Any small, icy body orbiting the Sun beyond Neptune. There are probably tens of thousands of such objects with diameters exceeding 100 km in a ring-shaped zone extending outwards from the orbit of Neptune (at 30 AU). They include objects in the main Kuiper Belt, scattered-disk objects, and objects in resonant orbits with Neptune. Most of the latter are in a 3:2 orbital resonance and are known as Plutinos, but there are smaller populations in other resonances, such as 2 : 1 and 4 : 3.
Subjects: Astronomy and Astrophysics.