'Earthlike' planet Kepler-22b found - but could you live there?

New planet could harbour liquid water but scientist casts doubt on whether it is habitable

LAST UPDATED AT 10:19 ON Tue 6 Dec 2011

NASA scientists have discovered a planet that is the closest yet to "earth's twin" orbiting a star 600 light years away from our solar system. Kepler-22b is the first of many such planets that it is hoped will be discovered by the Kepler space telescope.

Scientists say the new planet is 2.4 times the size of earth and orbits a star similar to our own sun, but a little smaller and cooler. At 290 days, the duration of a year on Kepler-22b is not far off our own. Crucially, Kepler-22b is situated in the 'habitable zone' - a distance from its star that would allow the existence of liquid water. The planet's surface temperature is a pleasant 22C.

"This is a major milestone on the road to finding Earth's twin," said Douglas Hudgins, a member of the Kepler telescope team.

Scientists do not yet know if Kepler-22b has a predominantly rocky, gaseous or liquid composition. A rocky surface would make the existence of life far more likely.

The Kepler space telescope has so far found 48 planets in the habitable zone of their own solar systems. Kepler-22b is just the first to have been confirmed by the observations of other telescopes.

Kepler-22b's confirmation came on the same day that the Planetary Habitability Laboratory at the University of Puerto Rico unveiled its Habitable Exoplanets Catalogue, which rates planets on the likelihood of their supporting life.

The catalogue identified just two planets out of over 700 as matching the criteria for habitability: Gliese 581d and HD 85512b.

Sadly, Kepler 22-b is unlikely to be the third. Professor Abel Mendez of the Planetary Habitability Laboratory took to Twitter to cast doubt on the likelihood that the new planet is habitable, saying it is probably too big.

However, as MSNBC reports, it is possible that a moon orbiting Kepler-22b could support life in a scenario similar to Pandora’s orbit of the gaseous planet Prometheus in the film Avatar. · 

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