The hunt for extraterrestrials has become a little easier after the discovery that up to 10 per cent of stars in our galaxy may harbour conditions necessary for complex life to emerge.
Although our solar system has been in the most hospitable region of the galaxy for five billion years, astronomers conclude that three quarters of the Milky Way’s other inhabited solar systems — if they exist — would have had one billion years longer, on average, to nurture life and advanced civilisations.
The estimates come from a new map of the Galactic Habitable Zone, an area of space whose boundaries are set by its safe environment, away from exploding stars and marauding planets (Earth destroyers), and which has access to the chemicals necessary for building terrestrial planets similar to Earth.
In a paper published on Friday in Science, Charles Lineweaver from the University of New South Wales and Yeshe Fenner and Brad Gibson of Swinburne University of Technology, Melbourne, have identified the region where life is most likely to prosper among the 300 billion stars in our Milky Way galaxy.
“What we have done for the first time is to quantify carefully where complex life is likely to exist,” Lineweaver said.
Mapping the possible distribution of life in the Milky Way may help increase the chance of success for future hunts for Earth-like planets. But Lineweaver said their discovery does not mean complex life necessarily exists beyond Earth. “Perhaps, there’s no life out there. But if there is life, we’ve determined where you are most likely to find it.”
Nasa’s Stardust spacecraft has entered the cloud of dust and gas surrounding the nucleus of comet Wild Two, which it is due to sample later on Friday.