About this world
TRAPPIST-1 f is an Earth-sized planet orbiting TRAPPIST-1, a cool red dwarf (type M8.0V) 40.5 light-years from Earth. It is about 1 times the size of Earth and holds 1 Earth masses. It completes an orbit every 9.21 days at 0.038 AU from its star, closer than Mercury is to the Sun.
Its equilibrium temperature is about 218 K (−55 °C), which places it in the conservative habitable zone: the band where liquid water could exist on a rocky surface. By the "cosmic shoreline", it has likely held on to an atmosphere. Its atmosphere has already been studied: 7 spectroscopic observations, 5 of them with the James Webb Space Telescope.
It was discovered in 2017 by transit with Multiple Observatories. A planet crosses its star and dims it by a tiny, periodic fraction. TRAPPIST-1 has 7 known planets; the others are TRAPPIST-1 b, TRAPPIST-1 c, TRAPPIST-1 d, TRAPPIST-1 e, TRAPPIST-1 g and TRAPPIST-1 h.