Astronomers think there’s another planet in our solar system — here’s everything we know about 'Plan Even before we can confirm "Planet 9," we found traces for a "Planet 10."

First There Was Planet Nine. Now There Might Be A 'Planet Ten' Last year we learned that there may be a hidden Planet Nine in the outer reaches of our Solar System. Now it turns out there may be a Planet Ten out there

Planet Nine: What Would It Mean? It could be the first new planet discovered in the last 170 years -- or at least the last 85, if you're one of those stubborn folk who still insist on calling Pluto a planet. Two Caltech astronome...

Planet Nine: What Would It Mean? It could be the first new planet discovered in the last 170 years -- or at least the last 85, if you're one of those stubborn folk who still insist on calling Pluto a planet. Two Caltech astronome...

Scientists May Have Just Found a Ninth Planet and It's Massive Planet Nine could show that there were five, not four, planetary cores that marked the beginning of the universe.

New evidence suggests a ninth planet lurking at the edge of the solar system The massive planet could take over 10,000 years to orbit the sun.

Powerlifting Motivation Planet Fitness Throws Out A Powerlifter From The Gym Because He Was “Intimidating”

Photos from Lonely Planet's post

Pluto is Something Way More Awesome Than a Mere Planet Stop hoping that Pluto will regain its former designation as a planet. It isn’t going to happen. But the good news is, Pluto is something much cooler than a mere planet. It’s the largest dwarf planet we know, and one half of the first binary plan Read more ... et system. Pluto didn’t get demoted, it got promoted.

The planet you've probably never heard of - CNN.com Way out beyond Mars, but before you get to Jupiter, is a planet. Well, it was a planet, then later an asteroid. Now it's called a dwarf planet.