizona's Lowell Observatory recently reported.

Researchers had hoped to learn more about the comet and its surprising composition during its closest approach to Earth on Tuesday (Nov. 25). However, this now seems unlikely.

But the comet's fragments will still be visible in the constellation Leo to anyone with a decent telescope or a pair of stargazing binoculars.

Other ATLAS(s)

C/2025 K1 is not the first comet to bear the name ATLAS. In fact, dozens of other comets have been found by the Asteroid Terrestrial-impact Last Alert System — a NASA-funded robotic survey, which has been scanning the night sky using telescopes in Hawaii, South Africa and Chile since 2015.

Over the last few years, several ATLAS comets have made the news, including C/2024 G3, which appeared in spectacular snaps by astronauts onboard the International Space Station (ISS) earlier this year, as well as a doomed sungrazer comet, the Halloween ATLAS comet and Comet Tsuchinshan-ATLAS, which all shone brightly in 2024.

But the most famous of the ATLASs is 3I/ATLAS, an alien comet that is traveling past us after being ejected from its own star system, potentially long before the solar system was born.

3I/ATLAS is currently on its way back out of the solar system, having reached its own perihelion on Oct. 29, and will reach its closest point to Earth on Dec. 19, when it will reach a minimum distance of 168 million miles (270 million km) from our planet. And despite what some people claim, the astronomical community is very much in agreement that it is not an alien spacecraft.

Only time will tell what wonders the future ATLAS comets will have in store for us.

NASA has released a treasure trove of comet 3I/ATLAS images, giving us some of the closest views yet of the interstellar visitor.

The U.S. government shutdown, which ran from Oct. 1 to Nov. 12, delayed the release of the highly anticipated images, which include snaps taken from instruments around Mars and the sun over the past several months.

Live Science has rounded up some stand-out shots from the comet 3I/ATLAST image drop for you to enjoy below, while the full gallery is available on NASA's website.

The High Resolution Imaging Science Experiment (HiRISE) captured this image of the comet from aboard NASA's Mars Reconnaissance Orbiter (MRO). The imager caught sight of comet 3I/ATLAS as the comet zoomed past Mars in early October.

While the comet was much closer to Mars in October than it will ever get to Earth, it still wasn't that close. This image was taken when the comet was around 19 million miles (30 million kilometers) from MRO. For reference, the moon's average distance from Earth is about 239,000 miles (384,000 km). The bright dot represents the comet's main body, or nucleus, while the diffuse cloud of particles around it is 3I/ATLAS' coma — a feature characteristic of most comets that get heated up by the sun while flying through our solar system.

The Mars Atmosphere and Volatile Evolution (MAVEN) orbiter got this trippy ultraviolet image of comet 3I/ATLAS near Mars (relatively speaking) on Sep. 28. MAVEN's Imaging Ultraviolet Spectrograph takes advantage of the ultraviolet part of the light spectrum to decipher the chemical composition of objects, according to NASA.

The blue in the image is hydrogen. The blue dot on the left represents hydrogen emitted from comet 3I/ATLAS, while the bright blue on the right is the hydrogen emitted by Mars. The dim blue oval in the middle is background hydrogen flowing through the solar system between planets. Researchers hope to use observations like this one to better understand the comet's makeup.

NASA released this GIF of comet 3I/ATLAS, created using images taken by the Polarimeter to Unify the Corona and Heliosphere (PUNCH) mission between Sept. 28 and Oct. 10. The PUNCH mission is made up of four small satellites in low-Earth orbit, focused on the sun. Comet 3I/ATLAS is the white dot in the center image, moving through a stream of blurred light from stars. The bright blob that flashes past the comet is Mars.

Comet 3I/ATLAS is pretty in pink in this observation, thanks to colorized images from the Solar Terrestrial Relations Observatory spacecraft (STEREO-A). The Heliocentric Imager-1 (H1) instrument aboard STEREO-A captured the image in visible light, which was then subsequently colorized to differentiate it from other spacecraft images, according to NASA.

Another image taken by a solar orbiter, this time from the European Space Agency and NASA's Solar and Heliospheric Observatory (SOHO). The SOHO mission launched all the way back in 1995 and is the longest-serving sun satellite yet, according to NASA. SOHO snapped this image of comet 3I/ATLAS between Oct. 15 and Oct. 26, while the comet was brightening on the way to its closest encounter with the sun.

This last GIF isn't particularly impressive to look at, but it was taken from the Martian surface, which is pretty cool if you ask us. NASA's Perseverance rover looked up to observe the comet fly by the Red Planet on Oct. 4. Perseverance was investigating Jezero Crater at the time, searching for ancient signs of life.

Since the discovery of comet 3I/ATLAS in July, there has been much speculation that this interstellar visitor could be an alien spacecraft. However, most astronomers are confident that 3I/ATLAS is a natural comet from an unknown star system. NASA was keen to stress that the comet was of natural origins when it presented the new images during a stream on Wednesday (Nov. 19).

"This object is a comet," NASA Associate Administrator Amit Kshatriya said during the stream. "It looks and behaves like a comet… and all evidence points to it being a comet. But this one came from outside the solar system, which makes it fascinating, exciting and scientifically very important."

NASA has finally released a cache of previously unseen images of comet 3I/ATLAS, as the space agency stresses that the interstellar visitor is a natural object.

Comet 3I/ATLAS has become a celestial celebrity since its discovery in July, in part because of endless speculation that it could be an alien spacecraft. While most astronomers are confident that the interstellar visitor is a natural comet from an unknown star system, NASA has been silent on the comet in recent weeks due to the U.S. government shutdown.

The shutdown, which ran from Oct. 1 to Nov. 12, coincided with comet 3I/ATLAS flying behind the far side of the sun, reaching its closest point to the sun (perihelion) on Oct. 29 and entering its most active phase. NASA’s delay in releasing the new images during this period fueled conspiracy theories, with some speculating that the government agency had something to hide.

When NASA hosted a Wednesday (Nov. 19) stream to present the highly anticipated images, it came out swinging. Soon after the conference began, NASA Associate Administrator Amit Kshatriya said he wanted to address what he described as "the rumors."

"This object is a comet," Kshatriya said. "It looks and behaves like a comet… and all evidence points to it being a comet. But this one came from outside the solar system, which makes it fascinating, exciting and scientifically very important."

The comet's natural origins shouldn't detract from 3I/ATLAS’s story. This object is only the third interstellar comet ever recorded, potentially the oldest comet ever seen and the most massive of its kind, so there are plenty of non-alien reasons for it to be of interest to humanity.

The new images were taken using a variety of different instruments, with the closest shots coming from NASA's Mars Reconnaissance Orbiter. This spacecraft has been orbiting Mars since 2006, searching for signs of water on the Red Planet with its onboard High Resolution Imaging Science Experiment (HiRISE). The imager snapped comet 3I/ATLAS as it zoomed past Mars in early October.

The Mars Atmosphere and Volatile Evolution (MAVEN) orbiter also captured ultraviolet images of comet 3I/ATLAS that will help researchers better understand the comet's makeup, according to NASA.

Elsewhere, sun-monitoring instruments like NASA's Solar Terrestrial Relations Observatory (STEREO) and the asteroid-chasing Psyche and Lucy spacecraft caught additional new glimpses of comet 3I/ATLAS. The space agency noted that these observations will provide details on the comet's tail. However, the images have only just been processed and are only now being studied, so findings from them thus far are limited.

The interstellar interloper originated somewhere beyond our solar system. Researchers don't know which star system it came from, but it could be billions of years old — potentially more than 3 billion years older than our sun.

While the comet's age has yet to be confirmed, Tom Statler, lead scientist for solar system small bodies at NASA's Planetary Science Division, said that because the comet is zooming along three times faster than the average rate at which stars in our cosmic neighborhood orbit the Milky Way’s center, it has likely been in interstellar space for a very long time.

"We can't say this for sure, but the likelihood is it came from a solar system older than our own solar system," Statler said during the stream. "Which gives me goosebumps to think about frankly, because that means that 3I/ATLAS is not just a window into another solar system; it's a window into the deep past, and so deep in the past that it predates even the formation of our Earth and our sun."

An astrophotographer has snapped a stunning shot of the interstellar visitor 3I/ATLAS photobombing a distant galaxy in the night sky. The remarkable image, which also captured the comet's multiple tails, is a reminder of the object's otherworldly nature — but that doesn't mean it was made by aliens, the photographer insists.

Satoru Murata, a New Mexico-based photographer who has previously worked on multiple astronomical research projects, captured the new image using a 0.2-meter (0.7 feet) telescope on Sunday (Nov. 16) shortly before sunrise. It shows a familiar green glow coming from 3I/ATLAS's coma, along with the comet's long ion tail and the reemergence of its shorter anti-tail, which is likely caused by excess dust blowing off its surface. In recent weeks, the comet briefly appeared to lose both these tails, although this was an optical illusion due to its position relative to Earth.

Eagle-eyed observers may also be able to see several smaller jets of gas shooting outward from the comet's coma. These are the result of "outgassing," which occurs when solar radiation heats comets' icy interiors, causing gasses to shoot out of cracks in their icy shells. This natural process provides a small amount of non-gravitational acceleration to the comet and was the basis of a recent rumor that wrongly claimed 3I/ATLAS had exploded.

In the top left of the image is the barred spiral galaxy NGC 4691, which is located around 70 million light-years from Earth. Seeing the interstellar comet alongside NGC 4691 "really gave the impression of the object being from another world," Murata wrote in a recent Facebook post. (However, the comet originated from a star system within the Milky Way, not another galaxy.)

While this new photo has given us an impressive glimpse of 3I/ATLAS, astronomers are eagerly awaiting new high-definition NASA photos of the comet, which will be released on Wednesday (Nov. 19). These images were captured by NASA's Mars Reconnaissance Orbiter during the comet's close flyby of the Red Planet on Oct. 3 but have remained unreleased due to the recent government shutdown.

On Friday (Nov. 14), the European Space Agency revealed that its own Mars photos had helped researchers narrow down 3I/ATLAS's predicted trajectory through the solar system.

Interstellar visitor

3I/ATLAS is the third interstellar object discovered to date and was first spotted in early July, shooting toward the sun at more than 130,000 mph (210,000 km/h). It likely originates from the "frontier" region of the Milky Way and could be up to 7 billion years old, making it significantly older than our solar system.

The comet recently reemerged from behind the sun's far-side relative to Earth, where it reached its closest point to our home star on Oct. 29. The trip around the sun was eventful, with 3I/ATLAS experiencing an unexpected brightening event and a temporary color change. The comet has also displayed several other anomalous characteristics in recent months, including a highly irradiated surface and an overabundance of certain chemicals.

These unusual traits have led some researchers to controversially propose that 3I/ATLAS might be an alien spaceship in disguise. However, the majority of the astronomical community agrees that the object is almost certainly a comet. (Similar claims were also made about the first interstellar object 'Oumuamua, which was discovered in 2017 and is most likely an asteroid.)

