A small Solar System body (SSSB) is an object in the Solar System that is neither a planet nor a dwarf planet, nor a satellite of a planet or dwarf planet:
All other objects, except satellites, orbiting the Sun shall be referred to collectively as "Small Solar System Bodies" ... These currently include most of the Solar System asteroids, most Trans-Neptunian Objects (TNOs), comets, and other small bodies.This encompasses all comets and all minor planets other than those classified as dwarf planets, i.e.:
- the classical asteroids, with the exception of Ceres;
- the centaurs and trojans;
- the trans-Neptunian objects, with the exception of Pluto, Haumea, Makemake and Eris.
The term was first defined in 2006 by the International Astronomical Union.
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, moons differ from small Solar System bodies not in size, but in their orbits. Moons' orbits are not centered around the Sun but around other Solar System objects such as planets, dwarf planets, and even small Solar System bodies themselves.
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.
Famous quotes containing the words small, solar, system and/or body:
“Come to me, Jenny, let’s dance a bit tonight,
The long small tremor’s at my back again....”
—Allen Tate (1899–1979)
“Our civilization has decided ... that determining the guilt or innocence of men is a thing too important to be trusted to trained men.... When it wants a library catalogued, or the solar system discovered, or any trifle of that kind, it uses up its specialists. But when it wishes anything done which is really serious, it collects twelve of the ordinary men standing round. The same thing was done, if I remember right, by the Founder of Christianity.”
—Gilbert Keith Chesterton (1874–1936)
“In a universe that is all gradations of matter, from gross to fine to finer, so that we end up with everything we are composed of in a lattice, a grid, a mesh, a mist, where particles or movements so small we cannot observe them are held in a strict and accurate web, that is nevertheless nonexistent to the eyes we use for ordinary living—in this system of fine and finer, where then is the substance of a thought?”
—Doris Lessing (b. 1919)
“Hereditary property sophisticates the mind, and the unfortunate victims to it ... swathed from their birth, seldom exert the locomotive faculty of body or mind; and, thus viewing every thing through one medium, and that a false one, they are unable to discern in what true merit and happiness consist.”
—Mary Wollstonecraft (1759–1797)