About this world
Proxima Cen b is an Earth-sized planet orbiting Proxima Cen, a cool red dwarf (type M5.5V) 4.24 light-years from Earth. It is about 1 times the size of Earth (its size estimated from its mass), with at least 1.1 Earth masses (a minimum, measured by radial velocity). It completes an orbit every 11.2 days at 0.048 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.
It was discovered in 2016 by radial velocity with European Southern Observatory. The star wobbles toward and away from us, Doppler-shifting its spectrum. Proxima Cen has 2 known planets; the others are Proxima Cen d.