Scientometrics — the statistical study of science itself — can be used to make predictions, Samuel Arbesman of Harvard Medical School and Greg Laughlin of the University of California, Santa Cruz suggest.

Over the past 15 years or so, the pace of exoplanet discoveries has been accelerating, with some 490 planets now known. “It is actually somewhat similar to Moore’s law of exponential growth,” Arbesman says.

Their calculations of a “habitability metric” (based on a planet’s mass and its surface temperature) suggest there is a 50 per cent chance that the first habitable exo-Earth will be found by May 2011, a 75 per cent chance it will be found by 2020, and a 95 per cent chance it will be found by 2264.

Journal reference: PLoS ONE (in press).