For the dwarf planet candidate, one trip around the sun takes over 24,000 years. Its orbit challenges a proposed path for a hypothetical Planet Nine.

Some scientists hypothesize that a mysterious, gigantic 9th planet may be lurking at our solar system’s edge. Why haven't we ...

Computer simulations show that planets could be flung out of the inner solar system, supporting the possible existence of a ...

The planet, which astronomers believe is orbiting a young red dwarf star approximately 34 light years away, has been dubbed ...

Scientists may have discovered a dwarf planet far beyond Neptune — an unearthing that may disprove a longstanding theory ...

It is also sometimes called Planet X, a name proposed for a hypothetical world beyond Neptune more than a century ago. Back in 1930, ...

New research shows there is at least a 40% chance of the existence of Planet Nine, but scientists are still looking for definitive proof.

Earth" that is located about 154 light-years away and is nearly twice as big and four times as massive as our planet.

Planet X has been hypothesized for years, but how such a planet could have appeared in the outer Solar System has long stumped scientists. A new study in Nature Astronomy reveals a novel theory, ...

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

The scientists announced in a news release that they have found a trans-Neptune Object(TNO), code-named 2017OF201, located past the icy and desolate region of the Kuplier Belt.