Astrobiology: pouring cold asteroid water on Aristotle
By David C. Catling
Over 2,300 years ago, in his book De Caelo (On the Heavens), Aristotle asked if other Earth-like worlds exist and dismissed the idea. But now, remarkably, the question is on the verge of being answered scientifically. NASA’s Kepler space telescope, launched in 2009, has collected data on the statistical occurrence of small planets that orbit stars at a distance where it’s the right temperature for liquid water and conceivably life.