• A new study suggests that unseen geologic activity may lurk just below the thin crust of Venus.

We’re slowly unraveling the mysteries of Earth’s strange twin.

Our nearest neighbor is only slightly smaller than the Earth… but that’s just about the only thing the two planets have in common. Permanently shrouded in a thick atmosphere, the surface is subjected to a punishing atmospheric pressure more than 90 times that of Earth at sea level, and temperatures reaching 460 degrees Celsius. This has also made Venus difficult to explore, to say the least, with the late Soviet Union’s Venera missions lasting for just hours on the surface.

Certainly, exploring enigmatic Venus is hard. A reminder of this literally came home this month, when the failed Soviet Venus lander Kosmos-482 reentered on May 10^th over the Indian Ocean region, after more than half a century in Earth orbit.

Now, a recent NASA-funded study published in Nature: Communications suggests that the interior of Venus may be equally strange as well.

Earth has an active surface and crust, with tectonic plates crashing together and rising and sinking back into the interior in a process known as subduction. In contrast, we see that Venus has no surface fault lines suggesting individual plates, with the crust of Venus instead seeming to be fused in one single piece.

Contrasting interiors of Venus versus Earth.

Credit: JAXA.

NASA’s Magellan mission created a radar map of the surface of Venus in the 1990s. Venus, however, is not dormant, but features vast active structures called coronae. These are circular surface features, thought to be caused by plumes of hot material pushing against the surface. Think bubbling cheese, on a piping-hot pizza. Though modern Earth has no direct analog, geologic coronae are thought to have been a feature common on early Earth. Evidence for modern volcanic activity on the surface of Venus includes the Maat Mons and the Ozza Mons regions.

The Artemis Corona feature on Venus.

Credit: NASA/Magellan.

Another recent study out earlier this month lends support to the idea that these circular coronae are still actively reshaping the surface of Venus.

This then presents a mystery, as Venus seems to lack a tectonic plate cycle, but somehow still remains volcanically active. What researchers in the study propose is a mechanism of crust metamorphism, coupled with rock density and melting cycles. Researchers ran models and simulations of the interior of Venus and came up with a surprising result: this activity limits the crust-mantle boundary to a depth of 25-40 miles (40 to 65 kilometers) at most… a surprisingly thin result. For context, we know that Earth’s crust is on average 3 to 44 miles (5-70 kilometers) thick (that’s oceanic, versus continental).

Crustal density and thickness for Venus, versus various basalt compositions and thermal gradients used in the study.

Nature/Creative Commons

"We are currently working on understanding the composition of the Venusian highlands since they do show similarities to Earth's continental crust, which would give us some insight on the geological evolution of Venus," Julia Semprich (Open University, United Kingdom) told Universe Today. "Modeling the interior with our new crustal densities would also be an option."

"This is surprisingly thin, given the conditions of the planet,” says Justin Filiberto (NASA-JSC Astromaterials Research and Exploration Science Division) said in a recent press release. “It turns out that, according to our models, as the crust grows thicker, the bottom of it becomes so dense that it either breaks off and becomes part of the mantle or gets hot enough to melt.” This could, in turn drive a recycling of material in the interior, and drive volcanic activity.

Venus Exploration: What’s Next

What we really need are direct measurements of Venus, in a dedicated seismology mission along the lines of NASA’s Mars InSight. Next up in the mission pipeline for Venus are the European Space Agency’s Envision set to study the surface and atmosphere of the planet, and NASA’s VERITAS (Venus Emissivity, Radio Science, InSAR, Topography, and Spectroscopy) and DAVINCI (Deep Atmosphere Venus Investigation of Noble gases, Chemistry and Imaging) missions, set for the early 2030s. As of writing this, the future of DAVINCI, VERITAS and much of NASA’s planetary science efforts is in doubt, thanks to proposed budget cuts.

"New missions will focus on high-resolution radar and emissivity maps allowing us to get better constraints on topography (and) crustal thickness as well as surface features and compositions," says Semprich. "The best way to answer the question whether Venus has plates would be to use seismometers to map the interior, and this seems not very likely in the near future."

For now, why Venus and Earth took two divergent paths remains a mystery. Venus transitioned from dusk into the dawn sky in early 2025, where it still dominates as the morning star.

Looking east on the morning of Saturday, May 24th.

Credit: Stellarium.

Certainly, our sister world doesn’t give up its secrets easily. A new series of missions could give us key insights, into the interior workings of our inner solar system neighbor.

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Sometimes, space enthusiasts blind themselves with techno-optimism about all the potential cool technological things we can do and the benefits they can offer humanity. We conveniently ignore that there are trade-offs: if one group gets to utilize the water available on the lunar surface, that means another group doesn't get to. Recognizing and attempting to come up with a plan to deal with those sorts of trade-offs is the intent of a new paper by Marissa Herron and Therese Jones of NASA's Office of Technology, Policy, and Strategy, as well as Amanda Hernandez of BryceTech, a contractor based out of Virginia. 

