The chance of alien life in space got a fresh boost tonight with the announcement that astronomers have discovered there are three times as many stars in the universe than was previously thought.
Scientists revealed that they have seriously underestimated the number of other suns in other galaxies – and that means there must be many more planets orbiting them where ET might live.
Galaxies are vast star cities, each containing many billions of stars. But as well as bright stars like the sun, there are many much fainter ones called red dwarfs.
The dimmer stars are difficult enough to detect in our own Milky Way spiral galaxy. But they are harder still to spot in more distant galaxies.
Now powerful instruments on the Keck Telescope on Hawaii has been able to pick out the red dwarfs in eight massive so-called elliptical galaxies which lie at a relatively close distance of 50 million to 300 million light-years.
The astronomers were startled to discover that red dwarfs – which are between a tenth and a fifth the mass of the sun – are 20 times more common in elliptical galaxies than they had imagined.
The discovery tripled the total number of stars of all types counted together throughout the universe. And it is exciting because a red dwarf called Gliese 581 in our own galaxy is already believed to host an Earthlike planet.
Red dwarfs are also billions of years older than stars like the sun which means any life would have had much longer to evolve.
Lead researcher Pieter van Dokkum, of America’s Yale University, whose paper appears this week in Nature, said: “There are possibly trillions of Earths orbiting these stars.”
He added: “No one knew how many of these stars there were. Different theoretical models predicted a wide range of possibilities, so this answers a longstanding question about just how abundant these stars are.”
Colleague Charlie Conroy of the Harvard-Smithsonian Center for Astrophysics, said: “We usually assume other galaxies look like our own. But this suggests other conditions are possible in other galaxies. So this discovery could have a major impact on our understanding of galaxy formation and evolution.”
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