Picture a planet so close to its star that the ground is melted rock. You'd expect it to look like a burnt pizza: dark and glowing. Instead, it is shiny.
Meet TOI-561 b
This planet sits about 280 light-years from us. Astronomers used the James Webb Space Telescope to watch it for more than 37 hours, almost four full trips around its star.
The surprise: it reflects about 75% of the light that hits it. That's like Venus, one of the brightest things in our night sky. A lava planet should not do that.
A giant sunscreen
The team thinks the planet has a thick atmosphere with clouds made of rock. Not rock as in stones, but silicate vapour, the stuff glass and sand are made of, turned into clouds in the heat. Those bright clouds bounce the starlight back into space, like sunscreen for a whole planet.
The atmosphere might be thick with carbon dioxide, like Venus, or with sulphur dioxide, like Jupiter's volcanic moon Io.
"Our discovery challenges current theories," says Dr Anjali Piette of the University of Birmingham. The work was led by Prof. Lisa Dang of the University of Waterloo in Canada and published in The Astronomical Journal.
Why it matters
Small, hot planets were supposed to lose their air fast. If this one kept a thick atmosphere, others might too. And that changes where we look for interesting worlds.
Meanwhile, on Earth, you still need to put on your own sunscreen. The planet's clouds don't cover you.