On August 24, 2006, our solar system lost a planet. It wasn't by cataclysmic destruction, but rather by the vote of the International Astronomical Union, which declared that Pluto, considered the ...

For the first time since Pluto was demoted, the idea of a true ninth planet is edging from speculation toward something testable. Instead of restoring Pluto, researchers are closing in on a different, ...

The science community may be ecstatic over the discovery of a ninth planet, but the former planet "Pluto" had a totally different reaction. Hours after scientists announced there's solid evidence of ...

There has been a lot of back and forth about the existence of a mysterious ninth planet, often referred to as "Planet Nine" or even "Planet X." Now, though, researchers say there is likely at least a ...

Does our solar system have a mysterious ninth planet? The discovery of a new dwarf world suggests not. It's an evocative idea that has long bedeviled scientists: a huge and mysterious planet is ...

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 ...