About this world
GJ 3378 b is a super-Earth orbiting GJ 3378, a cool red dwarf (type M4V) 25.2 light-years from Earth. It is about 1.3 times the size of Earth (its size estimated from its mass), with at least 2.3 Earth masses (a minimum, measured by radial velocity). It completes an orbit every 21.4 days at 0.097 AU from its star, closer than Mercury is to the Sun.
Its equilibrium temperature is about 272 K (−1 °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 2026 by radial velocity with Mauna Kea Observatory. The star wobbles toward and away from us, Doppler-shifting its spectrum.