Benjamin V. Rackham

Eavesdropping on a distant planet's atmosphere is hampered by the star's noise. In the TRAPPIST-1 system, astronomers used a planet-"bug": TRAPPIST-1 b — an airless neighbor that records only the interference.

Two new planets are circling dim red stars. One is nearly the size of Earth, the other is three and a half times larger. Both lie in what astronomers call the warm zone: a region where starlight doesn't scorch the surface but also doesn't leave it in perpetual cold. The host stars are red dwarfs, the most common stars in the galaxy.

Astronomers using the JWST (James Webb Space Telescope) have for the first time studied in detail the atmosphere of a young exoplanet, V1298 Tau c. This super-Earth, a planet more massive than Earth but less so than gas giants, is only 23 million years old.

A planet glides across a star's disk, and for a moment becomes a flashlight. It blocks a tiny patch of surface, revealing details that otherwise escape our view. That's exactly how astronomers peered into the dark spots on V1298 Tauri, a young twin of our Sun. They were aided by the James Webb Space Telescope JWST and three giant planets in orbit.

A quarter-century ago, Michel Mayor and Didier Queloz discovered the first hot Jupiter, and shattered all the rules of planet formation. A gas giant on a days-long orbit couldn't have formed next to the star: it's far too hot and lacks building material. So, it must have been born far away and then migrated.