Exoplanets, an infographic
An exoplanet, is a planet outside the Solar System. A total of 778 such planets (in 625 planetary systems and 101 multiple planetary systems) have been identified as of June 15, 2012. Estimates of the frequency of systems strongly suggest that more than 50% of Sun-like stars harbor at least one planet(1). In a 2012 study, each star of the 100 billion or so in our Milky Way galaxy is estimated to host “on average … at least 1.6 planets”(2). Accordingly, at least 160 billion star-bound planets may exist in the Milky Way Galaxy alone(2). Unbound free-floating planetary-mass bodies in the Milky Way may number in the trillions, with 100,000 objects larger than Pluto for every main-sequence star.(3)
On visul.ly there is an interactive version of the xkcd cartoon about exoplanets.
(1) M. Mayor, M. Marmier, C. Lovis, S. Udry, D. Ségransan, F. Pepe, W. Benz, J. -L. Bertaux, F. Bouchy, X. Dumusque, G. Lo Curto, C. Mordasini, D. Queloz, N. C. Santos (2011). The HARPS search for southern extra-solar planets XXXIV. Occurrence, mass distribution and orbital properties of super-Earths and Neptune-mass planets arXiv arXiv: 1109.2497v1
(2) Cassan, A., Kubas, D., Beaulieu, J.P., Dominik, M., Horne, K., Greenhill, J., Wambsganss, J., Menzies, J., Williams, A., Jørgensen, U.G. & (2012). One or more bound planets per Milky Way star from microlensing observations, Nature, 481 (7380) 169. DOI: 10.1038/nature10684
(3) Louis E. Strigari, Matteo Barnabe, Philip J. Marshall, Roger D. Blandford (2012). Nomads of the Galaxy arXiv arXiv: 1201.2687v1
Text source: Wikipedia
Image source: Information is beautiful