The first step on the moon was one of humanity's most exciting accomplishments. Now scientists are planning return trips – and dreaming of Mars beyond.

Next year, Nasa's Artemis II mission will send four astronauts to fly around the moon to test the spacecraft before future landings. The following year, two astronauts are expected to explore the surface of the moon for a week as part of Nasa's Artemis III mission.

And finally, the trip to Mars is planned for the 2030s. But there's an invisible threat standing in the way: cosmic rays.

When we look at the night sky, we see stars and nearby planets. If we're lucky enough to live somewhere without light pollution, we might catch meteors sliding across the sky. But cosmic rays – consisting of protons, helium nuclei, heavy ions and electrons – remain hidden. They stream in from exploding stars (galactic cosmic rays) and our very own sun (solar particle events).

They don't discriminate. These particles carry so much energy and move so fast that they can knock electrons off atoms and disrupt molecular structures of any material. That way, they can damage everything in their path, machines and humans alike.

The Earth's magnetic field and atmosphere shield us from most of this danger. But outside Earth's protection, space travellers will be routinely exposed. In deep space, cosmic rays can break DNA strands, disrupt proteins and damage other cellular components, increasing the risk of serious diseases such as cancer.

The research challenge is straightforward: measure how cosmic rays affect living organisms, then design strategies to reduce their damage.

Ideally, scientists would study these effects by sending tissues, organoids (artificially made organ-like structures) or lab animals (such as mice) directly into space. That does happen, but it's expensive and difficult. A more practical approach is to simulate cosmic radiation on Earth using particle accelerators.

Cosmic ray simulators in the US and Germany expose tissues, plants and animals to different components of cosmic rays in sequence. A new international accelerator facility being built in Germany will reach even higher energies, matching levels found in space that have never been tested on living organisms.

But these simulations aren't fully realistic. Many experiments deliver the entire mission dose in a single treatment. This is like using a tsunami to study the effects of rain.

In real space, cosmic rays arrive as a mixture of high-energy particles hitting simultaneously, not one type at a time. My colleagues and I have suggested building a multi-branch accelerator that could fire several tuneable particle beams at once, recreating the mixed radiation of deep space under controlled laboratory conditions. For now, though, this kind of facility exists only as a proposal.

Beyond better testing, we need better protection. Physical shields seem like the obvious first defense. Hydrogen-rich materials such as polyethylene and water-absorbing hydrogels can slow charged particles. Although they are used, or planned to be used, as spacecraft materials, their benefits are limited.

Particularly galactic cosmic rays, the ones that arrive from far exploding stars, are so energetic that they can penetrate through physical shielding. They can even generate secondary radiation that increases exposure. So, effective protection by using solely physical shields remains a major challenge.

Nature's armor

That's why scientists are exploring biological strategies. One approach is to use antioxidants. These molecules can protect DNA from harmful chemicals that are produced when cosmic rays hit living cells.

Supplementing with CDDO-EA, a synthetic antioxidant, reduces cognitive damage caused by simulated cosmic radiation in female mice. In the study, mice exposed to simulated cosmic radiation learned a simple task more slowly compared to unexposed mice. However, mice that received the synthetic antioxidant performed normally despite being exposed to simulated cosmic radiation.

Another approach involves learning from organisms with extraordinary abilities. Hibernating organisms become more resistant to radiation during hibernation. The mechanisms on how hibernation protects from radiation are not fully understood yet. Still, inducing hibernation-like conditions in non-hibernating animals is possible and can make them more radioresistant.

Tardigrades – microscopic creatures also known as water bears – are also extremely radioresistant, especially when dehydrated. Although we can't hibernate or dehydrate astronauts, the strategies these organisms use to protect cellular components might help us preserve other organisms during long space journeys.

Microbes, seeds, simple food sources and even animals that could later become our companions might be kept in a protected state for a while. Under calmer conditions, they could then be brought back to full activity. Therefore, understanding and harnessing these protective mechanisms could prove crucial for future space journeys.

A third strategy focuses on supporting organisms' own stress responses. Stressors on Earth, such as starvation or heat, have driven organisms to evolve cellular defenses that protect DNA and other cellular components. In a recent preprint (a paper that is yet to be peer reviewed), my colleague and I suggest that activating these mechanisms through specific diets or drugs may offer additional protection in space.

Physical shields alone won't be enough. But with biological strategies, more experiments in space and on Earth, and the construction of new dedicated accelerator complexes, humanity is getting closer to making routine space travel a reality. With current speed, we are probably decades away from fully solving cosmic-ray protection. Greater investment in space radiation research could shorten that timeline.

The ultimate goal is to journey beyond Earth's protective bubble without the constant threat of invisible, high-energy particles damaging our bodies and our spacecraft.

New research reveals that jet structures in the sun-facing "anti-tail" of this comet, estimated in some observations to stretch up to 620,000 miles (1 million kilometers), were wobbling every 7 hours and 45 minutes as 3I/ATLAS approached the sun. Of course, comets are famous for their tails and haloes, comprised of gas and dust that is blown from their nucleus as radiation from the sun heats them. However, these tails generally face away from the sun and the influx of solar radiation. A rare anti-tail is a cometary tail that points toward the sun, rather than away from it.

3I/ATLAS is only the third object known to have entered our solar system from around another star. The first was the cigar-shaped space-rock 'Oumuamua, discovered passing through the solar system in Oct. 2017, and the second was the first interstellar comet 2I/Borisov, spotted in our solar system in August 2019. Though rare, scientists have seen comets originating in the solar system display a sun-facing anti-tail before, and wobbling jets have been observed in these anti-tails. However, this is the first time that such an "outgassing" has been observed from an interstellar comet.

"Characterizing jets in 3I thus represents a rare opportunity to investigate the physical behavior of a pristine body formed in another planetary system," the researchers behind this discovery wrote in a paper published on the paper repository site arXiv.

The team discovered the wobbling jets in the coma of 3I/ATLAS after observing the comet across 37 nights between July 2 and Sept. 5, 2025, with the Two-meter Twin Telescope (TTT), a robotic facility located at the Teide Observatory in Tenerife, Canary Islands.

These observations allowed the researchers to track how the comet's coma evolved from a sun-facing fan of dust before August, to a pronounced antisolar tail. They attribute this transformation to the increasing influence of solar radiation on dust with the coma as 3I/ATLAS headed toward a close approach to the sun on Oct. 30, 2025, when it came to within around 130 million miles (210 million km) of our star.

The jet structure appeared within the anti-tail of 3I/ATLAS on 7 nights between Aug. 3 and Aug. 29, and its wobble or precessional motion implied to the team that the icy heart of this interstellar invader is rotating around once every 15 hours and 30 minutes. This is a shorter rotational period for 3I/ATLAS than has previously been estimated.

3I/ATLAS made its closest approach to Earth on Dec.19, coming to within around 168 million miles (270 million kilometers). Since then, the interstellar interloper has been making its way to the outer solar system. Like 'Oumuamua and 2I/Borisov before it, the comet is expected to eventually leave the solar system for good.However, as this research demonstrates, 3I/ATLAS may soon be gone, but thanks to its impact on science, it is unlikely to be forgotten.

Of these comets — the interstellar invader 3I/ATLAS, C/2025 A6 (Lemmon) and C/2025 R2 (SWAN) — not all survived their trial by solar radiation intact, while others drew the attention of a global audience thanks in part to their scientific significance and in some cases, the disinformation that swirled around them.

Join us as we look back at six of the most memorable cometary highlights of 2025, featuring stunning astrophotography, the unexpected advance of an interstellar invader and the dramatic demise of an icy visitor from the Oort Cloud.

5 incredible moments that made 2025 the year of the comet

1. Enter interstellar comet 3I/ATLAS

Comet 3I/ATLAS was discovered on July 1, 2025, by the NASA-funded ATLAS telescope in Rio Hurtado, Chile and was quickly confirmed to be just the third interstellar visitor to our solar system, after 1I'Oumuamua and 2I/Borisov.

Its exotic nature quickly seized the interest of the scientific community and the imagination of the public while simultaneously sending the conspiracy-peddling community into a frenzy, some of whom claimed that 3I/ATLAS was an alien spacecraft that had voyaged to the heliosphere for reasons unknown.

Follow-up observations confirmed 3I/ATLAS to be the brightest and potentially the largest interstellar object discovered to date, measuring up to 3.5 miles (5.6 kilometers) in diameter, based on observations from the Hubble Space Telescope, according to NASA.

2. When the cosmos gives you Lemmon, make astrophotography

If 3I/ATLAS was the most scientifically riveting of the cometary trio, C/2026 A6 (Lemmon) was arguably the most dynamic and photogenic. Comet Lemmon was discovered on Jan. 3 earlier this year and swiftly became a popular target among the astrophotography community, as it brightened from +21.5 to naked eye visibility around its close approach to the sun —known as perihelion — on Nov. 8.

Astrophotographers kept C/2026 A6 (Lemmon) firmly locked in their field of view throughout its journey, capturing each stage of its dramatic evolution. As it approached the sun, the increase in heat radiation caused icy matter in the comet's central nucleus to sublimate into gas, dragging dust particles with it.

The resulting cloud of cometary debris was then snatched up by the charged particles pouring out from the sun — called the solar wind — giving rise to a spectacular tail.

Astronomer Gianluca Masi captured a rare shot of the cosmic wanderer, when a glowing meteor tail in Earth's upper atmosphere appeared to wrap itself around Comet Lemmon's distant tail as it passed through the constellation Serpens on Oct. 24, creating a "a pure perspective miracle".

3. Comet SWAN dives through the Eagle Nebula

While Comet Lemmon's complex tail snagged the attention of astrophotographers worldwide, others took aim at the solar system wanderer C/2025 R2 (SWAN), which put on a magnificent show on Oct. 17, as it passed in front of the Eagle Nebula in the constellation Serpens.

Daniele Gasparri captured a striking view of C/2025 R2 (SWAN)'s vivid green coma as it hung in the pristine skies above the Atacama Desert in Chile, with the vast emission nebula serving as a jaw-dropping backdrop for the cometary body.

The pillars of creation, vast columns of interstellar dust and gas shaped by the radiation of nearby stars and made famous by the Hubble Space Telescope, can be seen nestled in the glowing heart of the vast nebula, to the left of the comet's glowing central nucleus.

4. Comet 3I/ATLAS reaches perihelion

Oct. 30 marked the climax of interstellar traveller 3I/ATLAS's headlong charge into the inner solar system, as it made its closest approach to the sun, passing 125 million miles (202 million km) from our parent star at the point of perihelion.

The event occurred just as 3I/ATLAS flew behind the sun from the perspective of Earth, robbing some of humanity's most powerful observatories of the chance to analyze the comet's chemical composition as it reached a peak of activity. Thankfully, perihelion was observed from elsewhere in the solar system by a flotilla of spacecraft orbiting Mars and travelling through interplanetary space.

3I/ATLAS finally emerged intact from behind the glare of the sun to become visible to Earthbound astronomers and skywatchers in early November, though it remained too dim to spot with the naked eye.

NASA subsequently held a press conference on Nov. 19 following the re-opening of the federal government, where it revealed several new images of the interstellar invader that documented its glowing central nucleus, sun-facing jet and growing tail. Conspiracy theorists were left somewhat broken-hearted by NASA Associate Administrator Amit Kshatriya, who noted, "It looks and behaves like a comet, and all evidence points to it being a comet", as opposed to the technologically advanced spaceship suggested by others.

5. K1 ATLAS breakup

One of the most dramatic cometary moments of 2025 occurred on the night of Nov. 11, when astronomers tracked the solar system comet C/2025 K1 (ATLAS) as its central nucleus broke into three massive pieces, following its close pass of the sun on Oct. 8.

The comet may have crumbled during its first visit to the inner solar system from the shell of icy material which surrounds its outer edge, known as the Oort Cloud.

The increase in heat radiation experienced during perihelion may have created a violent and sudden outflow of material from the nucleus, which could have undermined its structure, leading to the fracturing seen on Nov. 11, according to Elena Mazzotta Epifani of the Italian National Institute for Astrophysics.

Editor's Note: If you would like to share your astrophotography with Space.com's readers, then please send your photo(s), comments, and your name and location to spacephotos@space.com.

If you want better views of the night sky, we have expert-led guides to the best telescopes, binoculars and cameras to view and image the heavens.

Wednesday, Dec. 24: A crescent moon

If you’re looking for the quiet wonder of Christmas Eve, turn your gaze to the southwest sky as it gets dark. There, nicely illuminated, though not yet bright, will be a waxing crescent moon. A fifth of what you’ll see will be its day-side; the other four-fifths — its night-side — will be gently lit by sunlight reflected from our planet — Earthshine. If you have binoculars or a small telescope, point them at the terminator, that line between day and night, to see long shadows and craters in relief. Naked eye observers should look to the left of the moon for Fomalhaut (below) and Saturn (above).

Also read: How to choose binoculars for astronomy and skywatching

Thursday, Dec. 25: Jupiter as the ‘Star of Bethlehem’

Christmas Day needs a “Christmas Star,” and what better candidate than Jupiter, which tonight shines at magnitude -2.5 in the constellation Gemini. Look to the east anytime after dark, and you’ll see the giant planet close to “the twins” of Gemini — the stars Castor and Pollux — as it shines brighter than anything else in the night sky, save for the moon. Now is the ideal time to observe Jupiter, which reaches its annual opposition — when Earth is between it and the sun — on Jan. 10, 2026. Typically, an outer planet is at its best for a couple of weeks either side of its opposition; any small telescope should allow a glimpse of its cloud bands, with a 6-inch telescope able to see its Great Red Spot (when it’s facing Earth).

Also read: Best telescopes for seeing planets in 2025

Friday, Dec. 26: Saturn and the moon in conjunction

Get out of the house as soon as it gets dark on Boxing Day for one of the most beautiful sights of the week, a crescent moon and the planet Saturn. Now a 41%-illuminated waxing crescent, the moon will appear to curl around the sixth planet, and the two will be separated by a mere four degrees. That’s a bit less than the width of your three middle fingers held at arm’s length against the sky. Saturn will appear as a steady, golden point of light, though you’ll need a small telescope to glimpse its ring pattern.

Also read: Best beginner telescopes

Saturday, Dec. 27: Lava plains on the first quarter moon

It’s half-day, half-night on the moon tonight as it reaches its first quarter phase in the southern sky. For amateur astronomers, it’s a bittersweet moment — the next week will see the moon grow in brightness as it waxes towards full, making faint star clusters, galaxies and nebulae harder to see. However, a “half-moon” is one of the best times to explore the lunar surface if you have a pair of binoculars. The line between light and dark — the terminator — cuts right down the middle tonight, causing long shadows to stretch across the lunar plains, making every bump and ridge stand out like a black-and-white relief map. The dark regions you see on the right-hand side of the moon are called maria, Latin for seas, but these are no oceans. These are vast plains of lava that solidified billions of years ago in the aftermath of asteroids slamming into the young moon.

Also read: Best telescopes for deep space

Sunday, Dec. 28: Rosette Nebula

If you have a small telescope, find the ruddy star Betelgeuse in Orion and range left to the quiet constellation Monoceros, the Unicorn, home to an open cluster of stars about 5,000 light-years from the solar system. The Rosette Nebula (also called NGC 2244 and Caldwell 49) is an emission nebula — a cloud of gas that emits its own light because it's being energized by radiation from nearby stars — and a star-forming region. A flower-like shape, it’s visible through a pair of 10x50 or 15x70 binoculars in very dark skies, or easily in a small telescope. According to In-The-Sky.org, the Rosette Nebula is now well placed, reaching its highest in the sky around midnight local time. If you have trouble finding it, draw an imaginary line from Betelgeuse in Orion toward Procyon in Canis Minor. About one-third of the way along that line, just south of it, is the region of the Rosette Nebula. It’s about three times the diameter of the full moon.

Also read: Best smart telescopes

Monday, Dec. 29: Orion’s Snake

Orion’s Belt — the famous trio of stars in Orion, sometimes nicknamed the “Belt of Orion” or the “Three Kings” — is an icon of the late-December night sky. Look east tonight for Alnitak, Alnilam and Mintaka, strung out in a neat row, rising into the eastern sky as soon as it gets dark. Put a pair of binoculars on them, and you’ll discover great riches. Just to the right is, of course, the Great Nebula in Orion (also called M42). Lesser known is a delicate chain of faint stars curving across the field of view in a subtle “S” shape, running from just above Mintaka to just below Alnilam. It’s very clear through binoculars.

Also read: Best binoculars this holiday season

Tuesday, Dec. 30: Jupiter’s Galilean moons

Jupiter getting close to its opposition means more than it merely becoming brighter. Since it’s closest to Earth (about four Earth-sun distances), its disk is bigger in the sky, and it’s visible all night. Jupiter’s opposition is also the best time to see its largest four moons — Io, Callisto, Ganymede and Europa. These moons, called Galilean moons because they were first spotted by Italian astronomer Galileo Galilei in 1610, can be seen in any small telescope as pinpricks of light, but also in binoculars.

Also read: Best telescopes for deep space

Wednesday, Dec. 31: Pleiades and the moon in conjunction

As your final stargazing act of the year, step outside as it gets dark and find Orion’s Belt, that iconic trio of bright stars, rising from the eastern horizon like an arrow. Trace Orion’s Belt upward, and high above it, you’ll find the moon, now 92% illuminated. Just above the moon will be the Pleiades — also known as the Seven Sisters and M45 — one of the closest open clusters of stars to the solar system. The bright moonlight may make it hard to see the Pleiades with the naked eye, but any pair of binoculars should bring them into view.

Also read: How to choose binoculars for astronomy and skywatching

Astronomers study nebulae not just for their beauty, but for the secrets they hold about stellar evolution and the chemical makeup of galaxies. For the rest of us, they're a reminder that the cosmos is both mysterious and magnificent, with colors and shapes that look more like art than science.

But how well do you really know your nebulae?Matching names to these celestial wonders is trickier than it sounds.

Whether you're a seasoned stargazer or just curious about the night sky, this is your chance to prove you’re ready for a cosmic pop quiz.

See how well you score below!

Antarctica is one of the best places on Earth to fly these missions. NASA's annual Antarctic Long-Duration Balloon campaign operates from a site on the Ross Ice Shelf near the U.S. National Science Foundation's McMurdo Station.

In the austral summer, near-constant sunlight and stable polar wind patterns can support extended-duration flights, allowing payloads to gather data for days to weeks as they circle the continent.

What is it?

NASA's first scientific balloon flight of the 2025 Antarctica Balloon Campaign lifted off from the agency's Antarctic facility at 5:30 a.m. NZST Tuesday, Dec. 16 (11:30 a.m. Monday, Dec. 15 U.S. Eastern Time) and reached float altitude carrying an experiment called GAPS — the General AntiParticle Spectrometer.

Once airborne, NASA reported the balloon was floating at about 120,000 feet (36 kilometers) above Earth's surface.

Where is it?

This image was taken near Antarctica Rubilotta where the balloon launched.

Why is it amazing?

GAPS' goal is to look for rare particles from space called antimatter nuclei, specifically antideuterons, antiprotons, and antihelium. Scientists have never clearly seen antideuterons or antihelium in cosmic rays before. If GAPS detects even a single antideuteron, it could give us important clues about the mysterious substance known as dark matter, which makes up most of the universe but is invisible to us. GAPS uses a time-of-flight system to measure how fast the particles are moving and a tracker system to record the interaction.

Now that the balloon has been launched, the GAPS project is underway, hopefully revealing more about the universe around us in due course.

Want to learn more?

You can learn more about antimatter and dark matter.

NASA's SPHEREx observatory has completed its first map of the entire sky over Earth, and it is incredible.

Beyond its aesthetic value, the map and the rest of the data collected by SPHEREx, which launched in March this year, will help astronomers answer some of the biggest cosmic questions. Among these are: what happened during the first billionth of a trillionth of a trillionth of a second after the Big Bang, and how this has influenced the 3D distribution of hundreds of millions of galaxies in our universe?

Scientists will also use SPHEREx data to investigate the evolution of galaxies over the 13.8 billion-year history of the cosmos. This could include determining how the key elements needed for life were disbursed.

"It's incredible how much information SPHEREx has collected in just six months — information that will be especially valuable when used alongside our other missions’ data to better understand our universe," Shawn Domagal-Goldman, director of the Astrophysics Division at NASA Headquarters in Washington, said in a statement. "We essentially have 102 new maps of the entire sky, each one in a different wavelength and containing unique information about the objects it sees.

"I think every astronomer is going to find something of value here, as NASA's missions enable the world to answer fundamental questions about how the universe got its start, and how it changed to eventually create a home for us in it."

SPHEREx, which stands for the "Spectro-Photometer for the History of the Universe, Epoch of Reionization, and Ices Explorer," orbits Earth just under 15 times per day from the North Pole to the South Pole.

As it does, this conical spacecraft captures 3,600 images throughout each of its orbits, with the orbit of Earth around the sun shifting the space observatory's field of view.

Beginning operations in May, it took SPHEREx until this month to complete its first map of the entire sky over our planet. During its primary mission lasting two years, the spacecraft is expected to complete another three all-sky scans. This data will be merged with the existing map to create an even more detailed picture of the sky over Earth.

"SPHEREx is a mid-sized astrophysics mission delivering big science," JPL Director Dave Gallagher said. "It's a phenomenal example of how we turn bold ideas into reality, and in doing so, unlock enormous potential for discovery."

Our sun is about halfway through its life, which means Earth is as well. After a star exhausts its hydrogen nuclear fuel, its diameter expands more than a hundredfold, engulfing any unlucky planets in close orbits. That day is at least 5 billion years off for our solar system, but scientists have spotted a possible preview of our world’s fate.

Using data from the TESS (Transiting Exoplanet Survey Satellite) observatory, astronomers Edward Bryant of the University of Warwick and Vincent Van Eylen of University College London compared systems with stars in the main sequence of their lifetimes—fusing hydrogen, like the sun—with post–main sequence stars closer to the end of their lifetimes, both with and without planets.

"We saw that these planets are getting rarer [as stars age]," Bryant said. In other words, planets are disappearing as their host stars grow old. The comparison between planetary systems with younger and older stars makes it clear that the discrepancy does not stem from the fact that the planets weren't there in the first place: Elderly stars just get hungry.

