Pluto is in the Kuiper belt.
Pluto ( minor-planet designation : 134340 Pluto ) is a dwarf planet in the Kuiper belt , a ring of bodies beyond Neptune . After 1992 , its planethood was questioned following the discovery of several objects of similar size in the Kuiper belt . Like other Kuiper belt objects , Pluto is primarily made of ice and rock and is relatively small -- about one-sixth the mass of the Moon and one-third its volume .