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

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.

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

An unusual x-ray signal from the Helix Nebula, first detected in 19180, could stem from a star destroying a nearby planet. Credit: NASA/CXC/A. Hobart ...

Researchers in the US have suggested there is a 40 percent chance a ninth planet could exist in our solar system. Planet Nine ...

No telescope has basked in the night sky quite like the enormous new Vera Rubin Observatory. Here's what it could reveal ...

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

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.