"We're fairly confident that it's not due to a formation effect," Bryant explained, "because we don't see large differences in the mass and [chemical composition] of these stars versus the main sequence star populations."

Complete engulfment isn't the only way giant stars can obliterate planets. As they grow, giant stars also exert increasingly larger tidal forces on their satellites that make their orbits decay, strip them of their atmospheres, and can even tear them apart completely. The orbital decay aspect is potentially measurable, and this is the effect Bryant and Van Eylen considered in their model for how planets die.

"We're looking at how common planets are around different types of stars, with number of planets per star," Bryant said. Bryant and Van Eylen identified 456,941 post–main sequence stars in TESS data and, from those, found 130 planets and planet candidates with close-in orbits. "The fraction [of stars with planets] gets significantly lower for all stars and shorter-period planets, which is very much in line with the predictions from the theory that tidal decay becomes very strong as these stars evolved."

Astronomers use TESS to find exoplanets by looking for the diminishment in light as they pass in front of their host stars, a miniature eclipse known as a transit. As with any exoplanet detection method, transits are best suited to large, Jupiter-sized planets in relatively small orbits lasting less than half of an Earth year, sometimes much less. So these solar systems aren't much like ours in that respect. Studying planets orbiting post–main sequence stars poses additional challenges.

"If you have the same size planet but a larger star, you have a smaller transit," Bryant said. "That makes it harder to find these systems because the signals are much shallower."

However, though the stars in the sample data have a much greater surface area, they are comparable in mass to the sun, and that’s what matters most, the researchers said. A star with the same mass as the sun will go through the same life stages and die the same way, and that similarity is what helps reveal our solar system's future.

"The processes that take place once the star evolves [past main sequence] can tell us about the interaction between planets and host star," said Sabine Reffert, an astronomer at Universität Heidelberg who was not involved in the study. "We had never seen this kind of difference in planet occurrence rates between [main sequence] and giants before because we did not have enough planets to statistically see this difference before. It's a very promising approach."

Planets: Part of a balanced stellar breakfast

Exoplanet science is one of astronomy's biggest successes in the modern era: Since the first exoplanet discovery 30 years ago, astronomers have confirmed more than 6,000 planets and identified many more candidates for follow-up observations. At the same time, the work can be challenging when it comes to planets orbiting post–main sequence stars.

One tricky aspect of this work is related to the age of the stars, which formed billions of years before our sun. Older stars have a lower abundance of chemical elements heavier than helium, a measure astronomers call "metallicity." Observations have found a correlation between high metallicity and exoplanet abundance.

"A small difference in metallicity…could potentially double the occurrence rate," Reffert said, stressing that the general conclusions from the article would hold but the details would need to be refined with better metallicity data.

Future observations to measure metallicity using spectra, along with star and planet mass, would improve the model. In addition, the European Space Agency's Plato Mission, slated to launch in December 2026, will add more sensitive data to the TESS observations.

Earth's fiery fate is a long way in the future, but researchers have made a big step toward understanding how dying stars might eat their planets. With more TESS and Plato data, we might even glimpse the minute orbital changes that indicate a planet spiraling to its doom—a grim end for that world but a wonderful discovery for our understanding of the coevolution of planets and their host stars.

At the heart of the discovery is a signal from a so-called Luminous Fast Blue Optical Transient (LFBOT), designated AT 2024wpp, first spotted in 2024. The signal revealed to a team of scientists that LFBOTs are the result of extreme Tidal Disruption Events (TDEs), in which a black hole with a mass up to 100 times that of the sun, completely shreds a companion star in just a matter of days.

Just over a dozen LFBOTs have been discovered to date, and their cause has puzzled astronomers for around a decade. Now off the hook, previous suspects have included strange types of exploding stars (supernovas) and interstellar gas being gobbled up by black holes.

LFBOTs are so named because they are incredibly bright, visible at distances up to billions of light-years, shining high-energy light ranging from the blue end of the optical region of the electromagnetic spectrum through ultraviolet and X-ray wavelengths, and only last a few days. While the first LFBOT was spotted in 2014, it wasn't until four years later that astronomers caught one in enough detail to properly analyse.

This 2018 event was designated AT 2018cow, leading to its nickname Tthe Cow," with LFBOT that followed also getting zoological nicknames: the Koala (ZTF18abvkwla), the Tasmanian devil (AT 2022tsd), and the Finch (AT 2023fhn). AT 2024wpp doesn't have its nickname yet, but the Wasp is a fairly good bet.

No ordinary Tidal Disruption Event

When researchers assessed AT 2024wpp, they found that it emitted around 100 times as much energy as the average supernova, seemingly ruling exploding stars out as a potential cause. In fact, to produce this much energy, an exploding star would have to convert around 10% of its mass instantly into energy via Einstein's energy/mass relation E=mc^2 over the course of just a few weeks.

The team's observations, using the Gemini South observatory, revealed an excess of near-infrared light from the source of AT 2024wpp, something only seen before around AT 2018cow, which is not associated with normal supernovas.

"The sheer amount of radiated energy from these bursts is so large that you can't power them with a core collapse stellar explosion — or any other type of normal stellar explosion," team member Natalie LeBaron of the University of California, Berkeley said in a statement. "The main message from AT 2024wpp is that the model that we started off with is wrong. It's definitely not just an exploding star."

TDEs are fairly common occurrences across the cosmos, happening when stars venture too close to ravenous black holes and are "spaghettified," creating a noodle of stellar pasta that wraps around the culprit black hole like linguine around a fork. However, not all TDEs create an LFBOT, so the question is: what is so special about these particular TDEs?

The team theorizes that in the case of the TDE behind AT 2024wpp, the black hole has been parasitically feeding from a companion star for a long time. This resulted in the black hole being completely encased in a spherical shell of material. However, this shell is too far away from the black hole to be devoured by it.

However, the companion star eventually spirals close enough to the black hole to be spaghettified by its immense gravitational influence. This results in new stellar material slamming into the matter that the black hole has been stealing throughout the system's history. This generated X-ray, ultraviolet, and optical blue light, seen as AT 2024wpp. Radio waves are generated when material from around the black hole is channelled to its poles, where it is accelerated to around 40% the speed of light and blasted out as jets. The team estimated that the star shredded in the event that launched AT 2024wpp has a mass around 10 times that of the sun and was a highly evolved star nearing the end of its life, called a Wolf-Rayet star, explaining the weak hydrogen emission seen around AT 2024wpp. Stars like this are thought to be common in actively star-forming galaxies like the one 1.1 billion light-years away from which AT 2024wpp erupted.

The team's research has been accepted for publication in The Astrophysical Journal Letters and is currently available as a pre-peer-review paper on arXiv.

Astronomers may have discovered the first example of an explosive cosmic event called a "superkilonova," in the form of a gravitational wave signal detected on Aug. 18, 2025.

A kilonova describes the explosion generated when two neutron stars — stellar remnants left behind when massive stars die — slam together, creating the only environment in the known universe violent enough to forge elements heavier than iron, such as the gold and silver in your jewelry box.

Superkilonovas differ because they begin with the supernova explosion that marks the death of a star and the birth of two neutron stars, not one. These extreme dead stars then spiral together and merge, creating a scream of gravitational waves and a blast of electromagnetic radiation.

Thus far, astronomers have made the unambiguous detection of just one kilonova when, in 2017, the Laser Interferometer Gravitational-wave Observatory (LIGO) and its European partner, Virgo, detected the gravitational wave signal known as GW170817. This event was then seen in electromagnetic radiation by a host of space and ground-based telescopes, instruments of "traditional astronomy."

Thus, scientists were already excited when LIGO and Virgo "heard" a signal designated AT2025ulz, which seemed to be the second detection of a neutron star merger. However, the situation soon seemed to take on added complexity. After the detection, an alert was sent out to astronomers across the globe, with the Zwicky Transient Facility (ZTF), a survey camera at Palomar Observatory in California, the first to spot a rapidly fading red object 1.3 billion light-years away. That's around the same location as the source of the gravitational waves.

"At first, for about three days, the eruption looked just like the first kilonova in 2017," study lead author Mansi Kasliwal, an astronomy professor at the California Institute of Technology, said in a statement. "Everybody was intensely trying to observe and analyze it, but then it started to look more like a supernova, and some astronomers lost interest. Not us."

Kasliwal and colleagues began to realize that what this event seemed to be was a kilonova stemming from a supernova explosion that's obscuring the view of astronomers. That would make AT2025ulz the result of a superkilonova, a type of powerful cosmic event long hypothesized but never before detected.

A very strange signal

Following the detection of gravitational waves from this event, further investigation by several other telescopes, including the W. M. Keck Observatory in Hawai'i and the Fraunhofer telescope in Germany, revealed that the burst of light associated with AT2025ulz faded rapidly, leaving a glow in red wavelengths of light.

That was exactly the same pattern the electromagnetic signal associated with GW170817 had followed in 2017. This red glow is the result of heavy elements like gold around the kilonova blocking short-wavelength blue light but allowing longer-wavelength red light through. So far, so kilonova.

However, days after the explosion, AT2025ulz began to brighten and turn blue with evidence of hydrogen emissions appearing. These are characteristics of supernovas, not kilonovas. The problem is, while supernovas do generate gravitational waves, unlike a kilonova, a supernova 1.3 billion light-years away shouldn't be able to generate gravitational waves strong enough to be detected by LIGO.

While several astronomers were ready to conclude that AT2025ulz was just a run-of-the-mill supernova (if there is such a thing as a run-of-the-mill exploding star!), Kasliwal and team had noticed clues that indicated this was a very special event indeed. Specifically, the gravitational wave signal indicated that one of the neutron stars involved in the merger was less massive than the sun. Neutron stars are generally between 1.2 and two times the mass of the sun. This implied to the team that one or two small neutron stars might have merged to produce a kilonova.

Not all neutron stars are created equal

When stars with around 10 times the mass of the sun exhaust their fuel for nuclear fusion, their cores collapse under their own gravity, sending shockwaves rippling out that trigger a supernova explosion and blow away the outer layers of that star.

The result is a stellar core with a mass between 1.2 and 2 times the mass of the sun crammed into a diameter of around 12 miles (20 kilometers), packed with the densest matter in the known universe. However, scientists have theorized two ways in which some neutron stars could be created that are smaller than 1.2 solar masses.

The first scenario of undermassive neutron star creation suggests that, if a star that is spinning rapidly undergoes a supernova explosion, it could split into two sub-solar-mass neutron stars, a process called fission. In the second scenario, a rapidly spinning star undergoes a supernova explosion, but the resulting neutron star is surrounded by a disk of material that then gathers to form another neutron star, in a way similar to how planets form around infant stars.

In both cases, these neutron stars emit gravitational waves as they swirl around each other, carrying angular momentum away from the system. This causes the neutron stars to spiral together, collide and merge, churning out heavy elements. This would result in the red glow seen by the telescopes chasing AT2025ulz.However, the view of the kilonova was eventually obscured by the expanding shell of debris ejected by the supernova as it created the twin neutron stars.

"The only way theorists have come up with to birth sub-solar neutron stars is during the collapse of a very rapidly spinning star," team member Brian Metzger of Columbia University said in the same statement. "If these 'forbidden' stars pair up and merge by emitting gravitational waves, it is possible that such an event would be accompanied by a supernova rather than be seen as a bare kilonova."

Unfortunately, there currently isn't enough data to confirm that this is a superkilonova. The only way to do this is to gather more information.

"Future kilonovae events may not look like GW170817 and may be mistaken for supernovae," Kasliwal said. "We can look for new possibilities in data like this from ZTF as well as the Vera Rubin Observatory, and upcoming projects such as NASA's Nancy Roman Space Telescope, NASA's UVEX, Caltech's Deep Synoptic Array-2000, and Caltech's Cryoscope in the Antarctic. We do not know with certainty that we found a superkilonova, but the event is nevertheless eye-opening."

The team's research was published Dec. 15 in The Astrophysical Journal Letters.

Using the James Webb Space Telescope (JWST), astronomers watched as the Virgil transformed before their eyes, revealing its monstrous nature and a supermassive black hole at its heart that is feeding on matter at an incredible rate. The black hole now appears far too massive for its host galaxy to support, placing it in a rare category of "overmassive" black holes that challenge leading models of how galaxies first formed and of how they nurture supermassive black holes at their cores, growing in lock step.

"[The] JWST has shown that our ideas about how supermassive black holes formed were pretty much completely wrong," co-team leader George Rieke, of the University of Arizona, said in a statement. "It looks like the black holes actually get ahead of the galaxies in a lot of cases. That's the most exciting thing about what we're finding."

Virgil belongs to a mysterious class of objects known as "Little Red Dots," galaxies that JWST has been discovering in large numbers around 600 million years after the Big Bang. These objects seem to disappear by the time the universe reaches an age of around 2 billion years. Quite what these galaxies are is a mystery, but the more puzzling question is why they disappeared around 1.6 billion years after they reached their largest population.

The study of Virgil could solve this twin dilemma by suggesting what form Little Red Dots may have transformed into, allowing us to identify their descendants in the modern universe.

The research also suggests that some terrifying cosmic monsters may be out in the universe, hiding in plain sight.

An infrared monster

Light comes in multiple wavelengths, which astronomers often use to reveal different characteristics about the same objects. The true nature of Virgil was only revealed when astronomers studied this galaxy in infrared light, invisible to the human eye, using the JWST's Mid-infrared Instrument (MIRI).

"Virgil has two personalities," Rieke explained. "The UV and optical show its 'good' side – a typical young galaxy quietly forming stars. But when MIRI data are added, Virgil transforms into the host of a heavily obscured supermassive black hole pouring out immense quantities of energy."

This violent side of Virgil had remained hidden in other wavelengths of light because its heart, where the ravenous supermassive black hole dwells, is shrouded in thick clouds of dust. This dust is very good at absorbing ultraviolet and visible light, but infrared light is able to give it the slip. That means viewing Virgil in infrared gives a more complete picture of what is happening at its core.

"MIRI basically lets us observe beyond what UV and optical wavelengths allow us to detect," team co-leader Pierluigi Rinaldi of the Space Telescope Science Institute said. "It's easy to observe stars because they light up and catch our attention. But there's something more than just stars, something that only MIRI can unveil."

The research may have wider implications for astronomers, suggesting there could be a whole population of dust-obscured supermassive black hole monsters out in the cosmos, which may have played a significant early role in the evolution of the universe.

As of yet, scientists aren't aware of any other cosmic monsters like Virgil roaming the early universe, but that could be because the way we study the cosmos allows them to fool us with their mild-mannered alter egos.

"Are we simply blind to its siblings because equally deep MIRI data have not yet been obtained over larger regions of the sky?" Rinaldi said. "JWST will have a fascinating tale to tell as it slowly strips away the disguises into a common narrative."

The team's research was published on Dec. 8 in the journal Nature Astronomy.

Following this close approach and the opportunity it offers to investigate this interloper from beyond the solar system, 3I/ATLAS will begin to move back out to the outer regions of the solar system, before leaving altogether to continue its voyage through the Milky Way.

3I/ATLAS is just the third body discovered passing through the solar system from interstellar space, its predecessors being 1I/'Oumuamua in 2017 and comet 2I/Borisov in 2019. As such, 3I/ATLAS has been offering scientists the unique opportunity to study the raw materials that came together to form comets, asteroids, and planets orbiting stars other than the sun.

First spotted by NASA's Asteroid Terrestrial-impact Last Alert System (ATLAS) on July 1, 2025, with its trajectory indicating its origin lies elsewhere in the Milky Way.

In fact, its path through space suggests that this interstellar comet comes from a region of our galaxy that is much older than the 4.6 billion-year-old solar system.

The water-rich comet seems to originate from the Milky Way's "thick disk" of stars, rather than the thin stellar disk of which the sun is a member. The thick disk formed earlier than the thin disk, meaning 3I/ATLAS could be up to 7 billion years old.

"All non-interstellar comets, such as Halley's comet, formed at the same time as our solar system, so they are up to 4.5 billion years old," University of Oxford astronomer Matthew Hopkins said in a statement back in July. "But interstellar visitors have the potential to be far older, and of those known about so far, our statistical method suggests that 3I/ATLAS is very likely to be the oldest comet we have ever seen."

During its time within the solar system, 3I/ATLAS has continued to surprise astronomers. As it began to make its closest approach to the sun, or its perihelion, on Oct. 29, the comet brightened more than scientists had expected.

Comets tend to brighten as they approach our star due to solar radiation heating their icy cores and causing solid ice to transform straight into vapor, which erupts from the comet, growing its halo or "coma" and its characteristic glowing tail.

Quite why 3I/ATLAS brightened more than expected as observed by STEREO-A and STEREO-B, the twin spacecraft that make up Solar Terrestrial Relations Observatory (STEREO), the sun observing Solar and Heliospheric Observatory (SOHO), and the weather satellite GOES-19, is still unknown.

"The reason for 3I’s rapid brightening, which far exceeds the brightening rate of most Oort cloud comets at similar r [radial distance], remains unclear," the scientists behind the research, Qicheng Zhang of Lowell Observatory in Flagstaff, Arizona, and Karl Battams, an astrophysicist at the Naval Research Laboratory (NRL) in Washington DC, wrote in a paper discussing the observation published on the research repository site arXiv.

Though 3I/ATLAS is now in the final stage of its occupation of the solar system, the data collected from it will likely inform scientists for some time to come, continuing to paint a more intricate picture of the Milky Way beyond the solar system.

Using NASA’s Eyes on the Solar System interactive app, you can track comet 3I/ATLAS through the solar system and see where it’s headed next.

Interstellar comet 3I/ATLAS was discovered on July 1, 2025, by the NASA-funded ATLAS survey (Asteroid Terrestrial-impact Last Alert System) in Chile, a network of telescopes that scans the entire sky multiple times each night looking for moving objects that might pose a threat to Earth. Within hours, astronomers around the world were thrilled by the discovery: the object appeared to be the third-known interstellar object to pass through our solar system, behind 1I/'Oumuamua in 2017 and 2I/Borisov in 2019.

Such visitors offer astronomers a rare opportunity to study objects that may be unlike anything found in our own cosmic neck of the woods. But within months, observations from some of Earth's most powerful telescopes as well as multiple spacecraft and observatories in orbit revealed 3I/ATLAS to in fact be much like comets from our own solar system: it appears to have an icy nucleus surrounded by a coma, a bright cloud of gas and dust that sublimates away from the nucleus as the comet approaches the sun and warms up.

Nevertheless, in what may be indicative of the post-truth age and influencer-dominated media landscape we now live in, a feeding frenzy of sensationalism and misinformation sprang up around the comet throughout the latter half of 2025. Claims that 3I/ATLAS might be an alien spacecraft or some form of extraterrestrial probe spread rapidly throughout social media within weeks of its discovery.

Cable news channels caught on. Kim Kardashian published a viral request on X imploring acting NASA administrator Sean Duffy to spill the "tea" on the object. Even members of the U.S. Congress got interested, writing letters to implore NASA to release whatever data it may have on the comet.

How, or why, did this interstellar comet generate such mainstream interest and capture the public imagination throughout 2025? Where did all of the sensational claims come from?

"It all came during the shutdown"

For one, it came down to timing.

Qicheng Zhang, a postdoctoral fellow at the Lowell Observatory in Arizona and author of a study of the comet's brightness as it approached the sun earlier this year, said that because 3I/ATLAS was discovered months before its closest approaches to the sun and Earth (unlike the previous two interstellar objects), there was much more of an opportunity for misinformation to spread.

"That seems to have given it a whole lot of extra time for conspiracy theorists to run wild and drum up attention before their unsubstantiated predictions are disproven to the extent they can ever be and people lose interest," Zhang told Space.com.

Another aspect of the timing of the comet's discovery centered on the fact that the U.S. government was shut down from Oct. 1 to Nov. 12 as Congress deliberated over funding appropriations for the 2026 fiscal year. During that time, many NASA operations were paused, including most public affairs agencies that would normally issue press releases and answer questions from the media and the public.

But during that time, the comet was also racing through the solar system. On Oct. 2, NASA's Mars Reconnaissance Orbiter took images of 3I/ATLAS with its HiRISE camera, which, given the instrument's resolution, were thought to be the best opportunity astronomers had to nail down an estimate of the comet's size.

In the vacuum of any official information from NASA, unofficial theories flourished, particularly ones that accused the space agency of using the shutdown to hide the "true" nature of the comet, said Larry Denneau of the University of Hawaii, who discovered 3I/ATLAS.

"Unfortunately, it all came during the shutdown," Denneau told Space.com. "And so that created its own complications, because the folks out there, who, you know, are conspiracy bent, thought NASA was trying to hide something."

In fact, when asked about why the comet became such a mainstream topic throughout 2025, most of the sources Space.com spoke to had one singular answer: the Frank B. Baird, Jr. Professor of Science at Harvard University, Avi Loeb, who served as the chair of Harvard's astronomy department from 2011 to 2020.

"The public laps it up"

In July, just weeks after the comet's discovery, Loeb published a non-peer-reviewed paper on the open source repository arXiv, arguing that the comet's characteristics suggest it might actually be alien technology. Loeb later wrote that images of 3I/ATLAS were "held hostage for bureaucratic reasons at NASA" during the shutdown.

The claims spread like wildfire, and within weeks, the comet was dominating headlines and social media feeds. But many astronomers were baffled by the attention 3I/ATLAS was receiving.

"It doesn't help that we have a Harvard professor who's out there, you know, saying that this thing could be an alien spacecraft or this doing all of this weird stuff," Denneau told Space.com. "That's a whole thing in itself. Why is Avi Loeb doing that? It's kind of a mystery to some of us in the field," Denneau added.

Mick West, a science writer who has published books on how to debunk sensational claims, echoed the comet's discoverer. "It's because of Avi Loeb," West told Space.com. "His unremitting push, combined with the gravitas of his Harvard professorship, makes it an easy sensational story for the media. He has many technical critics who point out (with the math) that it's almost certainly just a comet.

"But that's boring, so the media goes with 'Harvard astrophysicist says alien probe' and the public laps it up."

Space.com reached out to Loeb to ask why he thought the comet captured so much public interest throughout the year.