Murata, too, is certain of 3I/ATLAS's cometary status.

"No, it's not an alien mothership, and the probability that it's any type of object created by extraterrestrial civilization is close to zero," he wrote in an Instagram post about the new photo. "As people have said, if it looks like a duck and behaves like a duck, it's a duck."

3I/ATLAS will reach its closest point to Earth on Dec. 19, when it will reach a minimum distance of 168 million miles (270 million km) from our planet.

Earthlings will soon have their chance to see NASA's clearest images yet of the interstellar comet 3I/ATLAS, and you can watch it right here.

The space agency recently announced a live news teleconference to take place today (Nov. 19) at 3 p.m. EST, during which NASA scientists and administrators will share and discuss never-before-seen images of the interstellar comet taken by telescopes and spacecraft over the past month or so.

The images will be posted to this NASA page shortly after the event starts, and we will also be covering the latest updates on our live blog.

Why now?

These images have yet to be shared with the public, as a majority of NASA personnel were furloughed during the U.S. government shutdown from Oct. 1 to Nov. 12, preventing the agency from communicating with the public.

It was an unlucky time for NASA to go silent, as comet 3I/ATLAS passed several huge milestones on its one-way trip through our solar system during that period. On Oct. 29, the interstellar comet made its closest approach to the sun, entering its brightest and most active phase as its surface ices started to melt and sublimate (shift from a solid to a gas).

And earlier, on Oct. 3 — just days after the government shutdown began — the comet made its closest approach to Mars, passing within just 19 million miles (30 million kilometers) of the Red Planet and the fleet of NASA and European Space Agency (ESA) spacecraft stationed there. That may sound like a comically vast distance, but it's the closest look we're likely to get of the interstellar interloper; 3I/ATLAS will get no closer than 170 million miles (270 million km) of Earth at its closest approach to our planet on Dec. 19, according to NASA.

The closest views of 3I/ATLAS so far

On Oct. 7, ESA released its own closest images of the comet taken so far, captured by its ExoMars Trace Gas Orbiter (TGO) and Mars Express orbiter. However, both of these spacecraft were designed to observe the surface of Mars just a few hundred miles below, not to track high-speed objects millions of miles away. The comet appears as little more than a bright, slinking blur in ESA's images — but, the observations confirmed that 3I/ATLAS bore the telltale cloud of ionized gas (a coma) that's characteristic of natural comets.

ESA scientists also compared the Mars orbiter data with observations from Earth telescopes, allowing them to better triangulate the comet's exact position and significantly narrow down its path through our solar system.

During the news conference, NASA is expected to share images taken by its Mars Reconnaissance Orbiter's HiRISE camera from the days before and after the comet's close approach to Mars, as well as observations from other telescopes, according to the agency's latest announcement.

The live stream will be hosted on the agency's website as well as on YouTube and Amazon Prime. Members of the public are invited to submit questions via the hashtag #AskNASA on social media, some of which may be addressed live on air.

Comet 3I/ATLAS was discovered in late June and confirmed to be an interstellar object in early July. It originates from an unknown star system far beyond our own, and is just the third object of its kind ever detected. Many mysteries about its nature and origins still remain, and dozens of observations from Earth and space-based telescopes are expected to come as the comet barrels toward its closest approach to Earth next month. Spacecraft near Jupiter will also observe it early next year, as the comet makes its final exit from our solar system.

Editor's note: This article was updated on Wednesday (Nov. 19) to indicate that the live stream is today

Researchers have narrowed down the exact route that the interstellar interloper 3I/ATLAS will take as it begins its one-way trip out of the solar system.

Thanks to data collected from the alien comet's recent close flyby of Mars, scientists at the European Space Agency (ESA) have refined the comet’s trajectory by ten-fold. And this could better help researchers unravel its secrets in the coming months, experts say.

3I/ATLAS is an interstellar object — the third of its kind ever seen — that was first spotted in early July, shooting toward the sun at more than 130,000 mph (210,000 km/h). It is a comet that was likely ejected from a star in the "frontier" region of the Milky Way up to 7 billion years ago. Scientists have observed a number of strange characteristics of the comet, including a highly irradiated surface and a puzzling anti-tail. This has led to wild rumors that 3I/ATLAS might be an alien spacecraft, which the majority of astronomers agree are almost certainly untrue.

After passing its closest point to the sun on Oct. 29, 3I/ATLAS has recently reemerged from behind the sun's far-side relative to Earth. The trip around the sun was an eventful one: with the comet experiencing an unexpected brightening event, a temporary color change and a brief vanishing of its tail.

But before this, the comet also had a close encounter with Mars, coming within 18.6 million miles (30 million kilometers) of the Red Planet on Oct. 3.

During the Mars flyby, the European Space Agency's (ESA) ExoMars Trace Gas Orbiter managed to snap highly detailed photos of 3I/ATLAS streaking toward the sun. By analyzing the orbiter's data from this encounter, ESA scientists have improved predictions of 3I/ATLAS's exit trajectory out of the solar system with a surprising level of success.

"While the scientists initially anticipated a modest improvement, the result was an impressive ten-fold leap in accuracy, reducing the uncertainty of the object’s location," ESA representatives wrote in a statement. "The improved trajectory allows astronomers to aim their instruments with confidence, enabling more detailed science of the third interstellar object ever detected."

Before now, researchers have been relying solely on ground-based observatories or Earth-orbiting spacecraft to track 3I/ATLAS's position, which only provides specific views of the anomalous object. But by using observations from Mars, the ESA team could better "triangulate" the comet's position, similar to how intelligence agencies track mobile phones using multiple cell towers.

However, factoring in the orbiter's precise movements around Mars relative to the comet's trajectory was no easy task. To make the process harder, the spacecraft's Colour and Stereo Surface Imaging System (CaSSIS) is designed to photograph the Red Planet's surface, not objects in space, the researchers wrote.

In fact, the method of imaging space objects with planetary orbiters is so hard that this is the first time that data from one of these spacecraft has been accepted into the International Astronomical Union's Minor Planet Center database, which tracks the movements of all near-Earth objects, researchers wrote.

ESA is now hoping to repeat the trick with its Jupiter Icy Moons Explorer (JUICE), which will get a good look at 3I/ATLAS later this month, researchers wrote. The agency's researchers have also previously suggested that two of its other spacecraft, Hera and Europa Clipper, could also pass through the comet's tail as it moves away from the sun.

During the recent Mars flyby, NASA's Mars Reconnaissance Orbiter also captured what could potentially be the best ever image of 3I/ATLAS, which some researchers predict could reveal more about its features. Due to the recent government shutdown, NASA has yet to release these images to the public. But recent reports suggest that these images could be released any day now.

3I/ATLAS will reach its closest point to Earth on Dec. 19, when it will reach a minimum distance of 168 million miles (270 million km) from our planet.

The "other" Comet ATLAS has fragmented, transforming into a cloud of debris that's streaming into space, new observations have revealed.

The comet, called C/2025 K1 (ATLAS), was discovered in May by astronomers at the Asteroid Terrestrial-impact Last Alert System (ATLAS) and passed perihelion, or closest point to the sun, on Oct. 8. It has no relation to the famous interstellar comet 3I/ATLAS, other than having been discovered by the same telescope network around the same time.

Initial observations appeared to suggest that Comet K1 survived its passage around our star at a minimum distance of 31 million miles (50 million kilometers), or roughly four times closer than Comet 3I/ATLAS got.

However, new observations taken by astronomer Gianluca Masi in Manciano, Italy, show that the gravitational strain of its voyage around the sun was too much for the comet, causing it to fragment into several pieces, or clouds.

"Several parts (sub-nuclei or clouds of debris) are visible, also a plume just below the leading (the first from the left) fragment," Masi, an astronomer at the Astronomical Observatory of Campo Catino and the founder of The Virtual Telescope Project, wrote in an update.

C/2025 K1's disintegration was portended by a sudden brightening event around perihelion, which saw the comet transform from the greenish hue seen in many comets that fly close to our sun (caused by the presence of diatomic carbon fluorescing in sunlight) into a streaking ribbon of gold.

The cause of this transformation is unclear; some scientists speculate that the change in color had something to do with a relative lack of carbon-bearing molecules in the comet's coma (the cloud of ice, gas and dust around the comet's body).

If you want to see the exploded comet for yourself, look in the constellation Leo, where it's shining at magnitude 9.9, according to The Sky Live. (In astronomy, a lower magnitude corresponds to a brighter object; Regulus, the brightest star in Leo, has an apparent magnitude of about 1.35, for example.) Although the comet is still too dim to be seen with the naked eye, it can be spotted with a good telescope or a pair of stargazing binoculars.

Whatever survives of the comet is set to pass closest to Earth on Nov. 25. It will come within about 37 million miles (60 million km), or just under half the average distance between Earth and the sun.

Astronomers have detected the first-ever "radio signal" coming from the interstellar comet 3I/ATLAS, right as it passed the halfway mark on its oneway trip through the solar system. And while this may seem like ostensible proof of the comet’s supposed alien origins — it's actually the complete opposite.

3I/ATLAS is the third-known interstellar object (ISO) to pass through our cosmic neighborhood. It was first spotted in early July, speeding toward the sun at more than 130,000 mph (210,000 km/h), although observations dating back to May have since been uncovered. Most researchers agree that it is a comet, potentially the oldest of its kind ever seen, that was catapulted out of an alien star system in the "frontier" region of the Milky Way up to 7 billion years ago.

However, ever since the interstellar interloper was discovered, a small group of scientists — led by Harvard University astrophysicist and renowned alien-hunter Avi Loeb — have been promoting the unevidenced theory that the comet is actually an alien spacecraft in disguise. This has led to a number of misleading stories about the comet, which experts say distracts from the real science surrounding the ISO. (This is similar to what happened to the first-ever ISO 'Oumumua, which Loeb and others also labelled as a potential alien mothership.)

So, when astronomers at South Africa's MeerKAT radio telescope recently announced that they had detected the first radio emissions from 3I/ATLAS, proponents of Loeb's theory were probably expecting to find evidence of some covert alien transmission, especially as it coincided with the comet's closest approach to the sun, or perihelion, which occurred on Oct. 29.

But the signals did not have a technological origin. Instead, they are the result of specific wavelength absorption related to the presence of hydroxyl radicals, or OH molecules, in the comet's coma.

These radicals are formed by the breakdown of water molecules as they are ejected from the comet via a natural process known as outgassing, which is a clear sign of cometary activity, according to a 2016 study.

This is not the first time that astronomers have seen evidence of water coming from 3I/ATLAS: In early October, NASA researchers spotted water spewing from the comet "like a fire hose" on full blast. But the latest findings show that this water is being broken down by solar radiation —as you would expect during perihelion.

Loeb acknowledged the detection of the hydroxyl radicals in the latest 3I/ATLAS update on his personal blog, which now has over 100,000 subscribers. However, he did not state whether this was a sign of classic cometary activity or not.

