Tagged With Planet 9

Planet 9, our solar system's mysterious missing world, could be an ancient black hole orbiting the sun, a new paper suggests


Astronomers think there's another planet in our solar system -- here's everything we know about 'Planet 10'


Is it Planet 9 or Planet X? Scientists spar over what to call the solar system's hypothetical missing world



There's a mysterious object doing a crazy loop around our solar system -- and scientists have no idea what it is