K2-150 is a cool M-dwarf (about 0.46 solar masses, 3,499 K, 0.44 solar radii), 102 light-years from Earth. K2-150 b is a planet with 2.0 Earth radii, with an orbital period of 10.6 days, at 0.073 AU from its star, discovered in 2018 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. K2-150 b orbits well inside Earth's distance from the Sun. Repeated transit observations constrain the planet's orbital inclination and stellar density, anchoring the system's physical scale.