Scientists are finally honing their searches:

Writing in the US journal Science, astronomers from six major centres, including Nasa, Harvard and the University of Colorado, outline how advances in technology suggest scientists are on the verge of being able to detect the presence of small, rocky planets, much like our own, around distant stars for the first time. The planets are considered the most likely havens for extraterrestrial life.

One technique relies on observing the shift in light coming from a star as a planet swings around it. Until recently, this "radial velocity" method has only been sensitive enough to pick up planets far more massive than Earth, but improvements now make the discovery of a second Earth highly likely, said Dave Latham, a co-author on the paper at the Harvard-Smithsonian Centre for Astrophysics.

"It could happen almost any time now. We have the technological capability to identify Earth-like planets around the smallest stars even now," he said.

(Hat tip: 3QD.)

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