LHS 1478 is a cool M-dwarf (about 0.24 solar masses, 3,381 K, 0.25 solar radii), 18.2 light-years from Earth. LHS 1478 b is a 2.3-Earth-mass planet, with an orbital period of 1.9 days, at 0.018 AU from its star, and an equilibrium temperature near 595 K, discovered in 2021 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. LHS 1478 b skims its star closer than Mercury orbits the Sun.