News

How Mars Can Help Us Understand ‘Marginal’ Exoplanets

Mars holds a special place in the Solar System. It represents marginal habitability. This means it transitioned from warm and wet and potentially hospitable, to cold and dry and inhospitable.

What can its transition tell us about exoplanet habitability?

New research to be published in the Planetary Science Journal examines the question. It’s titled “Mars as an Exoplanet: Lessons from a Planet at the Edge of Habitability.” The lead author is Stephen Kane, Professor of Planetary Astrophysics in the Earth & Planetary Sciences Dept. at the University of California, Riverside. The research is currently available at arxiv.org.

“Mars is the Solar System’s canonical small, rocky planet that transitioned from early geologic activity and surface liquid water to a cold and arid planet with a thin, cold, CO-dominated atmosphere,” the authors write. “The evolution of Mars, in the context of such planetary parameters as size, mass, atmosphere, insolation flux, magnetosphere, and impact history, harbor important diagnostics regarding the development and sustainability of habitable surface conditions.”

*This figure shows the planetary mass and radius data for confirmed exoplanets that have measurements extracted for both properties, extracted from the NASA Exoplanet Archive on 2025, December 31. The data are color-coded in proportion to the flux received from their host stars. The Solar System terrestrial planets are shown as stars. The shaded region indicates the sub-Earth regime. Image Credit: Kane et al. 2026. PSJ*

Our understanding of the exoplanet population has grown enormously in recent years. In exoplanet surveys, small rocky worlds are common and outnumber larger gas planets. But while we know they exist in large numbers, we lack a detailed understanding of their climates, their volatile budgets, and their long-term potential for habitability. According to the authors, Mars can help us understand its exoplanet cousins.

They point out that though size is a basic property of rocky planets, and a good starting point for understanding them, it doesn’t dictate how a planet evolves. “Venus, Earth, Mars, and even the Moon each underwent distinct volatile, tectonic, and atmospheric trajectories despite sharing the same stellar environment, illustrating that planet size alone does not uniquely determine planetary evolution,” they explain.

In this research, the authors synthesize research into how different aspects of Mars—including volatile delivery and loss, photochemistry, climate evolution, magnetism, and other factors—can help our overall understanding of exoplanets and their processes.

“Exoplanet studies often use Earth properties as standard units of measurements, particularly for those relevant to describing the capabilities of exoplanet detection
methods,” the authors write. Mars has many similar properties to Earth, but its diffferences are what’s important in this work.

*These schematic cross sections of Earth and Mars show the major internal components and atmospheric components to scale. For simplicity, oceanic and continental crust for Earth are not distinguished, nor is the interior structure of Earth’s mantle shown. Image Credit: Kane et al. 2026. PSJ*

First of all, Mars formed differently from Earth. It’s formation was rapid at first, then stalled at a sub-Earth mass. The authors describe it as a “stranded planetary embryo” instead of the result of later giant impacts.

The planet’s mass is important in its evolution, which isn’t surprising. “Mars occupies an important position in comparative planetology, since it is both a geologically rich world with a documented history of surface habitability, and a representative example of how small rocky planets can evolve toward atmospheric loss and climatic decline,” they write.

Mars can serve as a framework for understanding rocky exoplanets. One of the main conclusions is that Mars shows how planetary habitability isn’t a static condition. The authors describe it as “a time-dependent outcome governed by competing processes.”

For example, early Mars was volcanic, and released volatiles built up a thick atmosphere that trapped heat. But as its interior cooled and its dynamo stopped, atmospheric escape led to cooling and eventual loss of habitability. “These coupled processes can define a pathway that may be common for Mars-mass planets,” the authors write.

According to our understanding of Mars, habitability is likely to be fleeting more often than not, and Earth shines as a rare example of long-term habitability. “In
this context, Mars represents the edge of the habitable regime, being large enough to host transiently clement conditions, but small enough that atmospheric retention
and replenishment and long-term climate regulation are not guaranteed,” the authors write.

While Mars-mass planets are widely detected, there are shortcoming in those observations. “Our discussion of exoplanet demographics have shown that, while terrestrial-size planets are abundant, confirmed Mars-mass planets with well-constrained masses and radii remain relatively rare, largely due to detection shortcomings,” the authors write. That will change when the Nancy Grace Roman Telescope and its microlensing survey goes live.

As we discover more Mars-mass planets with well-measured constraints, we’re also developing future telescopes that get better at observing exoplanets. “Direct imaging and thermal emission studies, particularly with next-generation facilities, will ultimately determine whether such planets commonly retain thin CO2 atmospheres, undergo desiccation, or exhibit transient volatile cycles,” the researchers explain.

The key idea is that scientists can use what they learn about Mars to understand these observations. “Mars missions will continue to measure atmospheric escape rates, volatile inventories, and climate feedbacks with a level of detail unattainable for exoplanets, while exoplanet surveys contextualize Mars within a broader statistical population,” the authors write.

