A strong greenhouse effect allows these "super-Earth" exoplanets to masquerade as "mini-Neptunes."
An alien planet that orbits a star other than our sun is referred to as an "exoplanet." Learn more about the types of alien planets, including exoplanets and extrasolar planets, and get the latest news.
Citizen scientists recently helped direct astronomers to a pair of objects that straddle the line between planets and stars.
Rocky planets that formed early in our Milky Way galaxy's 13.2-billion-year history have a better chance of supporting life than worlds that were later to the party, a new study suggests.
Astronomers have spotted the exposed core of a massive alien planet, an unprecedented find that could shed considerable light on planet formation, evolution and diversity.
In our neighborhood, three quarters of planets have at least one moon, but no such object has been confidently discovered so far in distant star systems — such worlds are just too small and far away.
The brightest red dwarf star in the sky may be the best chance astronomers have yet to analyze the atmospheres of alien worlds — and perhaps detect whether those worlds have life, a new study finds.
Two veteran NASA planet-hunting missions found a Neptune-size planet that circles its young star every Earth week.
A satellite the size of a briefcase successfully detected an alien world, potentially paving the way for a future network of bantam planet-hunting spacecraft.
The closest alien planet to our solar system is even more Earth-like than scientists had thought, new observations suggest.
New imagery apparently pinpoints the spot where a baby planet is forming around the young star AB Aurigae, which lies 520 light-years from Earth.
Scientists suspect they have identified an intriguing new alien planet in a particularly roundabout way.
A new world has been confirmed in the Kepler-88 planetary system, tipping the scales at three-times the mass of solar system giant Jupiter.
Life can thrive in a 100% hydrogen atmosphere, according to a new study. The finding could completely change our understanding of how (and where) life might exist in the universe.
The alleged exoplanet Fomalhaut b was discovered in 2004 and disappeared in 2014. Astronomers now say it was never a planet to begin with.
Scientists analyzing archival data gathered by NASA's defunct Kepler spacecraft just found a hidden gem: an Earth-size world that may be capable of supporting life as we know it.