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| | ASP: Planet-Building on the Grandest Scales |
 | | Apart from the numerous comets and asteroids, it consists of four rocky planets (Mercury, Venus, Earth, and Mars), two giant gaseous planets (Jupiter and Saturn), two ice giant planets (Uranus and Neptune), and one icy planet with a comparably sized companion (Pluto and Charon). |
 | | In 1995, however, Michel Mayor and Didier Queloz, working at the Geneva Observatory, reported the discovery of an object with a mass approximately half that of Jupiter orbiting the star 51 Pegasi. |
 | | This object was detected using the radial velocity, or “Doppler wobble,” technique; the method uncovers the small radial motion imposed by the orbiting planet on its parent star and manifest as small-scale, periodic shifts of features in the star’s spectrum. |
| www.astrosociety.org /pubs/mercury/33_02/planet.html (407 words) |
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