The paper deals explicitly with trade-offs on the Moon, though most of the strategy could work elsewhere throughout the solar system. The Moon is probably the most important, though, as there has been a concerted push by NASA and other space agencies to set up a permanent presence there and start utilizing some of its resources. Reports like the 2022 National Cislunar Science and Technology Strategy and the 2020 Executive Order on Space Resources offer an impetus to utilize the Moon for humanity's benefit. However, ensuring it will be used for all humanity and not just a sliver of it is harder.

Lunar water is a good example of a relatively scarce resource that could be utilized in different ways. Some groups want to split the water into hydrogen and oxygen, using it to refuel rockets that can return larger samples of regolith and other materials off the surface. Other groups want to purify the water and use it for biological functions like drinking or showering. Who is responsible for determining who gets access to what resources and ensuring that they are equitably shared across competing interests is still up in the air, which the paper hopes to lay out.

Fraser talks about utilizing resources on the Moon.

The authors lay out a three-step framework. First, they want to map out the 63 objectives of NASA's Moon to Mars plan and figure out what, if any, requirements on lunar sites and resources are needed. They stress that collaboration from outside NASA, including other agencies and private organizations, is critical at this stage, despite the Moon to Mars architecture being a NASA-driven program.

The second step is a "Catalog". Essentially, it is a list of "concerns" - anything that could disrupt the use of a location or resource. The water use example from above is one such example - others abound, and aren't just limited to the surface. Orbits and Lagrange point locations are resources as well, and ensuring that they are fairly utilized is a key component of the framework.

The final step is the "Preservation" segment - essentially, it is the development of a plan to mitigate the concerns listed in the Catalog step. These mitigations could be the result of technological improvements like better solar collectors that could increase the overall power available at a specific location. Or they could be operational - they could mandate the joint use of a regolith collection machine by organizations that want to collect the water vs those that want to collect the iron for steel production. Finally, there could be policy practices, such as preserving historic sites like the Apollo landing sites or the final resting places of some of the recent lunar landers.

Fraser talks about the Lunar south pole, undoubtedly one of the more contested areas on the lunar surface because of its abundance of resources.

Both the Catalog and Preservation steps are intended to be repeated, with each being continuously updated. That would ensure that, if there are additional resources found somewhere unexpected, or another historic site comes into play for resource utilization, they are considered. The authors stress that the policy would not result in a static document, but a series of interconnected policy and operational priorities that would allow for the successful and harmonious exploitation of resources as we start to expand throughout the solar system. Given the conflict that has arisen on our home planet over those same resources, trying to plan ahead with all the knowledge that we have now on conflict resolution seems the right thing to do.

Learn More:

• M Herron, T Jones & A Hernandez - Benefits of a Proposed Process to Preserve Lunar Sites
• UT - Preserving Life's Blueprint Beyond the Earth
• UT - We've Entered a New Era: The Lunar Anthropocene
• UT - NASA Wants to Learn to Live Off the Land on the Moon

Our understanding of our Solar System is still evolving. As our telescopes have improved, they've brought the Solar System's deeper reaches into view. Pluto was disqualified as a planet because of it. Now, new research says another dwarf planet may reside at the edge of the Solar System. Its presence supports the Planet X hypothesis.

The ongoing effort to understand the distant Solar System led to the discovery of objects like Far Out in 2018. It's a trans-Neptunian object (TNO), one of thousands without names or numbers. TNOs are primordial objects, unaffected by the Sun at such great distances. They're significant because they can tell us how the Solar System's large planets migrated in the distant past.

Researchers have found another rare type of TNO called an ETNO, for Extreme trans-Neptunian Object. They're even more distant from the Sun. TNOs orbit the Sun at a greater distance than Neptune, with a semi-major axis of 30.1 astronomical units. ETNOs have perihelia greater than 70 astronomical units. The object's working name is 2017 OF201.

The discovery is presented in new research titled "Discovery of a dwarf planet candidate in an extremely wide orbit: 2017 OF201." The lead author is Sihao Cheng, an astrophysicist associated with the Perimeter Institute for Theoretical Physics and the Institute for Advanced Study.

2017 OF201 is notable for two reasons: its large size and its extremely wide orbit.

"It must have experienced close encounters with a giant planet, causing it to be ejected to a wide orbit." - Sihao Cheng, Perimeter Institute.

"We report the discovery of a dwarf planet candidate, 2017 OF201, currently located at a distance of 90.5 au," the authors write. "Its orbit is extremely wide and extends to the inner Oort cloud, with a semi-major axis of 838 au and a perihelion of 44.9 au precisely determined from 19 observations over seven years."

This image shows the current positions of Neptune, Pluto, and 2017 OF201.

