Galaxy has 'billions of Earths'

There could be one hundred billion Earth-like planets in our galaxy, a US conference has heard. Dr Alan Boss of the Carnegie Institution of Science said many of these worlds could be inhabited by simple lifeforms. He was speaking at the annual meeting of the American Association for the Advancement of Science in Chicago. So far, telescopes have been able to detect just over 300 planets outside our Solar System. Very few of these would be capable of supporting life, however. Most are gas giants like our Jupiter; and many orbit so close to their parent stars that any microbes would have to survive roasting temperatures.