But in recent years, astronomers have proposed that a ninth world, imaginatively nicknamed "Planet Nine," could be hiding in ...

Speculation swirls as scientists debate if Planet Nine is a celestial body or something darker. Clues emerge from unexplained gravitational anomalies far beyond Neptune. A radical hypothesis ...

Known as Planet Nine or Planet X, it is a hypothetical planet that has long been rumoured to exist in the outer solar system. Although "several claims to have found an extra planet have been made ...

Planet Nine, a massive icy world, may be lurking at the outer edge of our solar system, awaiting discovery by advanced telescopes. "It's really difficult to explain the solar system without Planet ...