Earth-like planets ‘may exist in their billions’

Around 100 “super-Earths” may be found on our galactic doorstep, at less than 30 light years from the sun.

Astronomers came up with the prediction after conducting a survey of red dwarf stars. They calculate that around 40 per cent of red dwarfs have a rocky planet not much bigger than Earth orbiting the “habitable zone” where liquid surface water can exist. Where there is water, there could be life.

Dr Xavier Bonfils, from Grenoble University in France, who led the international team, said: “Because red dwarfs are so common – there are about 160 billion of them in the Milky Way – this leads us to the astonishing result that there are tens of billions of these planets in our galaxy alone.”

The astronomers surveyed a carefully chosen sample of 102 red dwarfs using the European Southern Observatory’s 3.6-metre telescope at La Silla, Chile.

A total of nine super-Earths – planets with masses between one and ten times that of Earth – were found. Two were located within the habitable zones of the stars Gliese 581 and Gliese 667 C.

These data were combined with other observations.