About this world
K2-239 b is an Earth-sized planet orbiting K2-239, a cool red dwarf (type M3.0V) 101 light-years from Earth. It is about 1.1 times the size of Earth. It completes an orbit every 5.24 days at 0.044 AU from its star, closer than Mercury is to the Sun.
Its equilibrium temperature is about 502 K (229 °C): far too hot for liquid water on its surface. By the "cosmic shoreline", its star has probably stripped its atmosphere away, leaving bare rock.
It was discovered in 2018 by transit with K2. A planet crosses its star and dims it by a tiny, periodic fraction. K2-239 has 3 known planets; the others are K2-239 c and K2-239 d.