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 ...

When you buy through links on our articles, Future and its syndication partners may earn a commission. A composite image comparing the relative sizes of our solar system's known dwarf planets, ...

In 2006, updated research led to Pluto being controversially demoted to dwarf planet status by the International Astronomical Union. The reasoning was that Pluto's location in the far-flung ...

Is there a massive undiscovered planet on the outer reaches of the solar system? The idea has been around since before the discovery of Pluto in the 1930s. Labeled as planet X, prominent astronomers ...

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 ...

Once the quirky underdog of our solar system, Pluto held planetary status until 2006, when it got a cosmic demotion that still stings space fans. Discovered in 1930, Pluto was the ninth planet for ...