Excerpt from the American Astronomical Society meeting on January 7th, 2013. NASA's Kepler mission Monday announced the discovery of 461 new planet candidates. Four of the potential new planets are less than twice the size of Earth and orbit in their sun's "habitable zone," the region in the planetary system where liquid water might exist on the surface of a planet.

One of the four newly identified super Earth-size planet candidates, KOI-172.02, orbits in the habitable zone of a star similar to our sun. The possible planet is approximately 1.5 times the radius of Earth and orbits its host star every 242 days. Additional follow-up analysis will be required to confirm the candidate as a planet.

Based on observations conducted from May 2009 to March 2011, the findings show a steady increase in the number of smaller-size planet candidates and the number of stars with more than one candidate.

Since the last Kepler catalog was released in February 2012, the number of candidates discovered in the Kepler data has increased by 20 percent and now totals 2,740 potential planets orbiting 2,036 stars. The most dramatic increases are seen in the number of Earth-size and super Earth-size candidates discovered, which grew by 43 and 21 percent respectively.

The new data increases the number of stars discovered to have more than one planet candidate from 365 to 467. Today, 43 percent of Kepler's planet candidates are observed to have neighbor planets.

Credit: NASA/AAS