Space
JWST's First Exoplanet Atmosphere: What WASP-39b Revealed
In July 2022, the James Webb Space Telescope detected carbon dioxide in the atmosphere of WASP-39b — a hot Jupiter 700 light-years away — with a clarity no previous telescope could match. It was the sharpest single spectrum ever taken of an exoplanet atmosphere and the opening demonstration of what JWST was built to do. But the CO₂ detection was only the beginning: the same data revealed sulfur dioxide formed by photochemistry, a chemical map of how the planet formed, and a template for reading the atmospheres of smaller, cooler, potentially habitable worlds.