Pluto

space · dwarf planet · icy world

Used to be a planet. Pluto was counted as the ninth planet for many years, until astronomers made a new definition and reclassified it as a 'dwarf planet' instead.

Ice and rock. Like other objects in the Kuiper belt, Pluto is made mostly of ice and rock, and it's much smaller than the inner planets like Earth.

Tinier than the Moon. Pluto has only about one-sixth the mass of our Moon and one-third of its volume, making it a pretty small world.

Biggest by volume. It's the largest known object beyond Neptune by volume, though a rival named Eris is actually a bit heavier.

Way out there. Pluto lives in the Kuiper belt, a ring of icy bodies orbiting the Sun far beyond the planet Neptune.