TECH & SCIENCE DAILY
Imagine a planet so close to its star that a full year lasts about eleven hours. A world where the ground is an ocean of molten rock, where one side is locked in permanent daylight and the other in permanent night, and where every textbook says any atmosphere should have been blasted into space long, long ago. Now imagine that world is wearing a giant, shimmering sunscreen.
That, according to new James Webb Space Telescope observations published this week, is the strange reality of TOI-561 b, a lava planet about 280 light-years from Earth. The findings, reported in The Astronomical Journal and released on 27 October 2026 by a team led from the University of Waterloo in Canada with co-authors at the University of Birmingham, suggest the planet is wrapped in a thick atmosphere and swathed in reflective clouds. Astronomers did not expect it to have either.
"We would expect a heavily irradiated rocky planet like TOI-561 b to have lost its atmosphere billions of years ago," said Dr Anjali Piette, an assistant professor of astronomy at the University of Birmingham and a co-author on the study. The evidence, she said, suggests it "still has a significant atmosphere today."
Meet the hellworld
TOI-561 b is what astronomers call an ultra-short-period planet. Earlier work describes it as a super-Earth, roughly 1.45 times the diameter of our planet and about three times its mass. It circles its star in under eleven hours, so close that its surface is believed to be covered by a global ocean of molten rock. Because it is almost certainly tidally locked, in the same way the Moon always shows Earth the same face, one hemisphere bakes while the other sits in darkness.
On paper, this is the last place you would look for air. Intense radiation from a nearby star strips gas from small planets, and rocky worlds in tight orbits are widely assumed to end up as bare, scorched cinders. The planet has another twist: a 2021 study indicated it may have formed very early in the history of the Milky Way, implying rocky planets have been forming for at least ten billion years. If so, any atmosphere it has now has survived an almost unimaginable length of time under fire.
That is why TOI-561 b has become a favourite target for Webb. If a planet like this can keep an atmosphere, then the odds of finding air on other hot, rocky worlds go up sharply.
Thirty-seven hours of staring
To find out, the team pointed Webb's NIRSpec instrument at the planet for 37 hours, covering nearly four complete orbits. The technique is called a phase curve. As the planet circles its star, astronomers watch the total light from the system rise and fall, revealing how bright and how hot each side of the planet is as it rotates into view. It was the first time the planet's nightside had been observed in this way.
The results did not match the script. If TOI-561 b were a bare rock, its dayside should have been fiercely hot, with little heat reaching the dark side. Instead, the dayside turned out to be cooler than predicted, and heat appeared to be spread around the planet rather than trapped on the sunlit hemisphere. The team also found the planet was reflecting a surprising amount of starlight.
"The heat redistribution and light reflection together point to the presence of an atmosphere," said Professor Lisa Dang of the University of Waterloo, who led the project. The paper is titled "A Highly Reflective Atmosphere on the Lava World TOI-561b Revealed by JWST/NIRSpec Phase Curves".
The giant sunscreen
How reflective? According to the university's summary of the findings, TOI-561 b bounces back about 75 percent of the starlight that hits it. That is comparable to Venus, the brightest planet in our own sky, wrapped as it is in thick clouds. A bare lava surface, by contrast, is dark and absorbs most of the light that falls on it.
The leading explanation is a veil of clouds made of silicate minerals, the same family of materials as rock and sand. Climate simulations suggest silicon dioxide and magnesium silicate could condense high above the dayside, forming a layer that acts as a giant sunscreen, reflecting harmful radiation and keeping the dayside cooler than it would otherwise be. Yes, that means a planet whose clouds are, quite literally, made of vaporised rock.
The team stresses that the composition of the atmosphere is still unknown. Two main candidates have emerged. In one, the planet is a hotter cousin of Venus, with a thick blanket of carbon dioxide. In the other, it is an extreme version of Jupiter's moon Io, the most volcanically active body in the solar system, with an atmosphere dominated by sulphur dioxide.
How does a lava planet keep its air?