"My explanation for the viral interest in 3I/ATLAS involves its anomalies, as listed in my essay," Loeb said via email. "My essays received more than 5 million views over the month of November, and my interview on the Joe Rogan Experience received more than 7 million views for the same reason."

Loeb previously wrote that "seeking scientific data is key to learning the truth" in a blog post criticizing NASA for not releasing its data on 3I/ATLAS during the government shutdown. "By staying curious and humble while collecting clues in this detective story, science brings us together. When egos get in the way, politics and social media set us apart."

"Not too much is unusual there"

As more imagery and observations of 3I/ATLAS continue to be made, scientists aren't focused on these anomalies, but instead say the comet appears to be just that: a normal comet.

"You kind of know the signatures that you're looking for; we were quick to be able to say, 'Yep, it definitely behaves like a comet,'" Nicky Fox, associate administrator of NASA's Science Mission Directorate, said during a Nov. 19 press briefing during which the agency released imagery of 3I/ATLAS. "We certainly haven't seen any technosignatures or anything from it that would lead us to believe it was anything other than a comet."

Other astronomers have said the same. "We can see how much of each particular gas the comet is emitting and compare it to the gas coming out of solar system comets," Zhang said in a Lowell Observatory statement this month. "And so far, those ratios fall within the fairly typical range that we're seeing for solar system comets. So, not too much is unusual there."

Likewise, a new study published in Research Notes of the AAS based on observations by two different interplanetary spacecraft, NASA's Psyche spacecraft and Europe's Mars Trace Gas Orbiter, was able to calculate the non-gravitational acceleration 3I/ATLAS exhibited as it approached the sun caused by gases escaping its frozen shell. It found that 3I/ATLAS behaves as scientists expect a comet should.

"The results are pretty typical of ordinary comets, and certainly not record-breaking," lead author T. Marshall Eubanks told SpaceWeather.

But in a blog post in November 2025, Loeb criticized the "violent insistence of comet experts" that argued the acceleration was caused by this ordinary outgassing, "rather than thrusters on a spacecraft."

"Always an uphill battle"

The mainstream interest in 3I/ATLAS appears to have waned, but Earth-based telescopes and space-based observatories continue to study the comet.

Scientists working with the Gemini North telescope in Hawaii captured new images of the comet just after its close pass with the sun in late November.

Two European X-ray observatories, XMM-Newton and XRISM (a joint project with the Japanese space agency JAXA), recently captured images of the comet, revealing X-rays streaming out for nearly 250,000 miles (400,000 kilometers) around 3I/ATLAS's nucleus.

But as more data continues to be collected about the comet, it's unlikely these observations will make the types of headlines that 3I/ATLAS generated earlier in the year. The possibility of alien visitors from afar is far easier to understand than photometric analyses of cometary outgassing, and for decades, science fiction has encouraged us to keep our eyes to the skies not for conducting routine science, but in the search for signs of intelligent life out there in the vacuum of space.

Unfortunately, it truly appears that what made 3I/ATLAS such a popular topic throughout 2025 is the fact that one scientist with an impressive list of credentials made claims of possible alien technology, claims that landed him on television and podcasts, but that clouded the real, hard science being done to learn about the third-known object to fly through the solar system from another star.

"The misinformation is much easier to produce and much harder to squash, and so it's just always an uphill battle," Denneau told Space.com. "But you know, we're all doing what we can do right?"

Astronomers have been treated to a stunning fireworks display from around a young star called Fomalhaut. The events, detected in 2004 and 2023, represent the first collisions between large objects seen in a planetary system beyond our own. Observing collisions occurring in a young star system like that of Fomalhaut could provide astronomers with a window to the conditions under which our own planet and its siblings formed around the infant sun around 4.6 billion years ago.

Fomalhaut is located only around 25 light-years away and is just 440 million years old. If this seems far from "young," remember our planet is 4.6 billion years old, and is considered middle-aged. Young star systems like Fomalhaut are estimated to be a hub of such violent collisions as space rocks, asteroids, and larger planetesimals, objects smaller than dwarf planets, slam into each other. Often, planetesimals rebound away from each other, but sometimes they stick to one another and turn dust and ice into planets and moons. The largest collisions are rare, occurring maybe once every 100,000 years over the hundreds of millions of years it takes to form a planetary system like the solar system.

"We just witnessed the collision of two planetesimals and the dust cloud that gets spewed out of that violent event, which begins reflecting light from the host star," team leader Paul Kalas, of the University of California, Berkeley, said in a statement. It's like looking back in time in a sense, to that violent period of our solar system when it was less than a billion years old."

Kalas added that the team did not directly see the two objects that crashed into each other, instead spotting the aftermath of this enormous impact.

He and his colleagues first began investigating the young star Fomalhaut back in 1993, hunting for the debris leftover from planet birth, eventually finding a disk of this material around the star with the Hubble Space Telescope. Then, in 2008, Kalas found a bright spot in that so-called protoplanetary disk that was initially thought to be a planet. This new research suggests that this planet, Fomalhaut b, is actually a dust cloud that was stirred up by the collision between planetesimals in the protoplanetary disk.

"This is a new phenomenon, a point source that appears in a planetary system and then over 10 years or more slowly disappears," Kalas said. "It's masquerading as a planet because planets also look like tiny dots orbiting nearby stars."

The brightness of the events observed in 2004 and 2023 revealed that the bodies involved were around 37 miles wide (60 kilometers) or more, meaning they are each at least four times as large as the Chicxulub impactor, the asteroid that struck Earth 66 million years ago, wiping out the dinosaurs along with 75% of all species of animals and plants.

"The Fomalhaut system is a natural laboratory to probe how planetesimals behave when undergoing collisions, which in turn tells us about what they are made of and how they formed," team member Mark Wyatt, of the University of Cambridge in the United Kingdom, said. "The exciting aspect of this observation is that it allows us to estimate both the size of the colliding bodies and how many of them there are in the disk, information which is almost impossible to get by any other means." Indeed, the team estimates that there are around 300 million planetesimals in the region around Fomalhaut of sizes similar to those involved in these two crashes. The fact that carbon monoxide gas has previously been detected in this system indicates these objects are rich in volatiles, substances such as hydrogen, nitrogen, oxygen and methane that easily turn gaseous at low temperatures.

That makes these icy bodies in Fomalhaut similar to the frigid comets of the solar system, which are also packed with volatiles. In a further comparison with the solar system, Kalas suggested that the 2004 and 2023 dust clouds seen by the team are akin to the dust cloud created in 2022 when NASA struck the moonlet Dimorphos with the DART (Double Asteroid Redirection Test) to test if this could shift its parent asteroid Didemos.

Kalas and colleagues will continue to investigate Fomalhaut with Hubble, also adding the powerful infrared vision of the James Webb Space Telescope to their investigation. This should allow them to track how the cloud seen in 2023 evolves. It is already around 30% brighter than the 2003 cloud, and observations conducted in August 2025 confirmed that it is indeed still visible.

As this investigation continues, Kalas warns astronomers not to fall into the trap of mistaking dust clouds for newly formed planets around infant stars.

"These collisions that produce dust clouds happen in every planetary system," Kalas said. "Once we start probing stars with sensitive future telescopes such as the Habitable Worlds Observatory, which aims to directly image an Earth-like exoplanet, we have to be cautious because these faint points of light orbiting a star may not be planets."

The team's research was published on Thursday (Dec. 18) in the journal Science.

Interstellar comet 3I/ATLAS, the third confirmed object known to have originated outside our solar system, has now been imaged in X-ray light by both the European Space Agency's (ESA) XMM-Newton observatory and the X-Ray Imaging and Spectroscopy Mission (XRISM) led by the Japanese space agency JAXA in partnership with NASA and ESA. These X-ray observations allow scientists to detect and study gases that other instruments can't easily spot, according to a statement from ESA.

Comets shine in visible light when sunlight reflects off dust and gas escaping their icy core, while X-ray light tells a very different story. In space, the interaction between fast-moving charged particles from the sun — also known as solar wind — and a comet's surrounding gas cloud produces X-ray emissions. Detecting that glow lets scientists trace where and how these interactions occur and what kinds of gases are present at levels that optical telescopes might miss.

While NASA's James Webb Telescope and other instruments have already spotted abundant water vapor, carbon monoxide and carbon dioxide in 3I/ATLAS's coma, X-ray observations are uniquely sensitive to lighter gases such as hydrogen and nitrogen that are otherwise hard to detect.

The first X-ray observation of 3I/ATLAS was made by the XRISM space telescope, which observed the comet for 17 hours between Nov. 26 and 28. The resulting image was captured using XRISM's soft X-ray telescope, Xtend, whose field of view spans roughly 1.2 million square miles (3 million square kilometers), revealing X-ray emission extending about 250,000 miles (400,000 kilometers) from the comet's nucleus — evidence that the comet's gas is being energized by the solar wind, according to a statement from ESA releasing the image.

The XRISM data also carry spectral signatures of elements such as carbon, nitrogen and oxygen, which helps scientists begin to disentangle the mix of particles released from the comet's nucleus and how they interact with the high-energy environment near the sun, ESA officials said in the statement.

Shortly after, ESA's XMM-Newton X-ray observatory studied 3I/ATLAS for about 20 hours on Dec. 3, when the comet was roughly 175–177 million miles (282–285 million km) from the spacecraft. The image was captured using the telescope's most sensitive X-ray instrument, the European Photon Imaging Camera (EPIC)-pn, revealing a distinct X-ray glow (shown in red) surrounded by fainter gradients. These features mark regions where the solar wind is interacting with gas streaming off the comet, according to a statement from ESA releasing the image.

"3I/ATLAS presents a new opportunity to study an interstellar object, and observations in X-ray light will complement other observations to help scientists figure out what it is made of," ESA officials said in the statement.

Together, X-ray, optical, infrared and radio observations are offering fresh insights into 3I/ATLAS as it makes its rare journey through the inner solar system, with its upcoming closest approach to Earth expected around Dec. 19.

According to the orbital calculations from NASA's Jet Propulsion Laboratory (JPL) Horizons system, comet 3I/ATLAS was closest to Earth at 1 a.m. EST (0600 GMT) on Dec. 19. At that time, the comet was about 1.8 astronomical units away — roughly 168 million miles (270 million kilometers — or nearly twice the average distance between Earth and the sun.

Discovered on July 1, by NASA-funded ATLAS telescopes in Chile, 3I/ATLAS is only the third known interstellar object ever detected passing through our solar system, following 'Oumuamua in 2017 and 2I/Borisov in 2019.

While comet 3I/ATLAS will remain far too distant and faint to become a naked-eye spectacle as it passes Earth, its flyby is scientifically valuable because interstellar objects are so rare. Studying 3I/ATLAS near its closest approach provides astronomers with their best opportunity to examine material formed around another star, offering a fleeting glimpse into planetary systems beyond our own.

Skywatchers can also follow along with the flyby live online Dec.19-20 on Space.com courtesy of the Virtual Telescope Project. The livestream will begin at 11 p.m. EST on Dec. 19 (0400 GMT on Dec. 20), offering viewers a chance to see the interstellar visitor as it makes its closest approach to Earth, weather permitting.

Follow along with the latest 3I/ATLAS news with our live blog.

Editor's note: This article was updated at 1:30 a.m. EST (0630 GMT) to reflect the close approach that occurred as expected at 1:00 a.m. (0600 GMT) Dec. 19, 2025.

That not only makes this the first confirmed runaway supermassive black hole, but this object is also one of the fastest-moving bodies ever detected, rocketing through its home galaxy at 3,000 times the speed of sound at sea level here on Earth. If that isn't astounding enough, the black hole is pushing forward a literal galaxy-sized "bow-shock" of matter in front of it, while simultaneously dragging a 200,000 light-year-long tail behind it, within which gas is accumulating and triggering star formation.

"It boggles the mind!" discovery team leader Pieter van Dokkum of Yale University told Space.com. "The forces that are needed to dislodge such a massive black hole from its home are enormous. And yet, it was predicted that such escapes should occur!"

Supermassive black holes, which can reach masses billions of times that of the sun, are usually found at the hearts of their home galaxies, which they dominate with their immense gravity. The incredible speed of this supermassive black hole means it is around 230,000 light-years from its point of origin.

"This is the only black hole that has been found far away from its former home," van Dokkum said. "That made it the best candidate [for a] runaway supermassive black hole, but what was missing was confirmation. All we really had was a streak that was difficult to explain in any other way. With the JWST, we have now confirmed that there is indeed a black hole at the tip of the streak, and that it is speeding away from its former host."

How to spot a runaway

This now-confirmed runaway supermassive black hole was first identified by van Dokkum and colleagues back in 2023 using the Hubble Space Telescope, which spotted what appeared to be the wake of a massive body passing through space. Of course, like all black holes, this runaway is bounded by a one-way light-trapping surface called an event horizon, making it difficult to spot.

"The black hole is, well, black - and is very difficult to detect when it is moving through empty space. The reason why we spotted the object is because of the impact that the passage of the black hole has on its surroundings: we now know that it drives a shock wave in the gas that is moving through, and it is this shock wave, and the wake of the shock wave behind the black hole, that we see," van Dokkum said. "With the JWST, we discovered the huge displacement of the gas at the tip of the wake, where the black hole is pushing against it. The shock signatures are crystal clear, and there is just no doubt about what is happening here." The gas is pushed sideways away from the supermassive black hole at a velocity of hundreds of thousands of miles per hour (hundreds of km per second), a dynamical signature that the team saw with JWST.

"The velocity of the displaced gas is directly related to the velocity of the black hole, and this is how we determined the black hole's velocity from the JWST data," van Dokkum said. "It is moving at approximately 1000 km per second, faster than just about any other object in the universe. It is this high speed that enabled the black hole to escape the gravitational force of its former home."

How does a supermassive black hole 'go rogue?'

van Dokkum explained that two possible mechanisms could lead to a supermassive black hole being ejected from the heart of its own galaxy. Both scenarios begin when two galaxies collide and begin to merge, each bringing to the cosmic smash its own supermassive black hole. Both mechanisms are initiated when the supermassive black holes reach the center of the newly formed galaxy.

"The first mechanism is that the two black holes merge with each other, and that the gravitational radiation [gravitational waves] released in that merger imparts a powerful kick to the newly formed black hole. That kick could impart a speed of 1,000 km/s, enough to eject the black hole," van Dokkum said. "The second is a three-body interaction. That happens when one of the two galaxies had a pair of binary black holes at its center. When a third black hole enters the binary system, it becomes unstable, and one of the three black holes will get kicked out of the system."

The team believes that it is the first scenario that accounts for the runaway supermassive black hole in this instance. That would lead to a galaxy lacking a supermassive black hole at its center, which van Dokkum said is unlikely to impact said galaxy very much. However, this runaway supermassive black hole could have a huge impact on any other galaxy it encounters as it rockets through space.

"An encounter with another galaxy would be quite spectacular, mostly because of the huge, galaxy-sized shock wave that precedes the black hole," van Dokkum continued. "When this shock wave encounters the dense gas of another galaxy, it would compress and shock that gas and likely form a lot of new stars. It would be quite the show!"

Mergers between galaxies are common, occurring multiple times over the lifetime of a single galaxy. That means that ejected supermassive black holes may also be quite common, though population numbers vary based on how these collisions are modelled.

"Mergers happen often in the life of a galaxy; each galaxy with the size and mass of the Milky Way has experienced several during its lifetime. So black hole binaries should form pretty regularly. What we don't know is how quickly these binaries merge, if at all, and how often the resulting kick removes a black hole," van Dokkum said. "My view is empirical: now that we know how to look for them, we can find other examples - and then we can answer the question directly from data, by counting the number of escapes. The big thing is that black hole escapes lived purely in the realm of theory until now."Even though runaway supermassive black holes had been predicted by theory long before this discovery confirmed their existence, that doesn't mean these findings didn't deliver some unexpected twists.

"Everything about this research surprised me! I never expected to see such a thing, and confirming it with JWST was just incredible," van Dokkum said. "What we also had not quite appreciated is how much impact these escaping black holes have on the gas that they are moving through. In the wake, many new stars have formed from the shocked gas, about 100 million times the mass of the sun. This mode of star formation was unknown before, and it leads to a trail of stars far away from the galaxy, seemingly formed in empty space."

The Yale University researcher explained that the obvious next step for the team will be to search for more examples of runway black holes.

"You need space-based imaging to see them: the wake stood out to us because it is such a thin streak, and in ground-based images, it would be blurred beyond recognition," van Dokkum explained. "Fortunately, wide-field Hubble-quality imaging is just around the corner, thanks to the Roman Space Telescope, and, slightly blurrier, Euclid. Using machine learning algorithms to find thin streaks in the Roman data will be a cool project!"

The team's research has been submitted to The Astrophysical Journal Letters and is currently available as a pre-peer-reviewed paper on arXiv.

Editor's note: A previous version of this story described the runaway black hole as located in the Cosmic Owl galaxies, which is not the case.

MRO's HiRISE ("High Resolution Imaging Science Experiment") camera has now snapped 100,000 photos of the surface of Mars, NASA announced on Tuesday (Dec. 16).

Image number 100,000, which was captured on Oct. 7, "shows mesas and dunes within Syrtis Major, a region about 50 miles (80 kilometers) southeast of Jezero Crater, which NASA's Perseverance rover is exploring," NASA officials said in a statement on Tuesday.

"Scientists are analyzing the image to better understand the source of windblown sand that gets trapped in the region’s landscape, eventually forming dunes," they added.

MRO arrived in orbit around Mars in March 2006, tasked with searching for signs of past water activity on the Red Planet and conducting a variety of other investigations.

HiRISE — which is capable of resolving features as small as a coffee table on the Martian surface — has been key to that wide-ranging mission.

"HiRISE is the instrument the mission relies on for high-resolution images of features ranging from impact craters, sand dunes, and ice deposits to potential landing sites," NASA officials said in the statement. "Those images, in turn, help improve our understanding of Mars and prepare for NASA’s future human missions there."

Though MRO has been operating at Mars for more than 20 years, it's not the longest-lived NASA Red Planet orbiter. That distinction goes to Mars Odyssey, which has been studying the planet from above since October 2001.

MRO and Odyssey are two of nine spacecraft actively studying Mars up close. The others are NASA's Curiosity and Perseverance rovers and five other orbiters: NASA's MAVEN, Europe's Mars Express and ExoMars Trace Gas Orbiter, China's Tianwen 1 and the United Arab Emirates' Hope mission.

MAVEN may be in trouble, however: It has been silent since Dec. 4 and has apparently begun spinning in an unexpected way.

Eager skywatchers will soon have front-row seats to a rare cosmic encounter as interstellar comet 3I/ATLAS makes its closest approach to Earth, and you can watch it happen live online tonight!

The Virtual Telescope Project will host a free livestream starting at 11 p.m. EST on Dec. 19 (0400 GMT on Dec. 20), sharing real-time telescope views of comet 3I/ATLAS captured by its robotic observatories in Manciano, Italy, weather permitting.

Comet 3I/ATLAS made its closest approach to Earth at 1 a.m. EST (0600 GMT) on Dec. 19. At that time, it was about 1.8 astronomical units away — roughly 168 million miles (270 million kilometers), nearly twice the average distance between Earth and the sun.

Discovered in July 2025 by the ATLAS (Asteroid Terrestrial-impact Last Alert System) survey, 3I/ATLAS quickly captured the attention of both scientists and the public. It is only the third confirmed interstellar object ever detected passing through our solar system, following 1I/'Oumuamua in 2017 and 2I/Borisov in 2019. Researchers are especially interested in its composition and behavior, which could offer rare clues about how planetary systems form around other stars.

The comet is too faint to be seen with the naked eye and will be challenging even for small backyard telescopes. Under dark skies, observers with a telescope of 8 inches or larger may be able to spot it as a faint, fuzzy patch of light. If you're unable to look for the comet in person, you can sit back, relax and enjoy the view from the comfort of your own home via the livestream.

Editor's note: This article was updated Dec. 18 at 11 p.m. EST to notify readers that the livestream of interstellar comet 3I/ATLAS by the Virtual Telescope Project has been postponed one day due to rain at the observing site. It is now scheduled for Friday, Dec. 19, at 11 p.m. EST (0400 GMT).

• Comet 3I/ATLAS will approach within 168 million miles (270 million kilometers) of Earth when it makes its close flyby on Dec. 19.
• You can watch comet 3I/ATLAS's flyby live online in a free webcast.
• Who discovered comet 3I/ATLAS? We talked to the scientist behind the find

Latest Comet 3I/ATLAS news

Comet 3I/ATLAS has last hurrah this week

Good morning, Space Fans! As of today, we are T-2 days until the interstellar comet 3I/ATLAS makes its closest approach to Earth and then we'll have to say our goodbyes.

Whether or not you're in Team Comet or Team "Could It Be A Spaceship?" 3I/ATLAS has dominated the comet conversation since its discovery on July 1 by the ATLAS telescope in Chile. On Friday, Dec. 19, 2025, the comet will be at its closest to Earth at a range of roughly 168 million miles (270 million kilometers) before heading out of our solar system for good.

Over the next two days, we'll chronicle comet 3I/ATLAS's Earth flyby, and revisit its passage through our solar system — and its legacy.

Read our full preview of the comet's Earth flyby.

Comet 3I/ATLAS: An early Christmas gift for scientists

When 3I/ATLAS is closest to Earth on Dec. 19, all the features that we are looking for will be easier to detect with our telescopes and it has scientists as eager as kids on Christmas.

Comet 3I/ATLAS is the third large interstellar visitor (an asteroid or a comet) known to have passed through our solar system from beyond our solar system. By studying it closely, astronomers hope to learn more about other celestial objects through telescope observations.

"It has since been careening through the interstellar medium of the Milky Way galaxy for billions of years," Darryl Z. Seligman, an assistant professor of physics and astronomy at Michigan State University, wrote in an op-ed. "And we get front-row seats to watch as it gets close to our sun, for what is almost surely the first time it has ever gotten close to a star".

Read the full op-ed on the comet's Earth flyby here.

Who discovered Comet 3I/ATLAS?

If you've been as captivated as us here at Space.com by comet 3I/ATLAS's trip through the solar system, you might find yourself wondering exactly how it was discovered. So did we, which is why our own Kenna Hughes-Castleberry took it upon herself to find out  —  and the result was eye-opening!

What seemed like a normal July night ended up making history when astronomer Larry Denneau at the University of Hawaii's Institute for Astronomy discovered a new moving object while scrolling through data from ATLAS — the Asteroid Terrestrial-impact Last Alert System."I was the person reviewing at the time that 3I popped out of the pipeline," Denneau told Space.com "And at the time, it looked like a completely garden variety new Near Earth Object."

Read the full story behind the discovery of comet 3I/ATLAS here.

How to watch the comet 3I/ATLAS Earth flyby

The interstellar comet 3I/ATLAS will make its closest pass by Earth on Dec. 19, and you'll be able to watch its approach live online, but you'll need to tune a bit earlier than you'd think.

Astrophysicist Gianluca Masi of the Virtual Telescope Project will host a free livestream of comet 3I/ATLAS on Thursday, Dec. 18, at 11 p.m. EST Dec. 18 (0400 GMT on Dec. 19), weather permitting. You can watch the livestream here on Space.com.

Masi's livestream will run through comet 3I/ATLAS's closest approach at 1 a.m. EST (0600 GMT), but will depend on good weather from his telescope's observing site.

The comet is too faint to be seen with the naked eye and will be challenging even for small backyard telescopes. Under dark skies, observers with a telescope of 8 inches or larger may be able to spot it as a faint, fuzzy patch of light. Read how to watch the comet 3I/ATLAS flyby live online.

How far is Comet 3I/ATLAS from Earth right now?

As of 12 p.m. ET today (Dec. 17), Comet 3I/ATLAS is about 166.9 million miles (268.6 million kilometers) from the Earth and closing, ahead of its closest approach on Dec. 19.

You can track comet 3I/ATLAS yourself with the help of NASA's Eyes On The Solar System webpage, which has a "Distance Tool" that allows you to calculate the separation between the comet and any other solar system object included in the simulation.

Not the first interstellar comet

As its name suggests, comet 3I/ATLAS is not the first interstellar object known to come from beyond our solar system. To date, there have been three in total (hence the "3I" in the name, it stands for "3 Interstellar").

Comet 3I/ATLAS's discovery in 2025 followed the discovery of the first interstellar object, 1I/'Oumuamua, in 2017. Two years later, another object was spotted. That one was called comet 2I/Borisov in 2019. Both 'Oumuamua and 2I/Borisov spent months passing through the solar system, only to leave us behind for the void of interstellar space.

The same fate awaits 3I/ATLAS, so we should enjoy the comet while it's with us.

Is comet 3I/ATLAS really a comet?

You've probably heard all the theories: It's really an alien spaceship. It's changed direction. It spat out a tiny spacecraft.

Well, NASA recently made it official: Comet 3I/ATLAS is just what it looks like - a comet from beyond our solar system. In late November, NASA held a televised press conference to put the comet 3I/ATLAS rumours to bed.

"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 Associate Administrator Amit Kshatriya told reporters during the press briefing.

Here's the full story on NASA's take on comet 3I/ATLAS.

Good night, for now.

Good evening, Space Fans. We're wrapping up today's T-2 day countdown to the comet 3I/ATLAS flyby of Earth, but we'll be back tomorrow with another series of stories and a look back at the comet's legacy.

Tune in then!

Comet 3I/ATLAS is less than 1 day away from Earth flyby

Good morning, space fans! We are officially T-1 day away from the closest approach to Earth of comet 3I/ATLAS, with the flyby set for early Friday, Dec. 19.

We're keeping a close eye on the comet's progress and as of this posting, comet 3I/ATLAS is about 166.8 million miles (268.5 million kilometers) from Earth and closing. But there's no need to worry about the comet's approach.

At its closest point, comet 3I/ATLAS will be about 168 million miles (270 million kilometers) away. After that, it will get farther and farther with each passing minute until it's off to visit some other solar system.

We've got a great set of comet stories for you today, so check back here for the latest on 3I/ATLAS as we get closer to its Earth flyby.

How comet 3I/ATLAS captured our hearts with mystery

We'll admit it: We would love it if the interstellar comet 3I/ATLAS really was an alien spaceship, but at the end of the day, it's still a comet. Yet that does not mean 3I/ATLAS isn't still completely amazing; otherwise, we wouldn't have covered the comet's passage through our solar system as we've done over the last six months.

Why not read up on the four key things that NASA revealed about the comet in a long-awaited briefing following the reopening of the U.S. government in November? At the event, NASA Associate Administrator Amit Kshatriya explained "we very much want to find signs of life in our universe," before re-iterating, "but 3I/ATLAS is a comet".

Full article: 4 key things NASA just revealed about the interstellar comet 3I/ATLAS.

Interstellar comet 3I/ATLAS just revealed its secret wobble

Astronomers have spotted the first-ever wobbling jet from an interstellar comet and it is changing how we understand visitors from beyond our solar system.

Using the Two-meter Twin Telescope at Tenerife's Teide Observatory, researchers detected a faint jet of gas and dust blasting from 3I/ATLAS, slowly wobbling as the comet rotates. Crucially, that rhythmic motion confirms that 3I/ATLAS spins once every 14-17 hours, making it the first interstellar comet with a directly measured rotation period tied to visible activity on its surface.

What surprised scientists most is how familiar the behavior looks. Despite forming around another star, 3I/ATLAS behaves much like comets born closer to home. Scientists describe it as an "extraordinarily normal interstellar comet," complete with sunlight-driven jets.

The findings of this study are published in the journal Astronomy & Astrophysics.

Spacecraft reveal 3I/ATLAS's X-ray signature

Scientists are working hard to collect valuable data on 3I/ATLAS's spectral fingerprint before it disappears from our skies for good, in an attempt to shed light on the composition of the distant star system where it was born.

The European Space Agency's XMM-Newton observatory and the Japanese space agency-led X-Ray Imaging and Spectroscopy Mission (XRISM) revealed a vast 250,000 mile (400,000 kilometer) X-ray glow extending from the comet's nucleus. An analysis of this X-ray light, emitted by gasses interacting with the solar wind, will help scientists understand how the comet is being influenced by the high-energy environment surrounding our star after its marathon voyage through interstellar space.

Read the full story here: Scientists detect X-ray glow from interstellar comet 3I/ATLAS extending 250,000 miles into space.

How fast is interstellar comet 3I/ATLAS going?

Having made its closest approach to the sun on Oct. 30, comet 3I/ATLAS is now on its way back out of the solar system, charging away from our parent star at a breathtaking speed of 144.1 thousand miles per hour (231.9 thousand kilometers per hour) as it heads towards interstellar space.

The ancient interloper is already well beyond the orbit of Mars ahead of its closest pass of Earth on Dec. 19. Its next planetary rendezvous will be with Jupiter in March next year, when it will pass 36 million miles (58 million kilometers) from the gas giant, before continuing on an incident-free course to exit the heliosphere.

What time is comet 3I/ATLAS's closest Earth approach?

If you're hoping to try and watch comet 3I/ATLAS's closest approach to Earth live online, it would help to know exactly when to tune in. But don't worry, space fans, we've got you covered.

As Space.com's Daisy Dobrijevic reports, comet 3I/ATLAS closest point to Earth will occur at 1 a.m. EST (0600 GMT) as it zips past our planet at a whopping 144.1 thousand mph (231.9 thousand kph). At the time, it will be 168 million miles (270 million km) from Earth.

You'll be able to watch the flyby live online starting at 11 p.m. EST (0400 GMT), courtesy of the Virtual Telescope Project. Comet 3I/ATLAS is too far from Earth to see with the unaided eye, and you'd need a large telescope to try and spot it, so the livestream may be one of our last public looks at the interstellar visitor as it passes by.

How you can track interstellar comet 3I/ATLAS

You may not be able to see 3I/ATLAS with your own eyes or most telescopes, but there are multiple ways you can track it from home.In fact, there are four different ways you can track the interstellar comet right now, according to our skywatching writer Anthony Wood.

The coolest way to track comet 3I/ATLAS is through NASA's Eyes on the Solar System website, which allows you to follow the comet's progress in a very accessible format by creating a 3D model based on real-life observations. You can see that feature below as well, right now.

But there are other ways. The Comet Observation Database allows you to track the comet's brightness over time based on observations from amateur astronomers. A smartphone astronomy app (I like to use SkySafari) can also allow you to pinpoint where comet 3I/ATLAS is in the sky, even if we can't see it with the naked eye.

Finally, there is the Virtual Telescope Project run by astrophycisit Gianluca Masi, which will offer a livestream of comet 3I/ATLAS during its closest approach. That livestream begins at 11 p.m. ET (0400 GMT) and will run through the closest approach at 1 a.m. ET (0600 GMT), weather permitting.Happy comet hunting!

NASA's Europa Clipper sees comet 3I/ATLAS!

It may look like only a pale blue blob, but this is definitely the interstellar comet 3I/ATLAS.

This image was taken by NASA's Europa Clipper spacecraft, which is on its way to the Jupiter moon Europa, and publicly unveiled to the world today (Dec. 18), just one day before the comet's closest approach to Earth on Dec. 19.

The Europa Clipper spacecraft used its Ultraviolet Spectrograph (UVS) developed by the Southwest Research Institute (SwRI) to observe comet 3I/ATLAS on Nov. 6 at a time when it could not be seen properly from telescopes on Earth and spacecraft orbiting Mars. At the time, Europa Clipper was about 103 million miles (164 million kilometers) away from the comet.

"We’re excited that this opportunity to view another target on the way to Jupiter was completely unexpected,” SwRi's Kurt Retherford, principal investigator for Europa-UVS, said in a statement. "Our observations have allowed for a unique and nuanced view of the comet."

The Europa Clipper image looks sunward towards comet 3I/ATLAS, revealing its twin tails from behind, as well as a glimpse at the comet's head-like coma and surronding cloud of gas. The UVS instrument found signs of oxygen, hydrogen and dust-related features, "supporting the preponderance of data indicating that comet 3I/ATLAS underwent a period of high outgassing activity during the period just after its closest approach to the Sun," SWRI reported.

NASA launched Europa Clipper toward Jupiter in 2024. It should arrive at Jupiter in 2030 to begin orbiting the icy moon Europa.

3I/ATLAS close Earth flyby: What to know tonight

Okay, space fans, it's nearly make or break time for the close Earth flyby of the interstellar comet 3I/ATLAS.

In case you're just joining us, we are now just hours away from the closest approach to Earth by the interstellar comet 3I/ATLAS. We've been offering live coverage over the last two days for the flyby, with a series of stories and guides online, including how to watch the flyby in a livestream, different ways to track the comet and more. But it all goes down tonight. Comet 3I/ATLAS will make its closest approach to Earth at 1 a.m. EST (0600 GMT) tonight, when it will come within 168 million miles (270 million km) of our planet. That's about 1.8 astronomical units, or nearly twice as far from Earth as our own planet is away from the sun. So there's no danger of an impact to Earth.

Scientists around the world have been tracking the interstellar comet to understand how it differs from the comets and dust we see in our own solar system.

Comet 3I/ATLAS is the third known interstellar comet after 2017's 1I/'Oumuamua and 2019's 2I/Borisov. It was discovered on July 1, 2025 and made its closest approach to the sun in October. Now it is looping outward to exit the solar system. Once it's gone, it will be gone forever.

See you at 11 pm ET for comet 3I/ATLAS's Earth approach!

Okay, space fans, we're going to pause our updates for interstellar comet 3I/ATLAS for a few hours as we await the final countdown to its 1 a.m. EST (0600 GMT) approach to Earth. Thanks for joining us today.

We'll be back at 11 p.m. EST (0400 GMT) with the start of the livestream coverage of the comet from the Virtual Telescope Project by Gianluca Masi of Ceccano, Italy. PLEASE NOTE: The livestream is weather dependent. If the skies are cloudy over Ceccano, the livestream could be delayed or canceled. But we're hoping for good weather. See you at 11 p.m. ET, space fans.

Good night!

2 hours to Comet 3I/ATLAS flyby: Livestream postponed

The interstellar comet 3I/ATLAS is now less than 2 hours away from its closest approach to Earth.

We were expecting to begin sharing a livestream of the comet as seen by astrophysicist Gianluca Masi with the Virtual Telescope Project in Ceccano, Italy. However, Masi reports that rain over his observing site is thwarting observations.

"Because of rain, this event has been postponed," Masi wrote in an update.

The livestream has been rescheduled for Friday night, Dec. 19, at 11 p.m. EST (0400 GMT).

Meanwhile, comet 3I/ATLAS continues on its course by Earth.

As of 11 p.m. ET tonight, it was 166.8 milion miles (286.5 million km) from Earth and traveling at about 148,600 mies per hour (239,200 km/h), according to NASA's Eyes On The Solar System.

1 hour until comet 3I/ATLAS is closest to Earth

We are now one hour away and counting until the closest approach to Earth by comet 3I/ATLAS, the interstellar comet from beyond our solar system.

As of 12:08 a.m. EST (0500 GMT), the comet is beyond the orbit of Mars, as it is about 166.8 milion miles (286.5 million km) from Earth, according to NASA's Eyes On The Solar System site.

Comet 3I/ATLAS's closest poitn to Earth will come at abotu 1 a.m. EST (0600 GMT).

Did you see it? Interstellar comet 3I/ATLAS has just zoomed past Earth!

Good morning space fans!

Interstellar comet 3I/ATLAS made its closest approach to Earth moments ago, passing within 168 million miles (270 million km) of our planet. The icy visitor will now continue its journey through the outer solar system, passing Jupiter in early 2026, crossing the orbits of Saturn, Uranus and Neptune by 2028 and then head out to interstellar space, never to return.

As some of you may be aware, the comet livestream hosted by Gianluca Masi with the Virtual Telescope Project has been postponed until 11 p.m. EST Friday night, Dec. 19 (0400 GMT on Dec. 20), weather permitting. Join us later today to catch a glimpse of 3I/ATLAS before it's gone forever!

Stay tuned today as we continue to bring you the latest Comet 3/I ATLAS news and bid farewell to our icy visitor.

Farewell, 3I/ATLAS!

Our interstellar visitor has officially passed its closest approach to Earth and is now heading back out toward the outer solar system — and eventually beyond.

On Dec. 19, comet 3I/ATLAS came within about 168 million miles of our planet, giving scientists a rare chance to study material from beyond our solar system before it begins its long journey back into the Milky Way.

If you want to know what happens next, why this object is so special, you can read our wrap story here.

Why did comet 3I/ATLAS go viral in 2025?

Earth is in the rear-view mirror now for comet 3I/ATLAS after its closest approach to our planet today, but as we say farewell to the interstellar visitor, I have to be honest: I will not miss the "Is it a spaceship?" questions that bombarded me over the last six months. (Most recently at a company holiday party!)

But the widespread reach of that question - "Is comet 3I/ATLAS really a spaceship?" - really got us wondering, especially after NASA came out in November and outright said no, it was a comet.

So, to honor 3I/ATLAS's place in our collective hearts, managing editor Brett Tingley went out to find out why comet 3I/ATLAS seemed to go more viral than its predecessors. The answer, it seems, comes down to timing.

Read Brett's full story on How the interstellar comet 3I/ATLAS went from routine to viral in 2025.

Final Comet 3I/ATLAS

Hi, space fans, while the interstellar comet 3I/ATLAS is headed away from Earth, there is still another chance to see it tonight.

At 11 p.m. EST (0400 GMT) the Virtual Telescope Project by Gianluca Masi of Ceccano, Italy. will hold a free livestream that will run through 1 a.m. EST (0600 GMT). PLEASE NOTE: The livestream is weather dependent. If the skies are cloudy over Ceccano, the livestream could be delayed or canceled. But we're hoping for good weather.

Thank you for joining us on this awesome week of comet 3I/ATLAS's approach, and we look forward to the next interstellar visitor!

Good night!

Denneau is part of the team behind ATLAS — short for Asteroid Terrestrial-impact Last Alert System — a network of wide-field telescopes that repeatedly images huge swaths of sky to catch anything that moves, particularly near-Earth asteroids. The system snaps the same patch of sky four times in quick succession to create a short motion path, or "tracklet" that shows possible movement, then uses reference images where the sky is still to subtract out any stars and galaxies, leaving behind moving points that could be asteroids, comets, or something else. Candidates that survive these automated filters are sent to a human reviewer to verify they're real and ready to be catalogued by the Minor Planets Center.

That July evening, one of those survivors landed in front of Denneau. When 3I/ATLAS first showed up in the ATLAS software, it didn’t look special at all. "I was the person reviewing at the time that 3I popped out of the pipeline," Denneau told Space.com "And at the time, it looked like a completely garden variety new Near Earth Object." So Denneau did as the software he designed recommended he do. He clicked "submit."

When the discovery of a new interstellar object lit up astronomers' inboxes around the world, Larry Denneau was nowhere near his email.

He was up in the mountains at Mauna Loa, high on Hawaii's Big Island, servicing a telescope. For an entire day, he was effectively offline, while excitement quietly built around a strange object moving across the solar system.

When he finally got back that night, reality hit all at once.

"I was oblivious to them until we got back that night," he said. "And my inbox was completely exploded with all of this stuff […] At that point, we're thinking about where is it, how fast is it going? Within a day, because this object is so interesting, there are hundreds of observations from different telescopes all confirming the orbit."

The object was classified by the Minor Planets Center as 3I/ATLAS, only the third-known interstellar visitor ever observed passing through our solar system, following 1I/'Oumuamua's discovery in 2017 and 2I/Borisov's in 2019. Unlike typical asteroids or comets, interstellar objects are not gravitationally bound to the sun; they originate around other stars and are briefly visible to us only as they pass through our solar system.

To find these objects, software like the type ATLAS uses looks for any moving objects, just points of light shifting against a background of stars.

"What comes out of our pipeline are really positions," Denneau said. "Things that look like stars that are moving across the background."

At that stage, a human still has to make the call. Someone has to look at the data and decide whether it's real.

"So, yeah," Denneau said, "I'm literally the person who clicked the button and submitted the discovery observations for this object."

Only later did the oddities become clear, especially in the models showing from where 3I/ATLAS might have been moving. As Denneau explained, "Folks with follow-up telescopes go to these places in the sky and they'll see the thing moving in the direction that it’s supposed to be moving. And they'll send in the observations and then Minor Planet Center and the Jet Propulsion Laboratory (JPL) in Pasadena, at the same time, will fit the observations to the orbit and try to compute what the orbit should be."

These follow-up observations and models showed that the object's orbit didn’t behave like anything bound to the sun.

"All of the orbit fits turned out to be really poor," Denneau said. "They didn’t look like the solar system — they had this funny trajectory that said it's going really fast. It's not bound to the sun."

That's when it became obvious: this was something from outside our solar system entirely.

"I was getting asked by JPL, do we have any earlier possible observations that can confirm the trajectory and stuff?" He added. "So we scrambled to try to find some more observations from previous nights."

Where engineer meets astronomer

Denneau doesn't fit the traditional mold of an astronomer. He didn't start his career studying stars or planets — he started with code.

"I'm sort of a non-traditional astronomer," he said. "I started out my career in engineering, mostly computer programming, and so my degree is in EE actually, and not in physics or astronomy." Denneau eventually did receive a Ph.D. in astrophysics from Queen's University Belfast, but continued to use his software skills to shape his career.

After moving to Hawaii and working as the software architect for the asteroid detection pipeline on the Pan-STARRS telescope project, Denneau became deeply involved in building the software systems that modern sky surveys depend on. He eventually joined ATLAS, a NASA-funded project designed to scan the sky every night for near-Earth asteroids. From Denneau's perspective, astronomy depends on a mix of hardware and software.

"We built some telescopes," Denneau said, "but after the telescopes are built, it's really a software project." It would be that software project, one that Denneau helped develop, that would eventually capture images of an interstellar comet.

Each night, ATLAS telescopes take thousands of images of the sky. Because the system uses wide-field lenses, it can cover an area of the sky more than 100 full moons at once. This adds up to an area the size of nearly the entire visible sky every 24 hours, repeatedly revisiting the same regions to look for motion. Those images are automatically transferred, processed, compared and filtered by custom software designed to find anything that moves, especially asteroids close to Earth.

"We have automated software that controls the telescopes, copies the data to Honolulu and then searches these images […] for things that are moving," Denneau explained. That volume is intense as "four or five telescopes combined take a good fraction of a terabyte of data every night," he added. "We're a multi-petabyte project at this point. And so that's the kind of stuff that, as a computer person, keeps me awake, because it’s a lot of data to keep secure and backed up."

That’s why, for Denneau, studying the stars is more of a software project as opposed to a hardware project, as the system has to ingest, clean, subtract, detect, match and archive, all while helping to filter out false positives that could waste other astronomers’ time chasing ghosts.

"We're really sensitive to not wanting to put false things on the confirmation page," Denneau said. "Because other telescopes will spend precious telescope time chasing something that's not real."

ATLAS aims for near-perfect reliability before sending out an alert. "We want to be like 99-point-something-percent reliable on that front," he added.

Detecting other moving objects

Not only was Denneau the person who initially detected 3I/ATLAs using his software, but just months earlier, he'd also been the one on duty for another discovery: near-Earth asteroid YR4.

As with most ATLAS detections, YR4 first appeared as a faint moving point pulled out of the background. Denneau checked the detections and confirmed that they were real before sending the data to the Minor Planets Center. The building-sized YR4 was initially thought to only have slim chances of hitting Earth on Dec. 22, 2032. However, with more study from astronomers, NASA concluded that YR4 actually poses no significant impact threat at all.

Why 3I/ATLAS was hard to detect

Unlike YR4, finding earlier observations of 3I/ATLAS to model where it might have come from was easier said than done. During its July 1, 2025 detection, the interstellar object happened to be moving through a particularly crowded part of the sky, packed with stars from the Milky Way. That made detection much harder.

ATLAS requires four clean detections to officially flag a new object. Until 3I/ATLAS moved into a less cluttered region of the sky, it stayed hidden in the noise, which is most likely why it wasn't detected sooner.

"When there's so many stars in the background, sometimes an asteroid goes right on top of a star," Denneau explained. "And so you only get three out. Because it was in the Milky Way, we had to kind of wait for it to get to a less dense part of the sky, for our pipeline to automatically admit it. And so we got it a week later than we actually first thought." Once 3I/ATLAS did move to a less dense area, the software worked exactly as designed, and even dug up earlier, "precovery" observations that helped confirm its unusual orbit.

