DENVER — Small but rowdy space rocks pushing and jostling one another may have created the unusual orbits some astronomers cite as the signature of the hypothesized "Planet Nine," a new study suggests ...

Gravity is a fundamental force of physics, one which we Earthlings tend to take for granted. You can't really blame us. Having evolved over the course of billions of years in Earth's environment, we ...

Rocky worlds larger than Earth are commonplace in the galaxy, and a few of them may even be habitable. Which poses an interesting question: How difficult would it be for aliens living on these ...

"Super-Earth" planets are giant-size versions of Earth, and some research has suggested that they're more likely to be habitable than Earth-size worlds. But a new study reveals how difficult it would ...

Super-Earths have been seen as planets that have the potential to host alien life. These types of planets are more common than Earth. There is just one problem with Super-Earths: gravity. Stronger ...

Late-stage planetary collisions reshaped Earth and its neighboring planets, delivering water, altering their atmospheres, and ...