NASA has now released the third catalog featuring all the candidate planets discovered by the Kepler Space Telescope. This catalog contains 2321 candidates found during observations between May 2009 to September 2010. The histogram above summarizes the findings in the 27 February 2012 Kepler Planet Candidate catalog release by size.
The first 43 days of Kepler data was released in June 2010 and has 312 candidate planets (Borucki et al, 2010). The second release (Borucki et al, 2011) covered the first 13 months of data and was released in February 2011. It contains 1,235 candidate planets.
The third catalog contains 2,321 planet candidates identified during the first 16 months of observation. 46 planet candidates orbit within the habitable zone (liquid water) and ten of them are near Earth size.
Planets are identified by measuring the brightness of more than 150,000 stars. Planets that pass in front of a star (“transit”) cause the light to dim slightly. Candidates are considered possible if Kepler detects three transits.
The artist’s rendering below depicts the multiple planet systems discovered by NASA’s Kepler mission. Prior to the third catalog, scientists had verified six systems with multiple transiting planets (shown t the left in red).
Kepler’s observations have verified planets in 11 new planetary systems (shown to the right in green). Many of these systems contain additional planet candidates that are yet to be verified (shown here in dark purple).
For reference, the eight planets of the solar system are shown in blue (far left).