SPACE / COSMOS
Thin ice may have protected lake water on frozen Mars
Rice University
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Eleanor Moreland is a Rice graduate student and lead author of the study.
view moreCredit: Photo by Brandon Martin/Rice University
Small lakes on ancient Mars may have remained liquid for decades, even with average air temperatures well below freezing.
Using a climate model adapted for Martian conditions, a team of researchers from Rice University discovered that lakes in locations such as Gale Crater, near Mars’ equator, could have persisted under thin seasonal ice for at least decades and likely as long as climate conditions were stable. These findings contribute to resolving a long-standing puzzle in Mars science: Surface features shaped by sustained liquid water coexist alongside climate models suggesting that early Mars was too cold to support such conditions.
The study, published in AGU Advances Dec. 29, offers a new explanation for how lakes might have existed without a warm climate and why ancient Martian lake beds are so well-preserved today.
“Seeing ancient lake basins on Mars without clear evidence of thick, long-lasting ice made me question whether those lakes could have held water for more than a single season in a cold climate,” said Eleanor Moreland, a Rice graduate student and lead author of the study. “When our new model began showing lakes that could last for decades with only a thin, seasonally disappearing ice layer, it was exciting that we might finally have a physical mechanism that fits what we see on Mars today.”
Adapting Earth’s climate tool kit
The researchers adapted a climate modeling tool called Proxy System Modeling, initially developed by Earth climate researcher Sylvia Dee, to reconstruct ancient climates using indirect clues such as tree rings or ice cores.
While Earth has natural markers for these clues, Mars lacks trees or comparable indicators. Instead, the research team used measurements collected by Mars rovers, using the planet’s rock and mineral records as proxies for a climate record.
Over several years, they reworked the model for lakes to reflect Mars as it was about 3.6 billion years ago, accounting for differences such as weaker sunlight, a carbon dioxide-rich atmosphere and distinct seasonal patterns.
They ran 64 different test cases in the new Lake Modeling on Mars with Atmospheric Reconstructions and Simulations (LakeM2ARS) model, based on real data from NASA’s Curiosity rover in Gale Crater and Mars climate simulations.
Each test simulated a hypothetical lake inside the crater for 30 Martian years, equivalent to approximately 56 Earth years, allowing the researchers to determine whether the lake could realistically remain liquid under those conditions.
“It was fun to work through the thought experiment of how a lake model designed for Earth could be adapted for another planet, though this process came with a hefty amount of debugging when we had to change, say, gravity,” said Dee, an associate professor of Earth, environmental and planetary sciences and co-author of the study.
“We were surprised and encouraged by how sensitively the model responded to parameters like atmospheric pressure and temperature seasonality. It shows that with some creativity and experimentation, Earth-origin models can yield realistic climate scenarios for Mars.”
A hidden protector
In some simulations, the lakes completely froze during colder seasons, whereas in others, the lakes remained liquid and were covered by a thin layer of ice instead of freezing solid. This thin ice acted as an insulating lid, significantly reducing water loss while still allowing sunlight to warm the lake ice during warmer months.
As a result of this seasonal cycling, some simulated lakes barely changed in depth over decades, suggesting that they could be stable for longer durations even with average air temperatures below freezing for much of the time.
“This seasonal ice cover behaves like a natural blanket for the lake,” said Kirsten Siebach, an associate professor of Earth, environmental and planetary sciences and co-author of the study.
It insulates the water in winter while allowing it to melt in summer, Siebach said. “Because the ice is thin and temporary, it would leave little evidence behind, which could explain why rovers have not found clear signs of perennial ice or glaciers on Mars,” she said.
The findings suggest that early Mars may have supported long-lasting lakes without requiring consistently warm conditions, challenging earlier beliefs that surface water on Mars would require persistent warmth.
Future exploration
If ancient Martian lakes persisted under seasonal ice rather than thick permanent ice, features on Mars that have been difficult to reconcile with past climate models, including preserved shorelines, sediment layers and mineral deposits, may now have clearer interpretations.
The researchers said they look forward to applying LakeM2ARS to other Martian basins to investigate whether similar lakes could have existed elsewhere. They also aim to examine how factors such as changes in atmospheric composition or groundwater circulation might have affected the stability of lake ice over time.
“If similar patterns emerge across the planet, the results would support the idea that even a quite cold early Mars could sustain year-round liquid water, a key ingredient for environments to be suitable for life,” Moreland said.
The additional co-authors of this study include Rice undergraduate student Nyla Hartigan, Michael Mischna from the Jet Propulsion Laboratory at the California Institute of Technology, James Russell from Brown University and Grace Bischof and John Moores from York University. The Rice Faculty Initiative Fund and the Canadian Space Agency supported this research.
