Webb reveals the origin of the ultra-hot exoplanet WASP-121b

Tracing the origin of an ultra-hot exoplanet: The chemical composition of WASP-121b suggests that it formed in a cool zone of its natal disc, comparable to the region of gas and ice giants in our Solar System. Methane indicates unexpected atmospheric dynamics: Despite extreme heat, methane was detected on the nightside -- a finding that can be explained by strong vertical atmospheric circulation. First detection of silicon monoxide in a planetary atmosphere: Measurements of this refractory gas allow quantifying the rocky material the planet had accumulated.