A planet-hunting space telescope has found its first rocky world – the smallest yet discovered outside our own solar system – NASA revealed today.
The planet is less than one and a half time the size of the Earth and quite different to alien planets previously found which generally resemble giant balls of gas.
Its fingerprints were found in data collected by the £400 million Kepler space probe as it kept watch on thousands of stars in one small patch of the Milky Way.
The rocky planet, which is labelled Kepler-10b but has been dubbed Vulcan by its discoverers, gave itself away through tiny dips in its parent sun’s brightness as it passed in front of it.
Astronomers had to scour eight months of data from May 2009 to January last year to build convincing proof that it exists.
Natalie Batalha, of NASA’s Kepler team, said: “All of Kepler’s best capabilities have converged to yield the first solid evidence of a rocky planet orbiting a star other than our sun.”
Though the find is a breakthrough in the hunt for alien worlds, Kepler-10b is not a planet that Earthlike beings could inhabit.
It is more than 20 times closer to its star than innermost planet Mercury is to our own Sun and it zips round it in a year that lasts a fifth less than one of our days.
The astronomers used another telescope on Hawaii to make observations that helped confirm the new rocky world’s existence.
The Kepler telescope, launched in March 2009, keeps constant watch on more than 100,000 stars in the constellations of Lyra and Cygnus.
It is the first telescope capable of detecting small rocky planets like ours around other suns that could be home to aliens. And astronomers are optimistic that it will discover hundreds of Earth-sized planets in the next few years.
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