This section needs to beupdated. Please help update this article to reflect recent events or newly available information.(August 2023)
Positions of the main asteroid belt, Kuiper belt, and the Oort cloud in the Solar System
The current definition was included in the 2006 IAU resolution that defined the termplanet, demoting the status ofPluto to that ofdwarf planet. In the context, it should be interpreted as, "All objectsother than planets and dwarf planets orbiting the Sun shall be referred to collectively as 'Small Solar System Bodies'. The definition excludesinterstellar objects traveling through the Solar System, such as theinterstellar interlopers1I/ʻOumuamua,2I/Borisov, and3I/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 ofmeteoroids, the smallest macroscopic bodies in orbit around the Sun. (On a microscopic level there are even smaller objects such asinterplanetary dust, particles ofsolar wind and free particles ofhydrogen.)
Except for the largest, which are inhydrostatic 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 theSun, 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 inhydrostatic equilibrium.
The orbits of the vast majority of small Solar System bodies are located in two distinct areas, namely theasteroid belt and theKuiper belt. These two belts possess some internal structure related to perturbations by the major planets (particularlyJupiter andNeptune, respectively), and have fairly loosely defined boundaries. Other areas of the Solar System also encompass small bodies in smaller concentrations. These include thenear-Earth asteroids,centaurs,comets, andscattered disc objects.
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