Unlike our Moon, they can keep water in oceans liquid for more than 4 billion years.

We’ve discovered thousands of exoplanets — but not a single confirmed exomoon. That doesn’t mean they aren’t out there. In fact, moons may be even more common than planets — and in some cases, even ...

When we imagine alien life in books or on TV, we often think of planets like ours inhabited by extraterrestrial people. The Harry Vanderspeigle’s (Alan Tudyk) of the universe are basically human with ...

Add Yahoo as a preferred source to see more of our stories on Google. This artist’s concept depicts a potential volcanic exomoon between the exoplanet WASP-49Ab, left, and its parent star.

For the first time, scientists have directly detected molecules in a Frisbee of gas and dust swirling around an alien gas-giant planet. “I didn’t think this was possible,” says astronomer Sierra Grant ...