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James Webb Space Telescope uncovers new clues about the origins of ‘interstellar invader’ comet 3I/ATLAS

Using the James Webb Space Telescope (JWST), scientists have found that the interstellar comet 3I/ATLAS was built from tiny grains of ice mixed with dust that are quite different from the solar system’s comets.

These ice grains do, however, bear striking similarities to some icy bodies located at the edge of the solar system, beyond the orbit of Neptune, so-called trans-Neptunian objects (TNOs).

3I/ATLAS was discovered entering the solar system in the summer of 2025. It was only the third object found entering the solar system from farther afield in the Milky Way after 1I/'Oumuamua, seen in 2017, and 2I/Borisov, detected in 2019. This meant the interstellar comet offered a rare chance to glimpse the conditions under which such bodies form in other star systems. Thus, the JWST was quickly on the trail of 3I/ATLAS.

"We designed [JWST] to be ready the moment an active interstellar comet was found and to follow it over time," Martin Cordiner of NASA’s Goddard Space Flight Center and the Catholic University of America said in a statement.

Cordiner leads the JWST program to study objects such as 3I/ATLAS, and he is a co-author on a new research paper describing some of the findings.

The unclear origins of 3I/ATLAS

Researchers know that 3I/ATLAS wasn't born in the solar system, but nobody knows around which star 3I/ATLAS formed. What scientists are more sure of is the fact that this interstellar comet was produced within a planet-forming disk of gas and dust around a young star, possibly as long ago as 10 to 12 billion years. That's over twice the age of our solar system. It was then ejected from its home system somehow and left to wander interstellar space before encountering our solar system.

Like the familiar comets in our solar system, 3I/ATLAS is composed of grains of ice less than a micron – a millionth of a meter – in size. When the surface of the comet is warmed by the sun, gas erupts outwards, carrying ice grains into the cloud of ice and dust surrounding the comet, its coma, and its tail, where JWST can detect them.

When viewed spectroscopically, the water-ice in comets native to our solar system creates a strong absorption line in a comet’s spectrum at a wavelength of three microns, as well as less-prominent absorption lines at 1.5 and two microns.

Comparison between ice in the interstellar invader comet 3I/Atlas and icy bodies in our solar system.

Comparison between ice in the interstellar invader comet 3I/Atlas and icy bodies in our solar system. (Image credit: SwRI/Silvia Protopapa/NASA/ESA/CSA JWST)

Yet when the JWST’s Near-Infrared spectrograph (NIRSpec) instrument viewed 3I/ATLAS three times between August 2025, before its closest approach to the sun, and after closest approach in April 2026, scientists found the 1.5- and two micron absorption lines were missing, though the three-micron line remained strong.

"That combination was a puzzle," research lead author Silvia Protopapa of the South-west Research Institute said. "The strong three-micron band points to water-ice in the coma, but the weak or absent shorter-wavelength bands suggest the ice is not in the form we usually see in solar system comets."

The JWST's muddy 3I/ATLAS findings

Whenever presented with an unusual observational signature such the JWST delievered for 3I/ATLAS researchers turn to modeling to find the physical characteristics that best fit the spectrum.

The modeling suggested to Protopapa’s team that 3I/ATLAS was composed of sub-micron grains of dirty water-ice, rich in dust. In comparison, the grains from the solar system’s indigenous comets are much cleaner, with almost pure water-ice relatively uncontaminated by dust.

"What seems to set [3I/ATLAS’ grains] apart is how much dust is mixed into the ice," said Protopapa. "Those grains hold clues to the conditions where the comet was born."

Three boxes contain a glowing center that in the left box is blue, the middle box is yellow, and the right box is red.

The chemical composition of 3I/ATLAS (Image credit: NASA, ESA, CSA, STScI, Martin Cordiner (CUA, NASA-GSFC); Image Processing: Alyssa Pagan (STScI))

Comets are made of primordial material found in the planet-forming disk of gas and dust that surrounds a young star, and therefore the composition of comets can provide a window into the conditions in which planets form.

Whereas solar system comets tell us about the birth of Earth, an interstellar comet can tell us about conditions in which planets formed around another star, and how similar or dissimilar those conditions were to the birth of the solar system.

Yet comets are not the only icy remnants that date back to such primordial times. There are various families of bodies in the outer solar system, and 3I/ATLAS’ spectrum bears a resemblance to the spectrum of some medium-sized TNOs that are rich in carbon-dioxide ice and organic compounds (organic meaning containing carbon atoms). Indeed, in a separate 2025 study led by Cordiner, the JWST found 3I/ATLAS to have one of the greatest abundances of carbon dioxide ever seen in a comet.

