Number of extrasolar planets

Question: How many planets have been found outside of the solar system?

Thankfully there are people whose job it is to keep track of this number! Jean Schneider's Extrasolar Planets Encyclopedia lists all of the "confirmed" planets:

http://www.exoplanet.eu/catalog/

The number goes up every day, so be sure to check the catalog often.

In addition, the Kepler mission discovered many planet candidates, only some of which are officially confirmed. Confirmation requires either measurements of the planet's gravitational effect on the host star or a careful statistical analysis to rule out effects that mimic the eclipses that Kepler observes. Catalogs of Kepler candidates are linked here:

http://kepler.nasa.gov/Mission/discoveries/candidates/

-Sally Dodson-Robinson