Overview

• Observations with JWST’s NIRSpec instrument detected silicate vapor, water vapor, carbon monoxide and methane in WASP-121b’s atmosphere.
• The clear identification of silicate vapor is the first unambiguous detection of this molecule in any exoplanet atmosphere.
• Methane observed on the planet’s cooler nightside indicates strong vertical mixing that transports gas from deeper layers upward.
• An elevated carbon-to-oxygen ratio compared to the host star points to formation beyond the water ice line but within the methane ice line.
• WASP-121b migrated inward from its distant formation zone to its current 30.5-hour orbit, enduring day-side temperatures above 2700 °C and nightside near 1200 °C.