Journal
AGU Advances
Article Title
Seasonal Ice Cover Could Allow Liquid Lakes to Persist in a Cold Mars Paleoclimate
Earliest, hottest galaxy cluster gas on record could change our cosmological models
The scorching cloud of gas threaded between clusters of galaxies is five times hotter than current models predict, highlighting gaps in our models of galaxy cluster formation
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Artist’s impression of a forming galaxy cluster in the early Universe: radio jets from active galaxies are embedded in a hot intracluster atmosphere (red), illustrating a large thermal reservoir of gas in the nascent cluster.
view moreCredit: Lingxiao Yuan
An international team of astronomers led by Canadian researchers has found something the universe wasn’t supposed to have: a galaxy cluster blazing with hot gas just 1.4 billion years after the Big Bang, far earlier and hotter than theory predicts.
The result, published today in Nature, could upend current models of galaxy cluster formation, which predict such temperatures occur only in more mature, stable galaxy clusters later in the universe’s life.
“We didn’t expect to see such a hot cluster atmosphere so early in cosmic history,” said lead author Dazhi Zhou, a PhD candidate in the UBC department of physics and astronomy. “In fact, at first I was skeptical about the signal as it was too strong to be real. But after months of verification, we’ve confirmed this gas is at least five times hotter than predicted, and even hotter and more energetic than what we find in many present-day clusters.”
“This tells us that something in the early universe, likely three recently discovered supermassive black holes in the cluster, were already pumping huge amounts of energy into the surroundings and shaping the young cluster, much earlier and more strongly than we thought,” said co-author Dr. Scott Chapman, a professor at Dalhousie University who conducted the research while at the National Research Council of Canada (NRC)
Investigating a baby cluster
Peering back in time about 12 billion years, the researchers focused on a ‘baby’ galaxy cluster called SPT2349-56. To do so, the research team used a cluster of radio telescopes called the Atacama Large Millimeter/submillimeter Array (ALMA), which includes instruments designed, built, and tested by the NRC.
This infant cluster is massive for its relative youth, with a core measuring about 500,000 light years across, comparable to the size of the halo surrounding the Milky Way. It contains more than 30 active galaxies and forms stars more than 5,000 times faster than our own galaxy, all in a very compact region.
The research team focused on a cosmological tool called the Sunyaev-Zeldovich effect, which can help scientists work out the thermal energy of the intracluster medium:the gas existing between the galaxies of a given cluster.
“Understanding galaxy clusters is the key to understanding the biggest galaxies in the universe,” said Dr. Chapman, who is also a UBC affiliate professor. “These massive galaxies mostly reside in clusters, and their evolution is heavily shaped by the very strong environment of the clusters as they form, including the intracluster medium.”
Supermassive blackhole heating
Current models suggest the massive reservoirs of gas that form the intracluster medium are collected, and then heated, by gravitational interactions as an immature, unstable galaxy cluster matures and collapses inward to a stable state. The new finding suggests that this birth is more explosive and that scientists may need to rethink the sequence and speed of galaxy cluster evolution.
The researchers now want to investigate how all the pieces fit together. “We want to figure out how the intense star formation, the active black holes and this overheated atmosphere interact, and what it tells us about how present galaxy clusters were built,” said Zhou. “How can all of this be happening at once in such a young, compact system?”
Interview language(s): English (Chapman, Zhou)
Journal
Nature
Method of Research
Observational study
Subject of Research
Not applicable
Article Title
Sunyaev-Zeldovich detection of hot intracluster gas at redshift 4.3
Article Publication Date
5-Jan-2026
Astronomers Discover The First Gravitationally Lensed Superluminous Supernova
Liverpool Telescope images from 2025 October 4 (left panel), and the four lensed images of SN 2025wny (right panel) after subtracting out the lens and host galaxy light from archival images. CREDIT: Joel Johansson et al
January 4, 2026
By Eurasia Review
An international team of astronomers led by Oskar Klein Centre (OKC) researcher Joel Johansson has discovered SN 2025wny, the first spatially resolved, gravitationally lensed superluminous supernova ever observed. The discovery provides a striking confirmation of Einstein’s theory of General Relativity and a rare window into a powerful stellar explosion from the early Universe.
A cosmic magnifying glass reveals a record-distant explosion
The supernova SN 2025wny lies at an extraordinary distance – its light has travelled around 10 billion years to reach us. At the time the light was emitted, the Universe was only about 4 billion years old.
A supernova this distant would normally be far too faint to discover from earth. However, thanks to two foreground galaxies, acting as a gravitational lens, the supernova appears about 50 times brighter, making it visible to ground-based telescopes.