TNOs are sizable bodies that are located far beyond the orbit of Neptune, The TNOs in question would have formed in a different part of the Sun’s protoplanetary disk than most comets and their composition reflects that.

A purple and blue disk composed of rough concentric circles

Artist's illustration of a planetary disk, a region of dust and gas where planets form. The zoom-in insert displays carbon monoxide molecules in the ice phase. (Image credit: M.Weiss/Center for Astrophysics | Harvard & Smithsonian)

On the other hand, the results imply that 3I/ATLAS was formed around its star of origin from similar icy material to that which produced some of the TNOs in our solar system, showing that the building blocks of planets around other stars share a common range of properties with the building blocks that formed our solar system. Indeed, 3I/ATLAS could even be a fragment of a TNO-like body that was shattered in a collision.

"At first glance, 3I/ATLAS looks different from the icy comets we know," said Protopapa. "But when we placed it alongside distant icy worlds in our own solar system, it no longer looked out of place.

"This suggests that the icy building block of planets, here and around other stars, may share ice in the form of tiny, micron-scale grains, ranging from relatively pure ice to ice mixed with dust, with 3I/ATLAS toward the dusty end."

What this tells us is that these sub-micron-sized icy grains must form first in planet-forming disks, to then be incorporated into large bodies such as comets and protoplanets.

The team's findings were published on Monday (Oct. 26) in The Astrophysical Journal Letters.

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Scientists discover ‘chemical starter kit’ for life in planetary birthplaces

Methanol, coming as part of the 'chemical starter kit' around young stars, has produced some unexpected surprises that could ultimately reveal some of the conditions in which planets and potentially life form around protostars.

The methanol discoveries were made by astronomers using ALMA (the Atacama Large millimeter/submillimeter Array) in the Atacama Desert in Chile, as part of a project called COMPASS (the Complex Organic Molecules in Protostars with ALMA Spectral Surveys).

"Our work provides insight into the complex chemistry of young star systems and is ultimately an important piece of the puzzle in understanding the origin of life," said University of Bern astrophysicist Maria Drozdovskaya, who leads the COMPASS project, in a statement.

Drozdovskaya's multinational team of more than 30 astronomers has been chasing down complex organic molecules, large molecules that include carbon atoms, in the planetary construction yards around eleven young stars.

These molecules form part of the chemical inventory that ultimately builds planets and, perhaps, even life that will one day live on those planets.

Methanol matters

Methanol (CH3OH) is important because it is highly abundant in star- and planet-forming regions. In fact, it’s the most abundant complex organic molecule to be found in interstellar space, and is commonly found in planet-forming disks.

Its sheer abundance means that, of all the molecules found around young stars, methanol is the easiest in which to detect different forms where regular hydrogen atoms are replaced by a heavier isotope of hydrogen called deuterium.

How many molecules contain these heavier isotopes is highly dependent upon the conditions in which planets are forming within the disk.

That’s why the COMPASS team used ALMA to search for these forms of methanol in the gas belonging to the planet-forming disks around the 11 nearby low-mass protostars. The observations have also helped assess the general chemical diversity of these disks.

red clouds of gas and dust in deep space

The Perseus Molecular Cloud home to the protostar IRAS 4A2 (Image credit: NASA/JPL-Caltech)

The unexpected discovery of a methanol molecule containing deuterium was made in the planet-forming disk around only one of those 11 stars, namely the young star IRAS 4A2, located about a thousand light-years away in the Perseus Molecular Cloud.

IRAS refers to the Infrared Astronomical Satellite, which was a joint NASA–UK–Netherlands mission launched in 1983 and which first detected this young star as a source of infrared light through the thick gas and dust of the molecular cloud.

The COMPASS team also discovered methanol maser emission from more than half of the 11 protostars, favoring the youngest of the stars. A maser is a microwave version of a laser in the sense that the microwave emission is being stimulated and then amplified, but astrophysical masers occur naturally, often in shock fronts as methanol molecules collide and are excited.

Methanol masers have previously been detected in planet-forming disks around turbulent high-mass protostars, but COMPASS’ observations are the first detection of them around calmer lower-mass protostars.

"The fact that it has now also been found in a low-mass protostar shows that locally extreme physical conditions can prevail there analogously to massive stars and challenges our previous understanding of the formation of sun-like stars," said Drozdovskaya.

Some of the antennas in the ALMA array.

Some of the antennas in the ALMA array located in the Atacama Desert (Image credit: ESO/C. Malin)

The finding implies that methanol masers are a common product of all planet-forming discs and therefore are produced by processes that are universal in star- and planet-birth, regardless of the protostar's mass.

