The hunt for Planet Nine continues as new discoveries make the Solar System’s biggest mystery even harder to solve. Is there ...

Over the past century, astronomers have speculated about the existence of a mysterious 9th planet lurking in the outer reaches of our solar system. Although we’ve never directly observed the elusive ...

Astronomers may have demoted Pluto from full-fledged planet to dwarf status, but evidence suggests the solar system may still host a mysterious ninth planet — far beyond Neptune, cloaked in shadow and ...

The search for an unknown planet in our solar system has inspired astronomers for more than a century. Now, a recent study suggests a potential new candidate, which the paper’s authors have dubbed ...