About this world
Ross 128 b is an Earth-sized planet orbiting Ross 128, a cool red dwarf (type M4) 11 light-years from Earth. It is about 1.1 times the size of Earth (its size estimated from its mass), with at least 1.4 Earth masses (a minimum, measured by radial velocity). It completes an orbit every 9.87 days at 0.05 AU from its star, closer than Mercury is to the Sun.
Its equilibrium temperature is about 301 K (28 °C), which places it in the optimistic 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.
It was discovered in 2017 by radial velocity with La Silla Observatory. The star wobbles toward and away from us, Doppler-shifting its spectrum.