Image Credit: Jiaxuan Li and Sihao Cheng

AT about 700 km in diameter, it qualifies as a dwarf planet. It's also the second-largest known object in the ETNO population. (For comparison, Pluto is 2,377 km.) Its presence suggests that what astronomers thought was empty space beyond Neptune in the Kuiper Belt isn't empty after all. "Its high eccentricity suggests that it is part of a broader, unseen population of similar objects totalling about 1 % of Earth's mass," the authors write.

"The object's aphelion—the farthest point on the orbit from the Sun—is more than 1600 times that of the Earth's orbit," lead author Cheng said in a press release. "Meanwhile, its perihelion—the closest point on its orbit to the Sun—is 44.5 times that of the Earth's orbit, similar to Pluto's orbit."

The new object's orbit stands apart from other ETNOs and disagrees with the idea that our Solar System has a ninth planet. "Notably, the orbit of 2017 OF201 lies well outside the clustering of longitude of perihelion observed in extreme trans-Neptunian objects, which has been proposed as dynamical evidence for a distant, undetected planet," the authors write.

In 2025, researchers computed the most likely orbit for Planet X based on the clustering of other ETNOs. However, 2017 OF201 doesn't conform to the clustering. "Many extreme TNOs have orbits that appear to cluster in specific orientations, but 2017 OF201 deviates from this," said co-author Jiaxuan Li.

"These results suggest that the existence of 2017 OF201 may be difficult to reconcile with this particular instantiation of the Planet X hypothesis," the authors explain.

This illustration shows the orbits of TNOs with extremely wide orbits. Curiously, the new TNO has a distinct orbit, making it an outlier. Planet X's most likely orbit, according to 2025 research, is shown in black.

Image Credit: Cheng et al. 2025.

At such an extreme distance from the Sun, the object takes about 25,000 years to complete one orbit. The last time 2017 OF201 was in the position it's in now, humans were hunter-gatherers, busy refining stone tools in the Upper Paleolithic period.

The authors think that its orbit tells a tale of gravitational interactions. "It must have experienced close encounters with a giant planet, causing it to be ejected to a wide orbit," says Yang. "There may have been more than one step in its migration. It's possible that this object was first ejected to the Oort cloud, the most distant region in our solar system, which is home to many comets, and then sent back," Cheng adds.

There's good reason to think that there are many more difficult-to-detect objects in the outer Solar System that qualify as dwarf planets. Finding this one took some good fortune because it's usually too far away to detect.

"2017 OF201 spends only 1% of its orbital time close enough to us to be detectable. The presence of this single object suggests that there could be another hundred or so other objects with similar orbit and size; they are just too far away to be detectable now," Cheng states. "Even though advances in telescopes have enabled us to explore distant parts of the universe, there is still a great deal to discover about our own solar system."

"The discovery of 2017 OF201 suggests a population behind it with hundreds of objects possessing similar properties, because the probability for 2017 OF201 to be close enough and detectable is only 0.5%, given its wide and eccentric orbit," the authors write. Based on its large size, they also think that the population's total mass is 1% of Earth's mass, not an insignificant amount.

Though its presence doesn't outright falsify the Planet X/Planet Nine hypothesis, it does pose a challenge. However, if the hypothesized planet does exist, it could spell doom for 2017 OF201. "Our N-body simulations suggest that the presence of the Planet X / Planet 9 that produces the clustering will cause ejection of 2017 OF201 in a short timescale around 0.1 Gyr," the authors write.

If that happens, the tiny dwarf planet will join the population of rogue planets that drift through the Milky Way.

Press Release: 

• An Extreme Cousin for Pluto? Possible Dwarf Planet Discovered at Solar System’s Edge

Research: 

• Discovery of a dwarf planet candidate in an extremely wide orbit: 2017 OF201

Some 13,000 years ago, the Sun emitted a huge belch of radiation that bombarded Earth and left its imprint in ancient tree rings. That solar storm was the most powerful one ever recorded. The next strongest was the 1839 Carrington Event. It was spurred by a huge solar flare that triggered a powerful geomagnetic storm at Earth. The resulting "space weather" disrupted telegraph communications around the world. Today, as we move through this year's "solar maximum", a period of solar activity that occurs every 11 years, scientists want to prepare governments for the effects of severe solar storms.

In May 2024, Johns Hopkins Applied Physics Laboratory (APL) convened experts at a tabletop exercise designed to test governmental and tribal agency preparations for a strong solar storm like the earlier ones. Solar physicists, space agencies, satellite operators, grid owners, and many others have long known of space weather effects on advanced technologies. The exercise incorporated stakeholders at all levels of government and industry to improve our readiness for space weather events.

Space Weather Effects

When a geomagnetic storm strikes Earth, a number of things happen. Charged particles from the Sun are delivered by the solar wind. That smacks up against our magnetosphere, and those particles get caught up in lines of magnetic force, which results in a lovely display of northern and southern lights. An especially strong storm will cause, among other things, ground currents which can short out electrical power grids and disrupt ground-based communications. A strong bout of space weather can interfere with (or even destroy) satellites, threaten astronauts in space, disrupt radio communications, and degrade GPS performance. That affects navigation for trains, planes, ships, and cars, and affects cellular networks. Any of those disruptions can interrupt such everyday events as transferring money, making cell calls, and much more. In other words, much of our modern technology is at risk during space weather events.