For example, thermal bursts from the growing star as it accumulates gas from its surroundings could generate shocks in a planet-forming disk, stimulating maser activity in the abundant methanol.

"Both results underscore how important high-performance spectroscopic measurements like those from COMPASS with ALMA are for detecting rare and previously unknown chemical phenomena," said Drozdovskaya, referring to both the methanol masers and the deuterium-rich methanol molecules around IRAS 4A2. "They show just how much we still have to learn about the chemical processes in young protostellar systems."

A glowing golden disk made up of concentric rings

A protoplanetary disk contains the gassy and dusty material that gives rise to planets and their moons. A few planets have coalesced out of the disk in this artist’s impression. (Image credit: University of Copenhagen/Lars Buchhave)

The new findings have at least begun to answer some questions, such as how the diversity in this 'chemical starter kit' varies from star to star, with ALMA detecting some subtle differences, such as variations in the abundance of oxygen- and nitrogen-bearing molecular species among the eleven stars.

However, questions about how the chemistry of young star systems arises and how it influences the evolution of those systems remain unanswered.

For now, the COMPASS team is painstakingly and systematically studying the data on all the different types of molecules detected in their ALMA observations, and preparing follow-up studies with other facilities including the James Webb Space Telescope (JWST).

"The analysis of all the collected data will take several more years," said Drozdovskaya.

The first results from COMPASS are published in seven papers [1, 2, 3, 4, 5, 6, 7] in the October 2026 issue of the journal Astronomy & Astrophysics.

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Earth’s poles shifted surprisingly fast during the age of dinosaurs, ancient sea levels reveal

The location of Earth's geographic poles has changed several times over the past 320 million years in a process known as true polar wander, according to measurements of ancient flooding brought about by sea level changes resulting from our planet's crust shifting relative to Earth's spin axis.

Such a shift can affect climate, both on local scales and globally, as regions that were by the poles find themselves moving down to lower latitudes and vice versa. This can then affect atmospheric circulation patterns, which affect climate across the world.

The changes would have affected the environments in which life developed and evolved, from the age of the dinosaurs through to some of our oldest primate ancestors.

True polar wander is not the same as a change in the rotational axis of the Earth. Currently, Earth spins at an angle of 23.4 degrees relative to the plane of its orbit around the sun, and this rotational axis can vary periodically over tens of thousands of years as a result of the Milankovitch cycles caused by the gravitational pull of the sun and planets.

True polar wander is different. Here, the angle of Earth's spin axis does not change relative to its orbital plane. Instead, Earth's crust and mantle shift relative to that rotational axis. This is because Earth is not perfectly spherical. Instead, it is oblate, with Earth's rotation causing the equator to bulge out and the poles to slightly flatten. Because Earth is not spherical, it has multiple axes of inertia, the largest one being aligned with the rotational axis.

These axes need to be balanced to prevent Earth's rotation from becoming chaotic. However, plate tectonics and indeed the Milankovitch cycles can upset that balance of mass, for example by causing more continental crust to congregate in one hemisphere than another.

To rebalance things, Earth's crust and mantle must become decoupled from our planet's core, which stays aligned with the rotational axis. In physical terms, if there is more continental crust in one hemisphere, the crust and mantle might rotate in that direction relative to the rotational axis and the Earth's core in order to balance itself. This sees the geographical locations of the poles change, hence the name 'true polar wander'.

Currently, true polar wander takes place at a rate of 10 centimeters (4 inches) per year, but figuring out when and how fast true polar wander has occurred in the past is not without its difficulties, not least since plate tectonics can mask and even mimic the signal of true polar wander.

Previous studies relied on paleomagnetism, the study of residual magnetic traces in ancient rocks, since the orientation of those magnetic traces would have varied depending upon where that rock was located relative to Earth's magnetic field. Alas, it's not a terribly accurate means of measuring true polar wander and scientists arrived at substantially different conclusions using this technique.

Nevertheless, based on paleomagnetism, scientists had concluded that true polar wander had been negligible, or slow to proceed, in the distant past. However, new results from researchers at the Centre for Planetary Habitability at the University of Oslo in Norway, led by Mathew Domeier, have shown this not to be the case.

Domeier's team looked through the geological record to track how sea level has changed across millions of years. True polar wander would bring about an identifiable pattern in sea-level changes as the oceans reacted in response to changes in the mass distribution of the planet. The sea level changes would be equal but opposite between hemispheres — sea level rises on one side of one hemisphere would be matched by rises on the other side of the opposite hemisphere, creating a 'quadrupolar' effect.

