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The researchers based their calculations on planets already discovered by the US super-telescope Kepler, focusing on the question of which "red dwarf" stars could have potentially habitable Earth-size planets in their orbits.

Red dwarfs are smaller, cooler and fainter than our solar system's sun - and they are also the most commonly found stars in our galaxy, making up about three of every four stars in the Milky Way.


But most of those planets weren't quite the right size or temperature to support life, so the researchers narrowed the candidates to just three that were both warm and approximately Earth-sized.





So 13 light years away is hardly a quick jaunt.

But it's a whole lot closer than the 300-600 light years between us and the planet candidates Kepler has spotted to date in the so-called "habitable zone" where liquid water is capable of existing and thus supporting life.

The characteristics of red dwarfs make it relatively easy to spot planets orbiting them from far away - a process that relies on identifying dim spots created when the planet passes in front of its star.


Dressing also cautioned that an Earth-like planet orbiting a red dwarf would look quite different from the green-and-blue one we call home, but said the differences didn't rule out the existance of life.

"You don't need an Earth clone to have life," Dressing said.