MASCARA-1 is a Sun-like F-type star (about 1.90 solar masses, 7,490 K, 2.08 solar radii), 182 light-years from Earth. MASCARA-1 b is a planet with 17.9 Earth radii, with an orbital period of 2.1 days, at 0.040 AU from its star, and an equilibrium temperature near 2,594 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. MASCARA-1 b skims its star closer than Mercury orbits the Sun.