NEW YORK — Despite the doubts raised over the existence of the potentially habitable alien world Gliese 581g, the planet’s co-discoverer is standing behind his find.

On Thursday (April 17), NASA announced the historic discovery of Kepler-186f, an Earth-size alien planet in the habitable zone of its star. See our complete coverage of the major Earth cousin find.

Astronomers detect Earth-like planet orbiting around star system closest to our solar system, though some cautious about evidence ...

NASA has taken a giant leap closer to discovering whether we're alone in the universe by confirming the existence of the first planet, named Kepler-22b, that exists in the "habitable zone" of its ...

The star system closest to our own sun hosts a planet with roughly Earth's mass and may harbor other alien worlds as well, a new study reports.

The discovery of dimethyl sulfide on K2-18b, a planet 120 light-years away, has ignited hopes for extraterrestrial life due to its potential for liquid water. While scientists are excited about ...

NASA is about to announce some more big alien-planet news. The agency will hold a news conference Thursday (Dec. 14) at 1 p.m. EST (1800 GMT) to reveal a new discovery made by its prolific Kepler ...

Astronomers recently discovered an exoplanet that is the size of 11 Jupiters. The massive alien planet orbits star HD 106906, and is farther away from the star than any other planet in a sun-like ...