HAT-P-24 is a Sun-like F-type star (about 1.37 solar masses, 6,373 K, 1.38 solar radii), 415 light-years from Earth. HAT-P-24 b is a 0.75-Jupiter-mass companion, with an orbital period of 3.4 days, on an eccentric orbit (e ≈ 0.07), discovered in 2010 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. The planet's large radius (14.6 Earth radii) indicates a bloated atmosphere heated by intense stellar radiation.