Pluto

Pluto is the second-largest known dwarf planet in the Solar System. It was originally classified as a planet, Pluto is now known as a dwarf planet.

Pluto is composed primarily of rock and ice and is relatively small. It is approximately a fifth the mass of the Earth's satellite and a third it's volume. In the late 20th and early 21st century, many objects similar to Pluto were discovered in the outer Solar System.

Pluto has three satellites, it's largest satellite is Charon.