(CNN)You might have a replacement, Pluto. There could be another planet in our solar system. Researchers at the California Institute of Technology have found evidence in the outer solar system of an ...

For the first time since Pluto was demoted, the idea of a true ninth planet is edging from speculation toward something ...

There have been questions about a mysterious ninth planet in our solar system for nearly a decade. Pluto was unseated as number nine in 2006. Now, a group of international researchers say they may ...