The new radio signals were first detected on Oct. 24, shortly after 3I/ATLAS briefly disappeared behind the sun during perihelion. The comet's solar flyby was also notable for an unexpected brightening event and a temporary color change. And after reappearing earlier this month, the comet then appeared to have lost its tail, although this turned out not to be true.

The comet has previously displayed several other anomalous characteristics that have added fuel to the fires of alien conspiracy theorists, including a highly irradiated surface, an overabundance of carbon dioxide and a puzzling anti-tail. However, all of these traits have been properly explained by the astronomical community, which is almost unanimously convinced that 3I/ATLAS is a natural object.

A separate yet connected alien theory was also squashed this week when astronomers detected an "almost interstellar object" that reached its closest point to Earth on Tuesday (Nov. 11). Rumors suggested that it could have been a probe deployed by 3I/ATLAS during perihelion, but this was quickly trashed, with even Loeb admitting the claim was unlikely. Instead, the newly discovered object, dubbed C/2025 V1 (Borisov) is a typical solar system comet.

Other reports, which cited Loeb's calculations on 3I/ATLAS's non-gravitational acceleration, also suggested that the comet may have exploded due to its supposedly excessive loss of mass. However, recent observations have proved that this is not the case either.

Comet 3I/ATLAS lovers don't despair: Our favourite interstellar visitor most likely didn’t just explode, an expert says after examining the latest observations.

Yesterday (Nov. 10), Futurism reported that comet 3I/ATLAS may have broken into pieces after re-emerging from behind the far side of the sun. The science and technology website quoted the blog of Harvard University astrophysicist Avi Loeb, who calculated that the comet lost a lot of mass based on a 3I/ATLAS image captured by two small telescopes in Spain on Sunday (Nov 9).

However, Loeb's assessments of 3I/ATLAS have come under increased scrutiny in recent days. He was once again using his blog to speculate that the comet could be an alien spaceship. Yet most researchers are confident it's a natural object, and that it hasn’t, as a matter of fact, exploded.

"All the images I've seen show a fairly ordinary/healthy-looking comet," Qicheng Zhang, a postdoctoral fellow at the Lowell Observatory in Arizona who has been studying the comet, told Live Science in an email. "There's no sign at all that the nucleus broke apart."

Comet 3I/ATLAS recently disappeared (briefly) behind the sun, reaching its closest point to our star, known as perihelion, on Thursday (Oct. 29). As it reemerges, astronomers are eagerly watching it to learn more about its makeup. That’s because comets heat up as they fly closer to stars, causing ice on their surface to sublimate into gas which researchers can then detect and study.

That newly unleashed gas can burst through the comet’s surface in gargantuan jets, wrap around the comet’s body in a cloud called a coma, or be swept away into the comet’s long tail. All of these features are made brighter by the sun’s ionizing radiation, allowing even amateur astronomers to study the comet under the right conditions.

From Earth's perspective, the comet is currently rising higher and higher above the eastern horizon and, with the right conditions, is visible through a small telescope (6-inch lens) in much of the Northern Hemisphere.

And everyone is sure to be looking. Comet 3I/ATLAS has become a lightning rod of celestial speculation since its discovery in July, with Loeb and others suggesting that the comet — an interstellar visitor from beyond our solar system that’s thought to be more than 7 billion years old — might be an alien probe.

Yet most astronomers are confident that the interstellar visitor is a natural comet from an unknown star system in the Milky Way. The comet’s natural origins should be cause for excitement, not disappointment: 3I/ATLAS is only the third interstellar comet ever recorded, is the most massive of its kind, and potentially the oldest comet ever seen.

In an image taken by amateur astronomers Michael Buechner and Frank Niebling on Sunday (Nov. 9), jets appear to be shooting off the comet. This led Loeb to use an estimate of the amount of jetted material and the comet's corresponding mass to claim that it would have needed a much larger surface area than has been observed if it were a natural object.

Loeb's assessment also claimed that the comet should have broken up into at least 16 pieces — so if astronomers find that it hasn't broken up in upcoming observations, Loeb thinks scientists will have to consider that it isn't a natural comet.

To put it lightly, astronomers disagree.

"I checked Avi Loeb's blog, and it sounds like he's just built a house of cards on top of his unfounded claim about the comet's acceleration, which was an egregious misinterpretation of the comet's orbital parameters anyone who's ever computed any comet's orbit will immediately recognize as faulty," Zhang said.

Before his latest post, Loeb’s claims were already drawing strong criticisms from astronomers. On Sunday, Jason T Wright, a professor of astronomy and astrophysics at Penn State University, wrote in his blog that there weren't any indications that 3I/ATLAS was an alien spacecraft, breaking down ten of Loeb’s claims about unnatural “anomalies” point by point. He also questioned Loeb's expertise and criticised his posts and papers.

"In these papers and on his blog he regularly betrays an unfamiliarity with well-established planetary science concepts and misinterprets papers and comes to erroneous conclusions," Wright wrote.

3I/ATLAS will make its closest approach to Earth on Dec. 19. Until then, expect many more new observations and claims — just take them with a grain of salt.

A never-before-seen comet that shares some minor similarities with the infamous interstellar object 3I/ATLAS is about to make its closest approach to our planet just a few days after it was first spotted speeding toward us.

However, despite some suggestions to the contrary, the newly discovered comet is not related to our current interstellar visitor, and almost certainly originated within the solar system.

The new comet, named C/2025 V1 (Borisov), was first spotted on Nov. 2 by the Crimea-based amateur astronomer Gennadiy Borisov. It will reach its closest point to Earth on Tuesday (Nov. 11), when it will reach a minimum distance of 64 million miles (103 million kilometers) from our planet, or around 270 times further away than the moon, according to Orbital Today. It is set to reach its closest point to the sun, or perihelion, on Sunday (Nov. 16).

C/2025 V1 has an apparent magnitude of around 13.8, making it too faint to be seen with the naked eye. However, the new comet may be visible to stargazers with a decent telescope or a pair of stargazing binoculars. It is currently located in the constellation Virgo and is most clearly visible just before sunrise, according to TheSkyLive.com.

If the name "Borisov" rings a bell, it’s because Gennadiy Borisov also discovered the second-known interstellar object (ISO), dubbed "Comet Borisov," in 2019. Like 3I/ATLAS, which was first spotted in early July, this alien comet was ejected by a faraway star in the Milky Way and sailed through space for billions of years before coincidentally shooting right through our cosmic neighborhood at incredibly high speeds.

This association, along with some additional anomalous characteristics, was enough for some to draw comparisons between C/2025 V1 and 3I/ATLAS. They included the renowned Harvard University astrophysicist and alien-hunter Avi Loeb, who described it as a "nearly interstellar object" in a recent blog post.

How can an object be "nearly interstellar"? It comes down to its orbit. C/2025 V1 is slightly unusual, given its high eccentricity, meaning that it is traveling toward the sun along a very straight trajectory. This is similar to, although not as extreme as, the trajectory of 3I/ATLAS — and is the main reason for the latest comparisons, Loeb wrote. Like in some recent photos of 3I/ATLAS, the new comet also appears to be missing its tail, he added.

C/2025 V1 was discovered while 3I/ATLAS was still temporarily hidden from us, due to it being positioned on the opposite side of the sun to Earth. This has led some new outlets to speculate that C/2025 V1 could be an alien probe that was secretly deployed by its "mothership" 3I/ATLAS, which is a theory that was first postulated by Loeb shortly after the latest ISO was discovered.

However, in his latest post, Loeb downplayed this idea, writing that "C/2025 V1 is not related to 3I/ATLAS if it did not employ non-gravitational propulsion." The distance between the two objects at their minimum separation was also around 140 million miles (225 million km), which is likely too great to explain an association between them, he added.

Instead, the new comet likely originates from the Oort Cloud — a giant reservoir of comets and other icy objects located near the outer edge of the solar system. However, its origin point and orbital trajectory have not yet been properly calculated.

As for 3I/ATLAS, the alien comet has now reappeared from its short stint behind the sun, having reached perihelion on Oct. 29. This solar flyby was notable for several other reasons, including an unexpected brightening event and a temporary color change. It has now started its journey back out of the solar system and will reach its closest point to Earth on Dec. 19.

The ISO has displayed a number of other anomalous characteristics, including a highly irradiated surface and a puzzling anti-tail. However, despite what some people claim, there is no reliable evidence that 3I/ATLAS is anything other than a comet — just like C/2025 V1.

A new image of comet 3I/ATLAS has revealed that the interstellar visitor is glowing green and hiding its tail, but that doesn't mean there's anything wrong with it.

Qicheng Zhang, a researcher at the Lowell Observatory in Arizona, used the observatory's powerful Discovery Telescope to make fresh observations of the comet as it zoomed away from the sun on Wednesday (Nov. 5). The comet recently became visible again after swinging around the far side of our star.

Comets develop an atmosphere, or coma, as they fly close to the sun. This cloud of gas and dust grows larger and brighter as the sun heats up ice and other materials on the comet, which sublimate into gases that astronomers can observe. In this case, the atmosphere is brightest when viewed with a green filter, like with most comets that fly close to our star.

Zhang used a filter to detect diatomic carbon (C₂) particles, which glow green. He noted that there's a bunch of large molecules in the comet that contain carbon and hydrogen (hydrocarbons). And when the comet gets close to the sun, ultraviolet (UV) light breaks these molecules apart.

"It's sort of for the same reason that if we stay out in the sun too long without sunscreen, we get sunburnt," Zhang told Live Science. "The UV rays are destroying our DNA [in our skin cells], which is kind of a similar type of molecule in the sense that it's big and contains carbon."

When this happens on a comet, some of the molecule chunks are two carbon atoms stuck together, or diatomic carbon, which are easy for astronomers to detect.

The comet appears to lack a dust tail in the image, but it's still there. Zhang noted that if you look closely at the image, you can see it's a bit brighter on the left side of the comet than on the right. That slight asymmetric glow occurs because we're seeing the tail basically head-on, and it's right behind the comet, curving slightly off to the left. In other words, the comet's apparent lack of tail isn't anything to get excited about.

Comet 3I/ATLAS has become a celestial celebrity since its discovery in July. A lot of this buzz stems from speculation that the comet might be an alien spacecraft, even though most astronomers are confident that the interstellar visitor is a comet from an unknown star system in the Milky Way.

However, describing 3I/ATLAS as just a regular comet would do this rare solar system interloper an injustice. The comet is only the third interstellar visitor ever recorded and could be the oldest comet ever seen, with one study suggesting it's around 3 billion years older than the solar system.

Comet 3I/ATLAS has only recently become visible from Earth again after it briefly disappeared behind the sun, reaching its closest point to our star, known as perihelion, on Oct. 29. This post-perihelion phase opens up a critical window for astronomers hoping to learn more about the comet's gases and makeup, as comets tend to be their most active at perihelion.

