Is Earth Rarer Than We Think?

Is Earth Rarer Than We Think? : Discovery News: "“It is dangerous to assume life is common across the Universe.” These were the words of Charles Cockell at a Royal Society event on March 11 this year. While many people have freely debated the existence of extraterrestrial life, Cockell’s words carry a bit more weight than most. He happens to be the director of the U.K. Center for Astrobiology, based at the University of Edinburgh."