Back in the 1980’s, a now-defunct magazine called Science Digest held a contest to name Planet X — the still-undiscovered world that astronomers believed might lie out beyond Pluto. One of the best ...

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 ...

NASA’sNew Horizons spacecraft has delivered extraordinary video footage showing towering ice mountains on Pluto’s moon Nix. These ice peaks, some rising as high as 11,000 feet, are made of pure water ...