NASA's Kepler telescope spots over 200 new planet candidates

Washington: NASA's Kepler space telescope has spotted 219 new potential planets, of which at least 10 are near-Earth size with conditions suitable to host life. This brings the total number of planet candidates identified by Kepler to 4,034, of which 2,335 have been verified as exoplanets. Out of the roughly 50 near-Earth size habitable zone candidates detected by Kepler so far, more than 30 have been verified.

The new data is the most comprehensive and detailed catalogue release of candidate exoplanets, which are planets outside our solar system, from Kepler's first four years of data. It is also the final catalogue from the spacecraft's view of the patch of sky in the Cygnus constellation. The results using Kepler data suggest two distinct size groupings of small planets. Both results have significant implications for the search for life.

The final Kepler catalogue will serve as the foundation for more study to determine the prevalence and demographics of planets in the galaxy, while the discovery of the two distinct planetary populations shows that about half the planets we know of in the galaxy either have no surface, or lie beneath a deep, crushing atmosphere – an environment unlikely to host life. "The Kepler data set is unique, as it is the only one containing a population of these near Earth-analogues - planets with roughly the same size and orbit as Earth," said Mario Perez, Kepler programme scientist in the Astrophysics Division of NASA's Science Mission Directorate.

"Understanding their frequency in the galaxy will help inform the design of future NASA missions to directly image another Earth," Perez said. The Kepler space telescope hunts for planets by detecting the minuscule drop in a star's brightness that occurs when a planet crosses in front of it, called a transit. This is the eighth release of the Kepler candidate catalogue, gathered by reprocessing the entire set of data from Kepler's observations during the first four years of its primary mission.

This data will enable scientists to determine what planetary populations – from rocky bodies the size of Earth, to gas giants the size of Jupiter – make up the galaxy's planetary demographics. One research group used the Kepler data to make precise measurements of thousands of planets, showing two distinct groups of small planets.

The team found a clean division in the sizes of rocky, Earth-size planets and gaseous planets smaller than Neptune. Few planets were found between those groupings. Using the W M Keck Observatory in Hawaii, the group measured the sizes of 1,300 stars in the Kepler field of view to determine the radii of 2,000 Kepler planets with exquisite precision.