Its orbit is so large it would take nearly 20,000 years to go around the sun once.

In the four months since New Horizons’ historic flyby of Pluto, NASA has made incredible discoveries including two cryovolcanoes.

Rather than rest on its laurels after making its historic Pluto flyby, the New Horizons spacecraft will aim for a new icy target floating in the Kuiper Belt.

NASA's new full-color images reveal that Pluto's hazy atmosphere shines a brilliant blue, and beneath that sapphire haze lies several expanses of water ice.

Many of us still feel bitter about Pluto’s demotion to dwarf planet status in 2006. If you want a more specific target at which to direct your spite, read on to find out it all went down.

A curious orbital pattern among objects in the Kuiper Belt points to the presence of a hidden planet at the very edge of the solar system, too far for us to detect but large enough to exert strong gravitational effects on surrounding celestial...