Preliminary research suggested that prolonged exposure to space radiation has given comet 3I/ATLAS a thick irradiated crust that no longer resembles its home star system. If confirmed, this crust could mean scientists will have a harder time deciphering 3I/ATLAS' origins, as it will be venting irradiated material rather than pristine material from its home star system.

Zhang previously used the Lowell Discovery Telescope to get a first optical, post-perihelion look at 3I/ATLAS from Earth on Halloween (Oct. 31). As with his first observation, the new sighting was made during morning twilight. The comet is moving northward from our perspective, away from the northeastern horizon. At the moment, it's possible to observe the comet early in the morning, when the comet is rising above the horizon.

Zhang took multiple images of the comet with different filters. The diatomic carbon image, which he first posted to his Cometary blog on Wednesday, roughly depicts what the comet might look like if humans were able to see it with the naked eye.

On Oct. 28, Zhang and his colleague posted a study to the preprint server arXiv that suggested comet 3I/ATLAS underwent rapid brightening ahead of perihelion and was distinctly bluer than the sun. The green in the new image doesn't mean that the comet changed color after perihelion — it might have changed color before.

Zhang noted that, in astronomical terms, bluer or redder typically refers to longer (red) or shorter (blue) wavelengths of light, with the new observation matching the latter. The comet is a lot brighter when viewed with bluer filters than redder filters, though the bluer filters are more of a mix of green and blue, and not actually that sensitive to pure blue.

"It's brightest in the bluest filter that we have," Zhang said.

The Lowell Discovery Telescope was likely one of the largest telescopes that could point close enough to the horizon to see comet 3I/ATLAS immediately after perihelion, according to Zhang. However, he noted that the comet is now high enough above the horizon that a number of large telescopes can make observations — small personal telescopes with a 6-inch (15 centimeters) lens can also spot it.

Expect a flurry of interesting findings on the comet in the coming months.

New photos reveal that a recently discovered comet dubbed the "other ATLAS" has transformed into a spectacular golden ribbon after surviving a close approach to the sun — a journey that many experts believed would be the comet's doom.

The comet, called C/2025 K1 (ATLAS), was discovered in May by astronomers at the Asteroid Terrestrial-impact Last Alert System (ATLAS), which scans the night sky for moving objects using telescopes in Hawaii, Chile and South Africa. The object has largely gone under the radar until now, mainly due to the recent hype around the interstellar comet 3I/ATLAS, which was discovered by ATLAS astronomers in early July, and Comet Lemmon, which has been clearly visible in the night sky over recent weeks.

C/2025 K1 reached its closest point to the sun, or perihelion, on Oct. 8, coming within a minimum distance of 31 million miles (50 million kilometers) of our home star — around four times closer than 3I/ATLAS managed during its own perihelion on Oct. 29. Due to the intense gravitational strain from this close encounter, many experts believed that C/2025 K1 would be ripped apart, according to Spaceweather.com.

On Oct. 29, at the same time 3I/ATLAS achieved perihelion, astrophotographer Dan Bartlett snapped a stunning shot of C/2025 K1 from June Lake in California. The image shows the comet with a distinct golden glow and a long tail that looks as if it has been buffeted by the solar wind — similar to Comet Lemmon, which recently had its tail torn to pieces.

"This comet was not supposed to survive its Oct. 8th perihelion," Bartlett told Spaceweather.com. "But it did survive, and now it is displaying a red/brown/golden color rarely seen in comets." The same unique coloration was observed by at least two other photographers, in California and in Arizona.

Comets typically appear white because the sunlight they reflect contains all the wavelengths of visible light. However, when specific chemicals are present within the cloud of ice, gas and dust surrounding the comet, known as the coma, they can absorb specific wavelengths of light, causing the comet to shine with a different hue.

For example, several notable comets have turned green in recent years — including Comet Nishimura, the explosive "devil comet" 12P/Pons-Brooks and the aptly named "green comet" C/2022 E3 — due to the presence of either dicarbon or cyanide in their respective comas. Some comets can also turn blue if their comas contain carbon monoxide or ammonia, which may be happening to 3I/ATLAS, according to recent observations. However, the golden color of C/2025 K1 is much rarer.

In a recent blog post, astronomer David Schleicher, who has been studying C/2025 K1 from the Lowell Observatory in Arizona, wrote that the comet has a surprising lack of carbon-bearing molecules, such as dicarbon, carbon monoxide and cyanide. Only two other known comets have ever had fewer of these molecules, he wrote.

This depletion of carbon-bearing molecules is the most likely cause for the comet's gold coloration, but "we don't know exactly why," Spaceweather.com representatives wrote. But it could also have something to do with its recent solar flyby or its relatively low ratio of gas to dust, they added.

C/2025 K1 now has an apparent magnitude of 9, which is equally as bright as 3I/ATLAS following an unexpected brightening event that occurred during its flyby of the sun. Both objects are too dim to see with the naked eye, but they can be seen with a decent telescope or a pair of stargazing binoculars.

If you want to see it for yourself, C/2025 K1 is located between the constellations Virgo and Leo in the eastern sky, and it is most clearly visible shortly before sunrise, according to Spaceweather.com. It will reach its closest point to Earth on Nov. 25, meaning it will likely remain visible until early December.

Interstellar comet 3I/ATLAS may be developing a blueish hue after undergoing a rapid and unexpected brightening event while hidden behind the sun, new observations reveal. This is the third time that experts have noted a potential change to the comet's color — but, so far, none of them have stuck.

3I/ATLAS, the third-known interstellar object to visit our solar system, was spotted shooting toward the sun at more than 130,000 mph (210,000 km/h) in early July. The comet is potentially the oldest of its kind ever seen and was likely ejected from its home star system, somewhere in the Milky Way's frontier, more than 7 billion years ago. Since then, it has sailed through interstellar space, before making its current rendezvous with our solar system.

Following a close approach to Mars at the start of October, the interstellar comet has spent the last few weeks on the opposite side of the sun to Earth, making it largely unobservable from our planet (although a handful of orbiting spacecraft could still see it). But it is now starting to become visible to Earth-based telescopes once again.

The comet reached its closest point to the sun, known as perihelion, on Oct. 29, when it was mostly hidden from us, reaching a minimum distance of 130 million miles (210 million kilometers) from our home star — around 1.4 times farther from the sun than Earth. The day before, a pair of researchers analyzing data from spacecraft that could still see 3I/ATLAS revealed that the comet had brightened by several orders of magnitude after disappearing from view, which can't be fully explained by its proximity to the sun.

In the same paper, the researchers also wrote that the comet appears to be "distinctly bluer than the sun," which came as a surprise given that this color had not been seen in the comet until now. This color change is likely the result of a specific gas, such as carbon monoxide or ammonia, leaking from the comet, they argued. (This study has not yet been peer-reviewed, and no other observations have thus far confirmed the blue coloration.)

The researchers noted that the blue coloration is in sharp contrast to the initial red hue given off by the comet during early observations in July, which was likely the result of an abundance of dust coming off its surface. Then, in September, the comet briefly appeared to be turning green, likely due to the presence of dicarbon or cyanide within its coma.

But these changes of coloration were only temporary, and it's currently unclear why that is. Only time and continued observations will tell if the comet's new coloring will stick.

Over the next few weeks, the comet will become increasingly visible to stargazers in the Northern Hemisphere as it moves northward in the night sky. However, it will not be visible to the naked eye, meaning you will need a decent telescope or a pair of stargazing binoculars to see it for yourself.

3I/ATLAS will reach its closest point to our planet on Dec. 19, coming within a minimum distance of 168 million miles (270 million km) — around 1.8 times the Earth-sun distance. Between now and then, researchers will get a much better look at the comet, enabling them to study it in even greater detail. Two ESA spacecraft may also fly through the comet's long tail before it begins its journey back out of the solar system.

The extrasolar entity has displayed several unusual traits since it was first discovered, including an abundance of carbon dioxide, high levels of water leakage and a puzzling anti-tail. Researchers also believe that its icy shell may have been transformed by billions of years of cosmic ray bombardment, potentially making it harder to track the material of its home star system.

As a result of these anomalous characteristics, some researchers have controversially proposed that 3I/ATLAS may be a piece of alien technology in disguise. However, there is no solid evidence to support this theory, and most experts maintain that the object is behaving exactly as a comet should.

The interstellar comet 3I/ATLAS has become visible from Earth once again after zooming behind the sun, new images reveal.

An astronomer used the Lowell Observatory's powerful Discovery Telescope in Arizona to snap what is believed to be the first optical post-perihelion shot of the interstellar visitor on Halloween, Friday (Oct. 31).

Qicheng Zhang, a postdoctoral fellow at the observatory, has subsequently found that the comet is also visible using small telescopes, posting an example of this to his Cometary blog on Sunday (Nov. 2). According to Zhang, standard amateur telescopes should now start picking up the comet across much of the Northern Hemisphere.

"All you need is a clear sky and a very low eastern horizon," Zhang told Live Science on Friday. "It won't look very impressive, it's just a smudge, but it will be an increasingly visible smudge over the next few days."

Scientists have learned a lot about comet 3I/ATLAS since its discovery in July. The comet, which is only the third interstellar object ever recorded, appears to be zooming through our solar system at speeds in excess of 130,000 mph (210,000 km/h) in an unusually flat and straight trajectory.

The comet briefly disappeared from Earth's view as it slingshotted around the sun, reaching its closest point to our star, known as perihelion, on Thursday (Oct. 29) — it came within 1.4 astronomical units, or 130 million miles (210 million kilometers) of the sun. But researchers and amateur astronomers used data from space telescopes to continue following the comet's path even after it was obscured by the sun.

On Oct. 28, Zhang and his colleague posted a study to the preprint server arXiv that suggested comet 3I/ATLAS underwent rapid brightening ahead of perihelion and was distinctly bluer than the sun, which was consistent with gas emissions contributing a substantial fraction of the visible brightness near perihelion. Zhang noted that the comet could still be brightening, but more data is needed to say one way or the other.

The Lowell Discovery Telescope is likely one of the largest telescopes that can point close enough to the horizon to see comet 3I/ATLAS so soon after perihelion, according to Zhang. The comet is moving northward from our perspective, away from the northeastern horizon. Zhang noted that there's a window to observe the comet in the morning twilight, when the comet is just above the horizon but the sun is still far enough below it that the sky isn't too bright.

Time is a precious resource for large telescopes, so Zhang uses a small telescope (6-inch lens) to experiment and learn about what conditions to expect ahead of his scheduled windows on the Lowell Discovery Telescope. He successfully captured the new image when the comet was about 16 degrees away from the sun (5 degrees above the horizon).

Zhang noted that there have been radio observations of comet 3I/ATLAS throughout its perihelion, and it's possible someone else made an optical post-perihelion observation before him, but he hasn't seen any others.

We're entering an important period for observations of 3I/ATLAS. Comets heat up as they fly closer to stars, which causes ice on their surface to sublimate into gas. This means that researchers should be able to learn more about the comet's makeup as it flies away from our star.

