Add Yahoo as a preferred source to see more of our stories on Google. Digital art of distant planet - Dottedhippo/Getty Images On August 24, 2006, our solar system lost a planet. It wasn't by ...

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 ...

The solar system may have a ninth planet after all. This one is 5,000 times bigger than outcast Pluto and billions of miles farther away, say scientists who presented "good evidence" for a ...

A recent research paper suggests that a planet may exist far beyond Neptune — less than 20 years after the previous ninth planet, Pluto, was demoted. That research paper, accepted last month for ...

LONDON — The search for an unknown planet in our solar system has inspired astronomers for more than a century. Now, a recent study suggests a potential new candidate, which the paper's authors have ...

CAPE CANAVERAL, Fla. — The solar system may have a ninth planet after all. This one is 5,000 times bigger than outcast Pluto and billions of miles farther away, say scientists who presented “good ...

Caltech professor Mike Brown (L) and assistant professor Konstanin Batygin have been working together to investigate distant objects in our solar system for more than a year and a half. The two ...

Scientists reported Wednesday they finally have "good evidence" of Planet X, a true ninth planet on the fringes of our solar system. The gas giant is thought to be almost as big as Neptune and ...