HD 189733 b (or sometimes HD 189733 Ab) is an extrasolar planet approximately 63 light-years away in the constellation of Vulpecula (the Fox). The planet was discovered orbiting the star HD 189733 on October 5, 2005 (more precisely HD 189733 A since a star companion had been confirmed by then), when astronomers in France observed the planet transiting across the face of the star. The planet is classified as a hot Jupiter class Jovian planet, with a close orbit to its parent star. HD 189733 b was the first extrasolar planet to be mapped and the first to be discovered with carbon dioxide in its atmosphere.
Read more about HD 189733 B: Satellites, Physical Characteristics