Far beyond Neptune, something heavy appears to be tugging on the outer solar system, bending the paths of distant icy worlds in ways gravity alone should be able to explain. Planet 9, still invisible ...

Astronomers have long been on the hunt for "Planet Nine," a hypothetical planet that lies within our solar system just beyond Neptune. Scientific evidence has alternately pointed to and against the ...

Add Yahoo as a preferred source to see more of our stories on Google. An illustration showing Planet Nine, a hypothetical, undiscovered planet in our solar system. New research now suggests the ...

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. Labelled as planet X, prominent astronomers ...

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 ...

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 ...