Earth has a newly-discovered neighbor in the solar system. But the heavenly body – possibly a dwarf planet à la Pluto – isn't a frequent visitor. Located beyond Neptune, its extreme orbit ...

Why does it matter if Pluto is a planet or a dwarf planet? Because for me it just makes it more confusing in our solar system. I know that some things in space are planets and some are stars and some ...

Welcome to the edge, humanity. NASA’s flight to Pluto, called New Horizons, arrives Tuesday morning at the cold, dim, and above all mysterious rock that used to be the unofficial edge of the solar ...

Pluto's largest moon, Charon, likely formed through a capture event in the early, crowded Kuiper Belt. Three-body encounters ...

Some NASA scientists have joined together to propose a new definition for a planet that would let Pluto back into the fold. It's been more than a decade since Pluto got demoted from planet to dwarf ...

WATCH ABOVE: The planned fly-by of Pluto is a rare feat and ‘New Horizons’ is expected to get within 7800 miles of Pluto’s orbit. Scientists know very little about Pluto’s surface but a team at John ...

For billions of years, Pluto and its largest moon Charon have been facing each other in a mutual tidal lock. Since it’s about half the size of Pluto, the moon and its planet are sometimes referred to ...

Little Pluto, formerly the solar system's smallest planet, has been stripped of its status by the International Astronomical Union, reducing the number of planets to eight. The new guidelines — ...