It is the planetary system that gives two for the price of one. The star Kepler 62 hosts a pair of planets roughly the size of Earth. Both are orbiting in the star's habitable zone, the region where temperatures should be neither too hot nor too cold, but just right for liquid water to exist (see diagram).
Known as Kepler 62e and Kepler 62f
, these worlds are being hailed as the most life-friendly planets yet seen outside our solar system. But that doesn't mean they would support life quite as we know it.
For one thing, the star is smaller and cooler than our sun, so at least one of the planets would need a potentially toxic atmosphere to keep warm. For another, some models suggest that the planets are covered in water, hinting that, if there are extraterrestrials, they might have evolved almost entirely in marine environments.
To read more, click here.