The innermost planets in the TRAPPIST-1 system do not have thick atmospheres

Nature Astronomy, Published online: 24 April 2026; doi:10.1038/s41550-026-02805-w Thermal phase curves of the two innermost planets in the TRAPPIST-1 system show strong dayside emission and faint nightside emission — ruling out thick atmospheres on both planets. TRAPPIST-1 b seems to be airless. But TRAPPIST-1 c might host a tenuous atmosphere, or be a bare rock with different surface properties to TRAPPIST-1 b.