HD 209458 b orbits a Sun-like G-type star 157 light-years from Earth, a classic hot Jupiter with a radius of 15.6 × Earth. Orbiting every 3.5 days at 0.047 AU, it experiences intense stellar radiation causing atmospheric escape and a comet-like tail of hydrogen. As the pioneering transiting planet with measured evaporation, it revolutionized our understanding of close-in giant atmospheres. This iconic world endures in the Galactic Codex, symbolizing the dynamic interplay between stars and planets and the fragile beauty of evaporating atmospheres in the cosmos.
