Pluto has more in common with the inner planets than with its gas giant neighbors. Pluto is a small, rocky planet with very little atmosphere.
Little is known about Pluto. It is thought to have a very large, rocky core. The core could have a radius over 575 miles (925 km) or about 79 percent of Pluto's radius. Pluto's mantle is probably a frozen ocean of water, nitrogen, methane, and other ices. This mantle of frozen gases could be about 145 miles (235 km) thick or about 20 percent of Pluto's radius. If Pluto has a crust, it is probably only about one percent of the planet's total radius. Pluto's