The bigger puzzle is survival. Even a thick atmosphere should leak away over billions of years. Researchers offer two ideas, and the truth may be some mix of both. The planet may simply have started with an enormous amount of gas, enough to last. Or its magma ocean may act as a planet-sized volcano, continually releasing fresh gas to replace what escapes.
That second idea echoes earlier Webb results. In December 2025, Carnegie Science's Nicole Wallack and colleagues reported that TOI-561 b appeared to be "surrounded by a relatively thick blanket of gas," a finding that challenged ideas about ultra-short-period planets. Press coverage at the time nicknamed it a "wet lava ball", based on a model in which some gases escape to space while the interior keeps topping up others. Piette explained that gases like water vapour would absorb some near-infrared wavelengths emitted by the surface, which is one way an atmosphere would show up in Webb's data.
This week's phase-curve work builds on that picture, adding the first look at how heat and light move around the whole planet. Together they make a stronger case that the air is real, thick and, remarkably, long-lived.
Expert perspective: a rulebook on the edge
Why does this matter beyond one extreme planet? Because astronomers have been sorting the galaxy's rocky worlds into winners and losers on the basis of one assumption: that close-in planets lose their atmospheres. That assumption shapes where telescopes look, which targets get precious observing time, and how scientists judge whether a distant planet could ever be habitable.
Piette said the discovery "challenges current theories." If hot rocky planets can hold on to gas thanks to molten interiors that feed it, then the pool of worlds with atmospheres could be bigger than expected. That does not make TOI-561 b habitable; it is the opposite of habitable. But learning the mechanisms that keep air on an inferno helps researchers understand how atmospheres form, escape and regenerate on every kind of rocky planet, including cooler ones.
There is also the matter of our own system. Venus and Io, both invoked as comparisons, are close neighbours that we know only partially. A lava world 280 light-years away that looks like a hybrid of the two gives planetary scientists a natural laboratory in which to test ideas about volcanic outgassing and cloud formation.
What Webb will do next
The team has a clear to-do list. The first goal is to work out whether TOI-561 b is closer to a hotter Venus or a more extreme Io. Dang suggested observing at longer wavelengths with Webb to better understand how the planet has kept its atmosphere for billions of years. Different gases leave different fingerprints in the infrared, so a wider spectral window could settle the carbon dioxide versus sulphur dioxide question.
Other co-authors include Samuel Boucher, Alex McGinty, Johanna K. Teske, Raymond Pierrehumbert and Diana Valencia, among others, reflecting the cross-disciplinary effort between observers, atmospheric modellers and geophysicists that this kind of work requires. The paper appears in The Astronomical Journal, volume 172, issue 4, article 239.
It is worth noting what is still uncertain. The cloud explanation is based on climate simulations and has not been confirmed by direct detection of the minerals, and the composition of the atmosphere remains open. Science of this kind advances in small, careful steps, and a rival explanation for the reflectivity could still emerge.
What this means for you
You will never visit TOI-561 b, and you would not want to. But the story shows why a multi-billion-dollar space telescope keeps earning its keep. Every time Webb looks at a world that astronomers think they understand, there is a real chance that it will upend the textbook.
For anyone who has wondered whether we are alone, the finding is quietly encouraging. The more ways nature finds to give a planet an atmosphere, the more places there might be to look for one that can support life. Every extra mechanism, even one that works only on a world of liquid rock, widens the search.
And for the rest of us it is a reminder that the universe is stranger than our assumptions. A planet that should be a bare cinder is instead hiding behind a veil of vaporised stone, bright enough to rival Venus, and it has been doing so for a very long time.
The bottom line
TOI-561 b is a world that breaks the rules: too hot, too close, too old, and yet apparently still wrapped in air. Webb has shown that it is reflecting about three-quarters of its star's light, spreading heat around its globe and holding onto an atmosphere that theory says should be gone. Questions remain about what that atmosphere is made of and how it has endured. Answering them will take more time on the telescope and more careful modelling. For now, the sunscreen planet has earned its place as one of the most intriguing worlds Webb has found, and a strong reminder that in astronomy the most extreme places often teach the most.
