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

In 2016, Batygin and Brown first outlined in detail how the orbits of six of these objects could be explained by a specific Planet Nine. They predicted this world must have a mass at least 10 ...

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 ...

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 ...

Scientists have observed a huge planet approximately nine times the mass of Jupiter at a remarkably early stage of formation, describing it as still in the womb, in a discovery that challenges ...