By using statistical modeling on maps of sea level changes across intervals of 10 million years, Domeier's team identified four periods of true polar wander: in the early Jurassic period 190—200 million years ago, the late Jurassic — early Cretaceous period 140—150 million years ago, during the mid-Cretaceous 90—100 million years ago and from the Oligocene period 30 million years ago through to the Miocene 20 million years ago.

The results show that, contrary to established opinion, true polar wander can happen in bursts that are relatively fast on geological timescales, with the results showing that during the episodes of true polar wander the Earth's surface shifted by as much as 0.6 degrees per million years relative to the spin axis. This is slow by human standards, but fairly fast on geological timescales, certainly quicker than plate tectonics.

Domeier's team were also able to rule out a suspected case of true polar wander around 300 million years ago when the last great supercontinent, Pangea, migrated northwards. It turns out that Pangea's movements were entirely due to plate tectonics.

The findings were published on Oct. 1 in the journal Science.

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Space weather caused a 16-minute train delay in 1848: ‘Our research has a hint of a detective story’

Detective work by a team of space-weather experts has discovered the truth about a historical event that had been thought to be the first-ever case of technological disruption by geomagnetic activity from the sun, but has now been shown to have taken place seven years later.

From it being too hot or too wet to leaves on the track or cows on the line, there's a fine tradition of what the British public consider to be flimsy excuses for delays on the trains. Yet an 1871 edition of the journal Nature describes a very different event that caused a train departing Exeter, in Devon on the south-west coast of the U.K., to be delayed by 16 minutes: a solar storm that flooded the railway signals' electrical telegraph network with current.

"The Exeter train delay is a fascinating story because it sits right at the point where emerging technologies first began to encounter the realities of the space environment," said Jim Wild, who is a professor of space physics at Lancaster University and also the President of the Royal Astronomical Society, in a statement.

The event has frequently been cited as the first example of a solar storm disrupting technology on Earth, but when a team led by Wild went back through historical records to investigate further, they found that things didn't add up.

The original report in Nature stated that the electrical disturbance occurred at 10:05pm local time on Oct. 18, 1841. However, Wild's team found that particular train line didn't open until 1846.

So, they delved deeper into the history books to figure out the truth.

"Our research has a hint of a detective story — piecing together a wide range of archived records to better understand a historically severe space-weather event," said team-member Mike Hapgood, a space weather expert at RAL Space, which is the UK's National Space Laboratory, in Oxfordshire.

Combining data from railway timetables, old newspapers, plus historic reports of solar observations and the northern lights and digitized geomagnetic data, Wild and Hapgood's team were able to conclude that the most likely date for the train delay was Oct. 18, 1848, which coincided with a strong solar storm that hit Earth.

This revised date knocks it off top spot in the chronological list of such events. The first recorded disruption to electrical technologies is now a disturbance on the Midland railway network, which had lines covering much of the U.K., in March 1847.

"Although this means it is not the earliest recorded space weather impact, it remains one of the first clear examples of solar activity disrupting critical infrastructure," Wild said. "It also demonstrates the value of combining scientific records with contemporary newspaper reports and archival documents when reconstructing historic space weather events."

A view of a yellow sphere with some flares coming off of it.

Solar storms have been playing havoc with electrical technology on Earth since the 1840s. (Image credit: NASA/SDO)

The case reminds us that space weather has been a hazard to technology and modern systems for a long time, and isn't just a recent problem.

"Society has been experiencing the effects of space weather on technology for almost as long as electrical technologies have existed," said Wild.

The most dramatic example is the aforementioned Carrington event of 1859, representing the most significant solar storm on record as it caused telegraph poles to spark and battery power supplies to be disrupted. By this point, telegraph operators had grown used to electrical disturbances associated with auroral activity, but even the Carrington storm shocked them — quite literally in some cases, as extra current ran down the telegraph lines — with its ferocity. Should a similar event occur today, it would cause huge black outs, knock out power grids, disrupt communications and fry satellites.

"While today's space weather [monitoring] capabilities are far more advanced than anything available in the 1800s, the modern technologies we depend on are also much more vulnerable to solar storms," said Hapgood.

The current solar cycle 25 peaked in Oct. 2024 and we are just beginning to come out of an extended period of maximum activity. However, it remains to be seen how the rest of this cycle will play out before reaching solar minimum in about 2030. We've already seen severe geomagnetic storms caused by space weather in May 2024 — will we experience another powerful storm before the decade is out?

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22 years of science! NASA’s Roman Space Telescope doubles its lifetime with super-precise engine burn

NASA's newly launched Nancy Grace Roman Space Telescope is set to extend its lifespan and double its exciting potential for discovery thanks to an efficient use of fuel on its way to its final orbit.

