K2-131 is an orange K-type dwarf (about 0.80 solar masses, 5,120 K, 0.76 solar radii), 153 light-years from Earth. K2-131 b is a 7.9-Earth-mass planet, with an orbital period of 8.9 hours, at 0.009 AU from its star, and an equilibrium temperature near 2,223 K, discovered in 2017 via transit. The planet was found when it crossed the face of its star, producing periodic dips in brightness that reveal its size and orbital period to space-based photometry. K2-131 b skims its star closer than Mercury orbits the Sun.