HD 209458 b

HD 209458 b is a hot Jupiter exoplanet, sometimes informally called Osiris, orbiting the Sun-like star HD 209458 in the constellation Pegasus, about 157 light-years from the Solar System. It circles its star at just 0.047 astronomical units, one-eighth the radius of Mercury's orbit, giving it a year only 3.5 Earth-days long and an estimated surface temperature around 1,000 degrees Celsius. Its mass is about 220 times that of Earth and its volume roughly two and a half times that of Jupiter, marking it as a gas giant swollen by the intense heat of its star.