There has been some frenzied speculation in the media that 3I/ATLAS might be an alien spacecraft, but most astronomers are confident that this interstellar visitor is a regular comet from an unknown star system in the Milky Way. Comet 3I/ATLAS could also be the oldest comet ever seen, with one study suggesting it's around 3 billion years older than the solar system.

Some preliminary research has suggested that prolonged exposure to space radiation has transformed the interstellar traveler, giving it a thick irradiated crust that no longer resembles its home star system. If that's the case, scientists will have a harder time deciphering the comet's origins. Regardless, we can expect a flurry of new comet 3I/ATLAS research in the coming months as it reappears in the night sky.

"The comet is rapidly rising from the sun," Zhang said. "I think in one week it's going to be something like 25 or 30 degrees away from the sun, by which point there will be a large number of other big telescopes around the world that will also be able to start to follow it up."

Comet 3I/ATLAS is extremely irradiated from billions of years of cosmic ray bombardments, new research using observations from the James Webb Space Telescope (JWST) has revealed.

The comet has soaked up so many galactic cosmic rays during its interstellar journey through the Milky Way that it has developed a deep irradiated crust that no longer resembles the material of its home star system, the new research hints.

Using JWST observations and computer simulations, researchers have determined that the comet's previously documented "extreme" levels of carbon dioxide (CO₂) enrichment are from space radiation absorbed over its estimated 7-billion-year lifespan, according to the study posted to the preprint server arXiv on Friday (Oct. 31). The findings have not yet been peer reviewed.

Galactic cosmic rays — a kind of space radiation made up of high-energy particles from outside of the solar system — strike carbon monoxide (CO) in space to convert it to carbon dioxide (CO₂). In our solar system, the heliosphere — the enormous bubble of radiation emitted by the sun — shields Earth and its neighbors from a majority of this cosmic radiation. But in interstellar space, where 3I/ATLAS has spent most of its life, no such protection exists.

The authors of the new study concluded that over billions of years, cosmic rays have significantly altered the physical state of comet 3I/ATLAS' ice, down to a depth of about 50 to 65 feet (15 to 20 meters).

"It's very slow, but over billions of years, it's a very strong effect," study lead author Romain Maggiolo, a research scientist at the Royal Belgian Institute for Space Aeronomy, told Live Science.

The findings, which the researchers described as a "paradigm shift" for studying interstellar objects, suggest that objects like comet 3I/ATLAS are primarily made up of galactic cosmic ray-processed material rather than pristine material that is representative of the environments in which they formed.

In other words, comet 3I/ATLAS is now a product of its interstellar journey rather than where it came from — at least on the outside.

Tracking the interstellar visitor

Comet 3I/ATLAS is currently flying around the sun. The comet reached perihelion (its closest point to our star) on Thursday (Oct. 29). Comets heat up as they draw closer to stars, causing ices on their surface to sublimate into gas. The new findings suggest that before perihelion, any gases ejected from the comet were merely from its irradiated outer shell. This is likely to continue post-perihelion, but Maggiolo noted that while it's unlikely, solar erosion might be strong enough to expose the pristine materials from the comet’s home star that are locked away in its nucleus.

"It will be very interesting to compare observations before perihelion, so the first observation we had when it arrived in the solar system, with observations made after perihelion when there was some erosion," Maggiolo said. "Maybe by looking at these differences, we can have some indication about its initial composition."

Since its discovery in July, researchers have been using various telescopes to learn all they can about 3I/ATLAS. Their findings so far indicate that the comet is zooming through our solar system at speeds in excess of 130,000 mph (210,000 km/h) in an unusually flat and straight trajectory. 3I/ATLAS could also be the oldest comet ever seen, with one study suggesting it's around 3 billion years older than our 4.6 billion-year-old solar system.

The new research builds on a previous work that documented comet 3I/ATLAS is rich in CO₂, based on JWST's first images of the interstellar visitor in August, and observations from NASA's SPHEREx orbiter, also made in August.

Maggiolo and his colleagues had been studying the irradiation of a domestic comet (comet 67P), which passes between the orbits of Jupiter and Earth, and adapted their models from a 2020 study published in The Astrophysical Journal Letters to apply to comet 3I/ATLAS.

The team modeled the cumulative effects of galactic cosmic ray exposure on both ice structure and chemical composition after 1 billion years of irradiation. The method relies on laboratory experiments that simulated the effects of galactic cosmic rays, and thus might not be completely representative of interstellar conditions. Nonetheless, the tests offer a robust indicator of what comets experience on their lonely, multibillion-year journeys through interstellar space, according to the study.

The simulations found that 1 billion years of irradiation was sufficient for comet 3I/ATLAS to form its deep irradiated crust. Maggiolo noted that comet 3I/ATLAS is still full of interesting information, but it has aged and changed, which researchers will need to take into account during their analyses.

"We have to be careful and take into account aging processes, so it's more work for scientists, but [3I/ATLAS] remains very interesting," Maggiolo said.

3I/ATLAS is the third interstellar object ever discovered in our solar system. Telescope observations suggest it is a roughly 7-mile-wide (11 kilometers) comet zooming at more than 130,000 mph (210,000 km/h). Astronomers discovered it in early July as it emerged from beyond the orbit of Jupiter. An analysis of the comet’s composition and unusually flat, straight trajectory revealed that it did not originate within our cosmic neighborhood, and was likely ejected from a distant star system long before our sun ever formed.

The exotic comet has many peculiar properties, from its chemical composition to its large size. This has fuelled speculation that the comet is an alien spacecraft intentionally guided here. That’s almost certainly not the case, but it doesn’t mean that astronomers aren’t excited about studying it to better understand the conditions around other stars, the early Milky Way, and the frontier of interstellar space.

3I/ATLAS reached its closest point to Earth on Friday (Dec. 19) and is now zooming away forever. Research continues to pour in as telescopes around the solar system observe the strange comet's passage.

Comet 3I/ATLAS is rapidly brightening as it swings behind the sun, spacecraft observations have revealed.

The comet has been flying around the sun, obscuring it from Earth’s view, to reach perihelion (its closest point to our star) on Thursday (Oct. 29).

Yet, while most of the world has been waiting for it to re-emerge, some researchers and amateur astronomers have been using spacecraft to follow its path.

On Oct. 18, amateur astronomer and seasoned comet hunter Worachate Boonplod spotted the comet in images from the National Oceanic and Atmospheric Administration's GOES-19 weather satellite, which uses an instrument called CCOR-1 to observe the sun as part of its regular space weather monitoring. Boonplod noted that comet 3I/ATLAS was easily detectable and was set to remain visible to the spacecraft until Oct. 24.

"Its brightness is comparable to nearby stars with magnitude ~11," Boonplod wrote on the Comets Mailing List group, part of the group email service Groups.io. (In astronomy, a higher magnitude corresponds to a brighter object; typically, objects with a magnitude greater than 6 are too faint for the naked eye to see.) "The comet is moving from left to right (relative to both the field and background stars) and should go out of the CCOR-1 field on October 24."

The GOES-19 satellite wasn't the only satellite with comet 3I/ATLAS in its sights. Also tracking it are NASA's Polarimeter to Unify the Corona Heliosphere (PUNCH) mission, which includes four small satellites aimed at the sun, as well as NASA and the European Space Agency's Solar and Heliospheric Observatory (SOHO), Universe Today reported. SOHO orbits the sun at almost 1 million miles (1.5 million kilometers) from Earth, with its Large Angle and Spectrometric Coronagraph (LASCO C3) instrument keeping track of comet 3I/ATLAS until Oct. 26. Coronagraphs, like those used by SOHO and GOES-19, are instruments that intentionally block the sun in images in order to study the surrounding atmosphere, or corona.

On Wednesday (Oct. 28), two researchers posted a study to the preprint server arXiv that reported comet 3I/ATLAS underwent rapid brightening ahead of perihelion. The team estimates that, at perihelion, the comet will have brightened to roughly magnitude 9 — still too faint to be seen with the unaided eye, but bright enough to be seen by good backyard telescopes, if it were visible from Earth.

The study relied on space-based solar instruments like GOES-19 and SOHO, and found that the comet was distinctly bluer than the sun, which was consistent with gas emissions contributing substantially to the comet’s increased brightness near perihelion, according to the study's authors. This is expected of comets, which heat up as they approach the sun, causing surface ices to sublimate into gases that wrap around the comet’s body and contribute to its tail. Solar radiation ionizes the gas, causing further brightening.

Scientists have been using various telescopes to learn all they can about comet 3I/ATLAS since its discovery in July. The comet is only the third interstellar comet ever recorded, and findings thus far indicate that it's zooming through our solar system at speeds in excess of 130,000 mph (210,000 km/h) in an unusually flat and straight trajectory.

Despite some rather frenzied speculation that comet 3I/ATLAS could be an alien spacecraft, most astronomers are confident that this interstellar visitor is a space rock from an unknown star system far away.

The speed of the comet, which has the highest velocity ever recorded for a solar system object, suggests that it has been traveling for billions of years, gaining momentum from a gravitational slingshot effect as it whips by stars and nebulas, according to a NASA statement .

In fact, 3I/ATLAS could be the oldest comet ever seen, with one study suggesting it's around 3 billion years older than our 4.6 billion-year-old solar system. The comet is also likely the largest interstellar object ever seen, though researchers are still pinning down its exact size. Hubble Space Telescope data suggest that 3I/ATLAS has a maximum width of about 3.5 miles (5.6 km).

The comet will become visible again to Earth-based telescopes by early December, according to NASA, and may even be visible to spacecraft orbiting Jupiter as it makes a close approach to the gas giant in March, 2026.

An astronomer recently aimed his telescope above Manciano, Italy, and caught something incredible: a bright comet seemingly wrapped up in the corkscrewing trail of a meteor, glittering in the same patch of sky like a cosmic barber shop pole.

With millions of miles separating the foreground meteor and the background comet, the odds of capturing such a fortuitous shot were (excuse the pun) astronomically low.

"In this photograph, the meteor's afterglow appears to coil around the comet's ion tail — a pure perspective miracle," astronomer Gianluca Masi, founder of The Virtual Telescope Project and the photographer who captured the stunning shot, wrote in a statement. "The former is an atmospheric effect induced by the meteor, while the comet itself was about 100 million kilometers [62 million miles] away."

The comet seen here is C/2025 A6 (Lemmon) — one of three comets taking the solar system by storm right now, along with Comet R2 (SWAN) and the interstellar visitor 3I/ATLAS. Comet Lemmon, which reached its closest point to Earth on Oct. 21, is the brightest of the bunch and has remained visible enough to be seen through simple telescopes and stargazing binoculars for the following several days.

Masi spotted the comet on the night of Oct. 24. Its long, blue tail — the product of ionized gas that's been vaporized off of the comet's surface and blown away by the solar wind — was clearly visible. But for several minutes during Masi's observations, another streamer-like structure became visible near the comet: the wispy remnants of an ion trail left by a meteor plummeting through Earth's atmosphere.

