The Register reports astronomers estimate there are probably around 100 planets within a radius of just 30 light-years of our solar system that could support Earth-like life. By extrapolating these findings, they come to the conclusion that there could be tens of billions of such planets in the Milky Way.
The new astroboffinry involves examination of red dwarf stars - the most common type of star found in the galaxy - using the HARPS spectrograph on the 3.6-metre telescope at the La Silla Observatory in the mountains of Chile. The HARPS team surveyed 102 red dwarfs over a six-year period, discovering nine "super-Earths" (planets with masses between one and ten times that of Earth, thus probably rocky planets as opposed to gaseous ones). They were able to measure planetary mass and orbital distance from the parent stars.
The methods used could discern only a proportion of planets which exist, and the team's calculations applied to the results indicate that in general approximately 40 per cent of the red dwarfs in the Milky Way should possess an Earthlike, rocky planet lying within their "habitable zone" - that is orbiting at such a distance as to permit the existence of liquid water on the planet's surface.
"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," enthuses Xavier Bonfils, lead boffin on the investigation.