The artist's concept depicts Kepler-186f , the first validated Earth-size planet to orbit a distant star in the habitable zone—a range of distance from a star where liquid water might pool on the ...

Kepler-186f is a rocky little world in the Goldilocks zone around its star. It's the fifth planet from its parent star, and yet it orbits at a distance comparable with Mercury's orbit around our sun.

The first Earth-size planet orbiting a star in the “habitable zone” — the range of distance from a star where liquid water might pool on the surface of an orbiting planet.

Technicians working inside the Astrotech Space Operations facility near NASA's Kennedy Space Center look over the Kepler spacecraft soon after it arrived in Florida in preparation for launch. [Read ...