Seen here as a golden line spiraling around the comet; the meteor trail evolved constantly over the course of Masi's observations, briefly appearing like a part of the comet itself. In reality, the trail is a result of chemical reactions in the atmosphere triggered by the meteor's ultrafast passage.

"The phenomenon is associated with the ionization of molecular oxygen in the atmosphere caused by the meteor event, followed by its recombination, which produces the emission of light at that wavelength," Masi said.

While meteors typically move at more than 100,000 mph (160,000 km/h), their trails can linger in the sky for several minutes, according to NASA. During this time, winds blowing at different altitudes can sculpt those trails into meandering streamer shapes like the one seen here. Masi also posted a time-lapse video of the meteor event on YouTube showing how the glowing trail whipped through the sky in front of the comet for several minutes.

The phenomenon of spiral meteor trails has not been extensively studied, but they are considered relatively rare. A series of papers published in the 1980s and 1990s estimated that only 0.5% of observed meteors leave a nonlinear trail. However, this number is far from certain and may have been skewed by suboptimal camera settings used to record meteor trails at the time.

The annual Orionid meteor shower — an event triggered by the debris of Halley's comet — peaked on Oct. 20-21, the same night Comet Lemmon was at its brightest. Although the shower is waning, it will last until Nov. 7, meaning more "shooting stars" like the one Masi caught are possible at night. Keep your eyes on the skies, and maybe you'll spot a "miracle" of your own.

Even as a brilliant, naked-eye comet slices through Earth's sky (cheers, Comet Lemmon!), the most famous object in the solar system right now is hidden on the far side of the sun: the interstellar comet 3I/ATLAS.

This alien visitor, which most astronomers believe to be a comet originating from an unknown star system far beyond our own, is only the third interstellar object ever detected in our solar system. It is the largest, fastest-moving, and quite likely the oldest interstellar object ever seen.

Though it was just confirmed by NASA in early July, the freewheeling ball of ice and dust is already nearing the halfway point on its tour of our solar system. This Wednesday (Oct. 29), 3I/ATLAS will reach perihelion — its closest point to the sun — before beginning its months-long departure from our cosmic neighborhood.

We'll miss our interstellar friend, but at least we'll always have the photos. The image above, captured Aug. 27 by the National Science Foundation-operated Gemini South telescope in Chile, may be the clearest image we have so far. As 3I/ATLAS zooms closer to the sun, radiation from our star heats the ice on the comet's body (its nucleus), causing geysers of gas and dust to shoot outward and form a glowing plume (a coma) around it. Radiation pressure from our star's unrelenting solar wind pushes this material into a long, prominent tail angled away from the sun.

As 3I/ATLAS reaches perihelion this week — coming within 1.4 astronomical units, or 130 million miles (210 million kilometers) of the sun, according to NASA — it may start releasing gas in overdrive. When the comet becomes visible to telescopes again in early November, it may look both bigger and brighter than how it appeared two months ago. Instruments on the ground, in orbit and even on their way to Jupiter will snap to attention, making 3I/ATLAS an even bigger space celebrity as it zooms away from our solar system forever.

Studying the interstellar comet with the full range of humankind's astronomical instruments could yield untold secrets about the outer reaches of our galaxy and its mysterious history. Until then, all we can do is wait, feel the warm sunlight on our faces, and know that a trove of cosmic information lurks just on the other side of our star.

For more sublime space images, check out our Space Photo of the Week archives.

Newly released images of the interstellar comet 3I/ATLAS appear to show the alien object spitting out an enormous jet of gas and dust toward the sun — just as comets are expected to do.

Discovered in late June and confirmed by NASA in early July, the comet originates from an unknown star system far beyond our own. 3I/ATLAS is only the third interstellar object ever detected. At somewhere between 3 and 7 miles (5 to 11 kilometers) wide, it is the largest interstellar object ever to cross our path, and likely the oldest, potentially dating to billions of years before the birth of the sun.

These and other peculiarities have led a small group of researchers to controversially claim that the object may be an alien spacecraft sent to spy on us. However, the vast majority of scientists maintain that 3I/ATLAS is a high-speed comet behaving exactly as comets should. The new images of the interstellar interloper, captured Aug. 2 by the Two-meter Twin Telescope (TTT) at the Teide Observatory in Spain's Canary Islands, further cement the object's natural origins.

Combining 159 exposures lasting 50 seconds each, the composite image shows the icy body (or nucleus) of 3I/ATLAS as a big, black dot, surrounded by a white glow. A sudden, fan-shaped break in this glowing ring shows where researchers say a large, high-speed jet of material (marked in purple) is blasting off of the comet in the direction of the sun. The image was shared to the transient object monitoring site The Astronomer's Telegram on Oct. 15 but has not yet been published in a peer-reviewed study.

Comets are famous for their glowing tails of ionized gas, the largest of which can stretch for hundreds of millions of miles in the opposite direction of the sun. Comet jets, by comparison, are much smaller and can point toward the sun. While a cannon of dust aimed at our star might sound suspicious, it's just a standard part of a comet's anatomy, Miquel Serra-Ricart, an astrophysicist and chief science officer at the Teide Observatory's Light Bridges research institution, told Live Science in an email.

"This is the usual," Serra-Ricart, who posted the new images, told Live Science. "Jets are pointing to [the] sunward direction and [the] comet's tail in the anti-solar direction."

This is because comets inevitably heat up as they swoop closer to the sun — but they don't always heat evenly. The sun-facing side of the comet heats up the fastest, and if a particular weak spot on the comet's surface warms up enough, a growing supply of sublimated gases can blast out like a geyser, shooting cometary material thousands of miles toward the sun.

As the comet's nucleus rotates, the jet can take on a fan shape akin to what we see in the new TTT image, Serra-Ricart added. The famous naked-eye comet NEOWISE also developed fan-like jets after its close flyby of the sun in 2020, Hubble Space Telescope observations showed at the time.

Some of that jet material ends up in the comet's coma (the glowing plume of material that surrounds the nucleus), while some may be forced into the comet's tail by radiation pressure from the onslaught of incoming solar wind. This is why comets can sport both a sun-facing jet and an anti-sunward tail at the same time — no alien technology required.

It's unclear how far this newly discovered jet extends at the moment, but Serra-Ricart estimated that it could stretch roughly 6,200 miles (10,000 km) from 3I/ATLAS' surface. The jet is likely composed largely of dust particles and carbon dioxide, he added, which is consistent with the makeup of the large gassy plume that the James Webb Space Telescope detected around the comet in August.

3I/ATLAS swooped past Mars on Oct. 3 and is currently approaching its closest point to the sun (perihelion), which it will reach on Oct. 29. The comet is on the far side of the sun now and won't be visible from Earth again until mid-November. When it reemerges, astronomers will get a rare chance to see how the mysterious visitor changed after its date with the sun and to what extent its jet and tail may have grown.

A striking new photo of the superbright "Comet Lemmon" (C/2025 A6) shows the partial remains of its sizeable tail, shortly after the ethereal limb was temporarily torn apart by the sun. The cosmic shredding occurred just a few days before the comet is due to make its closest approach to Earth on Tuesday (Oct. 21).

Astrophotographer Petr Horálek captured the stunning shot from Lake Seč in Czechia (also known as the Czech Republic) in the late hours of Saturday (Oct. 18), according to Spaceweather.com. The original wide-field photo (see below) also features faint red-pink auroras that hung low in the night sky.

The auroras, or Northern Lights, were the result of a surprise G2 (moderate) class geomagnetic storm that began early the same day. This temporary disruption to Earth's magnetic field was triggered when a coronal mass ejection (CME) from the sun slammed into our planet, around two days later than originally expected. Comet Lemmon was also photographed alongside a much more vibrant aurora display over Scotland, which contained a much more diverse set of colors.

However, the CME did not shred the comet's tail. Instead, the damage was likely caused by a strong gust of solar wind, which twisted and — at several points — completely disrupted the trail of gas and dust. This type of rippling along the tail is not uncommon among major comets, especially as they approach the sun. But the total separation of parts of the flowing limb, known as disconnection events, are much rarer.

This is not the first time that Lemmon's tail has been battered by the sun. The tail was also wobbled by a strong solar gust in late September and experienced a minor disconnection event on Oct. 4, according to Live Science's sister site Space.com. In each case, the comet's tail likely returned to normal within a few hours of being disrupted.

Comet Lemmon was discovered earlier this year, on Jan. 3, by researchers at the Mt. Lemmon SkyCenter observatory in Arizona's Santa Catalina Mountains. It is a nonperiodic comet that has likely orbited the sun every 1,350 years.

Lemmon will make its closest approach to Earth today (Tuesday, Oct. 21), when it will come within 56 million miles (90 million kilometers) of our planet, before reaching its closest point to the sun, or perihelion, on Nov. 8.

The comet has become much brighter in recent weeks as its increased proximity to the sun has caused the cloud of gas, ice and dust surrounding it — known as its coma — to expand. It currently has an apparent magnitude of 4, making it clearly visible to the naked eye.

People in the Northern Hemisphere can see the comet in the northwestern sky, located just below the Big Dipper, shortly after sunset. While visible to the naked eye, the best views will be achieved with a decent backyard telescope or a pair of stargazing binoculars. To capture the best possible photos of Lemmon, you can check out our comet photography guide.

Another bright comet, dubbed SWAN, also reached its closest point to Earth on Monday (Oct. 20) and is currently observable in the night sky not far from Lemmon. However, SWAN is not visible to the naked eye and can only be seen using stargazing equipment.

Days before making its closest approach to Earth for more than 1,000 years, the superbright comet C/2025 A6 (Lemmon) has been snapped over the Scottish Highlands, appearing to fly through a technicolor swirl of auroras that suddenly exploded into the night sky.

Photographer Alan Tough took the spectacular shot in the early hours of Saturday (Oct. 18) from his backyard near the town of Elgin in northeast Scotland. He was originally planning to photograph the comet on its own when the auroras suddenly erupted, according to Spaceweather.com, which first shared the photos.

The auroras were the result of a surprise geomagnetic storm, or disturbance to Earth's magnetic field, triggered by a coronal mass ejection (CME) from the sun. This solar storm was originally predicted to hit our planet two days earlier but was delayed, reducing hopes of any resulting auroral displays. The disturbance eventually reached G2 (moderate) status, meaning auroras were potentially visible in up to 15 U.S. states, Live Science's sister site Space.com reported.

A wide range of aurora colors were visible within the auroral arc, including more typical colors, such as greens and reds, as well as rarer hues, like oranges and pinks, which only appear under specific conditions.

The bright comet was more than 230 times farther away from Earth than the moon when the image was taken.

Comet Lemmon was discovered on Jan. 3, by researchers at the Mt. Lemmon SkyCenter observatory in Arizona's Santa Catalina Mountains. It is a nonperiodic comet that likely orbits the sun every 1,350 years.

