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

Although Pluto was demoted to the status of a dwarf ... compelling mathematical models predicting the existence of Planet Nine. They argued that the strange orbits of several transNeptunian ...

Astronomers have long suspected that an enormous, unseen planet is hiding somewhere far beyond Neptune, quietly shaping the ...

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 ...