An artist's rendering shows a planet called Kepler-20e in this handout. (Reuters)
NASA's Kepler telescope has identified 503 new potential alien planets, some of which may even be habitable.
"Some of these new planet candidates are small and some reside in the habitable zone of their stars, but much work remains to be done to verify these results," said Kepler mission manager Roger Hunter, of NASA's Ames Research Center.
The latest finding brings Kepler's tally of exoplanet candidates to 3,216, SPACE.com reported.
While as just 132 of the potential planets have been confirmed by follow-up observations to date, however, mission scientists expect at least 90 per cent will end up being the real deal.
Researchers said the new haul was pulled from observations Kepler made during its first three years of operation, from May 2009 to March 2012.
The telescope has not done any planet hunting since being hobbled by a failure in its orientation-maintaining system last month.
The USD 600 million Kepler spacecraft launched in March 2009, kicking off a 3.5-year mission to determine how common Earth-like planets are throughout the Milky Way galaxy.
Kepler spots exoplanets by detecting the tiny brightness dips caused when they pass in front of their stars' faces from the instrument's perspective.
The observatory does this precision work by staying locked onto 150,000-plus target stars using three gyroscope-like devices called reaction wheels.