Since its initial classification, 3I/ATLAS's popularity has spilled from the astronomy community into headlines and social media feeds. Interstellar visitors are still so rare that each one captures the public imagination and 3I/ATLAS is no exception. Each of these objects offers a fleeting, invaluable glimpse of material formed around another star.

And in this case, that glimpse began not with a dramatic telescope view, but with software, data, and one person clicking a button at exactly the right time.

"Every day I still love coming to work and working on astronomy," Denneau said. "It's just super fun."

Atmospheric scientists at the Harvard John A. Paulson School of Engineering and Applied Sciences report the first direct measurements of five-day-old wildfire smoke in the upper troposphere, about nine miles (14.5 kilometers) above Earth's surface. They discovered large smoke particles that aren't represented in current climate models, and these particles appear to actually cool the atmosphere.

To capture fresh smoke directly, the team flew a NASA ER-2 high-altitude aircraft into a plume created by a New Mexico wildfire in June 2022, just five days after the fire ignited. Onboard instruments measured particle size, concentration and chemical composition.

Inside the smoke cloud, researchers detected aerosols roughly 500 nanometers wide — about twice the size of typical wildfire aerosols at lower altitudes. The team suggests the large size can be attributed to efficient coagulation.

"Particles can coagulate at any place in the atmosphere," Yaowei Li, the lead author of a study on the research, said in a statement. "But in that specific region, the air mixes very slowly. That allows wildfire smoke particles to remain concentrated and collide more often, making coagulation much more efficient."

Such aerosols play a role in changing the amount of radiation that gets to the Earth's surface, whether by absorbing sunlight or reflecting back toward space. In this study, the larger particles had a striking effect: They increased outgoing radiation by 30% to 36 compared to lower-altitude particles, producing a measurable cooling effect that current climate models don't account for.

More research is needed to determine further effects of such high-altitude wildfire smoke on both weather and climate. Study co-author and project scientist John Dykema suggests that the large coagulated smoke particles could affect atmospheric circulation through local heating, potentially shifting jet streams. "I think all of these things are possible, and we don't currently have enough information to say which way they could go," he said.

The study was published on Dec. 10 in the journal Science Advances.

Join our Space Forums to keep talking space on the latest missions, night sky and more! And if you have a news tip, correction or comment, let us know at: community@space.com.

NASA's Parker Solar Probe has captured the clearest view yet of solar material billowing away from the sun before some of it makes a "U-turn," falling back toward the star after an eruption.

The snapshots reveal how the sun recycles its magnetic energy — a process that helps shape the next solar storm and could allow scientists to forecast space weather farther in advance.

The video below stitches together images taken during Parker's record-setting close approach to the sun on Christmas Eve 2024, when the spacecraft swooped within 3.8 million miles (6.1 million kilometers) above the solar surface. During that flyby, Parker observed a solar flare erupting from the sun, just as scientists had hoped, capturing a bright blob of superheated material bursting into space.

Like a puff of breath on a cold winter day, the cloud of solar material can be seen coasting outward from the sun before thinning, with some of it curling back inward. That returning material was pulled back by powerful magnetic field lines that snap and rapidly realign into looping structures, some of which continue outward into space, while others stitch back to the sun, according to a NASA statement.

"We've previously seen hints that material can fall back into the sun this way, but to see it with this clarity is amazing," Nour Rawafi, the project scientist for Parker Solar Probe at the Johns Hopkins Applied Physics Laboratory in Maryland, said in the statement.

"This is a really fascinating, eye-opening glimpse into how the sun continuously recycles its coronal magnetic fields and material."

What Parker observed was a coronal mass ejection, or CME, which is an eruption of superheated plasma from the sun that, if directed toward Earth, can trigger powerful geomagnetic storms capable of disrupting power grids, radio communications and satellite navigation systems, while also igniting breathtaking auroras.

In the video above, as the CME expanded outward from the sun, nearby magnetic field lines stretched until they snapped apart "like the threads of an old piece of cloth pulled too tight," the NASA statement read. The torn magnetic fields quickly reconnected, forming giant loops, some of which continued traveling outward while others retracted back toward the sun, dragging blobs of solar material along in a process known as inflows.

As that material falls back, it interacts with and reshapes the magnetic fields closer to the sun's surface — changes that potentially alter the paths of future CMEs emerging from that region.

"That's enough to be the difference between a CME crashing into Mars versus sweeping by the planet with no or little effects," Angelos Vourlidas, who is the project scientist for WISPR, the instrument onboard Parker that captured the snapshots, and a researcher at Johns Hopkins Applied Physics Laboratory, said in the same statement.

Such inflows have previously been observed before from a distance by missions, including the sun-watching SOHO observatory. But Parker's close-up close-up images revealed the returning material on scales never seen before, scientists say.

For the first time, scientists were able to directly measure the speed and size of the blobs falling back toward the sun, findings that they are currently using to refine models of space weather and the sun's complex magnetic environment, the statement read.

"Ultimately, this work may help scientists better predict the impact of space weather across the solar system on longer timescales than currently possible."

Since astronomers discovered the first world outside the solar system in the mid-1990s, these extra-solar planets or "exoplanets" have astounded us with their strange characteristics.

A new discovery, made using the James Webb Space Telescope (JWST), may just be the weirdest exoplanet yet, possessing an atmosphere unlike any we've ever seen on an exoplanet. Currently, the team behind this discovery can't explain how such a planet came to be.

The planet, designated PSR J2322-2650b, has a mass around that of Jupiter and orbits a dead star called a pulsar that blasts out twin jets of radiation that sweep across the universe like a cosmic lighthouse. Technically, the system is classified as a "black window pulsar," a binary star normally containing both a pulsar and stellar body, which the pulsar erodes and devours with its jets of radiation.

That isn't in itself so strange. The first planets beyond the solar system ever confirmed, Poltergeist (PSR B1257+12 B) and Phobetor (PSR B1257+12 C), spotted in 1992, also orbit pulsars, a young, rapidly spinning form of neutron star.

However, what sets PSR J2322-2650b apart are the facts that it has an ellipsoid shape, like a planetary lemon or football, and that it has an atmosphere like none scientists have ever seen before.

"This was an absolute surprise," team member Peter Gao of the Carnegie Earth and Planets Laboratory said in a statement. "I remember after we got the data down, our collective reaction was 'What the heck is this?' It's extremely different from what we expected."

The atmosphere of PSR J2322-2650b is dominated by helium and carbon, and likely has clouds of carbon soot that condense to create diamonds that rain down onto the planet.

At just around 1 million miles (1.6 million km) from its pulsar parent star (the Earth is around 100 times as distant from the sun), PSR J2322-2650b completes an orbit once every 8 hours or so. Its lemon-like shape emerges from tidal forces generated within the planet by the powerful gravity of the dead star it clings to.

"A new type of planet atmosphere that nobody has ever seen before"

Like all neutron stars, pulsars are born when massive stars at least 10 times the size of the sun exhaust the fuel for nuclear fusion. This results in the star's outer layers, and most of its mass, being blown away in a supernova explosion.

Left behind is a core with between 1 and 2 times the mass of the sun that crushes down to a width of around 12 miles (20 kilometers), and because it retains angular momentum, it can spin as fast as 700 times per second!

The parent star of PSR J2322-2650b is just such a so-called millisecond pulsar, but while it blasts out intense gamma-ray radiation, it doesn't emit very much infrared light. Because the JWST has been designed to see the cosmos in infrared, that means this powerful dead star doesn't block the $10 billion space telescope's view of PSR J2322-2650b.

This allowed the team to investigate the atmosphere of PSR J2322-2650b in detail and uncover its unique composition.

"This is a new type of planet atmosphere that nobody has ever seen before," team leader Michael Zhang of the University of Chicago said. "Instead of finding the normal molecules we expect to see on an exoplanet — like water, methane, and carbon dioxide — we saw molecular carbon, specifically carbon-3 and carbon-2."

PSR J2322-2650b is tidally locked to its star, which means one side permanently faces the neutron star, the planet's dayside, while the other faces out into space in perpetuity, its nightside.

The dayside of PSR J2322-2650b has a maximum temperature of 3,700 degrees Fahrenheit (2,040 degrees Celsius), while the nightside has a minimum temperature of 1,200 degrees Fahrenheit (650 degrees Celsius).

At these temperatures, molecular carbon should bind with other types of atoms, only becoming dominant if there is almost no oxygen or nitrogen in the planet's atmosphere. Of the 150 or so exoplanet atmospheres studied to date, no others have possessed detectable molecular carbon.

"Did this thing form like a normal planet? No, because the composition is entirely different," Zhang said. "Did it form by stripping the outside of a star, like 'normal' black widow systems are formed?

"Probably not, because nuclear physics does not make pure carbon. It's very hard to imagine how you get this extremely carbon-enriched composition. It seems to rule out every known formation mechanism."

There is one possible route of the creation of this planet, hinging on a unique phenomenon occurring in the bizarre atmosphere of PSR J2322-2650b.

"As the companion cools down, the mixture of carbon and oxygen in the interior starts to crystallize. Pure carbon crystals float to the top and get mixed into the helium, and that's what we see," team member and Stanford University researcher Roger Romani said. "But then something has to happen to keep the oxygen and nitrogen away. And that's where the mystery comes in.

“But it's nice not to know everything. I'm looking forward to learning more about the weirdness of this atmosphere. It's great to have a puzzle to go after."

That's the remarkable hypothesis from Mark Matney, a planetary scientist in NASA's Orbital Debris Program Office by day and a self-declared Christmas junkie. "I love Christmas," Matney told Space.com. "I love Christmas music, I love Christmas decorations — I love the whole thing!"

It was this love of Christmas, expressed in a festive show at the planetarium that Matney worked at when he was in college, that inspired his interest in the Star of Bethlehem. A passage in the Bible's Book of Matthew describes how the star went before the wise men — known as 'magi', who were probably astrologers looking for signs in the sky — and stood over Bethlehem. The planetarium show suggested that no known astronomical event behaves in this bizarre way, but rather than accept that, Matney saw it as a challenge. "I remember sitting there and thinking, I can think of one thing that can behave that way," he recalled.

For Matney, there are three ways to look at the story of the Star of Bethlehem. One, which is how those of a religious leaning might see it, is as a miraculous, divine event, the archangel Gabriel shining the way towards the baby Jesus.

Another, more cynical, view is to believe the whole story to be a myth, at best perhaps a misrepresentation or embellishment. If the Star of Bethlehem was either of these two things, then there's no point in looking for a scientific explanation.

On the other hand, the third way of looking at it is as a real astronomical event. Over the years, astronomers have suggested everything from a conjunction of Jupiter and Saturn to a supernova and, yes, a comet.

The problem with all previous astronomical explanations, says Matney, is that "objects in the sky, whether it be the sun, moon, planets, ordinary stars or normal comets, rise in the east and set in the west, they don't go before you and hover over a location."

However, Matney realized that if an object came close enough, at just the right time, moving in just the right direction at just the right speed through the sky, then it could appear to do these things.

"I came up with the idea of temporary geosynchronous motion," said Matney. "It has to be just right, but in principle it can happen."

The Chinese comet of 5 BCE

Matney filed his idea away in the back of his brain, until later when he learned that Chinese astrologers (astronomers and astrologers back then were synonymous) had seen a bright comet in 5 BCE, which is believed to be the year that Jesus was born.

The recorded observations of the comet are not sufficient to chart its exact orbit, but instead its measured positions in the sky could belong to a range of possible orbits. By running numerical simulations describing all these possible orbits, Matney found a subset of orbits that would have brought the comet close to Earth, and one possible orbit where it would have been close as Earth's moon.

Matney isn't saying that the comet definitely came that close — it's just one of a number of possible orbits the comet could have had. Had it done so, however, it could be a tantalizing explanation for the Star of Bethlehem, explaining a great many things.

The Christmas festivities tell us that Jesus was born on Dec. 25, but theologians and historians aren't actually sure of his birth date. However, the Chinese comet was discovered in mid-March, 5 BCE and, in the possible orbit flagged as being of interest to the Star of Bethlehem story, it would have reached its closest point to Earth on June 8 that year.

This doesn't necessarily mean that Jesus was born in June either; it's also not clear how long after Jesus' birth the magi were said to have visited him. We do know that when Herod later learned of Jesus' birth, he ordered all infant boys under the age of two to be killed, adding more uncertainty to when Jesus was born.

Unusual behavior at the comet's closest approach

Regardless, the comet would have continued along its orbit unperturbed by what was happening on Earth. In the possible orbit of interest discovered by Matney, the comet's closest approach to Earth would have been at a distance of 241,685 miles (388,954 kilometers). This would have been closer to Earth than any other comet in recorded history, so close that Earth itself would have been encased in the comet's coma, its expansive halo of dust around its icy nucleus.

As the comet neared its closest approach, its direction of origin would have meant that its motion in the sky began to accelerate eastwards, not westwards, fast enough to begin to counter Earth's rotation in the opposite direction. Between 10 a.m. and 11:30 a.m. on the morning of June 8, as seen from the Jerusalem/Bethlehem area, this motion would have given the comet the illusion of remaining still in the daytime sky, as bright as the full moon and appearing to be above Bethlehem from the point of view of the magi.

Afterwards, the comet would have resumed westward motion on an orbit that would have seen it skim the sun's corona. We call such comets 'sungrazers' and the close encounter with the sun would have probably resulted in the comet breaking up and being destroyed.

That the comet would have been visible during the daytime, in its guise as the Star of Bethlehem, even solves a minor mystery of the Christmas story, according to Matney.

"All the Christmas cards have the magi on camels at night, but during those times people typically did not travel at night," he said, citing hazards such as unlit paths and the danger from robbers. "So the fact that this comet would have been visible in broad daylight makes sense to me, as they were more likely to have travelled during the day."

Comets, omens and history

If Matney is right, why doesn't the Book of Matthew refer to a comet rather than a star? To the ancients, everything in the celestial sky barring the sun and the moon was a star. Planets were 'wandering stars', while comets were 'hairy stars' or 'broom stars' to the Chinese. And while comets are often seen as portents of doom, Matney explains that it's not as simple as that.

"Comet omens of that period are nuanced, but they were often omens of great change," said Matney. Often, it really depended on your point of view. Herod was very interested in the duration that the star was in the sky, and he would of course have seen the comet as a bad omen.

It seems that the Chinese were also influenced by the comet's presence in the sky. Although there's no record in their annals of the comet growing so bright as to rival the moon in the daytime sky, the comet seems to have affected the astrological reckoning surrounding the emperor of that time, Emperor Ai of the Han dynasty.

"The Chinese had periods in the Emperor's reign, and I'm not 100% sure of this, but according to my Chinese colleague, the Chinese temporarily changed the dating of these periods in part because of the comet," said Matney. "So it was enough that it got their attention."

Even so, it does seem like it would require a remarkable set of coincidences for the comet to have been the Star of Bethlehem, by being in the right direction, at the right time, moving at the right speed and at the right distance — a Goldilocks comet, if you will.

"It is a very unusual set of parameters," conceded Matney. "It had to come at the right time so that the right longitude could see it. Twelve hours sooner and it would have been on the other side of the world. But even though it is a highly unlikely set of circumstances, it's not out of the question. After all, every comet's orbit is a unique set of parameters."

Despite how rare it is for comets to come as close to the Earth as our moon — if Matney is right, this is the only comet in the past 2030 years — we have seen in the past decade that it is possible for a comet to sail close to a planet. In 2014, comet C/2013 A1 (Siding Spring) passed within 140,000 kilometers (87,000 miles) of Mars.

Searching for more evidence

Such a close approach could have physically left its mark on Earth. As the comet's dusty coma would have swept across our planet, there would have been one heck of a meteor shower with its radiant in the constellation of Capricornus, the Sea Goat, and some of that cometary dust would have drifted through the atmosphere and settled onto Earth, finding its way into sediment, just waiting to be found as a thin geological layer.

"There might be something in the ice cores, a sudden jump in cometary or meteoritic dust," said Matney. "I did look for something like that but didn't find anything obvious. Maybe someone who studies ice cores for a living can take a better look."

Another problem with Matney's hypothesis is that other than the short section in the Book of Matthew, which is believed to have been written after 70 AD, the only other source of information regarding the comet and its possible link with the Star of Bethlehem is the Chinese observations of the comet. If anyone else did see the star, they didn't leave any records — or at least, no records that have survived across the millennia since. Still, Matney is hopeful that something else might yet turn up.

"The weakest link in my story is that we don't have other records, which is why I'm still on the lookout for some untapped historical or archaeological source that might provide more clues," he said.

Matney is not claiming his hypothesis to be the final solution to the mystery of the Star of Bethlehem. "I have no proof that the comet came that close, I just show that it could have," he said. "Unless we can turn over more records from the first century AD that can help us pinpoint the comet's orbit, it will stay in the realm of speculation."

We might never know what the Star of Bethlehem was, or even if there was a star at all. Matney's motivation was just to show that no matter how rare it might be, there is an astronomical event that in principle could behave like the Star of Bethlehem is reported to have behaved.

It's ironic; were a comet to come that close today, there'd probably be panic about it possibly crashing into Earth, but a little over 2,000 years ago, it might have been seen as the rise of a new king, the birth of a savior and the dawn of a new religion.

Matney's research into the Star of Bethlehem and the comet hypothesis was published on Dec. 3 in the Journal of the British Astronomical Association.

Scientists have spotted formations that challenge our understanding of physics, and theorists have dreamed up megastructures that could power entire civilizations.

This crossword quiz explores the weirdest of the weird, real astronomical anomalies, speculative alien engineering, and everything in between.

Whether it's a hexagon on Saturn or a star that dims like clockwork, each clue will test your knowledge of the universe's strangest sights.

Try it out below and see how well you score!

While dark matter is estimated to account for 85% of the matter in the universe, it is difficult to investigate because it doesn't interact with electromagnetic radiation (light) or it interacts so weakly that we can't directly detect it. As well as making dark matter effectively invisible, this lack of interaction with light tells scientists that the particles making up dark matter aren't the protons, neutrons, and electrons that comprise the everyday stuff we see around us on a day-to-day basis, ranging from the most massive stars to the viruses that make our lives miserable every winter. The search for a potential dark matter particle has delivered many suspects, but they've all remained frustratingly hypothetical.

Thus, the only way scientists can infer the presence of dark matter is by looking at the gravitational influence it has on the fabric of space and how this then impacts ordinary matter and light. This new research, published in the journal Nature Astronomy, suggests that the gravitational influence of dark matter may be the cause of strange young galaxies with unexpectedly elongated shapes. And investigating these shapes could reveal which of these hypothetical particles is the best recipe for dark matter.

Studying these elongated galaxies with the JWST might help reveal the presence of dark matter, scientists say. "In the expanding universe defined by Einstein’s theory of general relativity, galaxies grow over time from small clumps of dark matter that form the first star clusters and assemble into larger galaxies via their collective gravity," team member Rogier Windhorst, of Arizona State University, said in a statement.

"But now the JWST suggests that the earliest galaxies may be embedded in marked filamentary structures, which — unlike cold, dark matter — smoothly join the star-forming regions together, more akin to what is expected if dark matter is an ultralight particle that also shows quantum behavior."

Understanding dark matter is a stretch

When using simulations to recreate how the first galaxies formed in the early universe, allowing cool gas to gather along the threads in a web of dark matter is able to quite nicely recreate the mostly spheroid galaxies we see in the modern universe.

However, as the JWST has been allowing astronomers to look back at galaxies that existed in the very early stages of the universe, they have increasingly been finding filamentary elongated galaxies that aren't as easily recreated in simulations that stick to the standard mechanism of gas gathering to birth stars and grow galaxies.

To investigate this, Windhorst and colleagues looked at simulations of the universe involving different types of dark matter other than that found in the most accepted model of cosmology, the Lambda Cold Dark Matter (LCDM) model; "cold" dark matter, which doesn't refer to temperature but instead to the speed at which particles move.

This revealed that the wave-like behavior of "fuzzy dark matter" or ultralight axion particles could account for the elongated morphology of early galaxies seen by the JWST.

"If ultralight axion particles make up the dark matter, their quantum wave-like behavior would prevent physical scales smaller than a few light-years from forming for a while, contributing to the smooth filamentary behavior that JWST now sees at very large distances," team leader Álvaro Pozo of the Donostia International Physics Center said.

The team's modelling also indicated that faster-moving "warm dark matter" particles, like sterile neutrinos, could also give rise to early filamentary galaxies. In both the wave dark matter and warm dark matter scenarios, this is because these particles give rise to smoother filaments than cold dark matter. As gas and stars slowly flow down these filaments, elongated galaxies begin to form.

The JWST will continue to investigate oddly shaped galaxies in the early universe, while researchers here on Earth continue to evolve simulations of the early universe. Bringing these together could eventually help solve the mystery of dark matter.

The team's research was published on Dec. 8 in the journal Nature Astronomy.

Discovered on July 1 by the NASA-funded ATLAS telescopes in Chile, 3I/ATLAS is only the third confirmed interstellar object known to have passed through our cosmic neighborhood, following 1I/'Oumuamua in 2017 and comet 2I/Borisov in 2019. Its trajectory shows that it originated from beyond our solar system and will eventually travel back into interstellar space.

During its closest approach, the comet will come no nearer than about 1.8 astronomical units from Earth — roughly 168 million miles (270 million kilometers) — nearly twice the average Earth-sun distance, according to the European Space Agency (ESA). Comet 3I/ATLAS poses no danger to Earth or any other planets as it passes through the inner solar system.

While the comet will keep a safe distance from Earth, the flyby still holds significance for researchers. By observing 3I/ATLAS near its closest approach, astronomers will have an opportunity to study the dust and gases released from its icy nucleus as the comet is warmed by the sun, offering a rare insight into how comets and planetary material form around other stars.

In recent months, multiple space agencies and observatories have turned their attention to this interstellar visitor. Just last week, new images captured by the Hubble Space Telescope and JUICE Jupiter probe were released, showing the fleeting traveller racing through the inner solar system.

Follow along online

You can also follow the close approach of 3I/ATLAS online in a free livestream hosted by Gianluca Masi at the Virtual Telescope Project. The livestream will begin at 11 p.m. EST on Dec. 18 (0400 GMT on Dec. 19), weather permitting.

