An extrasolar planet, or exoplanet, is a planet outside the Solar System. Around a thousand such planets have been discovered (999 planets in 759 planetary systems including 169 multiple planetary systems as of 18 October 2013).
In the Milky Way galaxy, it is expected that there are many billions of planets (at least one planet, on average, orbiting around each star, resulting in 100–400 billion exoplanets),


http://en.wikipedia.org/wiki/List_of_extrasolar_planets