Everyone's favorite dwarf planet, Pluto, was discovered just 95 years ago. Here's the story of how the once-ninth planet was ...

Although Pluto's orbit was more elongated than the other planets ... (The object is now called Eris.) Over a thousand objects are now known to orbit the Sun beyond Neptune, and once again ...

Pluto, Eris, Ceres, Makemake ... Those guys are going to spend most of their time at the outer edge of their orbit, so they're hard to see," Brown said. "There might be a factor of ~5 more ...

Pluto and Charon orbit a shared center of mass, much like figure skaters spinning together, a result of their unique collision process. The collision deposited internal heat into both bodies ...