Kuiper Belt

A wide belt beyond the orbit of Neptune, the most distant planet from the Sun, that is theorized to contain tens of millions of icy bodies. The most famous member of the belt is Pluto, but it also includes three other objects that have been classified as dwarf planets. Most of the Kuiper Belt’s members are leftover “building blocks” from the birth of the planets. They were thrown into distant orbits by gravitational interactions with the giant outer planets.