Kepler-51 is a Sun-like F-type star (about 1.04 solar masses, 6,018 K, 0.94 solar radii), 784 light-years from Earth. Kepler-51's planets are super-puffs: nearly Jupiter-sized yet only a few Earth masses, with cotton-candy densities. Kepler-51 b is a 2.1-Earth-mass planet, with an orbital period of 45.2 days, at 0.251 AU from its star, and an equilibrium temperature near 543 K, discovered in 2012 via transit. Kepler-51 c is a 4.0-Earth-mass planet, with an orbital period of 85.3 days, at 0.384 AU from its star, and an equilibrium temperature near 439 K, discovered in 2012 via transit. Kepler-51 e is a 5.4-Earth-mass planet, with an orbital period of 264 days, discovered in 2024 via transit.