Webb Telescope Finds a Surprising Atmosphere on an Ancient Super-Earth

Astronomers using NASA’s James Webb Space Telescope have found evidence of a thick atmosphere wrapped around TOI-561 b, a rocky planet roughly twice the mass of Earth. The discovery, announced on March 22, 2026, was unexpected because the planet orbits its star in just over ten hours, at one-fortieth of Mercury’s distance from our Sun. Worlds this close to their stars were widely assumed to be bare, sun-blasted rock with any gases long since stripped away.

Instead, the research team, led by scientists at the Carnegie Institution for Science, used Webb’s Near-Infrared Spectrograph to detect signs of water vapor and possibly silicate clouds. They describe the planet as a kind of “wet lava ball,” where gases appear to cycle between a molten surface and the atmosphere above it. The measured dayside temperature, about 1,800 degrees Celsius, was notably cooler than predicted, suggesting strong winds may carry heat from the permanently lit dayside to the dark nightside.

“The discovery, announced on March 22, 2026, was unexpected because the planet orbits its star in just over ten hours, at one-fortieth of Mercury’s distance from our Sun.”

What makes the find especially intriguing is the planet’s setting. TOI-561 b orbits an ancient star more than twice the age of our Sun, in a region of the galaxy that is poor in heavy elements. The result published in The Astrophysical Journal Letters hints that even very old, metal-poor planetary systems may be able to form and hold onto atmospheres, broadening where scientists might look for chemically complex worlds.

The authors are careful to note that the interpretation is still being refined; confirming the exact atmospheric composition will require additional Webb observations. But the study is a reminder that the universe keeps overturning tidy assumptions. A planet that, by every rule of thumb, should be a dead rock instead appears to be a dynamic, gas-shrouded world, and a hopeful sign of how much remains to be discovered as our most powerful telescope keeps surveying the sky.