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Which kinds of objects are classified as small bodies in the solar system?
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Small body
Asteroid Ida and its satellite, Dactyl, photographed by the Galileo spacecraft on August 28, 1993, from a distance of about 10,870 km (6,750 miles). Ida is about 56 km (35 miles) long and shows the irregular shape and impact craters characteristic of many asteroids. The Galileo image revealed that Ida is accompanied by a tiny companion about 1.5 km (1 mile) wide, the first proof that some asteroids have natural satellites.
In astronomy, a small body is defined as any natural object within the solar system that is not the Sun, a major planet, a dwarf planet, or a natural satellite (moon).12
These objects are primarily considered to be remnant material from the formation of the solar system. They are classified into the following categories:2
- Asteroids: Also known as minor planets, these are predominantly rocky bodies, most of which are found in the asteroid belt between Mars and Jupiter.12
- Comets: These are predominantly icy bodies that originate in regions such as the Kuiper belt and the Oort cloud. They are characterized by the development of a coma or tail when they approach the Sun.12
- Meteoroids: These are fragments of asteroids and comets, typically ranging from a few tens of meters across down to microscopic sizes.132
- Interplanetary dust particles: Also called micrometeoroids, these are the smallest small bodies, consisting of grains less than a few hundred micrometers in diameter.32