Add Yahoo as a preferred source to see more of our stories on Google. Once the quirky underdog of our solar system, Pluto held planetary status until 2006, when it got a cosmic demotion that still ...

This story is part of Short Wave's series Space Camp about all the weird, wonderful things happening in the universe. Check out the rest of the series. If you were born in the last century you might ...

For the better part of a century, we believed there were nine planets in our solar system, with Pluto being the farthest from the sun. Since the discovery of more Pluto-sized dwarf planets, that ...

What is a planet anyway? In early times, "planet" simply meant anything in the sky that moved in a predictable way, said Mike Brown, an astronomer at the California Institute of Technology. Things got ...