WASP-15 is a Sun-like F-type star (about 1.18 solar masses, 6,300 K, 1.48 solar radii), 282 light-years from Earth. WASP-15 b is a 0.54-Jupiter-mass companion, with an orbital period of 3.8 days, discovered in 2009 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 (15.8 Earth radii) indicates a bloated atmosphere heated by intense stellar radiation.