Comet Lemmon will make its closest approach to Earth today (Oct. 21), when it will come within 56 million miles (90 million kilometers) of our planet, before reaching its closest point to the sun, or perihelion, on Nov. 8.

Lemmon has become much brighter in recent weeks as its increased proximity to the sun has caused the cloud of gas, ice and dust surrounding it — known as its coma — to expand. It currently has an apparent magnitude of 4, meaning it is clearly visible to the naked eye.

The comet has also grown a sizable tail, which has been frequently battered by solar wind as Lemmon swerves through the inner solar system.

People in the Northern Hemisphere can see the comet in the northwestern sky, located just below the Big Dipper, shortly after sunset. While visible to the naked eye, the best views will be achieved with a decent backyard telescope or a pair of stargazing binoculars. To capture the best possible photos of Lemmon, you can check out our comet photography guide.

Another bright comet, named SWAN, also reached its closest point to Earth on Monday (Oct. 20) and is currently observable in the night sky not far from Lemmon. However, SWAN is not visible to the naked eye and can only be seen using stargazing equipment.

If you want to see two comets, your best chance will be early this week. After a year without any comets bright enough to be seen without specialist equipment, two — Comet C/2025 A6 (Lemmon) and Comet C/2025 R2 (SWAN) — have come along at once.

Comet Lemmon may look more like a lime than its name suggests, but on Tuesday (Oct. 21), the dusty snowball from the outer solar system will reach its closest point to Earth and most likely shine at its brightest. It's now reached magnitude 4.5, according to SpaceWeather.com — about the same brightness as spring's Beehive Cluster (M44) and only a little dimmer than the Andromeda galaxy (M31).

While Comet Lemmon is technically visible to the naked eye in very dark skies, you'll need binoculars to glimpse another, fainter icy visitor, Comet C/2025 R2 (SWAN). Remarkably, Comet SWAN will get closest to Earth Monday (Oct. 20), the day before Comet Lemmon, but it'll be about three times dimmer, at magnitude 5.9. (In astronomy, the higher the magnitude, the dimmer the object.)

The best time to see both comets any night this week will be about an hour and a half after sunset; you can check local times on Timeanddate.com. On Monday, Comet Lemmon will be visible in the northwest sky, near the Big Dipper and the bright star Arcturus, and close to the horizon.

Follow the shape of stars in the Big Dipper's handle to "arc to Arcturus"; the comet will be about two-thirds of the way there. On Tuesday, it will be a little higher. For Comet SWAN, look for the Summer Triangle of bright stars — Vega, Deneb and Altair — in the southwest. You'll find Comet SWAN about halfway between Altair and the horizon.

Helpful finder charts and sky maps for both comets are available at The Sky Live, In-The-Sky.org and Stellarium, as well as in night-sky apps such as Sky Guide, Sky Tonight and SkySafari 7 Pro. If you want to try photographing the comets, our guide has you covered.

The two comets are on vastly different journeys. Comet Lemmon will get to within 56 million miles (89 million kilometers) of Earth Tuesday, according to The Sky Live, on its way to looping around the sun Nov. 8 during its 1,350-year orbit of the sun. (However, Jupiter sapped some of Comet Lemmon's orbital energy, shortening its period by nearly 200 years, according to Star Walk, so it will not return until 3179.)

Comet SWAN is a long-period comet, orbiting the sun every 20,000 years, according to Universe Today, and on Monday, it will be 24 million miles (39 million km) away as it exits the inner solar system. That's about a quarter the distance between Earth and the sun.

Skywatchers are set for something special after dark on Monday, Oct. 20, through Tuesday, Oct. 21, when an annual meteor shower produced by Halley's Comet peaks just as two recently discovered comets reach their brightest points in the night sky.

According to the American Meteor Society, the Orionid meteor shower runs from Oct. 2 through Nov. 7, peaking on Oct. 20 to Oct. 21. That coincides with a new moon — when the moon is between Earth and the sun and is absent from the night sky — meaning the rare sky show should benefit from profound darkness. However, clear weather will still be required to see meteors and the brightening comets Lemmon (C/2025 A6) and SWAN (C/2025 R2).

The Orionids are the main event in fall's "meteor season," during which a host of minor meteor showers take place. Around 20 "shooting stars" per hour are expected during the Orionids' peak, with meteors hitting Earth's atmosphere at a speed of 41 miles per second (66 kilometers per second). The "shooting stars" can occur anywhere in the night sky, but if you trace them backwards, they will appear to come from a region of the night sky just north of the bright reddish star Betelgeuse in the constellation Orion — hence the shower's name. NASA calls the Orionids one of the most beautiful showers of the year.

Orionids are the product of Halley's Comet, which was last seen in the inner solar system in 1986 and will next be seen in 2061. The other meteor shower caused by Halley's Comet is April's Eta Aquariids.

While the Orionid meteor shower will be best seen in the hours after midnight on Tuesday, Oct. 21, the viewing window for the comets will take place much earlier the previous evening. Both comets will be in the post-sunset night sky and will be best seen an hour and a half after sunset — primarily with stargazing binoculars, but perhaps with the naked eye too if viewed from a dark sky site.

Comet Lemmon, which was discovered in January by the Mt. Lemmon SkyCenter observatory in Arizona's Santa Catalina Mountains, will be low in the northwest between the end of the handle of the Big Dipper and the bright star Arcturus. Comet SWAN, which was first spotted in September by NASA's orbiting Solar Dynamics Observatory, will be low in the south, just below the bright star Altair, one of the three stars in the famous Summer Triangle shape.

The interstellar comet 3I/ATLAS began blasting water "like a fire hose" before it was anywhere near the sun, according to a recent study.

Researchers observed the comet scattering water unusually early in a discovery that sheds light on how the building blocks of life are distributed across other planetary systems.

Initial James Webb Space Telescope observations have suggested that 3I/ATLAS has a high carbon dioxide (CO2) to water (H2O) ratio. In the new study, published Sep. 30 in The Astrophysical Journal Letters, researchers explored water activity on the comet and provided the first clear evidence that it was shedding water while still remarkably far from the sun.

"When we detect water — or even its faint ultraviolet echo, OH — from an interstellar comet, we're reading a note from another planetary system," study co-author Dennis Bodewits, a professor of physics at Auburn University in Alabama, said in a statement. "It tells us that the ingredients for life's chemistry are not unique to our own."

NASA's Neil Gehrels Swift space observatory detected hydroxyl (OH) gas, an ultraviolet by-product of water, coming off the comet when it was nearly three times farther from the sun than Earth (2.9 astronomical units away), much farther away than the region of our solar system where water ice typically turns to gas on passing comets.

Researchers calculated that the comet was shedding about 88 pounds (40 kilograms) of water per second, which is about the equivalent of a fire hose running at full blast, according to the statement released by the researchers.

Since its discovery in July, scientists have been using various telescopes to learn all they can about 3I/ATLAS. Their findings so far indicate that the comet is zooming through our solar system at speeds in excess of 130,000 mph (210,000 km/h) in an unusually flat and straight trajectory.

3I/ATLAS is likely the largest interstellar object ever seen, though researchers are still pinning down its exact size. Hubble Space Telescope data suggest that 3I/ATLAS has a maximum width of about 3.5 miles (5.6 km). 3I/ATLAS could also be the oldest comet ever seen, with one study suggesting it's around 3 billion years older than our 4.6 billion-year-old solar system.

For the new study, researchers used observations made with the Neil Gehrels Swift Observatory's ultraviolet and optical telescope in July and August. The researchers suggested that the ultraviolet hydroxyl signal could be the result of sunlight heating small icy grains on the nucleus (head) of the comet, causing them to vaporize into gas.

3I/ATLAS is only the third interstellar comet ever recorded, following the discovery of the cigar-shaped 1I/'Oumuamua comet in 2017 and the pristine 2I/Borisov comet in 2019. So far, each interstellar visitor has had some differing characteristics, suggesting that there could be a variety of comet and planet-forming environments in the universe.

"Every interstellar comet so far has been a surprise," study lead author Zexi Xing, a postdoctoral researcher at Auburn University, said in the statement. "Oumuamua was dry, Borisov was rich in carbon monoxide, and now ATLAS is giving up water at a distance where we didn't expect it. Each one is rewriting what we thought we knew about how planets and comets form around stars."

Two spacecraft on Mars have captured new images of the interstellar comet 3I/ATLAS in the closest view that the European Space Agency (ESA) will get of the mysterious object, according to an ESA statement.

The comet, which came from an unknown star system far beyond our own, is currently taking a months-long tour of the inner solar system. It made its closest approach to Mars Friday (Oct. 3) ahead of a close encounter with the sun on Oct. 30. During its recent flyby of the Red Planet, the comet came within view of ESA and NASA's fleet of robotic explorers, including ESA's ExoMars Trace Gas Orbiter (TGO) and Mars Express orbiter.

Soaring 18.6 million miles (30 million kilometers) overhead, the comet proved too dim for Mars Express to capture. However, the ExoMars TGO satellite succeeded in snapping a series of images, which ESA combined into an animated GIF. The animation shows the comet — visible as a fuzzy, bright dot — descending toward the center of the frame as it zooms away from Mars at an estimated 130,000 mph (210,000 km/h).

What can we see?

The bright dot represents the comet's nucleus (the ball of icy rock that makes up the body of the comet) and its coma (the nebulous cloud of gas that streams off the nucleus as it heats up). As comets swoop closer to the sun, ice on their surfaces sublimates into gas, causing the coma to grow larger and brighter, according to NASA. Pressure from incoming solar wind can also blow the coma's gas and dust away from the sun, giving comets their distinctive tails.

Because TGO was designed to monitor the Martian surface from just a few hundred miles away, its instruments aren't the best at recording faraway, fast-moving objects like 3I/ATLAS, ESA officials noted.

"The comet is around 10,000 to 100,000 times fainter than our usual target," Nick Thomas, principal investigator for ExoMars' Colour and Stereo Surface Imaging System, said in the statement. As a result, no tail is visible in the new images. But that doesn't mean the comet doesn't have one; as 3I/ATLAS careens closer to the sun, both its coma and its tail are likely to grow and brighten, ESA officials added.

At the moment, the new images don't reveal any new insights about the peculiar object, but ESA will continue to analyze images from both of its Mars satellites in hopes of teasing out some new data on the comet's possible size and composition.

It remains uncertain whether any of NASA's dedicated Mars rovers or satellites also spotted the comet during its close approach, as the agency has paused all public communications during the ongoing U.S. government shutdown. However, a raw image captured by the Perseverance rover's Right Navigation Camera on Oct. 4 shows a bright, streaking object in the sky that may be Comet 3I/ATLAS, according to Live Science’s sister site Space.com. No official information about the image has been released.

3I/ATLAS is the third interstellar object ever confirmed — after 1I/'Oumuamua and 2I/Borisov — and appears to be the largest so far, with estimates placing it somewhere between 3 and 7 miles (5 to 11 km) wide. Its speed and trajectory suggest that it has been zooming through the galaxy for billions of years and is likely far older than the sun.

