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

For the better part of a century, we believed there were nine planets in our solar system, with Pluto being the farthest from the sun. Since the discovery of more Pluto-sized dwarf planets ...

Almost 10 years ago, a NASA spacecraft was able to take several photos of Pluto, known for decades as a planet before it was ...

Dubbed "Planet Nine," this hypothetical celestial body is believed to influence the orbits of distant, small objects beyond ...

So far, the only evidence has come from some oddities in the orbits of small Pluto-like bodies ... anything that changes — like, say, Planet Nine moving across the sky. "If it's there, we ...