The 12 Planets Most Likely To Contain Life

Scientists on Monday reported they had discovered a rocky "mega-Earth" that expands the definition of planets beyond our solar system that could potentially host life.

The new type of planet, Kepler-10c, weighs 17 times as much as Earth. Researchers previously thought this kind of world could not exist since any planet that large would attract hydrogen gas, becoming a gas giant like Jupiter rather than a solid planet.

"Finding Kepler-10c tells us that rocky planets could form much earlier than we thought. And if you can make rocks, you can make life," said Harvard-Smithsonian researcher Dimitar Sasselov in a media release.

Kepler-10c isn't the only potentially habitable (or inhabited) planet out there. The Planetary Habitability Laboratory run by the University of Puerto Rico at Arecibo maintains a list of exoplanets that are most similar to Earth, taking size, mass, and distance from their host stars into consideration - factors that are likely to support liquid water and be conducive to life as we know it.

The catalog does not guarantee that these planets host life but "lists the best candidates so far for potential habitable worlds and the objects of interest for the search of life outside the Solar System."

Here's a look at some of the top candidates from the catalog, ranked in order of Earth similarity.