“This is nature’s own telescope,” says Joel Johansson, lead author and researcher at the Oskar Klein Centre, Stockholm University. “The magnification lets us study a supernova at a distance where detailed observations would otherwise be impossible.”
A new method to probe the expansion of the Universe
The gravitational lensing effect does more than magnifying the supernova – it produces several distinct, spatially separated images of the same explosion. Each lensed image of the supernova takes a slightly different path around the deflecting galaxies, reaching Earth at different times. These time differences offer an independent, highly promising method to measure the Hubble constant, which describes how fast the Universe is expanding.
A current hot topic in modern cosmology is the so called “Hubble tension”, which refers to the growing discrepancy between two precise and independent measurements of how fast the Universe is expanding; one based on observations of the early cosmos and the other on nearby objects. This may suggest that our current cosmological model is incomplete, or that one of the methods currently used is flawed.
Ariel Goobar, group leader at the OKC and part of Joel Johansson’s research team considers this new approach to be a technical breakthrough: “A lensed supernova with multiple, well-resolved images, provides one of the cleanest ways to measure the expansion rate of the Universe. SN 2025wny is an important step toward resolving one of cosmology’s most significant challenges,” Ariel Goobar says.
A surprising and exceptionally hot explosion
Superluminous supernovae are a relatively newly discovered class of cosmic explosions, which are extremely energetic and rare in nature. Because the Universe is expanding, ultraviolet light emitted by SN 2025wny is “redshifted” to optical wavelengths, and can be detected with telescopes on the ground. The team’s observations show that SN 2025wny is unusually hot and bright, even for a superluminous supernova in its early stages.
The supernova is so bright that it lit up its host galaxy, allowing researchers to study its composition from narrow absorption lines in the spectrum. It appears to be a low-density, low-metallicity, star-forming dwarf galaxy, consistent with the kind of environments thought to produce superluminous supernovae. Seeing such a system at this early cosmic epoch provides rare insight into how stars and galaxies evolved in the young Universe.
How the Discovery Was Made
The discovery relied on a chain of cutting-edge observatories working together: Zwicky Transient Facility (ZTF) – a wide-field survey telescope at Palomar Observatory in California – first detected the explosion during its nightly monitoring of the sky.
While scanning through the daily list of new transients found by ZTF, Joel Johansson noticed that one of them was particularly promising. The Dark Energy Spectroscopic Instrument (DESI) had already provided the distance of the nearest galaxy to SN 2025wny, and archival images suggested that the surrounding galaxies could be lensed background galaxies. This immediately signalled that any associated transient must be either exceptionally bright and/or strongly lensed.
Early spectroscopy with the Nordic Optical Telescope (NOT) on La Palma in the Canary Islands showed that the transient was indeed a supernova, but the spectrum was difficult to match with more common supernova types the team had seen before.
On the same mountain, the Liverpool Telescope (LT) – somewhat larger than ZTF and with sharper imaging – delivered the crucial breakthrough: the team was able to resolve four separate images of SN 2025wny.
Jacob Wise, a PhD student at Liverpool John Moores University (LJMU) and lead of the LT programme, was the first to recognise the multiple-image nature of SN 2025wny: “I couldn’t believe my eyes when I saw the data, I thought that it must have been an artefact from the camera. However, when I carefully looked at our data from previous nights, I could still clearly see the multiple lensed images of the supernova. The realisation of what we had just discovered was by far the most exciting moment of my career so far,” he says.
His PhD advisor, Professor Dan Perley (LJMU), confirmed the detection and says: “The instant Jacob sent me the images I knew we had found something big – no one had ever seen multiple images of a supernova with a ground-based telescope before, and there it was in front of us, clear as day.”
Finally, the Keck Observatory (10-m telescopes) on Hawaii provided decisive spectra, confirming both the supernova type and its extreme distance. Yu-Jing Qin, a postdoctoral researcher at Caltech, led a series of spectroscopic observations targeting each of the individual supernova images and the lensing galaxies.
The Keck spectra revealed a forest of narrow absorption lines from the supernova’s host galaxy – the fingerprints of elements such as carbon, iron and silicon – which nailed down the redshift and nature of the event.
What Comes Next?
SN 2025wny demonstrates that strongly lensed supernovae at very high redshifts can be found and resolved with existing ground-based surveys.
The cosmology community is eager to measure the expansion rate of the Universe, and SN 2025wny provides an essential proof of concept for future discoveries from the Vera Rubin Observatory’s Legacy Survey of Space and Time (LSST). Hundreds of lensed supernovae should be within reach in LSST, following the technique pioneered by the SN 2025wny discovery team.
Follow-up observations with the Hubble and James Webb Space Telescopes are already underway. These data will refine the lens model, map the positions of the multiple images with exceptional precision, and ultimately measure the time delays needed for a new, independent determination of the Hubble constant.
