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- Lava worlds are rocky exoplanets<\/strong> that orbit so close to their stars that intense heat can melt rock on their surfaces. Scientists had expected that they would lose their atmospheres due to the intense radiation from their stars.<\/li>\n
- But it turns out some lava-worlds do have atmospheres,<\/strong> even thick ones! How is that possible?<\/li>\n
- A new model from researchers at Stanford University<\/strong> shows that gases slowly escaping from below the planets\u2019 surfaces can keep their atmospheres sustained.<\/li>\n<\/ul>\n
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Some lava-world exoplanets have atmospheres<\/h3>\n
Exoplanets that orbit very close to their stars are always in danger of losing their atmospheres. That\u2019s because the radiation and stellar winds from the stars can erode the atmospheres until there\u2019s little to nothing left. Some of these planets are rocky lava-worlds; the intense heat from the nearby star has melted rock on their surfaces. Scientists expect such planets to be airless. But some of them do still have their atmospheres, even thick atmospheres. <\/p>\n
How is that possible? A new study, led by researchers at Stanford University in California, suggests an explanation. The researchers said on August 25, 2026, that gases slowly escaping from below the planets\u2019 surfaces might replenish the gases that have been lost. The researchers published their peer-reviewed results in The Astrophysical Journal Letters<\/em> on August 25, 2026.<\/p>\n
That escape of gas into space is called outgassing<\/em>. According to the new study, these atmospheres could last for billions of years.<\/p>\n
![\"Lava-world](\"https:\/\/earthsky.org\/upl\/2026\/08\/TOI-561b-exoplanet-cosmic-sandbar-artist-concept-August-25-2026.jpeg\")
View larger. | Here\u2019s an artist\u2019s concept of exoplanet TOI-561b. The planet lies in the newly proposed \u201ccosmic sandbar,\u201d where some lava-world exoplanets may retain atmospheres despite intense stellar radiation. Image via Image via NASA\/ ESA\/ CSA\/ Ralf Crawford (STScI)\/ Stanford University.<\/figcaption><\/figure>\n Sandbar, shoreline, valley<\/h3>\n
According to the new model, these lava worlds exist on a kinda of cosmic sandbar<\/em>. What does that mean?<\/p>\n
Prior to this new study, astronomers began speaking of a cosmic shoreline<\/em>. They mean it to imply the boundary region in a distant solar system \u2013 at a particular distance from the central star \u2013 beyond which rocky exoplanets can<\/em> retain atmospheres. Think of the shoreline as the dividing line between \u201chas air\u201d and \u201cairless.\u201d <\/p>\n
Between this shoreline<\/em> and the hotter sandbar<\/em>, planets can lose their atmospheres and fail to replenish them. Astronomers refer that region of a distant solar system as an airless valley<\/em>.<\/p>\n
But now comes the cosmic sandbar<\/em>: the unexpectedly hot region where some lava worlds can maintain atmospheres because gases released from their molten interiors replenish what stellar radiation strips away.<\/p>\n
55 Cancri e is a good example. It\u2019s a super-Earth almost eight times the mass of Earth. It orbits its star about 20 times closer than Mercury orbits the sun. Yet is has a thick atmosphere. The James Webb Space Telescope discovered that atmosphere \u2013 the first found on a rocky exoplanet \u2013 in 2024.<\/p>\n
![\"Graphic](\"https:\/\/earthsky.org\/upl\/2026\/08\/cosmic-sandbar-airless-valley-cosmic-shoreline-graphic-Nguyen-et-al-August-25-2026.jpeg\")
View larger. | This graphic shows the differences between the cosmic sandbar, the wireless valley and the cosmic shoreline. Image via Nguyen et al. 2026\/ The Astrophysical Journal Letters.<\/figcaption><\/figure>\n \n
astrobiology.com\/2026\/08\/26\/w\u2026 #astrobiology #exoplanet<\/p>\n
\u2014 Astrobiology (@astrobiology.bsky.social) 2026-08-26T19:39:24.014Z<\/p>\n<\/blockquote>\n
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Continuous magmatic outgassing allows ultra-hot lava worlds to defy the cosmic shoreline theory and sustain thick atmospheres despite intense stellar radiation. www.labroots.com\/trending\/spa\u2026<\/p>\n
\u2014 Labroots Earth & Environmental Sciences (@earth-lr.bsky.social) 2026-08-26T18:32:12.623Z<\/p>\n<\/blockquote>\n
The \u2018cosmic sandbar\u2019<\/h3>\n