Follow along with the latest 3I/ATLAS news with our live blog!

Like the dinosaurs, these monster stars aren't around anymore, but like Earth's geology is populated by fossils of dinosaurs, the universe is filled with the "cosmic fossils" left behind by these earliest stars: black holes. In fact, confirming these stars existed at such tremendous masses in the early universe could help explain how supermassive black holes grew to masses equivalent to that of millions of suns before the cosmos was even 1 billion years old.

The James Webb Space Telescope's (JWST) tantalizing first evidence of these titanic stars was delivered when a team of astronomers set about investigating the chemical makeup of a galaxy called GS 3073, which is located around 12.7 billion light-years away and is seen as it was just 1.1 billion years after the Big Bang. The "smoking gun" in this case was an imbalance of nitrogen to oxygen in GS 3073 that can't be accounted for by any known type of star.

"Our latest discovery helps solve a 20-year cosmic mystery. With GS 3073, we have the first observational evidence that these monster stars existed," team member Daniel Whalen of the University of Portsmouth in the U.K., said in a statement. "These cosmic giants would have burned brilliantly for a brief time before collapsing into massive black holes, leaving behind the chemical signatures we can detect billions of years later. A bit like dinosaurs on Earth — they were enormous and primitive. And they had short lives, living for just a quarter of a million years — a cosmic blink of an eye."

A galaxy with strange chemistry

The "smoking gun" in this case was an imbalance of nitrogen to oxygen in GS 3073 that can't be accounted for by any known type of star. The galaxy has a nitrogen-to-oxygen ratio of 0.46, which is much greater than can be explained by any known type of star or stellar explosion.

"Chemical abundances act like a cosmic fingerprint, and the pattern in GS3073 is unlike anything ordinary stars can produce. Its extreme nitrogen matches only one kind of source we know of — primordial stars thousands of times more massive than our sun," team member Devesh Nandal from the Center for Astrophysics (CfA), Harvard and Smithsonian, said in the statement. "This tells us the first generation of stars included truly supermassive objects that helped shape the early galaxies and may have seeded today's supermassive black holes."

The team took this information and modeled the evolution of stars with masses ranging from 1,000 to 10,000 times the mass of the sun to determine what elements the stars would forge and then seed through their galactic homes following their supernova deaths. This revealed a specific mechanism that could create a massive amount of nitrogen.

These monster stars burn helium in their cores to create carbon, which then "leaks" into an outer shell of the star where hydrogen is burning. The fusion of carbon and hydrogen then creates nitrogen, which is disturbed through the star via convection. Following this, nitrogen-rich matter escapes into space, enriching the surrounding gaseous material.

The fact that this process continued for millions of years can account for the nitrogen abundance in GS3073. Stars with masses less than 1,000 solar masses, or greater than 10,000 solar masses, don't produce the same chemical enrichment.

The team's research also predicts what would happen when these dinosaur stars reach the ends of their lives, suggesting that they directly collapse into black holes. The absence of a supernova blast means these black holes can still have masses thousands of times that of the sun, which would give them a major head start in supermassive black hole growth.

Indeed, there is a feeding supermassive black hole at the heart of GS 3073 that could be the "daughter" of mergers between the black holes created by these monstrous stars.The team will now hunt for other early nitrogen-rich galaxies in the early universe, which will add strength to the existence of these monster stars.

The team's research was published in November in The Astrophysical Journal Letters.

The new maps, built using close-up measurements from NASA's Parker Solar Probe along with data from more distant spacecraft, show that this boundary grows larger, rougher and more jagged as the sun becomes more active, periods in its cycle that are marked by increased sunspots and solar flares.

The new findings, published Dec. 11 in The Astrophysical Journal Letters, could help improve space weather models of how solar activity affects Earth and sharpen predictions of atmospheric behavior around other stars, scientists say.

"Before, we could only estimate the sun's boundary from far away without a way to test if we got the right answer," study lead author Sam Badman, an astrophysicist at the Center for Astrophysics ∣ Harvard & Smithsonian (CfA) in Massachusetts, said in a statement. "But now we have an accurate map that we can use to navigate it as we study it."

"And, importantly, we also are able to watch it as it changes and match those changes with close-up data," he added. "That gives us a much clearer idea of what's really happening around the sun."

The boundary, known as the Alfvén surface, marks the point where the outward flow of the solar wind becomes faster than magnetic waves that would otherwise carry material back toward the sun. Beyond this "point of no return," solar particles can no longer fall back and instead stream permanently into interplanetary space.

Scientists knew that this boundary shifts with the sun's roughly 11-year activity cycle — expanding and becoming more complex during solar maximum, and shrinking during quieter solar minimum periods. Until now, however, they lacked direct confirmation of what those changes actually looked like.

"That's actually what we predicted in the past, but now we can confirm it directly," Badman said in the statement.

To build the new maps, the researchers combined close-up measurements from the Parker Solar Probe, which repeatedly plunged through the sun's outer atmosphere during record-breaking close passes as the solar cycle ramped up toward its peak, with data from the European Space Agency's Solar Orbiter and NASA's Wind mission, both of which reside about 1 million miles (1.5 million kilometers) from Earth.

Using an instrument onboard Parker called the Solar Wind Electrons Alphas and Protons (SWEAP), the team directly sampled the region beneath the Alfvén surface, confirming that the maps correctly show where the sun's magnetic influence fades and the solar wind escapes, according to the statement.

"This work shows without a doubt that Parker Solar Probe is diving deep with every orbit into the region where the solar wind is born," study co-author Michael Stevens, an astronomer at the CfA and the principal investigator of the SWEAP instrument, said in the statement.

Pinpointing where and how the solar wind escapes the sun is essential to answering some of the biggest open questions in solar physics, including why the sun's corona gets hotter the farther it extends away from the solar surface.

Understanding exactly where this boundary lies is also critical for improving space weather forecasts, which help protect astronauts in space, and satellites and power grids on Earth from disruptive solar storms, scientists say.

During the next solar minimum, the Parker Solar Probe will again plunge deep into the sun's atmosphere, allowing scientists to watch how this boundary evolves over a complete solar cycle, according to the statement.

"There are still a number of fascinating physics questions about the sun's corona that we don't fully understand," said Stevens.

Not only do the findings point to a way in which a historical record of Earth's atmosphere could be deposited on the moon, but they also imply a healthy abundance of elements that could be useful to humans should we ever set up a lunar base.

In samples of lunar regolith brought back from the moon by Apollo astronauts, scientists have found puzzling amounts of volatiles, which in this case are elements such as water, carbon dioxide, helium, argon and nitrogen that have low boiling or sublimation points. Some of these volatiles are brought to the moon from the sun via the solar wind, but the abundances of these volatiles, particularly nitrogen, cannot solely be explained by the solar wind.

So, in 2005, scientists at the University of Tokyo proposed that some of the volatiles have come from Earth, as particles leaking out from our planet's upper atmosphere when they receive a nudge from energetic particles riding the solar wind. However, the Tokyo scientists believed this could only have happened in the early days of Earth's history, before our planet had a chance to develop a strong global magnetic field that they thought would block particles from escaping.

However, a team at the University of Rochester now suggest that this assessment was wrong.

The Rochester team, led by graduate student Shubhonkar Paramanick and astronomy professor Eric Blackman, used computer simulations to model when these volatile particles could have reached the moon based on two different scenarios.

One scenario depicted the early Earth, when our planet's magnetic field was weak and the solar wind was much stronger, describing the period in Earth's history when the Tokyo team reckoned that our atmosphere was more susceptible to being lost to space. The other scenario represented the modern Earth environment, with a stronger planetary field and a weaker solar wind emanating from the older sun.

Somewhat unexpectedly, the Rochester team found that the modern Earth scenario was actually more adept at transporting Earth's atmospheric particles to the moon.

That's because the simulations showed that, rather than blocking the particles' escape route, the Earth's magnetic field provided a highway for the particles. Some of our planet's magnetic-field lines are long enough to reach all the way to the moon.

In 2024, researchers at the University of Oxford found evidence in 3.7-billion-year-old iron-rich rocks in Greenland that the ancient Earth had a magnetic field comparable in strength to today. This is the oldest evidence we have of Earth's magnetic field, so from at least that time, and possibly earlier, through to today Earth's atmosphere has been leaking bit by bit into space and onto the moon.

"By combining data from particles preserved in lunar soil with computational modeling of how the solar wind interacts with Earth's atmosphere, we can trace the history of Earth's atmosphere and its magnetic field," said Blackman in a statement.

This means that the lunar regolith could still hold a very long-term record of Earth's atmospheric history, which in turn could teach us about how Earth's climate, environment and even life has changed over billions of years. Furthermore, the insights gained don't have to be confined to our planet.

"Our study may also have broader implications for understanding early atmospheric escape on planets like Mars, which lacks a global magnetic field today but had one similar to Earth in the past, along with a likely thicker atmosphere," said Paramanick. "By examining planetary evolution alongside atmospheric escape across different epochs, we can gain insight into how these processes shape planetary habitability."

Elsewhere in the solar system, Pluto's thin atmosphere also leaks onto its largest moon, Charon, although Pluto does not have an intrinsic magnetic field with which to transport its atmospheric particles. Instead, it is Charon's gravity that tugs at the particles in Pluto's atmosphere, with Pluto's weak gravity allowing the atmospheric particles to be stolen away.

This swapping of atmospheric atoms and molecules could also have positive repercussions for a future human presence on the moon. Water, for example, has obvious uses. (Water was also brought to the moon long ago by asteroid and comet impacts.) The fact that the stream of particles from Earth to the moon has been flowing for so long means that more volatiles than scientists expect might have built up on the lunar surface, just waiting for astronauts to extract them. In a way, it could be the ultimate down payment toward a human presence on the moon.

Then findings were published on Dec. 11 in the journal Communications Earth & Environment.

Comet 3I/ATLAS is the third large interstellar visitor that we have ever discovered —- an asteroid or comet that originated outside of our solar system and was discovered passing through. Astronomers can glean information about celestial bodies by observing the light reflected off them with telescopes. When 3I/ATLAS is closest to the Earth, all the features that we are looking for will be easier to detect with our telescopes.

This interstellar vagabond presumably formed in a protoplanetary disk of gas and dust swirling around another star, the sites of active planet formation. Most likely, 3I/ATLAS was ejected by a close gravitational slingshot off a giant exoplanet. It has since been careening through the interstellar medium of the Milky Way galaxy for billions of years. And we get front-row seats to watch as it gets close to our sun, for what is almost surely the first time it has ever gotten close to a star.

On Dec. 19, just six days before Christmas, this erratic wanderer will be the closest to Earth that it will ever be over the lifetime of the entire universe. You'll be able to get a glimpse of it up close with a small telescope or very powerful binoculars. This close approach also offers astronomers our best opportunity to look up close and learn about how planet formation in exoplanetary systems is similar or different to how it unfolded in our solar system.

In the past seven years, we have discovered three members of an entirely new population of celestial bodies: interstellar objects. These objects have hyperbolic orbits, as opposed to the bound circular or elliptical orbits of everything native to the solar system. That's how we know that they come from elsewhere: they come and leave and never return. All we get is a fleeting look into the lifetime of these objects, and the measurements we take during their brief passage through our solar system could provide critical clues into our understanding of planet formation throughout the galaxy.

We know that the solar system ejected a huge amount of material into the Milky Way galaxy in the form of interstellar comets. Our best computer simulations have shown that, in order to reproduce the structure of the solar system that we see today, there was most likely a violent period during which the giant planets Jupiter, Uranus, Saturn, and Neptune migrated, flinging material into the Kuiper Belt and the Oort Cloud. During that process, we probably liberated about 30 Earth masses of 3I/ATLAS-sized comets into the interstellar medium.

In the last 30 years, we have discovered that planets are surprisingly common around other stars. It is therefore not surprising that other planetary systems should also have ejected comets into the Milky Way galaxy. The first known interstellar object, 1I/'Oumuamua, was discovered in 2017. Two years later, we discovered 2I/Borisov, which displayed a prominent cometary tail, and its composition was much different than those of solar system comets. Our telescopic observations revealed that it contains more carbon monoxide than water. Most solar system comets are comprised of a lot more water than any other type of ice.

The ices we see in a comet can tell us something about the conditions in which they formed. For example, water freezes at cold temperatures. The farther away from the sun a comet forms, the colder it is. Therefore, the fact that comets in our solar system have water as their main ice tells us that they mostly formed around where Jupiter is now, about five times more distant than the Earth. Carbon monoxide and carbon dioxide freeze at much colder temperatures than water. Therefore, 2I/Borisov's carbon monoxide tells us that it probably formed at a much farther distance from its star than the typical comets left in our solar system.

Astronomers had been looking for interstellar objects unsuccessfully for six years until we spotted 3I/ATLAS this July. And 3I/ATLAS has been well worth the wait. We have been monitoring it since we discovered it, and our early observations with facilities like the James Webb Space Telescope have revealed that it is enriched in carbon dioxide. This is probably telling us that, like 2I/Borisov, 3I/ATLAS formed much farther out in its progenitor star system than our solar system comets did.

Mere days before Christmas 3I/ATLAS will be at its closest approach to the Earth. This is exciting for everyone, because anyone can go see 3I/ATLAS with a powerful amateur telescope. And for us astronomers, all these critical ice features are easier to detect the closer 3I/ATLAS is to Earth.

These observations might be telling us that comet formation occurs in much farther regions than we previously thought possible based on our inferences from the solar system. In that way, the solar system would be somewhat unique. Alternatively, it's possible that we also produced such distant comets, but all of them were subsequently ejected. And then maybe the solar system is not so unique after all. Either way, 3I/ATLAS is giving us a new window to put our solar system into its cosmic context this Christmas.

To celebrate the thrill of space exploration and the joy of learning, we've created a special crossword puzzle built entirely from this week's top Space.com stories. It's a fun, brain-tickling way to revisit the highlights, whether you're a casual stargazer or a die-hard astrophysics fan.

Expect clues that span planetary science, rocket launches, stargazing, and entertainment tied to the stars. If you read about it on Space.com last week, it might just show up in this puzzle. And if you didn't? Well, now's your chance to catch up while flexing your trivia muscles.

So channel your inner astronaut, and dive into this week's interstellar quiz. The answers are out there, you just have to connect the clues.

Try it out below and see how well you do!

Scientists working with the James Webb Space Telescope discovered three unusual astronomical objects in early 2025, which may be examples of dark stars. The concept of dark stars has existed for some time and could alter scientists' understanding of how ordinary stars form. However, their name is somewhat misleading.

"Dark stars" is one of those unfortunate names that, on the surface, does not accurately describe the objects it represents. Dark stars are not exactly stars, and they are certainly not dark.

Still, the name captures the essence of this phenomenon. The "dark" in the name refers not to how bright these objects are, but to the process that makes them shine — driven by a mysterious substance called dark matter. The sheer size of these objects makes it difficult to classify them as stars.

As a physicist, I've been fascinated by dark matter, and I've been trying to find a way to see its traces using particle accelerators. I'm curious whether dark stars could provide an alternative method to find dark matter.

What makes dark matter dark?

Dark matter, which makes up approximately 27% of the universe but cannot be directly observed, is a key idea behind the phenomenon of dark stars. Astrophysicists have studied this mysterious substance for nearly a century, yet we haven't seen any direct evidence of it besides its gravitational effects. So, what makes dark matter dark?

Humans primarily observe the universe by detecting electromagnetic waves emitted by or reflected off various objects. For instance, the moon is visible to the naked eye because it reflects sunlight. Atoms on the moon's surface absorb photons – the particles of light – sent from the sun, causing electrons within atoms to move and send some of that light toward us.

More advanced telescopes detect electromagnetic waves beyond the visible spectrum, such as ultraviolet, infrared or radio waves. They use the same principle: Electrically charged components of atoms react to these electromagnetic waves. But how can they detect a substance – dark matter – that not only has no electric charge but also has no electrically charged components?

Although scientists don't know the exact nature of dark matter, many models suggest that it is made up of electrically neutral particles – those without an electric charge. This trait makes it impossible to observe dark matter in the same way that we observe ordinary matter.

Dark matter is thought to be made of particles that are their own antiparticles. Antiparticles are the "mirror" versions of particles. They have the same mass but opposite electric charge and other properties. When a particle encounters its antiparticle, the two annihilate each other in a burst of energy.

If dark matter particles are their own antiparticles, they would annihilate upon colliding with each other, potentially releasing large amounts of energy. Scientists predict that this process plays a key role in the formation of dark stars, as long as the density of dark matter particles inside these stars is sufficiently high. The dark matter density determines how often dark matter particles encounter, and annihilate, each other. If the dark matter density inside dark stars is high, they would annihilate frequently.

What makes a dark star shine?

The concept of dark stars stems from a fundamental yet unresolved question in astrophysics: How do stars form? In the widely accepted view, clouds of primordial hydrogen and helium — the chemical elements formed in the first minutes after the Big Bang, approximately 13.8 billion years ago — collapsed under gravity. They heated up and initiated nuclear fusion, which formed heavier elements from the hydrogen and helium. This process led to the formation of the first generation of stars.

In the standard view of star formation, dark matter is seen as a passive element that merely exerts a gravitational pull on everything around it, including primordial hydrogen and helium. But what if dark matter had a more active role in the process? That’s exactly the question a group of astrophysicists raised in 2008.

In the dense environment of the early universe, dark matter particles would collide with, and annihilate, each other, releasing energy in the process. This energy could heat the hydrogen and helium gas, preventing it from further collapse and delaying, or even preventing, the typical ignition of nuclear fusion.

The outcome would be a starlike object — but one powered by dark matter heating instead of fusion. Unlike regular stars, these dark stars might live much longer because they would continue to shine as long as they attracted dark matter. This trait would make them distinct from ordinary stars, as their cooler temperature would result in lower emissions of various particles.

Can we observe dark stars?

Several unique characteristics help astronomers identify potential dark stars. First, these objects must be very old. As the universe expands, the frequency of light coming from objects far away from Earth decreases, shifting toward the infrared end of the electromagnetic spectrum, meaning it gets "redshifted." The oldest objects appear the most redshifted to observers.

Since dark stars form from primordial hydrogen and helium, they are expected to contain little to no heavier elements, such as oxygen. They would be very large and cooler on the surface, yet highly luminous because their size — and the surface area emitting light — compensates for their lower surface brightness.

They are also expected to be enormous, with radii of about tens of astronomical units — a cosmic distance measurement equal to the average distance between Earth and the sun. Some supermassive dark stars are theorized to reach masses of roughly 10,000 to 10 million times that of the sun, depending on how much dark matter and hydrogen or helium gas they can accumulate during their growth.

So, have astronomers observed dark stars? Possibly. Data from the James Webb Space Telescope has revealed some very high-redshift objects that seem brighter — and possibly more massive — than what scientists expect of typical early galaxies or stars. These results have led some researchers to propose that dark stars might explain these objects.

Dark stars may explain early black holes

What happens when a dark star runs out of dark matter? It depends on the size of the dark star. For the lightest dark stars, the depletion of dark matter would mean gravity compresses the remaining hydrogen, igniting nuclear fusion. In this case, the dark star would eventually become an ordinary star, so some stars may have begun as dark stars.

Supermassive dark stars are even more intriguing. At the end of their lifespan, a dead supermassive dark star would collapse directly into a black hole. This black hole could start the formation of a supermassive black hole, like the kind astronomers observe at the centers of galaxies, including our own Milky Way.

Dark stars might also explain how supermassive black holes formed in the early universe. They could shed light on some unique black holes observed by astronomers. For example, a black hole in the galaxy UHZ-1 has a mass approaching 10 million solar masses, and is very old – it formed just 500 million years after the Big Bang. Traditional models struggle to explain how such massive black holes could form so quickly.

The idea of dark stars is not universally accepted. These dark star candidates might still turn out just to be unusual galaxies. Some astrophysicists argue that matter accretion — a process in which massive objects pull in surrounding matter — alone can produce massive stars, and that studies using observations from the James Webb telescope cannot distinguish between massive ordinary stars and less dense, cooler dark stars.

Researchers emphasize that they will need more observational data and theoretical advancements to solve this mystery.

This swirling of spacetime first emerged from Albert Einstein's 1915 theory of general relativity, which predicted that objects with mass "warp" the fabric of space and time (united as a single entity called spacetime) and that gravity arises from this geometric effect. The greater the mass of the object, the larger its impact on spacetime and thus the greater its gravitational influence. In 1918, the concept of massive, rotating objects dragging spacetime along with it was then solidified using general relativity by Austrian physicists Josef Lense and Hans Thirring.

Since then, however, this effect has been difficult for scientists to observe, meaning the new research could offer scientists a new way to study the spin of black holes, the way in which they feed on, or "accrete," matter torn from stars in tidal disruption events (TDE), and how TDEs give rise to powerful outflows, or jets.

"Our study shows the most compelling evidence yet of Lense-Thirring precession — a black hole dragging space time along with it in much the same way that a spinning top might drag the water around it in a whirlpool," team member Cosimo Inserra of Cardiff University in the UK, said in a statement. "This is a real gift for physicists as we confirm predictions made more than a century ago. Not only that, but these observations also tell us more about the nature of TDEs – when a star is shredded by the immense gravitational forces exerted by a black hole."

Watch the wobble

The team set about investigating Lense-Thirring precession by studying the TDE designated AT2020afhd using X-ray data collected by a NASA spacecraft, the Neil Gehrels Swift Observatory (Swift), and radio-wave observations from the Earth-based Karl G. Jansky Very Large Array (VLA).

A TDE occurs when a star wanders too close to a supermassive black hole, and the immense gravitational influence of that cosmic titan, which can be as massive as billions of suns, generates tidal forces within the star that squeeze it horizontally while simultaneously stretching it vertically. This process, called spaghettification, creates a strand of stellar pasta that twists around the black hole like a noodle around a fork, forming a flattened cloud called an accretion disk.

Matter from the accretion disk is gradually fed to the black hole, but these galaxy-dominating titans are notoriously messy eaters, with some material channeled from the poles of the black holes by powerful magnetic fields. From there, this matter is blasted out as twin near-light-speed jets of plasma.

