Kepler-45 is a cool M-dwarf (about 0.59 solar masses, 3,820 K, 0.55 solar radii), 382 light-years from Earth. Kepler-45 b is a 0.51-Jupiter-mass companion, with an orbital period of 2.5 days, at 0.030 AU from its star, and an equilibrium temperature near 1,000 K, on an eccentric orbit (e ≈ 0.11), discovered in 2011 via transit. The inner world is a hot Jupiter — a gas giant hugging its star at a fraction of Mercury's distance — a class that forced astronomers to rethink how giant planets form and migrate inward.