Home away from home
The existence of the most Earthlike planet yet has just been confirmed
ONE of the more memorable slogans to come out of the climate-change talks in Durban over the past few days is: “there is no planet B”. But what if there were? Over the past couple of decades astronomers have logged thousands of so-called “exoplanets”—worlds which orbit stars other than the sun. On December 5th the scientists in charge of Kepler, a space telescope designed to look for such planets, confirmed their instrument's discovery of its first Earthlike world. It is dubbed, rather unromantically, Kepler 22b.
The existence of this planet, which circles a star 600 light-years away, in the constellation of Lyra, had previously been suspected. Kepler, which belongs to NASA, America's space agency, works by observing dips in a star's brightness as a planet passes in front of it. It flags likely looking reductions as “candidate planets”, of which Kepler 22b was one. But three passes are needed to confirm a planet's existence, and Kepler 22b has now passed this test. Crucially, it orbits well within its star's “Goldilocks zone”: neither too close nor too far away for liquid water (and therefore, perhaps, life) to exist on its surface.
This article appeared in the Science & technology section of the print edition under the headline "Home away from home"
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