Damage to transformers (right) caused by the 1989 solar storm.

Courtesy PSE&G.

As an example, in March 1989, a powerful solar outburst triggered a solar storm that resulted in a power outage in eastern Canada. Millions were left without electricity for about nine hours. A power plant in New Jersey was also damaged during the same storm. In 2024, another storm hit over the U.S. Mother's Day weekend, resulting in brilliant auroral displays across much of the world. The space weather event also affected some broadcast and radio signals, and some power companies took steps to safeguard their systems. It also affected some satellite communications. That was, by comparison to the 1989 and 1839, a relatively benign space weather event.

Thanks to lessons learned during prior events, electrical grid and satellite operators (among others) are now better prepared. But more needs to be done to supply early warnings so that governments, companies, and individuals can be ready. That's where the tabletop exercise at APL comes in handy.

How Ready Are We for Strong Space Weather?

Spaceweather understanding and predictions have come a long way since the dawn of the space age and the deployment of Sun-watching satellite missions. We do get more early warnings of outbursts, and past events have taught us to "harden" our technologies against geomagnetic storms. However, there are still gaps in agency and government preparedness for and responses to such events.

The tabletop session uncovered many steps necessary to respond when space weather strikes. "This exercise brought together space weather experts alongside those responsible for emergency management, response, and recovery,” said Ian Cohen, APL Exercise Science Lead. “This helped us scientists to not only provide awareness to these senior leaders, but also highlight the key research and observational gaps, as well as learn how to best communicate the complicated topics of space weather to decision-makers.”

Flares and outbursts on the Sun during the May 2024 Mother's Day storm.

Courtesy NASA/SDO.

In the "After Action Report" from the exercise, released this year, the attendees acknowledged that our preparation is better than in the past, but there are still crucial needs to fill. Among them are better coordination among agencies and other stakeholders to produce meaningful and understandable space weather notifications that outline the impacts on various pieces of infrastructure. The whole government needs to be involved in such coordination, and communication between agencies (such as between NASA and NOAA or NOAA and safety agencies). In addition, upgrades in forecasting and early warning are needed, along with more public education about the effects of space weather and how governments and institutions handle the results of such storms.

In an interesting twist of fate, the tabletop exercise began just as the Sun unleashed another burst of radiation and charged particles toward Earth. It resulted in the Mother's Day storm of 2024 and gave participants in the exercise a chance to go beyond simulated exercises and manage a real-world case of space weather effects on Earth.

For More Information

• Nation's First Space Weather Simulation Exercise Examines U.S. Preparedness
• How NASA Tracked the Most Intense Solar Storm in Decades
• Space Weather Tabletop Exercise (PDF)

It was big news years ago when Mars orbiters found streaks of what appeared to be water running down Martian cliffs and crater walls. Scientists worked hard to figure out what they were. Some proposed that they were seasonal streaks of briny ice, melting as the weak Mars summer arrived. New research says no to that.

Our understanding of Mars, its past, and its ancient habitability hinges on our understanding of its water. The planet is cold and dry now, but was warm and wet in its past. One of the critical questions concerns what happened to its oceans' worth of water.

When scientists started finding dark streaks on the Martian surface that looked like they could be seasonal water flows, it generated quite a bit of excitement. Could this be the remnants of Mars' ancient water, seeping onto the surface from where it's sequestered underground? Could this underground reservoir provide habitat for simple life?

The streaks were named recurring slope lineae (RSL). They appear and reappear in the same places and can extend for hundreds of meters down slopes.

This image from the HiRISE camera on NASA's Mars Reconnaissance Orbiter shows recurring slope lineae in Palikir Crater.

Image Credit: NASA/JPL-Caltech/UArizona

New research in Nature Communications examined the issue and concluded that RSL and other streaks are not water-related. It's titled "Streaks on martian slopes are dry," and the authors are Valentin Bickel and Adomas Valantinas. Bickel is from the Center for Space and Habitability at the University of Bern in Switzerland, and Valantinas is from the Department of Earth, Environmental and Planetary Sciences at Brown University.

The research is focused on two related phenomena: RSL, which appear and disappear seasonally, and slope streaks, which can take years to fade.

"Slope streaks are dark albedo features on Martian slopes that form spontaneously and fade over years to decades," the researchers write. "Along with seasonally recurring slope lineae, streak formation has been attributed to aqueous processes, implying the presence of transient yet substantial amounts of liquid water or brines on Mars' surface, with important implications for present-day Mars' habitability."

Previous research has identified many potential explanations for streaks and RSL. Ground springs of briny water, seasonal melt of briny ice, impact Marsquakes, and wind have all been proposed. Researchers have found that while RSL occur predominantly in the southern summer, streak formation is enhanced in the northern autumn and winter. "To date, it remains unclear whether slope streaks and RSL are different expressions of the same process, or fundamentally different features," the authors write.