"As a result of exquisite planning by our orbital dynamics team, brilliant execution by the operations team, and a precise launch from SpaceX, Roman has fuel for at least 22 years of potential science operations," said Jamie Dunn, the center director at NASA's Goddard Space Flight Center, in a statement.

The space telescope, which launched from Cape Canaveral on Aug. 30 on a mission to measure dark energy and search for exoplanets, is headed to the L2 Lagrange point. There, it will join the likes of the James Webb Space Telescope on the opposite side of Earth to the sun. Its primary mission will last five years, and scientists were hoping for an additional five years if funding allowed.. Now, however, that potential extended mission could go on for a lot longer — and it's all thanks to the spacecraft coming in less massive than the original design had projected.

A diagram showing the Lagrange points.

The Lagrange points depicted in a diagram. (Image credit: NASA Goddard Space Flight Center Scientific Visualization Studio)

At the beginning of Roman's design process, the fuel capacity was chosen to permit a maximum mass of 21,605 pounds (9,800 kilograms), yet the finished spacecraft came in lighter at 17,760 pounds (8,065 kilograms). And because it was lighter, there was a surplus of available mass that could be used for more fuel.

"A spacecraft's mass changes throughout the design and build process, so we base the propellant on a set maximum value so we won't come up short," Alison Rao, who leads Roman's propulsion systems at NASA Goddard, said in the statement. "We track the propellant needed based on actual mass throughout integration and testing as well, to make sure we have wiggle room. Since Roman's [mass] was lower than we budgeted for, we were able to fill the propellant tanks to their capacity rather than only filling them as much as we needed to for the 10-year requirement."

The extra fuel loaded onto the telescope before launch meant it had enough for at least a 14-year mission. Then, within a day of launching, the space telescope had to fire its engine for three minutes to push it onto a trajectory to take it to L2. This engine burn was more precise and hence more efficient than anyone could have hoped for, sending Roman on its way to L2 with 99% accuracy. In doing so, it used only 40 pounds (18 kilograms) of fuel, which is less than 10% of the 441 pounds (200 kilograms) of fuel that had been budgeted for the maneuver. This is thought to have bought Roman an additional four years of life, bringing the tally to 18 years.

Then there's the added bonus. The precision with which the Aug. 31 engine burn was conducted means that the second course correction, required to take Roman into its orbit at L2 in early December, will also now require much less fuel. This will add yet another four years to Roman's operational lifetime, so long as nothing goes wrong with the telescope. Once in orbit at L2, only minor burns once every 28 days are needed for station keeping — a negligible amount of fuel.

In total, this observatory could be probing the final frontier and making incredible discoveries for at least the next 22 years, taking it up to 2048 at minimum. For the next two or three decades, we're going to be hearing a lot about the Nancy Grace Roman Space Telescope.

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Making rocket fuel out of Mars’ thin air: New breakthrough could make it happen

Astronauts could travel back to Earth from Mars using rocket fuel converted directly from the carbon dioxide in the Red Planet's atmosphere, using a technique known as electrochemical reduction, a recent study reports.

It's an old method involving electrolysis, which is the application of an electrical current to drive a chemical reaction, but the new trick produces methane pure enough to be used as liquid propellant. (A number of rocket engines these days burn liquid oxygen and liquid methane — including the Raptors that power Starship, the rocket SpaceX is developing to help humanity get to Mars.)

"The work we're doing is basically taking CO2 and using electricity to convert it into carbon-containing fuels and chemicals," said Carter Racine in a statement. Racine is a Ph.D. student in mechanical engineering at Texas A&M University and a member of the study team, which was led by University of Mississippi chemical engineer Ahmed Badreldin.

"You can't bring up everything you need [on Mars] from Earth, because every additional kilogram adds enormous cost and complexity to launch and escape Earth's gravity," added Badreldin. "So the question becomes, How do we make the fuels and chemicals needed for space exploration from the resources already available at the destination?"

One answer is electrochemical reduction, which takes place in an electrolyzer, with electrons flowing from the negatively charged anode to the positively charged cathode. Water at the anode is oxidized, meaning it loses an electron, which is transferred to the carbon dioxide at the cathode, where one of its atoms gains an electron and becomes what chemists refer to as "reduced" (meaning its oxidation state is lowered). It can then react with the hydrogen and oxygen atoms that have split from the oxidized water molecules.

The anode contains a catalyst, and the choice of material for the catalyst dictates what carbon-based compounds are produced when the reduced carbon reacts with the hydrogen and oxygen. For example, a gold catalyst leads to the production of carbon monoxide (CO), while copper produces more complex compounds including alcohols, ethanol and methane (CH4).

