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 ...

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 ...

"The Pluto flyby happened, and I was in the right place at the right time - perfectly positioned to fall in love with it," ...

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

This Feb. 18 marks 95 years since the Lowell Observatory hit paydirt, an achievement made not by one of the observatory’s professional astronomers, but by amateur Clyde Tombaugh, who at the time was ...

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 ...

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 — ...