GJ 486 b is about 30% larger than the Earth and three times as massive, which means it is a rocky world with stronger gravity than Earth. It orbits a red dwarf star in just under 1.5 Earth days. It is too close to its star to be within the habitable zone, with a surface temperature of about 800 degrees Fahrenheit. And yet, Webb observations show hints of water vapor.

The water vapor could be from an atmosphere enveloping the planet, in which case it would need to be continually replenished due to losses from stellar irradiation. But an equally likely possibility is that the water vapor is actually from the outer layer of the planet’s cool host star. Additional Webb observations will help answer the question: Can a rocky planet maintain, or reestablish, an atmosphere in the harsh environment near a red dwarf star?