For about a decade, he and other researchers have been trying to prove that the so-called "Planet 9" exists. So far, the only evidence has come from some oddities in the orbits of small Pluto-like ...

Some scientists are convinced that beyond Neptune, there's a planet they've yet to see. This so-called "Planet 9" is so far ...

A small team of planetary scientists from the California Institute of Technology, Université Côte d'Azur and Southwest ...

A powerful new observatory is the best hope yet for finding the elusive Planet 9, a large planet that some scientists say is ...