Astronomers detect exoplanet orbiting closer to its parent star than any other known planet
Of the more than 300 planets found beyond the solar system, none lies closer to its parent star than the recently detected WASP-12b. Residing at just one-eighteenth the average distance that Mercury — the solar system’s innermost planet — orbits the sun, the sizzling planet is both the hottest planet known and the fattest.
Codiscoverer Leslie Hebb of the University of St. Andrews in Scotland and her colleagues estimate that the planet, which whips about its star in just 1.09 days, has an average temperature of 2,500 kelvins — nearly half that of the visible solar surface — and a diameter almost twice that of Jupiter, the solar system’s biggest planet. Blasted by its parent star, the close-in planet receives the highest dose of radiation of any known planet. Although this high intensity probably contributes to its puffiness, the extreme radiation can’t fully explain the body’s large si