Understanding these features correctly has consequences. If they have a wet formation mechanism, the planet has a more pronounced hydrological cycle than previously thought. That would affect our understanding of Mars' climate, weather, surface evolution, and potential habitability. We'll also have to be much more cautious about exploring Mars. "In addition, liquid water or brines on Mars' surface would evoke serious concerns about planetary protection," the authors point out.

To understand these streaks, the researchers created a catalogue of 500,000 of them. They found a total of 13,026 bright and 484,019 dark slope streaks. They display various morphologies and are both 'light' and 'dark' streaks. There's no absolutely clear delineation between bright and dark, but dark streaks are younger and appeared more recently, while light streaks are older.

This figure shows the global distribution of RSL and streaks on Mars and their colours.

Image Credit: Bickel and Valantinas 2025, Nature Communications.

"Once we had this global map, we could compare it to databases and catalogs of other things like temperature, wind speed, hydration, rock slide activity and other factors," Bickel said. "Then we could look for correlations over hundreds of thousands of cases to better understand the conditions under which these features form."

After examining the data, the researchers reached some conclusions. "Our observations discard three previously proposed dry streak formation mechanisms: dust devils, rockfalls, and thermal cycling do not appear to play a globally important role in triggering slope streaks," they write.

This figure shows the distribution of slope streaks (bright, white; dark, black) and RSL (red) overlain on a Viking merged colour mosaic. The blue lines indicate valley networks, and yellow shapes represent confirmed rockfall locations. The researchers found no global correlation between streaks, RSL, and rockfall locations.

Image Credit: Bickel and Valantinas 2025, Nature Communications.

They also found that their observations didn't support any wet-formation scenarios either. Streaks don't favour any particular slope orientation, challenging the idea that CO₂ frost is a trigger.

However, dry formation scenarios are supported. "We identify three global-scale, statistically significant relations that support dry formation hypotheses for slope streaks," the authors write. Streak populations are located slightly closer to new impacts, experience above-average surface wind velocities, and also experience above-average dust deposition rates in the northern winter, which coincides with their enhanced seasonal formation.

"A big focus of Mars research is understanding modern-day processes on Mars — including the possibility of liquid water on the surface," said lead author Valantinas in a press release. "Our study reviewed these features but found no evidence of water. Our model favors dry formation processes."

"Our findings suggest that martian slopes currently do not experience seasonal, transient flows of liquid water or brines, underscoring the dry, desert-like nature of Mars," the researchers write in their conclusion. This alleviates one of the concerns about exploring regions where streaks and RSL appear. If they're wet, the potential for inadvertent contamination by Earth life has to be taken seriously. If they're dry, there's much less concern.

"This implies that slope streak and RSL locations are not likely to be habitable, alleviating strict planetary protection measures for future landed missions to those regions," the authors conclude.

"That’s the advantage of this big data approach," Valantinas said. "It helps us to rule out some hypotheses from orbit before we send spacecraft to explore."

Press Release: 

• Streaked slopes on Mars probably not signs of water flow, study finds

Research:

• Streaks on Martian slopes are dry

Extreme solar storms are a relatively rare event. However, as more and more of our critical infrastructure moves into space, they will begin to have more and more of an impact on our daily lives, rather than just providing an impressive light show at night. So it's best to know what's coming, and a new paper from an international team of researchers led by Kseniia Golubenko and Ilya Usoskin of the University of Oulu in Finalnd found a massive Extreme Solar Particle Event (ESPE) that happened 12350 years ago, which is now considered to be the most energetic on record. 

During an ESPE, the Sun releases a stream of particles that collide with Earth's atmosphere. This type of event isn't the same as probably the most famous "solar storm" of all time, the Carrington Event, which set fire to telegraph stations worldwide in 1859. The Carrington Event was a geomagnetic storm caused by a coronal mass ejection (CME) that directly interacted with Earth's magnetic field. It didn't have as much effect on the Earth's atmosphere, especially compared to the ancient ESPE.

ESPEs, as their name suggests, are caused by a massive influx of particles from the Sun. These particles interact directly with the Earth's atmosphere, and, importantly for the purposes of dating, have a noticeable impact on Carbon-14 levels. Specifically, the amount of C-14, as it's commonly known in chemistry, is increased dramatically compared to a baseline. Since living things like trees sequester carbon, we can tell when events like this happen to measure the amount of C-14 embedded in those previously living things using a technique called radiocarbon dating.

Fraser talks through the Carrington event and how it impacts our engineering designs now.

The paper does not describe new data—the tree rings they used to capture the 12350 BC event were found in southwestern Europe and described in a paper in 2023. The new work done in this paper was to apply a climatic model known as SOCOL:14C-Ex and use it to understand the impact the environment at the time had on the capture and sequestration of the C-14 isotopes from the ESPE. 