The magnification also gives astronomers a chance to study the explosion mechanism of a distant superluminous supernova and its surrounding environment in unprecedented detail.
Longest observation of an active solar region
ETH Zurich
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The European space probe Solar Orbiter delivers images of the sun, including observations of what is, from our perspective, its far side.
view moreCredit: ESA / AOES
Our sun rotates around its axis once every 28 days. From earth, therefore, active regions of the sun can only be observed for up to two weeks at a time. After this, they rotate beyond our field of view, remaining hidden from us for two weeks. “Fortunately, the Solar Orbiter mission, launched by the European Space Agency (ESA) in 2020, has broadened our perspective,” says Ioannis Kontogiannis, solar physicist at ETH Zurich and the Istituto ricerche solari Aldo e Cele Daccò (IRSOL) in Locarno.
The Solar Orbiter spacecraft orbits the sun once every six months, also observing its far side. Between April and July 2024, it was able to monitor one of the most active regions in the last twenty years. In May 2024, the region known as NOAA 13664 rotated to the side of the sun facing us, triggering the strongest geomagnetic storms on Earth since 2003. “This region caused the spectacular aurora borealis that was visible as far south as Switzerland,” says Louise Harra, professor at ETH Zurich and director of the Davos Physical Meteorological Observatory.
Data from two space probes combined
To better understand the formation, development and effects of such superactive regions on the sun, Harra and Kontogiannis brought together an international team of researchers. This team combined the data collected by NOAA 13664’s Solar Orbiter on the far side of the sun with data from NASA’s Solar Dynamics Observatory spacecraft, which is located on the earth–sun line and observes the near side.
This allowed the group to track region NOAA 13664 almost continuously for 94 days. “This is the longest continuous series of images ever created for a single active region: it’s a milestone in solar physics,” says Kontogiannis. The team observed the birth of NOAA 13664 on 16 April 2024 on the far side of the sun, as well as all the changes that the active region underwent until its decay after 18 July 2024.
Complex magnetic fields causing solar storms
Strong and complex magnetic fields prevail in the active regions of the sun. They occur when strongly magnetised plasma reaches the sun’s surface, and they often cause violent eruptions. These solar storms emit enormous amounts of electromagnetic radiation, known as flares, and eject plasma from the sun’s atmosphere as well as high-energy particles into space.
In addition to auroras, solar storms can also cause significant damage to our high-tech world. They can cause power outages on earth, disrupt communication signals, expose aircraft crews to increased radiation or cause satellites to crash, as happened in February 2022, when 38 of 49 Starlink satellites belonging to US space company SpaceX were lost within two days of their launch.
Unnerving effects
“Even signals on railway lines can be affected and switch from red to green or vice versa,” says Harra. “That’s really scary.” NOAA 13664 also had caused problems in May 2024. “Modern digital agriculture was particularly affected,” says the scientist. “Signals from satellites, drones and sensors were disrupted, causing farmers to lose working days and leading to crop failures with considerable economic losses.”
“It’s a good reminder that the sun is the only star that influences our activities,” adds Kontogiannis. “We live with this star, so it’s really important we observe it and try to understand how it works and how it affects our environment.”
Thanks to data from space probes, researchers were able to track three solar rotations for the first time ever, observing how the magnetic field of a superactive region developed over several episodes, becoming increasingly complex. Ultimately, an intertwined magnetic structure was formed, before the strongest flare in the past twenty years was released on the far side of the sun on 20 May 2024.
Weather forecasts in space
It is hoped that these observations will contribute to a better understanding of solar storms and their potential impact on earth. The aim is to improve the accuracy of space weather forecasts, so that sensitive modern technology can be better protected. “When we see a region on the sun with an extremely complex magnetic field, we can assume that there is a large amount of energy there that will have to be released as solar storms,” explains Harra.
Currently, however, researchers are unable to predict how large an eruption will be, whether there will be one strong eruption or several weaker ones, and when these might occur. “We’re not there yet. But we’re currently developing a new space probe at ESA called Vigil which will be dedicated exclusively to improving our understanding of space weather,” says the scientist. The mission is planned for launch in 2031.
Reference
Kontogiannis I, Zhu Y, Barczynski K, Stiefel M, Collier H, McKevitt J, Castellanos Durà n J, Berdyugina S, Harra L. Near-continuous tracking of solar active region NOAA 13664 over three solar rotations. Astronomy & Astrophysics, Volume 704, Dezember 2025, doi: 10.1051/0004-6361/202556136
Journal
Astronomy and Astrophysics
Article Title
Near-continuous tracking of solar active region NOAA 13664 over three solar rotations
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