The current definition was included in the 2006 IAU resolution that defined the term
planet, demoting the status of
Pluto to that of
dwarf planet. In the context, it should be interpreted as, "All objects
other than planets and dwarf planets orbiting the Sun shall be referred to collectively as 'Small Solar System Bodies'. The definition excludes
interstellar objects traveling through the Solar System, such as the
interstellar interlopers
1I/ʻOumuamua,
2I/Borisov, and
3I/ATLAS. It is not presently clear whether a lower size bound will be established as part of the definition of small Solar System bodies in the future, or if it will encompass all material down to the level of
meteoroids, the smallest macroscopic bodies in orbit around the Sun. (On a microscopic level there are even smaller objects such as
interplanetary dust, particles of
solar wind and free particles of
hydrogen.) Except for the largest, which are in
hydrostatic equilibrium,
natural satellites (moons) differ from small Solar System bodies not in size, but in their orbits. The orbits of natural satellites are not centered on the
Sun, but around other Solar System objects such as planets,
dwarf planets, and small Solar System bodies. Some of the larger small Solar System bodies may be reclassified in future as dwarf planets, pending further examination to determine whether or not they are in
hydrostatic equilibrium. The orbits of the vast majority of small Solar System bodies are located in two distinct areas, namely the
asteroid belt and the
Kuiper belt. These two belts possess some internal structure related to perturbations by the major planets (particularly
Jupiter and
Neptune, respectively), and have fairly loosely defined boundaries. Other areas of the Solar System also encompass small bodies in smaller concentrations. These include the
near-Earth asteroids,
centaurs,
comets, and
scattered disc objects. == See also ==