When the ESPE hit, the Earth was in an entirely different geological age, known as the Late Glacial period, at the end of the last Ice Age, as compared to the Holocene period that has existed for the last 10,000 years. That means there were pretty massive geological differences that could play a role in how the C-14 was captured in the rings.

The Earth had weaker geomagnetic shielding in 12350 BC, allowing more particles to enter the atmosphere than a similarly-sized event would have in the modern day. However, it also had lower CO2 levels, meaning there was less Carbon-12 (a more stable isotope) to be transmuted into C-14. The climate itself was different, and while it could have impacted the C-14 levels by changing the efficacy of carbon sinks or increasing how the C-14 particles moved about the atmosphere, the study found that it had a relatively limited impact on the differences between modern-day and the carbon levels back then.

Solar storms can get pretty bad, as Fraser explains.

To prove what "modern day" would have been like, the researchers used one of eight other known extreme ESPEs found in other tree rings. This one occurred in 775 and was previously the most intense ESPE known to science. Plenty of other tree rings from Germany, New Zealand, Argentina, the US, and elsewhere already had known C-14 levels that could be used as a calibration, in this case, a proof of concept.

The researchers tested SOCOL:14C-Ex to estimate the storm's intensity in 775 and proved the model worked then. They then adjusted some of the parameters based on the above considerations to calculate the ESPE intensity in 12350 BC. They found that it was about 18% stronger than the event in 775, making it the strongest known ESPE yet found.

Understanding how the Sun's extremes can affect us will continue to play a central role as we move more and more of our infrastructure off-planet. Engineers will have to plan for these extremes, and knowing the limits will only help us understand what we need to design. And who knows, there may be even more extreme events in the fossil record that SOCOL:14C-Ex will eventually find.

Learn More:

• K Golubenko et al - New SOCOL:14C-Ex model reveals that the Late-Glacial radiocarbon spike in 12350 BC was caused by the record-strong extreme solar storm
• UT - It's Been a Year Since the Most Powerful Solar Storm in Decades. What Did We Learn?
• UT - How Bad Can Solar Storms Get? Ask the Trees
• UT - New Research Indicates the Sun may be More Prone to Flares Than we Thought

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When the JWST came to life and began observations, one of its first jobs was to gaze back in time at the early Universe. The Assembly of Galaxies is one of the space telescope's four main science themes, and when it observed the Universe's first galaxies, it uncovered a mystery. Some of them appear to have supermassive black holes (SMBH) in their centers that are fuelling active galactic nuclei (AGN). However, they're not emitting X-rays, which is one of the hallmarks of AGN.

Little Red Dot (LRD) galaxies are small, red galaxies that formed about 600 million years after the Big Bang. The JWST has found more than 300 of them, but they remain a mystery collectively. Their brightness indicated they're more massive and swollen with stars than they should be at an early age. Our models suggest there wasn't enough time for them to grow so massive.

Astronomers then discovered AGN signatures that could explain the excess light. Rather than only stars, the LRD's excess light came from AGN. That would mean that the LRDs wouldn't need to be so massive to emit all that light, and their size wouldn't challenge our galaxy evolution models.

Unfortunately, that potential conclusion causes another problem. AGN emit powerful X-rays as the material swirling around in their accretion disks heats up. However, according to new research, LRDs appear to emit no X-rays.

The new research, titled "Chandra Rules Out Super-Eddington Accretion For Little Red Dots," has been submitted to The Astrophysical Journal. The authors are Andrea Sacchi and Akos Bogdan, both from the Harvard and Smithsonian Centers for Astrophysics. The paper is currently available at arxiv.org.

"A key feature of LRDs is their extreme X-ray weakness: analyses of individual and stacked sources have yielded non-detections or only tentative, inconclusive X-ray signals, except for a handful of individual cases," the authors write.

The lack of X-rays winds everything backward. If there are no X-rays, there can't be AGN with accretion disks. If there are no accretion disks, then LRD's powerful brightness can't come from SMBHs. If it can't come from SMBHs, it has to come from stars. Then we're back to square one: trying to explain how early galaxies were so massive and swollen with stars.

This Chandra image from the research shows the 55 LRDs in the Chandra Deep Field South in the 0.3 − 7 keV X-ray band. This range encompasses both soft X-rays and a good portion of the hard X-ray band. It's a broad and informative band for astrophysical observations, yet it turned up no X-ray detections.

Image Credit: Sacchi and Bogdan, 2025, The Astrophysical Journal.

Some researchers have suggested another solution. They say that the SMBHs are experiencing super-Eddington accretion rates.

SMBH black hole accretion is governed by the Eddington limit. The Eddington limit is a fundamental concept in astrophysics that explains the maximum brightness and accretion rates for astrophysical objects like SMBH. An object reaches the Eddington limit when two forces are balanced: outward radiation and inward gravitation. If one of these forces is too powerful, the object either expels its outer layers or ceases further accretion.