The researchers explain that as Mars exploration and exoplanet characterization converge, it will deliver an effective new way to better understand the large numbers of small rocky worlds. Scientists will better understand key properties of exoplanets, like the mass necessary to sustain geological activity like plate tectonics. They’ll also develop a better understanding the stellar environment and how it shapes atmospheric survival, as well as other planetary characteristics that shape habitability.

“Within this framework, Mars provides a fundamental benchmark for evaluating the diversity, evolution, and potential habitability of rocky planets throughout the Galaxy,” the authors conclude.

News

It Took a Century, but Astronomers Imaged Betelgeuse’s Companion

Most of us are familiar with Betelgeuse (also known as alpha Orionis), the bright shoulder star in the constellation Orion. It’s a red supergiant star that lies somewhere between 400 and 550 light-years away from us and is quite bright. Betelgeuse contains about 14 times the mass of the Sun and is a fairly young star compared to ours. It appears to be no more than 10 million years old, which means that it evolved rapidly from a protostar to the red giant we see today. That lifecycle means Betelgeuse will explode as a supernova sometime in the relatively near future — say within the next 100,000 years.

For all these reasons (and more), astronomers are quite interested in this star and have observed it for decades using multiwavelength detectors from Earth and space. The star’s brightness and pulsations make it difficult to determine its exact diameter over time. The fact that Betelgeuse is so bright hides any possible companion(s) that it could outshine, but astronomers have suspected for years that the brightness (and variations) hid a secret companion. Other telescopes and techniques have found hints of it, but until recently, there’s been little positive proof that such a star was actually there.

This image is a color composite made from exposures from the Digitized Sky Survey 2 (DSS2). The field of view is approximately 2.0 x 1.5 degrees. Courtesy ESO/Digitized Sky Survey 2. Acknowledgment: Davide De Martin.

Now, for the first time, astronomers using the Very Large Telescope in Chile have announced the clearest image of what looks to be that companion star from images and data taken in 2024. It’s called Betelgeuse B, with the nickname of Siwarha, and it appears to be about 2 or 3 times the mass of the Sun, according to astronomer Miguel Montargès, who led the observation team. “This is the conclusion of a century-long quest,” Montargès said. Honestly, I thought we did not have the sensitivity to detect Betelgeuse B as it was predicted. Because it is more massive than predicted, we see it!” Originally thought to be about as massive as the Sun, the new observations reveal that Betelgeuse B has around two to three times the mass of the Sun. “The fact that we can still discover a nearby companion, more massive and brighter than the Sun, around such a well-studied star is remarkable,” says Montargès. “These are among the best moments in science: seeing something new, unexpected.”

This image, taken with ESO’s Very Large Telescope (VLT), shows the clearest image ever of what likely is Betelgeuse B (nicknamed Siwarha), a star orbiting Betelgeuse. The image was taken with the SPHERE instrument in December 2024, when the companion was predicted to be furthest apart from Betelgeuse as seen from Earth. The circle indicates the size of Betelgeuse, which has been removed. The bright source to the left, marked with a crosshair, is consistent with being Betelgeuse B. Credit: ESO/M. Montargès et al.

The Search for Betelgeuse’s Companion

Astronomers have long suspected Betelgeuse had a companion, and found tantalizing evidence of it. But it’s always been tough to spot, due to Betelgeuse’s brightness and its variations in luminosity. Betelgeuse itself appears to be embedded in a lopsided envelope of material that it has ejected as it aged. That’s pretty normal as a supergiant like this evolves. It happens because the star has moved into a period in its evolution where it has stopped hydrogen fusion in its core. That change has led to mass-loss ejections of material now seen around the star.

An infrared view of Betelgeuse taken using the VISIR camera on the Very Large Telescope in Chile. It shows the extent of material being thrown off into space as Betelgeuse ages. This mass loss is a critical part of its stellar evolution. The small red circle in the middle has a diameter about four and a half times that of the Earth’s orbit and represents the location of Betelgeuse’s visible surface. The black disc corresponds to a very bright part of the image that was masked to allow the fainter nebula to be seen. Courtesy ESO/P. Kervella

Betelgeuse is a pulsating variable, which causes its brightness to vary over time as its size and temperature change. In 2019, observers began noticing that Betelgeuse was going through an unexpected dimming phase. Hubble Space Telescope images and data showed evidence of dense material moving through Betelgeuse’s atmosphere before being ejected to space. Observers concluded that as the hot material cooled, it formed a dust cloud that temporarily blocked light from the star. Astronomers also suggested that starspots might be dimming the star. Such variations in brightness very likely made it more difficult to find the companion star. More recent Hubble observations of Betelgeuse seemed to find strong evidence of a trail of dense gas swirling through the star’s atmosphere. The trail is caused by Betelgeuse B/Siwarha as it orbits around a common center of gravity with Betelgeuse itself.

