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:
“Do but consider this small dust, here running in the glass,
By atoms moved.
Could you believe that this the body was
Of one that loved?
And in his mistress’ flame playing like a fly,
Turned to cinders by her eye?
Yes, and in death as life unblest,
To have’t expressed,
Even ashes of lovers find no rest.”
—Ben Jonson (1572–1637)
“The solar system has no anxiety about its reputation, and the credit of truth and honesty is as safe; nor have I any fear that a skeptical bias can be given by leaning hard on the sides of fate, of practical power, or of trade, which the doctrine of Faith cannot down-weigh.”
—Ralph Waldo Emerson (1803–1882)
“[Madness] is the jail we could all end up in. And we know it. And watch our step. For a lifetime. We behave. A fantastic and entire system of social control, by the threat of example as effective over the general population as detention centers in dictatorships, the image of the madhouse floats through every mind for the course of its lifetime.”
—Kate Millett (b. 1934)
“Let every woman ask herself: “Why am I the slave of man? Why is my brain said not to be the equal of his brain? Why is my work not paid equally with his? Why must my body be controlled by my husband? Why may he take my labor in the household, giving me in exchange what he deems fit? Why may he take my children from me? Will them away while yet unborn?” Let every woman ask.”
—Voltairine Decleyre (1866–1912)