The comet is currently traveling on the far side of the sun, out of Earth's view, but it will become visible to ground-based telescopes again in early December. The comet will whiz past Jupiter in March 2026, before heading out of our solar system forever.

Astronomers may be closing in on the age and origin of the interstellar comet 3I/ATLAS as it barrels toward the center of our solar system.

A new study that models the last 4 million years of the comet's journey through the Milky Way hints that the interstellar visitor came from far, far away — potentially originating from the wild frontier where the galaxy's oldest and youngest stars meet. If that's the case, the comet may be a relic of the early galaxy, dating billions of years older than Earth's sun.

First spotted in late June and confirmed by NASA in early July, 3I/ATLAS is a peculiar comet whose staggering speed and odd trajectory indicate that it came from a star system beyond our own. It is only the third interstellar object ever detected — after 1I/'Oumuamua and 2I/Borisov — and appears to be the largest so far, with recent estimates putting it somewhere between 3 and 7 miles (4.8 to 11.2 kilometers) wide.

Galactic grand tour

This cosmic visitor is currently taking a months-long sightseeing tour through our inner solar system, completing a close approach to Mars on Friday (Oct. 3) and poised to make its closest swoop past the sun on Oct. 30, according to NASA. After that, it will head out toward interstellar space again, passing Jupiter in March of 2026 before finally disappearing from view. The comet poses no threat to Earth.

While 3I/ATLAS's immediate trajectory is easy to predict, figuring out where it came from is much harder.

Traveling at about 130,000 miles per hour (210,000 kmh), a record for interstellar objects, the renegade ice ball has been picking up speed for millions, if not billions, of years. That leaves it vulnerable to the gravitational tugs of an untold number of Milky Way stars. Just as NASA uses the gravitational influence of our solar system's planets to slingshot spacecraft into deeper orbits, 3I/ATLAS could easily have been knocked off its original trajectory by the gravity of massive stars intervening in its path.

Now, new research published to the preprint server arXiv makes the best effort yet to pin down the comet's origins by looking at which nearby stars, if any, may have influenced its orbit.

Using data from the European Space Agency's now-retired Gaia space telescope, the study authors traced the comet's trajectory back in time 4.27 million years and identified 62 nearby stars that the interstellar object likely encountered along the way. Using Gaia's high-definition data on the stars' motions, velocities and sizes, the study authors concluded that none of them have significantly altered the comet's orbit — hinting that it did not originate anywhere near us.

"We have found that none of the stars in the solar neighborhood can explain the trajectory and high velocity of 3I/ATLAS," lead study author Xabier Pérez-Couto, an astrophysics postgraduate student at Spain's Universidade da Coruña, told Live Science in an email. Only one nearby star, measuring about 70% the mass of the sun, appears to have impacted the comet's trajectory at all, but it was only by a negligible amount, the researchers added in their paper.

This led the team to postulate that "3I/ATLAS is a very old object, that has been traveling for [billions of years], and that its origin belongs to the border of the thin disk," Pérez-Couto said.

Object from the wild frontier?

What's so special about that? Spiral galaxies like the Milky Way divide their stars between a thin disk and a thick disk. Slicing through the central bulge of our galaxy, the younger and smaller thin disk is thought to contain the vast majority of the Milky Way's stars and star-forming gases — most of which are rich in elements heavier than hydrogen and helium, picked up from the older generations of stars that lived and died before them. By contrast the broader thick disk, wrapped around the borders of the thin disk, has long ceased its star formation. It contains a smaller — but much older — sampling of stars that are poor in heavy metals, according to Swinburne University of Technology in Australia.

If comet 3I/ATLAS did indeed originate from the border of these two disks, it could mean the object is incredibly old — potentially 10 billion years old, making it more than double the age of our roughly 4 billion-year-old sun. According to Pérez-Couto, the comet was likely "ejected from the primordial disk of an early formed planetary system," potentially making it a valuable time capsule of the ancient Milky Way.

However, the new study acknowledges the limitations of its approach: by looking at nearby stars, the analysis only accounts for a few million years of the comet's long history, making its exact origin still highly uncertain. As 3I/ATLAS continues to zoom through the solar system, scientific instruments on Earth and Mars, as well as those in orbit around Jupiter, will soon have the chance to study it in much greater detail. Unraveling the interstellar object's composition will provide essential clues to its cosmic birthplace — and potentially open a precious window into our galaxy's past.

A newly discovered comet, dubbed "Lemmon," is gearing up for a close flyby of Earth later this month and could even become visible to the naked eye, some researchers claim. However, Lemmon may end up looking more like a different citrus fruit, thanks to its lime-green glow.

Comet C/2025 A6 (Lemmon) is a nonperiodic comet, which means it has a variable orbital period that spans over a millennium and is hard to predict. Observations hint that the comet currently orbits the sun every 1,350 years and spends a majority of this time lurking within the Oort Cloud — the giant shell of comets and other icy objects at the very edge of the solar system.

Lemmon was first spotted on Jan. 3 by researchers at the Mt. Lemmon SkyCenter observatory in Arizona's Santa Catalina Mountains as the comet was speeding toward the inner solar system at up to 130,000 mph (209,000 km/h). But it has largely gone under the radar until now, thanks to other more notable comets, such as SWAN R2 and the interstellar comet 3I/ATLAS, which are in the midst of their own solar flybys.

Lemmon will reach its closest point to Earth on Oct. 21, when it will come within 56 million miles (90 million kilometers) of our planet — more than 230 times farther from us than the moon is. A few weeks later, on Nov. 8, it will reach its closest point to the sun, or perihelion, before beginning its long journey back into the outer solar system.

As it gets closer to the sun, the comet will brighten as the cloud of gas, ice and dust surrounding it — known as its coma — expands, allowing it to reflect more sunlight back to Earth. It is expected to reach a maximum brightness, or apparent magnitude, of around 5, making it slightly too faint to be seen with the naked eye.

However, some experts are predicting that Comet Lemmon could reach an apparent magnitude of 4 — just bright enough to be seen without stargazing equipment, Live Science's sister site Space.com reported. (Apparent magnitude is measured on a reverse logarithmic scale, meaning a lower number equates to a higher brightness.)

Multiple photos of the comet show it giving off an eerie emerald glow. This is likely caused by the presence of diatomic carbon, or dicarbon — a rare, gaseous form of carbon where pairs of the element's atoms stick together — within its coma. In recent years, we have seen several other green comets, including the aptly named "green comet" C/2022 E3, which passed by us in 2023, and the "devil comet" 12P/Pons-Brooks, which turned green as it sailed past the sun in 2024. Recent photos suggest that 3I/ATLAS may be turning green, too.

Lemmon also has a striking tail, which first appeared in late August and is made of ice, gas and dust that is blown off the comet by solar radiation. In late September, this tail was buffeted by a strong gust of solar wind that caused this glowing limb to ripple in space (see below).

Researchers think Lemmon's upcoming solar flyby could drastically alter its future trajectory around the sun.

Even though Comet Lemmon will only reach a minimum distance of 48 million miles (77 million km) of our home star — around half the distance between Earth and the sun — experts think its orbital period could shorten by up to 200 years. This is likely because of a recent close flyby of Jupiter, which has gravitationally tugged the comet off its original path, according to Space.com.

How to see Comet Lemmon

Comet Lemmon can already be seen with most stargazing equipment, but it will become easier to spot as it brightens over the coming weeks. It may become visible to the naked eye, but if not, it will still be easy to spot with a decent backyard telescope or a pair of stargazing binoculars.

"This comet is developing very nicely and it is already an impressive object, well-placed for observation in the morning sky," Nick James, director of the Comet Section of the British Astronomical Association, recently told Spaceweather.com. "It is definitely worth getting up for!"

The comet will be visible in the constellation Lynx, between Jupiter and the stars within the Big Dipper, and it will reach its peak brightness in mid-October, according to the BBC's Sky at Night Magazine. For most people in the Northern Hemisphere, Comet Lemmon will be easiest to spot just before sunrise or shortly after sunset.

For a more up-to-date and location-specific guide on where to spot the comet, you can search for it in online databases, such as TheSkyLive.com.

Depending on when you look and where in the world you are searching from, you may also be able to spot comets SWAN R2 and 3I/ATLAS at the same time.

A long-tailed comet has been spotted close to the sun, and some astronomers are predicting it could be seen with the naked eye in mid-October — just as another comet is forecast to do the same. It could mean two bright comets will be visible in the night sky at the same time, on the peak night of a meteor shower.

Comet C/2025 R2 (SWAN), or SWAN R2 for short, was discovered on Sept. 12 by NASA's orbiting Solar Dynamics Observatory, whose Solar Wind Anisotropies (SWAN) instrument is used to find comets close to the sun. The previously unknown comet was found in SWAN's images by Vladimir Bezugly, a Ukrainian amateur astronomer, according to Universe Today, and it was initially called SWAN25B. Three days later, the International Astronomical Union's Minor Planet Center classified the object as a comet and renamed it C/2025 R2 (SWAN).

This long-period comet appears to orbit the sun every 22,554 years, according to EarthSky, and its tail is about the same length as five full moons.

Although SWAN R2 is still very close to the sun — passing close to Mars just after dusk, and best seen from the Southern Hemisphere, for now — that's set to change on Oct. 21, when SWAN R2 will be only 0.27 astronomical units (AU) from Earth, according to The Sky Live. That's about one-quarter the distance from Earth to the sun.

At that time, the comet could get as bright as magnitude 4, potentially making it visible to the naked eye in dark skies, even in the Northern Hemisphere. Earth may even pass through debris from the comet around Oct. 4-6, which could potentially cause a unique meteor shower. Even if it doesn't brighten sufficiently to be seen with the unaided eye, the comet should be easily visible through a pair of stargazing binoculars or a good backyard telescope.

This comet has come to light just as another comet is brightening. Discovered in January by the Mount Lemmon Survey in Arizona, Comet C/2025 A6 (Lemmon) will get closest to Earth on Oct. 21 — the same day as SWAN R2's closest approach. Comet Lemmon will be about 0.60 AU from Earth and will be visible in the morning and evening. According to Space.com, Lemmon could also get as bright as magnitude 4, which would make it possible to see with the naked eye in a dark sky.

The best nights to see both comets — if they survive their increasingly close approaches to the sun, which is not guaranteed, and they brighten as predicted — will be Oct. 20-23, when they are closest to Earth. Oct. 21 is the date of the new moon, when night skies will be free of moonlight. Oct. 20-21 is also the peak of the Orionid meteor shower, when about 20 "shooting stars" per hour are expected. You won't want to miss the prospect of two bright comets and meteors in a dark sky.

The last bright comet that was visible to the naked eye was C/2020 F3 (NEOWISE), in summer 2020, although in October 2024, Comet C/2023 A3 (Tsuchinshan-ATLAS) became visible through binoculars during a close approach to Earth.