trappist-1

TRAPPIST-1e, Proxima b, LHS 1140 b, TOI-700 d and more: how the most Earth-like planets compare, and what each has and has not shown about air and water.

A guide to the nearest potentially habitable exoplanets, from Proxima b to TRAPPIST-1e, what JWST has found, and why 'habitable' rarely means confirmed.

For most of the history of exoplanet science, astronomers could detect planets but not smell them. They could measure orbital periods, estimate masses, and infer temperatures — but the chemical composition of another world's atmosphere was almost entirely out of reach. JWST changed that. In its first two years, it detected carbon dioxide on a gas giant 700 light-years away, found evidence of methane and CO₂ on a possible ocean world 120 light-years out, and ruled out thick atmospheres on the rocky TRAPPIST-1 planets — all using a technique called transmission spectroscopy that is as elegant as it is precise.

Tidal locking happens when a body's rotation period equals its orbital period, so one face always points at its partner. The Moon is locked to Earth, Mercury is caught in a 3:2 resonance instead, and many planets around red dwarf stars are probably locked to their stars.