NASA's Kepler mission has identified 461 new planet candidates, the space agency announced today.
Four of the planet candidates orbit in their sun's "habitable zone," meaning liquid water might exist on their surfaces, NASA said. The new findings are based on an analysis of data collected from May 2009 to March 2011.
Kepler has now identified a total of 2,740 potential planets orbiting 2,036 stars. NASA estimates there are billions of Earth-size alien planets in the Milky Way galaxy alone -- perhaps 100 billion or more.
The Kepler space telescope identifies planet candidates by repeatedly measuring the change in brightness of more than 150,000 stars in search of planets that pass in front of, or "transit," their host star. At least three transits are required to verify a signal as a potential planet.
The latest data show a 43-percent increase in potential Earth-size planets and a 21 percent jump in "Super Earth" planet candidates.
"There is no better way to kick off the start of the Kepler extended mission than to discover more possible outposts on the frontier of potentially life-bearing worlds," Christopher Burke, a Kepler scientist leading the analysis, said of the discoveries.
The Kepler space telescope has been detecting potential alien planets since March 2009. You can find more about the "Search For Another Earth" at PlanetQuest, a website maintained by NASA's Jet Propulsion Laboratory in California.
Take a look at a breakdown of the newest planet candidates, courtesy of NASA: