Known as Planet Nine or Planet X, it is a hypothetical planet that has long been rumoured to exist in the outer solar system.

This hypothetical extra planet, often referred to as "Planet Nine" or "Planet X" has been long-theorized to explain weird and ...

Known as "Planet Nine," a team of researcher from Caltech has claimed that an unseen planet exists in the solar system based on the movement of other objects. In their latest papers, the ...