More than 100 planetary systems beyond the Sun have been discovered since the mid-1990s. Half the stars known to have planets might possess Earth-like worlds, it was claimed today.
So far only giant gas-planets, similar to Jupiter, have been found by detecting the gravitational effect they have on their parent stars.
But astronomers believe many smaller, rocky planets are waiting to be discovered - and some may be able to support life.
British scientists have based their calculations on a detailed study of nine systems, inform scotsman.com
Within 10 years, telescopes should be powerful enough to detect these planets directly and reveal whether their atmospheres contain tell-tale traces of life, they say. These far distant planets cannot be seen with telescopes, but they can be indirectly detected. If planets are big enough and close enough to a star, their gravitational pull causes the star to wobble slightly - a motion that can be detected from Earth. Prof Barrie Jones of the Open University told the Royal Astronomical Society's conference in Milton Keynes,"We now think that at least 10 per cent of stars in the Earth's backyard have planetary systems," he said and added,"If only half of these are able to sustain a rocky planet in the habitable zone, it means that one in 20 could harbour life. It is possible that the universe is teeming with life," reports webindia123.com
According to BBC Finding chemicals such as carbon dioxide, water and ozone would be intriguing evidence of life.
But even if those chemical signs were detected, it would not be possible to send a space mission, Professor Jones said.
"It's likely the nearest Earth-type world in the habitable zone would be a few tens of light-years away, maybe 100 light-years away; that's being optimistic," he told BBC News Online.
"There's not much prospect of travelling to these worlds; all we can do is rely on instruments orbiting somewhere in the solar system and making observations.
Its results are more optimistic than a similar study led by Dr Kristen Menou, of Princeton University, US, last year which found perhaps less than a quarter of extrasolar planetary systems might contain Earth-like worlds.