What makes the work of Badreldin's team stand apart from previous experiments is that they have developed a nanometer-scale copper catalyst doped in nitrogen that is able to produce nearly pure methane.

Electrochemical reduction of carbon dioxide has been used to produce methane before, in applications on Earth. The problem is, those methods have produced a lot of byproducts alongside methane. On Earth we have complex equipment that separates the methane from the other unwanted compounds, but astronauts are not going to be able to take such unwieldy devices to Mars when every kilogram counts. That's a problem, because for methane to be used as a liquid propellant in rocket fuel it needs to be pure.

artist's illustration of a small human outpost on mars

NASA wants to send astronauts to Mars in the late 2030s or early 2040s. (Image credit: NASA)

However, the specific copper catalyst used by Badreldin's team is able to preferentially produce methane over other compounds, thereby creating it pure without having to refine it. And there's plenty of carbon dioxide available on Mars to use: While Mars' atmosphere is thin, it is nonetheless composed of 96% carbon dioxide.

Even if astronauts never go to Mars, the usefulness of this technique on Earth is clear. Rather than drilling for this natural gas, we can create methane from the carbon dioxide already in our atmosphere.

"We want to do that because right now many of these carbon-based products ultimately come from virgin fossil resources," said Racine. "If we can make them using captured CO2 and renewable electricity, it could reduce reliance on virgin fossil carbon and help close the carbon cycle."

Consequently, electrochemical reduction has also been suggested for use on Earth as a carbon sequestration technique, drawing carbon dioxide out of our atmosphere where it acts as an unwanted greenhouse gas.

The problem with that is, converting carbon dioxide into methane to be burned as a fuel simply releases that carbon dioxide straight back into the atmosphere in a net-zero cycle. Ideally, we want to lock that carbon dioxide away from the atmosphere for a long period of time, but Badreldin doesn't think the technology is ready yet.

"What we are ultimately interested in is seeing whether we can move beyond simply recycling CO2 and toward pathways that are net-negative," he said. "That means using CO2 as a carbon source while converting it into products where the carbon is stored or used long enough that it is not immediately released back into the atmosphere."

It should be noted that the best way to alleviate climate change is to cease burning all fossil fuels, including methane. However, using methane created from electrochemical carbon dioxide reduction in a net-zero process rather than drilling for it could help during the transition from fossil fuels to renewable resources.

The study reporting this research was published in April in the journal ACS Catalysis.

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James Webb Space Telescope and Hubble discover 27 puzzling new objects orbiting the sun far beyond Neptune

The Hubble and James Webb space telescopes have teamed up to target some of the smallest, most distant objects in the solar system, discovering that the history of these tiny objects is more puzzling than we'd realized.

The two orbiting observatories collectively discovered 27 new Trans-Neptunian Objects, or TNOs, all less than 25 miles (40 kilometers) across, with the smallest being only 6 miles (10 kilometers) in diameter. As their name suggests, TNOs orbit the sun from far beyond Neptune. Some of them were born out there, at the dawn of the solar system, as small planetesimals unable to take the extra step to form planets.

Models of how these TNOs formed predicted that they should have been peppered with impacts that mixed up their surface material so that their composition, and therefore color, would be different than larger TNOs. Yet new observations, led by two PhD candidates, Anastasia Morgan of Northern Arizona University and Marielle Eduardo of the University of Victoria found the opposite – the little TNOs still look as pristine as the day they formed.

"You could imagine a scenario where getting knocked around and fragmented would change the surface composition, and then you would see a different surface color for tiny TNOs compared to their larger siblings," said Morgan, who led the color and composition analysis, in a statement. "So it's really fascinating to see that the smallest objects are somehow 'remembering' and preserving the history of how they were made."

TNOs native to the Kuiper Belt move in near-circular orbits around the sun and are level with the ecliptic plane, the imaginary flat 'disc' on which the planets and other objects orbit our star. They are said to be dynamically 'cold' because they haven't really budged since they formed.

Other TNOs, however, formed between the seventh and eighth planets, Uranus and Neptune, but before they could be assimilated into those worlds while those planets were growing, they were ejected by gravitational resonances into the region far beyond Neptune, collectively forming a 'Scattered Disk' of objects on highly elongated orbits significantly inclined to the plane of the solar system. Such TNOs are referred to as being dynamically 'hot'.

Yet even the 'hot' TNOs seem to have resisted any changes to their surface composition.

