two planets are shown in this artist's rendering

Hubble Measures Atmospheric Structure of Extrasolar Planet Hd 209458b Caption This artist's illustration shows the layer-cake structure of the atmopshere of extrasolar planet HD 209458b. Hubble discovered a dense upper layer of hot hydrogen gas where the super-hot planet's atmosphere is bleeding off into space. Credits NASA, ESA, and A. Feild (STScI)