The small world was found during a search for the hypothetical Planet Nine, and astronomers say the next time it will reach ...

Earth is full of surprises — and some of them look totally out of this world. This video explores stunning locations that could be mistaken for alien landscapes. From strange colors to bizarre rock ...

As it orbits the sun once every 25,000 years, the celestial body 2017 OF201 travels beyond the Kuiper Belt into a region ...

U.S. astronomers hunting for "Planet Nine" have instead stumbled on what appears to be a new dwarf planet in the solar system's outer reaches.

It's an evocative idea that has long bedeviled scientists: a huge and mysterious planet is lurking in the darkness at the ...

But new research from the University of Chicago is urging caution. After analyzing data from multiple observations of the ...

A new study may finally explain how planets can end up orbiting their stars at extremely large distances—sometimes hundreds ...

In the cold, dark outskirts of planetary systems far beyond the reach of the known planets, mysterious gas giants and ...

Scientists are intrigued after spotting a highly unusual celestial object lurking at the very edge of our solar system.

Astronomers find evidence of a possible ninth planet beyond Neptune, reigniting the debate about the formation of the Solar ...

The Martian released 10 years ago, and showed humans on Mars in 2035. With another 10 years to go before that time finally ...

Methyl halides, detected in space, are key biosignatures in the search for extraterrestrial life, indicating potential ...