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

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

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

Discovery of a possible dwarf planet suggests our cosmic backyard holds many more secrets to uncover It is an evocative idea ...

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

Some astronomers say the strange, clustered orbits of icy rocks beyond Neptune indicate that something big is out there, ...

There’s a new object in the distant reaches of our solar system, and it might just offer clues to a long-standing cosmic ...

The chance of a planet forming in the outer reaches of the solar system - a hypothetical Planet Nine - could be as high as 40 ...

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

Learn how a possible ninth planet, the theoretical Planet X, could have acquired its wide orbit in the outer Solar System — a ...

There’s a new frozen oddball orbiting the Sun, and it’s not your average space rock. It’s a planet—a minor one, to be ...

A new dwarf planet, discovered beyond Neptune and described as Pluto's 'cousin,' could void the hypothesis of a Planet X in ...