Astronomers find evidence of a possible ninth planet beyond Neptune, reigniting the debate about the formation of the Solar ...

Scientists are intrigued after spotting a highly unusual celestial object lurking at the very edge of our solar system. It's ...

Planets with unusually wide orbits may be normal by-products of the formation of planetary systems. This is suggested by new simulations.

Researchers from Rice University claim to have fresh evidence of Planet Nine - as well as a method to find it.