Both the accretion disk of these TDE-perpetrating black holes and the jets they erupt radiate brightly across the electromagnetic spectrum, and because these emissions originate from immediately outside the black hole, they should be impacted by Lense-Thirring precession. This effect translates to a "wobble" in the orbit of matter in the accretion disk around the supermassive black hole.Indeed, while observing AT2020afhd, the team saw rhythmic changes in both X-rays and radio waves coming from this TDE that implied the accretion disk and jet were wobbling in unison, with this motion repeating every 20 Earth-days.

"Unlike previous TDEs studied, which have steady radio signals, the signal for AT2020afhd showed short-term changes, which we were unable to attribute to the energy release from the black hole and its surrounding components," Inserra continued. "This further confirmed the dragging effect in our minds and offers scientists a new method for probing black holes."

Modelling the data from Swift and the VLA, the team was able to confirm these variations were the result of frame-dragging. Further analysis of these results could help scientists better understand the physics behind the Lense-Thirring effect.

"By showing that a black hole can drag space time and create this frame-dragging effect, we are also beginning to understand the mechanics of the process," Inserra said. "So, in the same way a charged object creates a magnetic field when it rotates, we’re seeing how a massive spinning object – in this case a black hole – generates a gravitomagnetic field that influences the motion of stars and other cosmic objects nearby.

"It's a reminder to us, especially during the festive season as we gaze up at the night sky in wonder, that we have within our grasp the opportunity to identify ever more extraordinary objects in all the variations and flavours that nature has produced."

The team's research was published on Wednesday (Dec. 10) in the journal Science Advances.

NASA's Galileo spacecraft (whose mission ended in 2003) spotted the unique feature — officially named Damhán Alla, an Irish word meaning "spider" or "wall demon" — within Europa's Manannán crater. The starburst-like pattern first appeared in images captured by the spacecraft in the late 1990s, but scientists are only now piecing together how it may have formed, according to a statement from Trinity College Dublin.

The spider-like features exhibit branching ridges and troughs that resemble "lake stars" on Earth — delicate, dendritic patterns carved into snow and ice by flowing meltwater. This resemblance, combined with field observations, lab experiments and computer modelling, suggests that the Damhán Alla features may have formed from briny water eruptions beneath the moon's ice, offering clues about subsurface liquid water and the potential for life on Europa.

"The significance of our research is really exciting," Lauren Mc Keown, lead author of the study, said in the statement. "Surface features like these can tell us a lot about what's happening beneath the ice. If we see more of them with Europa Clipper, they could point to local brine pools below the surface."

On Earth, lake stars emerge when snow falls on frozen lakes and holes form in the ice, allowing water to flow upwards and melt surrounding snow, carving radial, branching channels as it spreads. Such patterns are common in nature, from lightning scars to tidal channels, illustrating the movement of fluids and energy through different surfaces.

The researchers suggest that Europa's version might form the same way — except the liquid in this case would be salty brine forced upward after an impact disrupted the ice shell. Under Europa's frigid conditions, such brine could briefly flow, etching star-like tendrils before freezing in place. If correct, features like Damhán Alla could hint at localized pockets of liquid water trapped within Europa's crust.

While current research is limited to images from the Galileo spacecraft, higher-resolution imagery from NASA's Europa Clipper mission, scheduled to arrive at the Jupiter system in April 2030, could reveal new clues about the icy moon.

"Lake stars are really beautiful, and they are pretty common on snow or slush-covered frozen lakes and ponds," McKeown said in the statement. "It is wonderful to think that they may give us a glimpse into processes occurring on Europa and maybe even other icy ocean worlds in our solar system."

Their findings were published Dec. 2 in the Planetary Science Journal.

New images from NASA's Chandra X-ray Observatory give galaxy clusters a bold new splash of color, highlighting the beauty of these cosmic giants.

Galaxy clusters are the most massive objects in the universe held together by gravity, containing galaxies, hot gas, and dark matter, offering clues on how cosmic structures form and evolve. Many host central supermassive black holes, whose powerful outbursts create jets and bubbles that transfer energy to surrounding gas, producing complex structures like hooks, rings, arcs and wings.

Using a novel image-processing technique called "X‑arithmetic," scientists were able to study the nature of different features in the hot gas of galaxy clusters, revealing the dramatic influence of supermassive black holes in vivid detail, according to a statement from NASA.

"By splitting Chandra data into lower-energy and higher-energy X-rays and comparing the strengths of each structure in both, researchers can classify them into three distinct types, which they have colored differently," NASA officials said in the statement.

The new set of images, released on Tuesday (Dec. 9), shows jet‑blown bubbles in yellow, cooling or slow-moving gas in blue and rippling sound waves or weak shock fronts in neon pink. Five major galaxy clusters are featured: MS 0735+7421, the Perseus Cluster, M87 in the Virgo Cluster, Abell 2052 and Cygnus A. While astronomers have studied these objects for years, the new processing technique uncovers structures and dynamics that show how physical processes shape the clusters, rather than just highlighting where the gas shines brightest.

The images highlight remarkable differences between galaxy clusters and smaller galaxy groups, suggesting that black hole feedback — where energy from black hole outbursts heat and reshape surrounding gas — is stronger in galaxy groups, whose weaker gravity makes them more easily disrupted than massive clusters.

"The galaxy clusters in the study often have large regions of cooling or slow-moving gas near their centers, and only some show evidence for shock fronts," NASA officials said in the statement. "The galaxy groups, on the other hand, are different. They show multiple shock fronts in their central regions and smaller amounts of cooling and slow-moving gas compared to the sample of galaxy clusters."

The X‑arithmetic technique offers a powerful new way to map the physics of other galactic structures across the universe and track how black holes shape their environments over millions of years.

The findings were published Aug. 12 in the Astrophysical Journal.

The findings are courtesy of the Center for High Angular Resolution Astronomy (CHARA) array, which is an optical interferometer that combines the light of six telescopes on Mount Wilson in California. CHARA targeted two events of this kind, which astronomers call nova eruptions.

A nova doesn't destroy the white dwarf like a Type 1a supernova does, but rather occurs when the white dwarf siphons too much matter from a companion red giant star. This matter builds up on the surface of the white dwarf until the temperature and pressure grows so great that a localized thermonuclear detonates and extends across the white dwarf's surface while leaving the white dwarf's interior intact. (A white dwarf goes supernova only once the matter it steals from its red giant companion takes the white dwarf above the critical mass of 1.44 times the mass of our sun.)

From Earth, we see a nova eruption as a brilliant brightening of the star, often to naked-eye visibility, hence why the sixteenth century astronomer Tycho Brahe christened this type of object a "nova," which is Latin for "new star."

Previously, astronomers had been unable to observe a nova as anything but a point-source of light, and had assumed that a nova was a single eruption of matter from one point on the white dwarf's surface. However, the Fermi Space Telescope has in the past detected puzzling high-energy gamma-ray emissions from a host of nova eruptions, which implies there's more going on than meets the eye.

Astronomers used CHARA in 2021 to target two nova eruptions within days of them brightening, namely nova V1674 Herculis and nova V1405 Cassiopeia.

"The images give us a close-up view of how material is ejected away from the star during the explosion," Gail Schaefer of Georgia State University and Director of the CHARA array, said in a statement.

Both were very different from each other. V1674 Herculis experienced one of the fastest nova eruptions on record, brightening to magnitude 6 and fading in a matter of days. CHARA detected two bipolar outflows perpendicular to each other, rather than a global eruption all across the white dwarf’s surface. At the same time, the Fermi Space Telescope detected gamma rays from shocks as multiple components in the outflows violently collided.

Nova V1405 Cassiopeiae was, by comparison, a rather sluggish eruption with delayed outflows. CHARA showed that it took fifty days after the initial brightening for material to be lifted off the surface of the white dwarf at the center of the eruption. When the matter was finally ejected, it sparked new shocks as the outflows collided, also emitted gamma rays, and brightened to magnitude 5.5, making it just visible to the unaided eye from the darkest of observing sites. Its brightness stayed more or less the same for seven months before fading.

Additional information also came from the Multi-Object Spectrograph on the 8.1-meter Gemini North Telescope on Mauna Kea in Hawaii. It tracked the matter ejected by the two nova eruptions through the spectral fingerprints of their chemical composition, such as ionized iron, showing how features in the spectrum of each nova aligned with outflow structures seen by CHARA.

"By seeing how and when the material is ejected, we can finally connect the dots between the nuclear reactions on the star’s surface, the geometry of the ejected material and the high-energy radiation we detect from space," said Laura Chomiuk of Michigan State University.

The findings were published on Dec. 5 in the journal Nature Astronomy.

The observations were made using the Atacama Large Millimeter/submillimeter Array (ALMA), a collection of 66 radio antennas in northern Chile that come together to comprise the largest astronomical project in existence.

The dying star being investigated by ALMA, with assistance from the Very Large Telescope (VLT), is W Hydrae, a red giant or AGB star, located 320 light-years from Earth. ALMA looked at this red giant in an entirely new way by observing the emissions and absorption of light by 57 different molecules, so-called spectral lines, each revealing a different layer of W Hydrae's turbulent and violent atmosphere.

"With ALMA, we can now see the atmosphere of a dying star with a level of clarity in a similar way to what we do for the sun, but through dozens of different molecular views," team leader Keiichi Ohnaka, from Universidad Andres Bello (Chile), said in a statement. "Each molecule reveals a different face of W Hydrae, revealing a surprisingly dynamic and complex environment.

"The combination of ALMA and VLT/SPHERE data lets us connect gas motions, molecular chemistry, and dust formation almost in real time — something that has been difficult until now."

Different molecules tell a different story about dying stars

It is the exceptional sensitivity of ALMA, which is capable of capturing the equivalent of snapping a picture of a grain of rice at a distance of 6.2 miles (10 kilometers) away, that allowed the team to see shifting structures within the red giant and its atmosphere. These included "clumps, arcs and plumes," all of which varied depending on the molecule studied. The different molecules offer unique views of W Hydrae because the spectral lines seen by ALMA, the optical "fingerprints" of different chemicals, form under different conditions.

When viewed in these different spectral lines, the red giant was swollen out to many times its original size. In fact, were it placed where the sun sits in the solar system, its outer layers would engulf the planets all the way out to the orbit of Mars. These expanded regions appear as clouds that are sculpted by shocks, pulsations and the transfer of heat from the central star.

The ALMA observations showed a variation in the motion of gas around W Hydrae, with gas closer to the heart of the red giant barreling outwards at speeds of around 22,400 miles per hour (36,000 km/h), while gas in higher layers is falling inward with a speed of around 29,000 miles per hour (46,000 km/h). This creates a constantly shifting layered flow pattern, which matches 3D modelling of how convective cells and pulsation-driven shocks shape the atmosphere of red giants.

One of the most remarkable elements of the team's findings was the revelation of the observed molecules and newborn dust, which emerged when ALMA findings were compared with data collected by VLT's SPHERE instrument. The fact that the two sets of observations were made with just nine days between them allowed the team to link gas chemistry to dust formation in real time. The team found that molecules such as silicon monoxide, water vapor, and aluminum monoxide appear exactly where clumpy dust clouds were seen in the VLT data. That indicates that these chemicals are directly involved in the formation of dust grains.

They also found that other molecules, such as sulfur monoxide, sulfur dioxide, titanium oxide, and possibly titanium dioxide, overlap with dust in some regions around W Hydrae and may therefore contribute to dust formation through shock-driven chemistry. On the other hand, molecules like hydrogen cyanide were found to form close to the star but don't appear to directly participate in dust formation.

As dying stars like W Hydrae shed their outer layers, they enrich their cosmic surroundings, or the interstellar medium, with molecules that become the building blocks of new stars and planets. This research and the observations of dust formation and outflows from a red giant could help better understand how AGB stars lose mass, one of the longest-standing unresolved problems in stellar astrophysics.

"Mass loss in AGB stars is one of the biggest unsolved challenges in stellar astrophysics," team member Ka Tat Wong, from Uppsala University, said. "With ALMA, we can now directly observe the regions where this outflow begins, where shocks, chemistry, and dust formation all interact. W Hydrae gives us a rare opportunity to test and refine our models with real, spatially resolved data."

W Hydrae may also act as a scientific crystal ball, providing a preview of the sun's fate and how our star will enrich our cosmic backyard with the stuff needed for new stars, planets, and even life itself.

The team's research was published on Dec. 2 in the journal Astronomy & Astrophysics.

This exoplanet is six times closer to its parent stars than any previously directly imaged binary system exoplanet, yet despite this relative proximity, it still has a year that lasts 300 times as long as an Earth year.

The discovery of this planet, designated HD 143811 AB b (referring to the fact that it orbits the stars HD 143811 A and HD 143811 B in the system HD 143811 AB), and located 446 light-years away from Earth, is an exciting find for scientists. That is because planets are very rarely detected around binary stars, meaning HD 143811 AB b offers a rare chance to study how stars and planets orbit together, while also investigating planet formation mechanisms.

"Of the 6,000 exoplanets that we know of, only a very small fraction of them orbit binaries," team member and exoplanet imaging expert Jason Wang of Northwestern University said in a statement. "Of those, we only have a direct image of a handful of them, meaning we can have an image of the binary and the planet itself. Imaging both the planet and the binary is interesting because it’s the only type of planetary system where we can trace both the orbit of the binary star and the planet in the sky at the same time.

"We're excited to keep watching it in the future as they move, so we can see how the three bodies move across the sky."

A new discovery from decade-old data

This exoplanet may be new to astronomers, but it isn't actually a new observation. Wang and colleagues discovered HD 143811 AB b in archival data collected almost 10 years ago by the Gemini South telescope and its Gemini Planet Imager (GPI) instrument. GPI captured images of exoplanets by blocking out the overwhelming glare of their parent stars using a coronagraph, an instrument that acts almost like the artificial equivalent of an eclipse. The instrument then used adaptive optics to sharpen the images of these faint planets around their bright stars.

GPI operated from 2014 to 2022, when it was removed from Gemini South and transferred to the University of Notre Dame in Indiana to undergo a major upgrade of the whole system called GPI 2.0. Next year, once upgrades are completed, GPI 2.0 will be moved to the Gemini North telescope atop Mauna Kea, Hawaii.

This discovery came about when Wang and colleagues decided to revisit the GPI data ahead of its new life as GPI 2.0. "I didn’t think we’d find any new planets," Wang said. "But I thought we should do our due diligence and check carefully anyway."

"During the instrument's lifetime, we observed more than 500 stars and found only one new planet," Wang said. "It would have been nice to have seen more, but it did tell us something about just how rare exoplanets are."

Team member Nathalie Jones of the Center for Interdisciplinary Exploration and Research in Astrophysics (CIERA) assessed GPI data gathered over three years between 2016 and 2019, cross-referencing it with data collected by the W.M. Keck Observatory. This led to a tantalizing discovery, a faint object following the motion of a star.

"Stars don't stand still in a galaxy; they move around," Wang explained. "We look for objects and then revisit them later to see if they have moved elsewhere. If a planet is bound to a star, then it will move with the star. Sometimes, when we revisit a 'planet,' we find it's not moving with its star, then we know it was just a photobombing star passing through. If they are both moving together, then that's a sign that it’s an orbiting planet."

Astronomers can determine the difference between light coming directly from a star and light being reflected by a planet, meaning they can also look at data and compare it to what it would look like if a mystery object is indeed a planet. These tests allowed Jones to determine that HD 143811 AB b is indeed a planet that was first captured by GPI in 2016 but was subsequently missed by astronomers. This conclusion was also arrived at by an independent team of astronomers from the University of Exeter in the UK.

Astronomers were also able to learn a lot more about HD 143811 AB b, discovering that this planet is a whopper, at around six times the size of Jupiter. The planet was also determined to be around 13 million years old, which may sound ancient until you consider the Earth is 4.6 billion years old.

"That sounds like a long time ago, but it's 50 million years after dinosaurs went extinct," Wang said. "That's relatively young in universe speak, so it still retains some of the heat from when it formed."

It isn't just the planet that is relatively close to its binary stellar parents; these stars are also quite close together, taking just 18 Earth days to orbit each other. Yet, despite its proximity to the stars compared to other planets found in binary systems, HD 143811 AB b still takes 300 Earth-years to complete just one orbit.

What the team doesn't yet understand is quite how this planet formed around its binary stars.

"Exactly how it works is still uncertain," Wang said. "Because we have only detected a few dozen planets like this, we don’t have enough data yet to put the picture together."

Answering this question could require the team to further study HD 143811 AB.

"I'm asking for more telescope time, so we can continue looking at this planet," Jones said. "We want to track the planet and monitor its orbit, as well as the orbit of the binary stars, so we can learn more about the interactions between binary stars and planets."

In the meantime, Jones intends to continue hunting through archival data to discover more planets. "There are a couple of suspicious objects, but what they are, exactly, remains to be seen," Jones concluded.

The team's research was published on Thursday (Dec. 11) in The Astrophysical Journal Letters.

The findings challenge the prevailing wisdom that relatively small planets orbiting extremely close to their stars cannot sustain atmospheres.

The ultra-hot super-Earth, TOI-561 b, is the innermost of at least three planets circling a 10-billion-year-old star located about 280 light-years from Earth. The planet orbits at just one-fortieth the distance between Mercury and the sun, completing a full orbit in under 11 hours.

That extreme proximity places it in a class of ultra-short-period super-Earths that are heated to temperatures high enough to melt rock. Under such conditions, scientists generally expect planets to lose any atmosphere due to intense stellar radiation, leaving behind bare, airless rock. But observations from NASA's TESS space telescope have shown TOI-561 b has an unusually low density for a purely rocky world, suggesting that another explanation may be needed.

"It must have formed in a very different chemical environment from planets in our own solar system," Johanna Teske, a staff scientist at the Carnegie Earth and Planets Lab in Washington D.C. who led the new paper, said in a statement.

To test whether the planet has an atmosphere, the team used the JWST's NIRSpec instrument to measure the temperature of TOI-561 b's dayside. In May 2024, JWST observed the planet–star system continuously for more than 37 hours, capturing four full orbits. Scientists focused on moments when the planet passed behind its star, events known as "secondary eclipses" when the planet's own light briefly disappeared. By measuring the tiny drop in the system's total brightness during each eclipse, the team could isolate the planet's infrared glow and directly determine its dayside temperature.

If TOI-561 b had no atmosphere, its dayside should reach roughly 4,900 degrees Fahrenheit (2,700 degrees Celsius). Instead, the JWST measured a temperature much cooler, around 3,100 degrees Fahrenheit (1,700 degrees Celsius). To understand why, the researchers tested a range of possible surfaces and atmospheric types to see which could reproduce the signal observed by JWST.

"We really need a thick volatile-rich atmosphere to explain all the observations," study co-author Anjali Piette of the University of Birmingham said in the statement. "Strong winds would cool the dayside by transporting heat over to the nightside."

The team suggests the planet may maintain a balance between its molten surface and its atmosphere, allowing gases to cycle between them and potentially replenishing its atmosphere.

"While gases are coming out of the planet to feed the atmosphere, the magma ocean is sucking them back into the interior," study co-author Tim Lichtenberg of the University of Groningen in the Netherlands said in the statement. "It's really like a wet lava ball."

The results open the door to probe the interiors and geological activity of such extremely hot rocky planets by studying their atmospheres, the researchers note.

The findings were published on Dec. 11 in the The Astrophysical Journal Letters.

Billions of years ago, before the Red Planet became the frigid desert it is today, water sculpted its surface on a massive scale. For decades, Mars has tempted scientists with whispered clues of that watery past, long-dry rivers that carved valleys and spilled through crater rims into deep canyons, hinting at a world that once looked far more like Earth. But although scientists had cataloged thousands of these ancient waterways, they didn't know how they fit together, or whether Mars once hosted large, integrated river systems similar to those that support some of Earth's most biodiverse environments.

"We've known for a long time that there were rivers on Mars," Timothy Goudge, an assistant professor in the department of geological sciences at the University of Texas at Austin, said in a statement. "But we really didn't know the extent to which the rivers were organized in large drainage systems at the global scale."

Stitching together Mars' watery past

In a new study, Goudge and his colleagues have now compiled decades of orbital observations and previously published maps of valleys, lakebeds and outlet canyons, drawing on datasets from NASA's Mars Odyssey spacecraft, which has mapped more than 90% of the planet. The team then traced how these features once connected, revealing which belonged to cohesive, basin-spanning drainage networks.

"We did the simplest thing that could be done — we just mapped them and pieced them together," Abdallah Zaki, a postdoctoral fellow in the department of Earth and planetary sciences at the University of Austin, who led the new study, said in the same statement.

In regions where impact craters or billions of years of erosion had distorted the ancient landscape, the researchers inferred how rivers once flowed by examining topography and the orientations of surrounding valleys, the study notes.

Their results suggest that early Mars was a patchwork of isolated watersheds, but that a small number of mega-basins acted as planetary conveyor belts, transporting nutrients and potential biosignatures across immense distances.

The team identified 16 major drainage basins, each spanning at least 38,610 square miles (100,000 square kilometers), the same minimum size used to define large river basins on Earth. Together, these networks once covered about 1.5 million square miles (4 million square kilometers), or roughly 5% of Mars' ancient terrain. That fraction is also likely conservative, the researchers note, as impact events and wind erosion have erased much of the planet's original fluvial landscape.

On Earth, tectonics build mountain ranges and deep lowlands that guide and connect river systems. Without that process, Mars ended up with just 16 major basins compared with Earth's roughly 91.

Despite their small footprint, those few Martian basins may be among the most scientifically valuable places yet to explore, scientists say. When the researchers estimated how much sediment ancient rivers carried, they found that the 16 large basins transported nearly half of all river-eroded sediment on Mars, suggesting they had an outsized influence on Mars' geologic evolution. One basin alone, feeding into one of the largest canyons on Mars called Ma'adim Vallis, accounted for roughly 15 percent of the total.

On Earth, large-scale river systems are biodiversity hotspots, where water flows through diverse rock types and creates long-lived, chemically rich environments. Mars' mega-basins may have played a similar role when liquid water was abundant. And if life ever gained a foothold on the Red Planet, the team says these ancient river highways — which once carried nearly half the sediment Mars' rivers ever moved — may be the places where evidence of it still lingers.

