Webb uncovers icy clouds on a nearby Jupiter-like world, nudging exoplanet atmosphere models

The James Webb Space Telescope detected evidence for thick water-ice clouds high in Epsilon Indi Ab’s upper atmosphere. The ammonia signature expected for such a cold giant was weaker than predicted, suggesting that the clouds were muting it. This finding shows that many atmospheric models for giant exoplanets have omitted cloud physics, reminding scientists that clouds shape what we can see and interpret in a planet’s chemistry and temperature. The next steps are to confirm the clouds with more Webb observations, map their distribution, incorporate cloud physics into models, and check whether other cold giants show a similar ammonia shortfall.