Extrasolar planet. 2 January 2013: Astronomers state that the Milky Way may contain as many as 400 billion exoplanets, with almost every star hosting at least one planet.[1][2][3] An exoplanet or extrasolar planet is a planet outside the Solar System.
Around 1800 such planets have been discovered[5][6][7] (1783 planets in 1105 planetary systems including 460 multiple planetary systems as of 18 April 2014).[8] Extrasolar Planets - Explore the Cosmos. Extrasolar Visions - An Extrasolar Planets Guide. Extrasolar-planets.com. Exoplanet Orbit Database. Extrasolar Planet News.