Astrophysicists know that the Eddington limit influences SMBH growth. However, they've proposed what's called super-Eddington accretion to explain how these massive objects became so massive so early in the Universe. Objects can exceed the Eddington limit for periods of time and experience super-Eddington accretion. Can that explain why LRDs are so bright while also being so weak in X-rays?

The authors point out that the only other explanation for the lack of X-rays is obscuration, and that explanation hasn't held up.

"As the most natural explanation, high obscuration, is disfavored by JWST spectroscopic evidence, several authors have suggested that the X-ray weakness of LRDs is intrinsic, due to super-Eddington accretion rates," the authors write. "In this work, we test that scenario by stacking X-ray data for 55 LRDs in the Chandra Deep Field South, accumulating a total exposure time of nearly 400 Ms."

400 megaseconds is the cumulative observing time for the 55 LRDs combined, not the total telescope observing time. That's an impressive depth of observation for the 55 objects. If super-Eddington accretion were occurring, that would explain the lack of X-rays.

Super-Eddington accretion still creates X-rays. However, those photons can get trapped in the accretion flow. They can also be absorbed or scattered by outflows and winds, or obscured by the thick disk or envelope around the SMBH. Current models show that super-Eddington accretion still emits X-rays, but as lower-energy soft X-rays. 400 megaseconds of stacked X-ray observations should detect them.

However, they didn't.

The Chandra X-ray Observatory is the world's most powerful X-ray telescope. It has eight times greater resolution and can detect sources more than 20 times fainter than any previous X-ray telescope. 400 megaseconds of stacked observing time should've detected X-rays if they were being emitted.

Image Credit: NASA/CXC & J. Vaughan

"Despite reaching unprecedented X-ray depths, our stack still yields a non-detection," the authors write. "The corresponding upper limits are deep enough to rule out current super-Eddington accretion models, and are compatible only with extremely high levels of obscuration."

The authors say we're left with only one explanation: "To explain the X-ray weakness of LRDs, we therefore speculate that the SMBHs in these systems are neither as massive nor as luminous as currently believed. " Other researchers have also suggested this.

So what's going on if observations show no X-rays, and if the JWST shows that dust obscuration is responsible?

"If the bolometric luminosities are overestimated by an order of magnitude, much lower levels of obscuration can hide the X-ray emission from accreting SMBHs without invoking super-Eddington accretion," the authors conclude.

The JWST has fulfilled its promise by revealing the Universe's earliest galaxies. That the results go against our models isn't surprising. Every new mission and telescope delivers some surprises, and scientists often look forward to surprising results.

For now, the LRD galaxies are unexplained. In fact, the mystery has deepened.

Examine just about any extraterrestrial body in the Solar System, and you will find that they all have the same thing in common: a long history of impacts. Whether it is the Moon, Mercury, Mars, or virtually all of the icy moons of the outer Solar System, the surface of these objects is pockmarked with craters. These craters tell a story about the evolution of these bodies and the kinds of forces that shaped them. Now, a team of researchers led by Brown University has determined that craters can be used to determine a body's subsurface composition.

The team was led by Aleksandra Sokolowska, a UKRI Fellow with the Department of Earth Science and Engineering (DESE) at Imperial College London. She was joined by Gareth S. Collins, a DESE Professor at Imperial, Ingrid J. Daubar, an Associate Professor with the Department of Earth, Environmental and Planetary Sciences (DEEPS) at Brown University, and Dr. Martin Jutzi, a Privatdozent with the Physics Institute at the University of Bern. Their research was published in the Journal of Geophysical Research: Planets. 

For decades, scientists have examined the size and shape of craters on extraterrestrial bodies to learn about what lies beneath the surface. According to Sokolowska's research, the rock layers and other ejecta produced by an impact can vary in size depending on the composition of materials beneath the impact point. Several factors play a role in altering a crater's characteristics, including the strength of the subsurface material and its porousness. This allows scientists to study planetary interiors from orbit without having to land and take drill samples.

Sokolowska performed the work with Dauba as a postdoctoral researcher at Brown University. This technique could allow scientists to spot patches of subsurface ice on Mars and other bodies based on data collected by orbiting missions. As Sokolowska indicated in a Brown University news release:

“Historically, researchers have used the size and shape of impact craters to infer the properties of materials in the subsurface. But we show that the size of the ejecta blanket around a crater is sensitive to subsurface properties as well. That gives us a new observable on the surface to help constrain materials present underground.”

For their study, Sokolowska and her colleagues sought to determine if crater ejecta could provide another source of information. This consisted of running models co-developed by Collins that simulate the physics of planetary impacts. The simulations also allowed them to vary the characteristics of the materials beneath the surface (single, layered, mixed) and the materials themselves (bedrock, sediment, loose rock with ice, solid glacial ice). The simulations showed that these characteristics produced a wide range of ejecta patterns.

