The Kepler Mission Is Launched
The Kepler Mission uses a NASA space telescope designed to discover Earth-like planets orbiting other stars.
With a planned mission lifetime of at least 3.5 years, Kepler uses a photometer developed by NASA to continuously monitor the brightness of over 145,000 main sequence stars in a fixed field of view. The data collected from these observations will be analyzed to detect periodic fluctuations that indicate the presence of extrasolar planets (planets outside our solar system) that are in the process of crossing the face of other stars. The mission is named in honor of German astronomer Johannes Kepler.
An extrasolar planet, or exoplanet, is a planet that orbits a star other than the Sun and that is thus beyond the Solar System. As of 18 December 2009 (2009 -12-18), there are 415 planets listed in the Extrasolar Planets Encyclopaedia. The vast majority of them have been detected through radial velocity observations and other indirect methods rather than actual imaging. It is expected that confirmation of new planets discovered by the Kepler mission will be announced on January 4, 2010 at the AAS meeting Most of those currently known are giant planets thought to resemble Jupiter; however, sampling bias exists since more massive planets are much easier to detect with current technology. A few relatively lightweight exoplanets, only a few times more massive than Earth, have now been detected and projections suggest that planets of roughly Earth-like mass will eventually be found to outnumber extrasolar gas giants.