Pluto

On the two-year anniversary of the New Horizons probe's flyby of Pluto, mission scientists unveiled two detailed global maps of the dwarf planet and its largest moon, Charon.

The frigid, faraway body that NASA's New Horizons spacecraft will zoom by 18 months from now may actually be a cluster of small objects, new observations suggest.

New Horizons team members have traveled to Argentina and South Africa to watch the Kuiper Belt object 2014 MU69 — the mission's next flyby target — pass in front of a distant star.

Some scientists believe Pluto's red "whale"-shaped region is the mark of a giant impact — the same one that produced Pluto's huge moon Charon.

The first up-close look at Pluto was so intriguing that some researchers want to go back and spend a lot more time studying the icy world.

I don't know about you, but I was shocked when NASA's New Horizons mission sent back its first batch of high-resolution images of the surface of Pluto.

Recent observations that a tiny object in our solar system is a likely dwarf planet has some planetary scientists grumbling again about Pluto's demotion to that status.

NASA's New Horizons spacecraft is now more than halfway from Pluto, which it famously flew past in July 2015, to its next flyby target: a distant object known as 2014 MU69.

After more than a decade of controversy, the debate over the icy world's demotion to "dwarf planet" status shows no sign of stopping

A group of planetary scientists is making the case for a new definition of a planet; this one would include Pluto and most moons. Here's why these researchers think the new definition is better.