Harrison Nicholls

After the Moon's birth, Earth resembled a sizzling lump of dough: a continuous liquid magma and a dense shroud of gases. The Moon acted like a giant spoon, constantly kneading this lump with its gravity. Friction generated heat, delaying cooling.

A star warms its planet like an oven warms a kettle. For most sub-Neptunes (worlds larger than Earth but smaller than Neptune), the heat is enough to keep an ocean of molten rock eternally churning beneath a hydrogen sky.

A scorching rocky planet is like a pot of boiling soup, except its lid is the atmosphere. Gases escape from the magma, wrap the world in a thick blanket, and in turn influence how quickly the celestial body cools. For GJ 1132 b, which orbits so close to its star that a year lasts just one and a half Earth days, this connection is especially important.

The mystery of the radius valley — a sharp drop in the number of exoplanets with radii ~1.8 Earth — haunts astronomers. JWST, transit surveys like Kepler and TESS draw a clear gap: rocky super-Earths and gaseous sub-Neptunes are separated by almost a chasm.

When the JWST telescope breaks the light of a distant exoplanet into a spectrum, it reads a chemical chronicle. But this chronicle is not a monolithic truth; it's an atmosphere constantly rewritten by the star's radiation.