Small Solar System body
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Small Solar System Body (SSSB) is a term defined in 2006 by the International Astronomical Union to describe objects in the Solar System that are neither planets nor dwarf planets:
| “ | All other objects 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.[1] | ” |
This encompasses:
- all minor planets apart from the dwarf planets, i.e.:
- the classical asteroids, (except for 1 Ceres, the largest);
- the centaurs and Neptune Trojans;
- the trans-Neptunian objects (except for dwarf planets such as Pluto and Eris);
- all comets.
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.
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 a 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. This includes the near-earth asteroids, centaurs, comets, or Scattered disc objects.
The smallest macroscopic bodies in orbit around the Sun are called Meteoroids. (There are also even smaller objects such as interplanetary dust, particles of solar wind and free particles of hydrogen). The NEO-definition incorporates objects up to 50 m in diameter in the Meteoroid category. The Royal Astronomical Society has proposed a new definition where a meteoroid is between 100 µm (0,1 mm) and 10 m across. Any smaller objects would then be interplanetary dust, molecules in gas clouds or single atoms.
[edit] See also
- Vulcanoid asteroid
- Near-earth asteroids
- Hungaria asteroids
- Main belt
- Cybele asteroids
- Hilda asteroids
- Trojan asteroids
- Centaur (planetoid)
- Kuiper belt
- Trans-Neptunian objects
- Comets
- Meteoroids
[edit] References
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