Nasa Kepler telescope discovers 715 new planets

MORE than 700 planets, including four that could possibly be inhabited by humans, have been discovered by scientists searching through data collected by Nasa's Kepler telescope.

The 715 newly discovered planets dotted around the galaxy represent the largest single find in the past 20 years, the BBC reports. In the previous two decades, researchers had detected just over 1,000 new worlds.

"This is the largest windfall of planets that's ever been announced at one time," said Douglas Hudgins from Nasa's astrophysics division.

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They orbit 305 stars in all, indicating that many exist in multi-planet systems like our own solar system.

The size of the planets appears to vary, but the vast majority of them - 95 per cent - appear to be smaller than Neptune, which is approximately four times the diameter of Earth.

Scientists identified new planets by studying images from the space observatory in search of transits - slight changes in brightness that occur when a planet travels across the face of its host star.

Variations can occur for a variety of reasons, such as when one star orbits or eclipses another, making the detection of a new planet relatively rare.

The discovery of so many planets was the result of a new statistical approach to detection known as "verification through multiplicity".

This technique rests on the theory that multiple dips in light are only attributable to the movement of planets because it is "very difficult for several stars to orbit each other in a similar way and maintain a stable configuration", the BBC reports.

The technique will result in "wholesale planet validation" said Jack Lissauer, a planetary scientist at Nasa's Ames Research Center. "These results are based on the first two years of Kepler observations and with each additional year, we'll be able to bring in a few hundred more planets," he explained.

Four of the planets are believed to be in the "habitable" range of the star they orbit – known as the 'Goldilocks zone'. This is an area where water could exist in its liquid state, and the planet could hypothetically support life as we know it as conditions are "just right".

Verification of planets outside our solar system was previously a "laborious process" reports the Daily Mail. But the new technique has enabled scientists to "amaze and excite" researchers, said John Grunsfeld, associate administrator of Nasa's Science Mission Directorate in Washington. "That these new planets and solar systems look somewhat like our own portends a great future", he added.