"The longer the distance, the more you have water interacting with rocks, so there's a higher chance of chemical reactions that could be translated into signs of life," Zaki said in the statement.

The new megabasin map could thus serve as a powerful roadmap for future Mars missions, especially those searching for chemical traces of life or planning sample-return campaigns, the researchers say.

"It's a really important thing to think about for future missions and where you might go to look for life," Goudge said in the statement.

This research is described in a paper published Nov. 24 in the journal Proceedings of the National Academy of Sciences.

What is it?

In this recent image, the Hubble Space Telescope captured NGC 4535's spiral arms studded with bright blue star clusters: tightly packed families of young, hot stars. Around many of these clusters are soft pink-red glowing areas, which are zones of ionized hydrogen gas known as H II regions. These H II regions act like neon signs advertising recent star formation. Massive, newly formed stars pour out intense ultraviolet radiation and powerful stellar winds, energizing the surrounding gas and making it glow.

Where is it?

The "Lost Galaxy" is found around 50 million light-years away in the Virgo constellation.

Why is it amazing?

This new image is part of a larger effort by astronomers to catalog roughly 50,000 H II regions in nearby star-forming galaxies. BY systematically mapping these glowing clouds in galaxies like NGC 4535, astronomers can better understand where and how stars form, how long star-forming regions last and how newborn stars affect the cold gas from which they came, which is part of NASA's larger PHANGS observing program.

From being a faint smudge on an Earth-based telescope to high-resolution photographs from the Hubble, NGC 4535 is no longer quite so "lost." Instead, it's emerging as a laboratory to understand how galaxies grow their stars.

Want to learn more?

You can learn more about star formation and the Hubble Space Telescope.

Discovered on July 1 by the NASA-funded ATLAS telescope in Chile, 3I/ATLAS is only the third confirmed visitor from another solar system, following 1I/'Oumuamua in 2017 and comet 2I/Borisov in 2019.

In November, both the European Space Agency's Jupiter-bound JUICE spacecraft and the Hubble Space Telescope captured new views of the fleeting traveler as it raced through the inner solar system, providing valuable clues about the chemistry and dynamics of bodies born around other stars, scientists say.

On Nov. 2, JUICE pointed five of its science instruments at 3I/ATLAS during a planned campaign to study the comet's activity and composition. That high-resolution data won't reach Earth until February 2026, however. The spacecraft is currently using its main high-gain antenna as a heat shield to protect itself from the sun, according to an ESA statement.

"Our JUICE team couldn't wait that long," ESA wrote. Eager for a sneak peek, engineers used the spacecraft's smaller, slower antenna to trickle home just one-quarter of a single frame from JUICE's Navigation Camera (NavCam), a low-resolution imager designed not for science but for navigating JUICE around Jupiter's icy moons after its 2031 arrival.

The resulting grainy teaser reveals the comet's bright nucleus surrounded by a glowing coma of gas and dust. If you look closely, a faint tail stretches upward. That is the comet's plasma tail, created when sunlight ionizes gas released from its warming surface and the solar wind sweeps those charged particles away from the sun, according to ESA.

If you squint harder, you might also spot a subtler dust tail drifting down and to the left. Recent observations show this dust shows slightly atypical properties, hinting that its grain sizes differ from those of local comets, NASA revealed at a news briefing last month.

The snapshot was taken on Nov. 2, just two days before JUICE's closest approach to 3I/ATLAS, when the spacecraft passed about 41 million miles (66 million kilometers) from the comet. Because JUICE observed the comet just after its closest approach to the sun, on Oct. 30, mission scientists expect the full dataset to reveal even more vigorous, sun-driven activity.

Just weeks after JUICE captured its preview, the Hubble Space Telescope turned its Wide Field Camera 3 back toward 3I/ATLAS for a second round of observations on Nov. 30. The comet was then about 178 million miles (286 million kilometers) from Earth and racing across the background stars. Hubble tracked the comet's motion, causing the stars to smear into thin streaks in the image, a second ESA statement read.

Hubble first imaged 3I/ATLAS in July, shortly after its discovery, revealing a teardrop-shaped cocoon of dust streaming from the comet's icy nucleus. The new observations show a bright central core similarly wrapped in a glow of dust, confirming continued activity.

A recent coordinated NASA-led campaign, which drew on dozens of spacecraft and telescopes from Earth orbit to Mars and beyond, hints at unusual chemistry in the comet’s dust, including a higher-than-normal carbon-dioxide–to–water ratio and gas unusually rich in nickel relative to iron. Both findings may point to formation conditions unlike those in our own solar system, NASA scientists said at a November news briefing.

At the briefing, scientists also said 3I/ATLAS has probably spent a very long time drifting through interstellar space. Its incoming speed suggests it may have been born in an ancient planetary system, possibly one that predates our own.

That "gives me goosebumps to think about, frankly," said Tom Statler, the lead scientist at NASA for solar system small bodies.

At the same briefing, Nicky Fox, the associate administrator of NASA's Science Mission Directorate, stressed that 3I/ATLAS poses no threat to Earth. The comet will come no closer than 170 million miles (270 million kilometers) to our planet and will not pass near any planets as it exits the solar system, including when it crosses Jupiter's orbit in spring 2026.

The objects in our solar system, Fox said, "will be just fine."

The extrasolar planet, or exoplanet, in question is WASP-121b, also known as "Tylos," located around 858 light-years away. WASP-121b is an example of an "ultrahot Jupiter," a massive gas giant planet found so close to its parent star that it can complete an orbit in a matter of hours. As WASP-121b whips around its star once every 30 hours, intense radiation from its stellar parent heats its atmosphere to around 4,200 degrees Fahrenheit (2,300 degrees Celsius).

When a planet undergoes this type of heating, it causes gases of lighter elements like hydrogen and helium to flow into space, a slow atmospheric escape lasting millions of years that alters the planet's size, composition, and how it will evolve. Previously, scientists had caught glimpses of atmospheric escape as exoplanets passed in front of their parent stars, an event called a "transit." But this left a gap in our understanding of this process because scientists couldn't be sure if planetary atmospheres continued to leak outside of those few hours when the planets were observed during a transit.

These new observations, made using the JWST's Near-Infrared Spectrograph (NIRSpec) over around 37 consecutive hours, therefore represent the first most comprehensive continuous observation ever made of the presence of helium on a planet and how it leaks during a complete orbit.

"We were incredibly surprised to see how long the helium escape lasted," team leader Romain Allart, of the University of Montreal, said in a statement. "This discovery reveals the complexity of the physical processes that sculpt exoplanetary atmospheres and their interaction with their stellar environment. We are only beginning to discover the true complexity of these worlds.

A tale of two tails

Helium is one of the most important tracers of atmospheric escape from exoplanets, and the incredible sensitivity of the JWST allows the element to be observed at vast distances. Tracking the light absorbed by helium atoms, the researchers found that the envelope of gas around WASP-121b stretches out far beyond this hot Jupiter. The helium signal lasted for over half the orbit of the planet, making this the longest continuous detection of atmospheric escape yet.

The most remarkable thing about this investigation is the fact that the helium leaking from WASP-121b forms two distinct tails, one of which is pushed back behind the exoplanet by radiation and stellar winds from its parent star. The other tail leads the planet in its orbit, likely pulled forward toward the star by its gravity.

Combined, the helium tails are 100 times as long as WASP-121b is wide, and three times the distance between the hot Jupiter and its star. And the dual tails are something that scientists can't explain with current models.

"Very often, new observations reveal the limitations of our numerical models and push us to explore new physical mechanisms to further our understanding of these distant worlds," team member Vincent Bourrier, of the Department of Astronomy at the Faculty of Science of the University of Geneva, said.

The team's research was published on Monday (Dec. 8) in the journal Nature Communications.

The results come courtesy of the Euclid space telescope, which is a European Space Agency mission that's designed to study dark matter and dark energy by measuring and mapping billions of galaxies. Researchers took a "small" subset of a million of the galaxies Euclid is charting and used them to chronicle the causes of AGN.

An AGN describes a supermassive black hole at the center of a galaxy that suddenly begins consuming vast amounts of material. That material cannot all fit into the black hole's maw all at once, so it waits its turn in an accretion disk circling around the black hole. Think of it as a logjam of gas, and as more and more gas piles up, the density rises and the temperature increases, causing the disk to shine brilliantly. Furthermore, powerful magnetic fields can whip away some of the charged particles within the disk and spit them out in beams moving at almost the speed of light. When we see an AGN with beams coming towards us we call it a quasar or, for the most powerful that are pointed directly at us, a blazar.

It has long been strongly suspected that mergers play a crucial role in sparking AGN activity, because something needs to push all that gas into the nucleus of a galaxy, but suspecting and having confirmation are two different things. Validating this hasn't been as easy as one might think, because the most powerful AGN are at a great distance from us (the closest quasar is 3C273, which is 2.3 billion light-years away) and clearly resolving galaxies at such distances so that we can see that they are definitely merging has been difficult. While the Hubble Space Telescope and James Webb Space Telescope can resolve them, they don't cover a wide enough area of sky to be able to image enough to obtain a census.

Following its launch in 2023, Euclid has changed all that. With its 1.2-meter telescopic mirror, 600 megapixel camera and wide field of vision, in just one week it can provide higher quality images than most other telescopes while covering an area of sky similar to the total area that has been observed by the Hubble Space Telescope during its entire 35 years in service.

Astronomers in the Euclid Collaboration divided the million galaxies seen by Euclid into two categories: one where the galaxies appear to be merging, and one where no merger is taking place.

They then employed an artificial intelligence image decomposition tool developed by Berta Margalef-Bentabol and Lingyu Wang from SRON, the Netherlands Institute for Space Research, to identify AGN in these galaxies and even quantify their power output to determine which are the most energetic.

"This new approach can even reveal faint AGN that other identification methods will miss," said Margalef-Bentabol in a statement.

The team found that there were between two and six times as many AGN in galaxies in the category of mergers than those not experiencing a merger.

In the case of mergers that have begun relatively recently and which have kicked up a lot of interstellar dust such that it shrouds the nucleus, making it only visible in infrared light, there are six times more AGN. In the case of mergers that are nearing their end stages and in which the dust has all settled, there are still twice as many AGN than in the non-merger galaxies.

"The difference between the two AGN types could mean that many AGN found in non-mergers are actually in merged galaxies that have completed the chaotic stages and appear as a single galaxy in a regular form," said Antonio la Marca of the University of Groningen.

The observational evidence not only heavily supports the concept of mergers being a trigger of AGN activity, but also indicates that mergers are the primary cause, particularly for the most luminous AGN.

"We also conclude that mergers are very likely to be the only mechanism capable of feeding the most luminous AGN," said la Marca. "At the very least they are the primary trigger."

AGN represent the most rapid growth phase of supermassive black holes, and the outpouring of radiation from these gluttonous black holes can heat the molecular gas in a galaxy, preventing it from forming stars. AGN can therefore have a long-term impact on their host galaxy, and understanding that the host is likely to be merging is important to know when modeling the evolution of galaxies.

The findings are set to be published in the journal Astronomy & Astrophysics, and are available as two pre-prints, one detailing the analysis of merging galaxies and AGN, and the other describing the AI image decomposition tool.

This realization, resulting from placing old data from Voyager 2 under new scrutiny, could help explain several puzzling aspects of Uranus's magnetic envelope.

When the fast component of the solar wind, which emanates through coronal holes on the sun and is somewhat irregular, slams into slower portions of the solar wind, it results in electromagnetic shocks in the sleet of charged particles carried on the wind. Such an event is referred to as a co-rotating interaction region, and when one occurs near Earth, it can be one of the causes of geomagnetic storms that can result in the aurora.

The solar wind extends out past Earth, and even beyond Uranus, Neptune and the Kuiper Belt to form the 'heliosphere', which is a magnetic bubble around the solar system. The realization that a co-rotating interaction region may have been passing Uranus at the same time as the Voyager 2 encounter on Jan. 24, 1986 could be the missing piece of the puzzle that has eluded scientists for nearly four decades.

Voyager 2 remains the only mission to have visited Uranus (and Neptune, for that matter). What it found was a cold, icy gas bag with a very strange magnetosphere, which is what we call the magnetic envelope generated by the planet's intrinsic magnetic field. The north–south orientation of that magnetic field is tilted by 59 degrees relative to Uranus' axis of rotation, which itself is tilted by 98 degrees relative to the ecliptic plane. Furthermore, the magnetosphere is off-center inside Uranus, allowing for a much stronger magnetic field in the north than in the south.

Just as Earth's magnetosphere is ringed by belts of radiation in the form of charged particles, so is Uranus. Yet, when Voyager 2 arrived in 1986, it found that there was barely any plasma (ionized gas) contained within Uranus' magnetosphere. In fact, the magnetosphere had been compressed and the plasma seemingly squeezed out. What was in abundance were electrons, contained in surprisingly densely populated belts.

Back in 1986, scientists thought that a solar-wind event like a co-rotating interaction region would scatter electrons present in Uranus' magnetosphere into the planet's atmosphere. However, almost four decades of studying the solar wind and how it interacts with planets has taught us something different.

"Science has come a long way since the Voyager 2 fly-by," said the Southwest Research Institute's Robert Allen, who led the new research, in a statement. "We decided to take a comparative approach looking at the Voyager 2 data and compare it to Earth observations we've made in the decades since."

While on some occasions co-rotating interaction regions can scatter electrons into a planet's atmosphere, studies of their interaction with Earth have shown that such an event can also dump a lot of energy into the magnetosphere.

"In 2019, Earth experienced one of these events, which caused an immense amount of radiation-belt electron acceleration," said Sarah Vines, who is also from the Southwest Research Institute. "If a similar mechanism interacted with the Uranian system, it would explain why Voyager 2 saw all this unexpected additional energy."

In the absence of a second mission to Uranus after Voyager 2, scientists have learned to squeeze all they can out of the old Voyager 2 data instead, using new insights and techniques garnered over the past four decades, to learn more about the ice giant. These new findings come just a year after another team looked at the old data to conclude that the solar wind had indeed compressed Uranus' magnetosphere, squeezing out the plasma normally present.

For those four decades, scientists had thought that Uranus' magnetosphere was always in this bizarre state, but now we are learning that we simply caught it at a rare moment, and that what Voyager 2 measured might not be the status quo.

"This is just one more reason to send a mission targeting Uranus," said Allen.

Uranus is not alone in having a strange magnetosphere. When Voyager 2 encountered Neptune three-and-a-half years later, it found that it too had a displaced and tilted magnetosphere, just like Uranus. Indeed, the findings of the new analysis of the old Uranus data "have some important implications for similar systems, such as Neptune's," added Allen.

Perhaps misaligned magnetospheres are typical of all ice giants, both in the solar system or beyond. Or perhaps they are atypical, or symptoms of Uranus and Neptune's unique histories. Either way, new missions are urgently needed to provide the first close-up data in nearly 40 years and counting. Fortunately, a new Uranus mission is currently a top priority for NASA.

The new analysis of the old Voyager 2 data can be found in a paper published on Nov. 21 in Geophysical Research Letters.

What is it?

Construction on the ELT officially began in 2014, with the observatory designed around a segmented primary mirror that's 128 feet (39 meters) wide — nearly five times larger than any current ground-based optical telescope mirror. Once operational, the ELT will use advanced adaptive optics to correct for atmospheric turbulence, yielding images 15 times sharper than those from the Hubble Space Telescope.

Where is it?

This drone image was taken high above Cerro Armazones, the 9,993 -oot-tall (3,046 m) mountain where the ELT is located.

Why is it amazing?

Given its advanced instruments, the ELT's overarching mission is to push observational astronomy into a new precision era. The huge telescope will directly image small, rocky exoplanets and look for possible conditions suitable for life outside our solar system. The ELT will also help scientists study our universe's origins by looking at distant galaxies while also measuring the universe's rate of expansion. This telescope will also be used to study stellar dynamics and how stars are born, evolve and sometimes turn into black holes.

As the ELT's construction nears completion, the world waits to see just what this cutting-edge telescope will show us about the world we live in.

Want to learn more?

You can learn more about the Extremely Large Telescope and other ground-based telescopes.

In the letter, Genzel and 30 other world-leading astronomers urge Chilean leaders to protect the pristine, unpolluted night sky above Cerro Paranal, an 8,740-foot-high (2,664-meter) peak in the Atacama Desert that is home to the European Southern Observatory's (ESO) most valuable astronomical observatories including the Extremely Large Telescope (ELT), which when built will be the world's largest telescope.

The astronomers believe that the Paranal Observatory, currently considered among the least light-polluted astronomical sites in the world, will suffer if a planned clean hydrogen plant gets a go-ahead. "As currently conceived, the project represents an imminent threat to some of the most advanced astronomical facilities on Earth, operating under one of the world's last pristine dark skies," the scientists wrote in the letter, criticizing the placement of the clean hydrogen plant, called INNA, just a few miles from the summit of Cerro Paranal. "Earlier this year, an in-depth, data-driven technical analysis by ESO revealed that INNA would cause an increase of up to 35% in light pollution above Cerro Paranal."

It's not just light pollution that poses a threat, however. the letter continues. The signing scientists write that the same analysis "also revealed other impacts of the project, from creating micro-vibrations that will negatively affect and possibly impede the operation of some of the most cutting-edge astronomical facilities, to increasing turbulence that blurs our view of the universe."

The Paranal Observatory is home to the Very Large Telescope (VLT), which is actually a quartet of telescopes with 27-foot-wide (8.2 meters) mirrors that can work in concert as a so-called interferometer to maximize the facility's sky-observing abilities.

Genzel, who won the 2020 Nobel Prize in Physics for his research of the Sagittarius A* black hole at the heart of the Milky Way galaxy, used VLT to observe the movements of stars close to the galaxy's center to determine the black hole's properties.

Cerro Paranal is also home to the Cherenkov Telescope Array, the world's most powerful observatory for research of high-energy gamma rays, extremely energetic radiation emitted from black holes and released in supernova explosions. According to the ESO analysis, the Cherenkov array could suffer an up to 50% light pollution increase from the proposed plant, being located only 3 miles (5 kilometers) away from the prospected site.

The astronomers think that interference from the hydrogen plant might degrade Paranal from being the world's premium astronomy site to a merely mediocre one.

"We might lose the ability to observe about 30% of the faintest galaxies," Xavier Barcons, ESO's Director General, told Space.com in an earlier interview. "We are at the point of starting to be able to see details of exoplanet atmospheres, but if the sky gets brighter, we may not be able to see those details anymore."

The unspoiled nature of the Paranal sky, together with the world's most favorable weather conditions for astronomy, prompted ESO to choose the neighboring Cerro Armazones as a site of the next-generation ELT. ELT, currently under construction, will be fitted with a single 130-foot-wide (39.3m) mirror and will become the world's largest telescope capable of studying the universe in visible light.

The $1.4-billion observer should enable astronomers to directly image exoplanets orbiting nearby stars and observe the most distant galaxies. The presence of INNA, however, is likely to increase the brightness of the sky above ELT by 5%, reducing the telescope's scientific potential.

The $10 billion INNA renewable hydrogen plant, developed by the U.S.-headquartered energy company AES, will spread across 7,500 acres (3,021 hectares) of land and consist of three solar farms, three wind farms, a battery energy storage system and facilities for the production of hydrogen.

AES submitted its environmental assessment for the development a year ago and is awaiting a decision by local authorities. The astronomers call for the plant's relocation away from Atacama's precious observatories.

"While we recognize the need, both in Chile and globally, to develop green energy facilities, the proximity and extent of the infrastructure associated with the INNA project pose a grave threat, which cannot be mitigated given the closeness of the planned installation to the observatory," the scientists wrote in the letter. "We are convinced that economic development and scientific progress can and must coexist to the benefit of all people in Chile, but not at the irreversible expense of one of Earth's unique and irreplaceable windows to the universe."

AES previously told Space.com that the site's impact on the Paranal night sky would be negligible.

NASA just released striking new video and audio that reveal the sounds of dust storms on Mars crackling with tiny lightning-like sparks.

The footage, which NASA released on Dec. 3, was captured by the Perseverance rover inside Jezero Crater on Sept. 6, as Martian dust devils swept across the surface. Meanwhile, the rover's SuperCam microphone also picked up the sounds of faint crackles and mini-sonic booms, marking the first clear recording of electrical discharge inside a Martian dust storm, according to a statement from NASA.

For decades, researchers suspected that wind-blown dust on Mars could build up enough static charge to spark, but that idea long remained mostly theoretical. Mars' thin atmosphere lowers the threshold for electrical discharge, allowing even small swirls of dust to generate sparks that would never form in Earth's denser air.

Perseverance has now confirmed those theories — not just in raw sensor data, but in sound you can actually hear. While the discovery was first detailed in a study published Nov. 26 in the journal Nature, NASA has now released, for the first time, a striking GIF and audio clip showcasing the electrified dust devils in action.

"We got some good ones where you can clearly hear the 'snap' sound of the spark," Ralph Lorenz, co-author of the study and a Perseverance scientist, said in the statement.

Dust devils on Mars form when air near the warm surface heats up and rises through cooler surrounding air, causing nearby air to rush in and start rotating. As this spinning air column accelerates, it lifts dust from the ground, creating a swirling dust devil.

Electrical sparks then form when dust particles in the swirling column rub and collide, building up static electricity. When the charge gets strong enough, it discharges as a tiny spark — a process called the triboelectric effect, which is similar to the static shock a person may experience from walking on a carpet and touching a metal doorknob.

These sparks aren't dramatic lightning bolts like on Earth — they're tiny, localized and only centimeters long. Studying them helps researchers better understand Mars' atmospheric chemistry, climate and habitability, and could guide the design of future robotic and human missions to the Red Planet.

While exploring Mars, Perseverance has logged dozens of these electrical events, and at least one passed directly over the rover, letting its microphone capture the crackling walls of dust as grains collided and discharged.

"In the Sol 215 dust devil recording, you can hear not only the electrical sound, but also the wall of the dust devil moving over the rover," Lorenz said in the statement. (A sol, or Martian day, is about 40 minutes longer than a day here on Earth.) "And in the Sol 1,296 dust devil, you hear all that plus some of the particles impacting the microphone."

The new audio and visual data from Perseverance provide a fresh look at Mars, capturing the sparks and crackles in the swirling dust storms that rage across the planet's surface.