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10 NASA images of planets like Earth

July 17, 2012, 7:08 p.m.
Kepler, space, planet

Photo: NASA/JPL-CalTech

9 of 11

A new world

Does a planet have to be just like Earth to support life? NASA isn’t sure. Here we see an artist’s conception of a planet around a star that is cooler than our sun — these are called M-dwarfs and brown dwarfs. It is still unclear if cooler stars can support young planets with the same life-forming chemical mix that began life on Earth. For a planet to sustain life, it must be able to carry water below boiling point yet above freezing. In addition, it must have enough air — but not too much. This delicate balance depends on the proximity of the star to the planet.