Exoplanet Count to 700
One can look up and count the stars that can be seen. Finding exoplanets orbiting these stars is a different matter because they cannot be seen by the naked eye. There are two main counters of the exoplanents: NASA and the European count. NASA is more conservative while Europe will include the new exoplanet when it is announced. So Europe will also be slightly more. The count topped 500 in November 2010, and it passed 600 just two months ago when scientists with the European Southern Observatory announced 50 newfound planets, including one super-Earth that might be a good candidate for hosting life. Now it is 700.
The present count stands at 702 exoplanets, according to the Extrasolar Planets Encyclopedia, a database compiled by astrobiologist Jean Schneider of the Paris-Meudon Observatory.
PlanetQuest: New Worlds Atlas, run by NASA's Jet Propulsion Laboratory. PlanetQuest's current count stands at 687.
For centuries, human beings have pondered whether other worlds orbited other stars. Medieval scholars speculated that other worlds must exist and that some would harbor other forms of life. In our time, advances in science and technology have brought us to the threshold of finding an answer to this timeless question.
The recent discovery of numerous planets around stars other than the sun confirms that our solar system is not unique. Indeed, these "exoplanets" appear to be common in our galactic neighborhood.
Extrasolar planets became an object of investigation in the 19th century. Many supposed that they existed, but there was no way of knowing how common they are or how similar they are to the planets of our solar system. The first confirmed detection was in 1992, with the discovery of several terrestrial-mass planets orbiting the pulsar PSR B1257+12. The first confirmed detection of an exoplanet orbiting a main-sequence star was made in 1995, when a giant planet, 51 Pegasi b, was found in a four-day orbit around the nearby G-type star 51 Pegasi. The frequency of detections has increased since then.
Many exoplanets are detected through radial velocity observations and other indirect methods rather than sensor imaging. Most are giant planets resembling Jupiter; this partly reflects a sampling bias, as more massive planets are easier to observe. Several relatively lightweight exoplanets, only a few times more massive than Earth, were detected and projections suggest that these outnumber giant planets.
For further information: http://planetquest.jpl.nasa.gov/atlas/atlas_index.cfm or http://news.discovery.com/space/exoplanet-count-sails-past-700-alien-worlds-111121.html#mkcpgn=rssnws1?ewrd=1 or http://www.space.com/13680-700-alien-planets-kepler-mission.html
Photo: NASA and Kepler