K2-54 is an orange K-type dwarf (about 0.61 solar masses, 3,990 K, 0.64 solar radii), 175 light-years from Earth. K2-54 b is a planet with 2.6 Earth radii, with an orbital period of 9.8 days, at 0.076 AU from its star, and an equilibrium temperature near 560 K, on an eccentric orbit (e ≈ 0.24), discovered in 2016 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.