Kepler is a spacecraft launched by NASA in March of 2009. It has a 0.95 meter telescope that is looking at 156,453 stars in a small 12 degree diameter patch of the sky. By measuring the brightness of a star over time the Kepler detectors can determine the details of any orbiting planets.
So far 1202 potential planets have been discovered! Here is a summary of the types already discovered:
- 68 Earth-size exoplanets with a radius (Rp) of less than 1.25 Earth radius (Re)
- 288 super-Earth size exoplanets with 1.25 x Re < Rp ≤ 2.0 x Re
- 662 Neptune-size exoplanets with 2.0 x Re < Rp ≤ 6.0 x Re
- 165 Jupiter-size exoplanets with 6.0 x Re < Rp ≤ 15 x Re
- 19 very-large-size with 15.0 x Re < Rp ≤ 22 x Re
Details fo the Kepler mission details can be viewed at kepler.nasa.gov. The SETI Institute has a very good article that sums up the Kepler mission discoveries and data. See this article.
The Kepler sensors are only looking at a small 12 degree patch of sky. Hopefully, in the future, more resources will be appropriated to explore more of the sky.