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

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.

Scientists hunting for the hypothetical Planet Nine have discovered a potential new dwarf planet, 2017 OF201, in the outer ...

They said: ‘The discovery of 2017 OF201 is significant because it’s found in a region of the Solar System thought to be empty ...

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

Scientists have identified an object about 435 miles (700 km) wide inhabiting the frigid outer reaches of our solar system that might qualify as a dwarf planet, spotting it as it travels on a highly ...

For centuries, astronomers have sought to understand the formation and evolution of the solar system and the dynamics that ...

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

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

OF201 is incredibly lightweight on a cosmic scale. Scientists estimate its mass is about 20,000 times less than Earth's and ...

WASHINGTON: A group of scientists has found a strange new object about 435 miles wide at the far edge of the solar system. It ...

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