"These dynamically hot TNOs retain a signature of where they were born, even though they've been orbitally scrambled since then," said David Trilling of Northern Arizona University.

an irregularly-shaped rock on a starry background

An artist's interpretation of a trans-Neptunian object. (Image credit: Artwork: NASA, ESA, and G. Bacon (STScI); Science: NASA, ESA, and C. Fuentes (Harvard-Smithsonian Center for Astrophysics))

This leads to one of two surprising possibilities. Either there are far fewer impacts taking place far from the sun than astronomers thought, which doesn't match with what we think we know about the population density of objects out there, or the impacts and collisions do take place but for some reason do not tear up the surface of the small TNOs as much as we might expect.

Thanks to the James Webb Space Telescope's (JWST's) infrared vision, Marielle Eduardo was able to figure out the size distribution of the TNOs. When we look in visible light, how bright a TNO appears depends in part on how reflective its surface is, a property referred to as albedo. A larger body with a composition that isn't very reflective might appear fainter at the same distance as a smaller object covered in shiny ice.

However, at infrared wavelengths the brightness of an object is dependent mostly on its size, allowing accurate determinations of the diameters of the 27 TNOs. Surprisingly, there seem to be fewer of the very small TNOs than what models of their formation predict.

"It's very interesting that the process of planetesimal formation ends up producing the same distribution of sizes for both cold and hot populations, despite forming in different regions of the early solar system," said Eduardo. "The process seems to be insensitive to [planet-forming] disk conditions, producing similar planetesimal sizes whether the disk is hot or cold, and dense or fluffy."

These observations push Hubble's and JWST's abilities to the limit. The TNOs are incredibly faint, shining between magnitudes 24.1 and 29.3, described as being equivalent to seeing a swarm of fireflies on the moon from Earth. As such, it is the deepest survey yet into the relatively unknown realm beyond Neptune, just as you'd expect from these two powerful space telescopes getting together.

The research was published in The Astronomical Journal as two separate papers on Sept. 8, one on color and composition, the other on the size distribution of the TNOs.

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Scientists discover mysterious new X-ray objects ‘unlike any they have seen before’

NASA's Chandra X-ray Observatory has found a brand new type of an otherwise familiar object – compact binary systems that steal gas from other stars, but which do so while emitting very low-energy X-rays but copious amounts of ultraviolet.

Chandra spotted 84 suspicious object emitting very low-energy X-rays in six galaxies – four evolved ellipticals and two spirals, namely our near-neighbor the Andromeda Galaxy (M31) and the Pinwheel Galaxy (M101).

"We've never encountered a group of objects that act like this," said Mustafa Muhibullah of the University of Alabama in a statement.

Compact objects, in the form of black holes, neutron stars and white dwarfs, are the remains of stars that have died. Their small size and powerful gravity means that they're adept at getting close to orbiting companion stars and ripping the stars' outer layers of gas away. The gas swirls around the compact object, falling onto its surface, and this accretionary process usually produces torrents of high-energy X-rays because the stolen gas becomes superheated by the compact object's gravitational vice-like grip.

Because of their weak X-rays, Muhibullah's team refer to them as 'hypersoft X-ray sources'. Since low-energy X-rays and ultraviolet light are next to each other on the electromagnetic spectrum, Muhibullah and his team suspect that the low-energy X-rays are spillover from objects emitting prodigious amounts of ultraviolet. Moreover, they think that these objects are lower-level compact binaries.

They're hard to find though, because the interstellar medium of hydrogen and helium gas between the stars absorbs ultraviolet light. This could be why we have yet to find any hypersoft X-ray sources in our own galaxy, because we have to look through the interstellar medium through the plane of the Milky Way.

Consequently, there could be a large population of hypersoft X-ray sources that remain undiscovered and they could have an important effect on the universe around them.

"These clandestine X-ray sources are actually among the most energetic objects in galaxies, and they could be solving two cosmic mysteries at once," said Muhibullah.

The interstellar medium is filled with ionized gas where atoms have been shorn of electrons. Hot, massive stars do output a lot of high-energy ultraviolet light, but there are not enough of these stars to account for all the ionization. If hypersoft X-ray sources are dumping torrents of ultraviolet into space, they could explain the ionization instead. For stars to form, gas has to be cold and not ionized, so hypersoft X-ray sources could be gently regulating star formation within galaxies.

The second mystery is the puzzle over how exactly type Ia supernova explosions detonate. We know that they are fueled by white dwarfs accreting matter from a close companion star and, once the accumulated matter raises the white dwarf's mass beyond 1.44 times the mass of our sun – known as the Chandrasekhar limit – it explodes, but the details of what on the white dwarf actually ignites and how are fuzzy.

Studying a new breed of compact binary might finally reveal the answers and offer more clues about when white dwarfs become ready to explode.

