Astronomers have searched for Planet X for over a century without success. This video explains why distance, darkness, and technology make it so hard to detect distant worlds. It shows how past ...

For almost a decade, astronomers have been searching for a ninth planet in the solar system. Recently, new evidence of another possible planet, dubbed Planet Y, was uncovered, and it could be around ...

A new study has proposed the existence of Planet Y, an alternative Planet Nine candidate that is smaller and closer to Earth than the hypothetical Planet X, which astronomers have been hunting for ...

Is there a massive undiscovered planet on the outer reaches of the solar system? The idea has been around since before the discovery of Pluto in the 1930s. Labeled as planet X, prominent astronomers ...

LONDON — 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 ...