Betelgeuse B was directly imaged despite Betelgeuse’s brightness when astronomers used the SPHERE instrument on ESO’s VLT. The team used extreme adaptive optics and then performed image processing on the data. While there’s definitely a companion there, astronomers have not yet determined if it’s gravitationally bound. Betelgeuse B appears to be a 2.6 to 3.1 solar-mass B-type young main-sequence star.

Watching the Betelgeuse System

VLT was the first telescope to directly image the star, but other telescopes have tried to see the companion, too, including the Gemini North Telescope in Hawai’i. According to study co-author Anthony Boccaletti, more observations will help solidify the find. “It is remarkable to see how SPHERE and advanced post-processing techniques, originally developed to find exoplanets, also excel at detecting a companion around a massive, evolved star like Betelgeuse,” said Boccaletti. “To be certain that the companion is really there, we still need to observe it in one year on the other side of the star, but there is very little space left for doubt,” adds Montargès.

Betelgeuse’s recent dimming episode raised a lot of questions about its lifetime. Astronomers speculated that the star might be on the precipice of a supernova explosion. The discovery of the dust clouds mitigated some of that speculation, and it appears that the star won’t be blasting itself to pieces any time soon.

The presence of the companion has prompted astronomers to investigate how it might affect Betelgeuse’s anticipated supernova explosion. “The question is truly open whether this companion is going to have an impact on the evolution of the red supergiant,” said Montargès.

If Betelgeuse’s evolution goes as expected, sometime in the next 100,000 years, it will go through a catastrophic mass-loss phase and what’s left will collapse down onto the core of the star. That will compress the core into a remnant — possibly a neutron star or even a black hole. The light from the explosion will brighten our night skies for several months before dimming down. The companion could be completely destroyed by the explosion, or perhaps a remnant of it, too, will survive. For now, however, astronomers will continue to observe Betelgeuse and its companion to finally verify Siwarha’s existence, characteristics, and effects on its larger companion as Betelgeuse slowly moves through old age.

For More Information

Astronomers Find Strongest Evidence Yet that Betelgeuse Has a Companion

VLT/SPHERE Images of the Candidate Companion of Betelgeuse

NASA Hubble Helps Detect ‘Wake’ of Betelgeuse’s Elusive Companion Star

What is Betelgeuse? Inside the Strange, Volatile Star

News

Boyle Heights warehouse fire recovery nears halfway point, officials say

urlhttps3A2F2Fcalifornia times brightspot.s3.amazonaws.com2Fb12F4e2Fcb6944aa403ba7543b972103

Cleanup efforts at the Lineage cold-storage warehouse in Boyle Heights are nearing the halfway mark, six weeks after a fire at the depot left millions of pounds of rotting food to pollute the Los Angeles neighborhood.

The city’s focus is shifting from providing immediate relief to removing noxious debris, reducing foul odors and tainted air, and putting affected residents into interim housing, said Jon Brown, assistant general manager of the Los Angeles Emergency Management Department.

“Recovery is not linear,” Brown said at a city Emergency Operations Board meeting Thursday afternoon. “Right now we are right at that intersection of short, intermediate and long-term recovery.”

The fire broke out on June 17, burning for more than a week and collapsing the 500,000-square-foot facility. The disaster left Boyle Heights wrapped in a cloud of severe odor, pest infestations and potentially toxic air, leaving the community outraged over ongoing cleanup delays.

Cleanup continues at the Lineage warehouse in Boyle Heights on Wednesday.

Millions of pounds of spoiled food remain inside the collapsed warehouse facility, two weeks before classes begin for local L.A. Unified students.

Brown declined to comment when asked about the status of Mayor Karen Bass’ order to remove food waste and debris within 45 days, but emphasized that officials are moving quickly to hold Lineage Logistics responsible.

Lineage has racked up fines from both the Los Angeles County health department and the South Coast Air Quality Management District over the last several weeks as residents file complaints over ongoing odor issues.

“We know that the Boyle Heights and East L.A. communities have been underserved and have a history of environmental impact,” Brown said. “We have a huge responsibility to stabilize the households, businesses, and the communities within the impacted area, accelerate remediation and restore infrastructure.”

On Monday, Lineage representatives filed permits with the city to rebuild the warehouse to its “pre-fire condition,” drawing swift condemnation from locals and Bass, who decried the application as “a slap in the face” to Boyle Heights families.

The Emergency Management Department is expected to release a status report on neighborhood recovery efforts Friday.

News

Former Lt. Gov. Mandela Barnes Exits Race for Wisconsin Governor

With a democratic socialist, Francesca Hong, leading in polls, former Lt. Gov. Mandela Barnes said he was ending his campaign in the closely divided state.