"If we could find a way to spot these type Ia supernova explosions before they go off, that would be really important," said Jimmy Irwin of the University of Alabama, who is a member of Muhibullah's team. "Right now, we study them after they've exploded and astronomers have struggled to understand what is actually ignited."

Since type Ia supernova explosions are used as markers on the cosmic distance ladder, used for measuring the strength of dark energy and the expansion of the Universe, the benefits from understanding them better are clear to see in our efforts to understand how the Universe is evolving.

The findings were published on Sept. 9 in Nature Astronomy.

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Earth’s moon could have formed in just 5 hours after giant impact

The moon could have formed in a matter of hours following the giant impact between Earth and a Mars-size protoplanet early in the history of the solar system. The theory comes from new simulations that take into account how the internal temperature of young protoplanets affected their geologic properties and therefore the collisions they experienced.

This giant impact scenario has become the leading theory of how the moon formed, thanks in particular to work done by planetary scientist Robin Canup. Since 2001, she has conducted and refined numerous computer simulations that describe how a Mars-size body called Theia collided at an angle just right to throw debris into orbit around the proto-Earth.

Now other researchers are getting in on the act. Adeene Denton of the South-west Research Institute led a team who performed some of the most detailed simulations of the collision yet, taking into account more of the geologic properties of the colliding worlds.

"Models have evolved to include material strength, something that's really important when you're studying collisions between smaller bodies like asteroids or for my previous paper about the formation of the Pluto–Charon system," said Denton in a statement. "We weren't sure it would matter for the moon or not. When we did the simulations, we found it actually matters quite a bit."

It turns out that warmer bodies are weaker than colder ones. After the planets formed, they were still hot inside from their formation, which would have affected their material strength. Given that the moon-forming impact occurred not long after the solar system's formation, this would have affected the collision with Theia — but to what degree depends on exactly when the collision occurred and how much Theia had cooled.

As Theia smashed into Earth, it was utterly destroyed. While much of what was left of Theia's shattered iron core sank into the Earth, a large ring of debris wrapped around Earth to form the moon.

The main effect of the temperature being warmer in the outer few hundred miles of Theia was that it would have affected its ability to deform upon impact and absorb the momentum of the collision. This, in turn, would have affected how debris was strewn around Earth to form the moon. Therefore, by including varying temperatures and material strengths in the simulations, Denton's team was able to get a better look at how the collision and the resulting formation of our moon played out.

Previous simulations have shown two possible scenarios. One is that the ring of debris hung around for a substantial amount of time, allowing the moon to accrete from it gradually. The other scenario, first depicted in NASA-led simulations in 2022, implies that the moon came together from this debris in a matter of hours.

Now, Denton's models potentially bolster this startling possibility.

If Theia was colder, meaning that the impact occurred a little later in the history of the solar system, perhaps 100 to 150 million years after the birth of the planets, then the ring of debris would have formed in such a way as to allow the moon to accrete gradually. And because it was stronger, more of Theia would have survived intact to merge with Earth.

On the other hand, a warmer Theia that impacted Earth less than 60 million years after the planets' formation, would create a scenario where the moon could form very quickly while Theia itself would be obliterated.

"Depending on how hot the Earth and Theia are prior to the collision, the impact can destroy Theia and produce this massive disk of debris that eventually forms the moon," said Denton. "But when I used the same parameters as original impact modeling – down to the equal temperature structures inside both bodies — within around five hours, an intact moon emerged."

That would have been quite a day in the history of our planet, acquiring a new moon and an almighty headache all at once.

"These surprising and exciting new results imply a potential connection between the physical properties of the moon today, including perhaps its volatile content, and the thermal state of the Earth and Theia at the time of the giant impact," said the Southwest Research Institute's Robin Canup, who was not involved in this study. "This in turn might help scientists better constrain when the moon-forming event occurred."

In both scenarios, the moon appears to be made mostly from Theia's mantle material, with just a little bit of Earth's mantle mixed in. This latter finding is surprising, given the similarities between the moon's composition and Earth's mantle. However, research has shown that there's clearly more to the story because despite the similarities there are also some puzzling differences in the levels of isotopes that cannot be easily explained by current simulations, including Denton's.

The simulations could have repercussions in the search for exomoons. If the moon did form in a matter of hours, then searching for exomoon-forming disks around terrestrial exoplanets might be a fruitless endeavor because such disks would be so short-lived. Moon-forming disks around gas giant exoplanets would be a different matter, however, because those disks do not form from impacts, but rather from material leftover from assembling those planets.

The results were published on Sept. 1 in The Astrophysical Journal Letters.