The team then tested their results by examining two fresh impact craters on Mars, which were already known to have taken place over bedrock and subsurface ice. Since the ejected materials were young, they had not yet eroded much, making it easy to measure their distance from the impact site. They found that the ejecta pattern over the bedrock site was much larger than the one over subsurface ice. This was consistent with model predictions, confirming that differences in ejecta radius reflect subsurface properties. 

"The differences in ejecta radius can be quite large, and we predict that they could be measured from orbit with the HiRISE camera onboard Mars Reconnaissance Orbiter." Said Sokolowska. "Once the method is thoroughly tested, it could become a promising new tool for investigating subsurface properties. Turning this proof-of-concept work into a tool is the subject of my current fellowship at Imperial."

The team indicates that this method could be useful for current and future missions as they continue to explore Mars for clues about its past and where crewed missions could land someday. However, the team's findings have applications in the study of other astronomical bodies in the Solar System. This includes the double asteroid system Didymos, which the ESA's Hera spacecraft will rendezvous with in February 2026. In September 2022, NASA's Double Asteroid Redirect Test (DART) conducted the first kinetic impact test with Dimorphos, the small satellite that orbits Didymos.

When it arrives, Hera will examine the crater created by the impact to learn more about the asteroid's interior. Sokolowska said that examining the ejecta pattern could assist in this objective: "Our work suggests that ejecta that did not escape from the asteroid and blanketed its surface could hold valuable information about the asteroid's interior."

Further Reading: 

• Brown University, 
• JGR Planets

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On March 15th, 2024, the Sun released a powerful solar flare that coincided with a heightened period of solar activity. This was accompanied by a coronal mass ejection (CME), a massive cloud of solar energetic particles (SEP) that led to auroras all across the Solar System. This included Mars, where NASA's Perseverance rover made history by capturing a visible light image of the event with its Mastcam-Z instrument. This was the first time that an aurora was witnessed from the surface of another planet.

On Earth, auroras are a common phenomenon that occurs whenever solar particles interact with the global magnetic field. This field channels these energetic particles towards the poles, where they interact with atmospheric gases to produce the famous Northern Lights (Aurora Borealis) and Southern Lights (Aurora Australis). While Mars does not have a global magnetic field like Earth, it has localized magnetic fields and a very thin atmosphere by comparison (less than 1% of the atmospheric pressure).

On Earth, the most common color associated with auroras is green, which is caused by the excitation of oxygen atoms. For years, scientists predicted that Mars might also experience green light auroras, except they would be far fainter and more difficult to image. Hence why all previous observations of auroras on Mars have been by orbiters in ultraviolet wavelengths. This includes NASA's Mars Atmosphere and Volatile EvolutioN (MAVEN), which observed an SEP aurora from orbit in 2014.

Consequently, capturing this image required serious coordination and timing. Elise Knutsen, a postdoctoral researcher at the University of Oslo in Norway, was the lead author of the study that reported the detection, which recently appeared in Science Advances. Since SEPs typically occur during solar storms, especially during the peak of the Sun's eleven-year solar cycle (aka solar maximum), Knutsen and her team planned their observations to coincide with the peak of the Sun's current solar cycle.

They also created models that determined the optical angle for the Perseverance rover's SuperCam spectrometer and Mastcam-Z camera to observe it. The next step consisted of waiting for the right type of CME to happen. This task fell to NASA's Moon to Mars (M2M) Space Weather Analysis Office and the Community Coordinated Modeling Center (CCMC) at NASA's Goddard Space Flight Center. The former provides real-time analysis of solar eruptions to the CCMC, which uses the data to run simulations of CMEs and determine if they could impact NASA missions.

When their simulations predict a potentially hazardous CME, the M2M team sends out of alert. As Knutsen explained in a NASA press release:

"The trick was to pick a good CME, one that would accelerate and inject many charged particles into Mars' atmosphere. When we saw the strength of this one, we estimated it could trigger [an] aurora bright enough for our instruments to detect. This exciting discovery opens up new possibilities for auroral research and confirms that auroras could be visible to future astronauts on Mars' surface."

The team included researchers from Colorado's Laboratory for Atmospheric and Space Physics (LASP), UC Berkeley, NASA's Goddard Space Flight Center, and Jet Propulsion Laboratory, which collaboratively oversee NASA's MAVEN mission. By coordinating Perseverance's observations with measurements from MAVEN's SEP instrument, the teams helped determine that the light detected was the same emission line as green auroras on Earth.

"Perseverance's observations of the visible-light aurora confirm a new way to study these phenomena that's complementary to what we can observe with our Mars orbiters," said Katie Stack Morgan, acting project scientist for Perseverance at NASA's Jet Propulsion Laboratory. "A better understanding of auroras and the conditions around Mars that lead to their formation are especially important as we prepare to send human explorers there safely."

What's more, future astronauts are likely to be able to see this type of aurora from the Martian surface. While most will be difficult to see, mission crews could spend up to a year on the surface,

Further Reading: 

• NASA