Pluto is the biggest trans-Neptunian object by volume that is known.
Pluto -LRB- minor-planet designation : 134340 Pluto -RRB- is a dwarf planet in the Kuiper belt , a ring of bodies beyond Neptune.
A trans-Neptunian object -LRB- TNO , also written transneptunian object -RRB- is any minor planet in the Solar System that orbits the Sun at a greater average distance -LRB- semi-major axis -RRB- than Neptune , 30 astronomical units -LRB- AU -RRB-.
