Astronomers may be one step closer to solving the mystery of TRAPPIST-1e — one of the most Earth-like planets ever discovered. Thanks to the James Webb Space Telescope, scientists have now ruled out some big possibilities about its atmosphere.

TRAPPIST-1e sits in the habitable zone of its star — the “Goldilocks zone” where liquid water could exist. But what kind of air, if any, surrounds this planet?

New JWST data suggests it almost certainly does not have a thick hydrogen-rich atmosphere. Even more exciting: the observations also rule out Venus-like or Mars-like atmospheres, dominated by carbon dioxide. That means TRAPPIST-1e is not likely to be a runaway greenhouse world, or a frozen desert.

Instead, it could still host a thinner, nitrogen-rich atmosphere — something more like Earth or even Saturn’s moon Titan. And if that’s true, it raises the tantalizing possibility of oceans on the surface.

We don’t yet know for sure if TRAPPIST-1e has an atmosphere at all. But every new observation brings us closer to finding out whether this rocky world could actually be habitable.

If TRAPPIST-1e does have oceans and a nitrogen-rich sky, could it really be Earth’s twin — or would it be something completely alien?