The research team has proposed a new region around stars called the \u201ccosmic sandbar.\u201d It is an extension of the \u201ccosmic shoreline,\u201d which is analogous to shorelines on Earth between land and water. For stars, it represents the boundary where a planet can keep or lose its atmosphere. In our solar system, Earth and Venus are on the cosmic shoreline. They remain cool enough that radiation from the sun doesn\u2019t burn off their atmospheres.<\/p>\n
But there\u2019s a catch. Some lava-worlds are closer to their stars than that cosmic shoreline boundary. So how do they maintain their atmospheres?<\/p>\n
The researchers have called this region the cosmic sandbar. It is analogous to the sandy ridges that form offshore in oceans. As lead author Barron Nguyen at the Stanford Doerr School of Sustainability explained it:<\/p>\n
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These lava-worlds have pointed to something being wrong with the cosmic shoreline boundary, but we\u2019ve found a way for them to preserve their atmospheres by proposing a new regime beyond it.<\/p>\n<\/blockquote>\n
Co-author Laura Schaefer added:<\/p>\n
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Where the shoreline boundary is between airless worlds and those capable of sustaining an atmosphere has been a major open question in planetary science. The new model expands our understanding of this boundary and the factors that go into determining where it lies for specific stars and planets.<\/p>\n<\/blockquote>\n
![\"Rocky](\"https:\/\/earthsky.org\/upl\/2026\/08\/55-Cancri-e-exoplanet-lava-world-NASA.jpeg\")
View larger. | Artist\u2019s concept of 55 Cancri e, a lava-world exoplanet 41 light-years from Earth. Image via NASA.<\/figcaption><\/figure>\n The \u2018airless valley\u2019<\/h3>\n
There\u2019s also another region called the \u201cairless valley.\u201d That\u2019s between the shoreline and the sandbar. The planets are close enough to their stars for their atmospheres to be stripped away, but then they cool off too quickly after formation for those atmospheres to be replenished.<\/p>\n
![\"Black](\"https:\/\/earthsky.org\/upl\/2026\/08\/Barron-Nguyen-Stanford-University.jpeg\")
Barron Nguyen at Stanford University led the new study about lava-worlds and their atmospheres. Image via Barron Nguyen.<\/figcaption><\/figure>\n Follow the atmospheres<\/h3>\n
One of the major \u2013 and most exciting \u2013 aspects of studying exoplanets is the search for life. To do this, scientists \u201cfollow the atmospheres.\u201d As a first step, they need to find rocky planets that have atmospheres. Then they can analyze those atmospheres for possible biosignatures, chemical fingerprints of living organisms. Nguyen said:<\/p>\n
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Scientists have been interested in figuring out which planets have atmospheres and which do not, because that\u2019s the first step of looking at planetary habitability.<\/p>\n<\/blockquote>\n
That\u2019s why planets that do have atmospheres, despite being so close to their stars, is so interesting. It expands the range of planets that could be potentially habitable. Although in the case of lava-worlds, they are likely simply too hot for life. At least on the surface.<\/p>\n
The cosmic shoreline might not be as definitive as previously thought when determining which exoplanets could be habitable. It\u2019s not completely a lost cause though, either. Nguyen said:<\/p>\n
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A major takeaway from our study is that the cosmic shoreline isn\u2019t a lost cause. There had been some pessimism about it because of these lava worlds, but now we know there\u2019s a broader set of parameters that can enable a planet to generate and maintain an atmosphere.<\/p>\n<\/blockquote>\n
Scientists also reported finding a atmosphere on another lava-world, TOI-561 b, earlier this year. It is a super-Earth 560 light-years away.<\/p>\n
Bottom line: A new study from researchers at Stanford University helps explain how hot lava-world exoplanets orbiting close to their stars can maintain their atmospheres.<\/p>\n
Source: An Evolving Cosmic Shoreline and Sandbar Bounding the Rocky Airless Valley<\/p>\n
Via Stanford University<\/p>\n
Read more: Possible atmosphere on rocky exoplanet found for 1st time<\/p>\n
Read more: Atmosphere on lava planet is an exciting surprise<\/p>\n
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\n - But it turns out some lava-worlds do have atmospheres,<\/strong> even thick ones! How is that possible?<\/li>\n