The discovery of 2017 OF201 is significant, as it challenges the hypothesis of Planet Nine, a hypothetical planet thought to ...

In the cold, distant reaches of the Solar System, far beyond Pluto, astronomers have just identified what could be a new ...

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 ...

At the very edge of our solar system, beyond the grasp of Neptune and even past the icy sprawl of Pluto’s domain, a new ...

Scientists believe such an extreme orbit means the object was pushed and pulled by the gravity of giant planets like Jupiter ...

A small team led by Sihao Cheng, Martin A. and Helen Chooljian Member in the Institute for Advanced Study's School of Natural ...

T he Solar System has just gotten a new official member. Currently, with the name of 2017 OF 201, this is a trans-Neptunian ...

The presence of another planet in the solar system could explain the odd movements of some of the bodies in the Kuiper Belt.

Researchers say they found a curious dot on infrared images taken 23 years apart that seems to be moving in a manner consistent with a large, distant planet.

A ninth planet the size of Neptune may be hidden in the far reaches of the solar system, but the evidence has left some experts skeptical.

Pluto was unseated as number ... The argument for the planet has to do with the Kuiper Belt: a region of icy debris far beyond Neptune’s orbit. The hypothetical planet would explain some strange ...