Definition

Noun 1. A small celestial body orbiting the Sun: A "minor planet" is any of the many small astronomical objects that revolve around the Sun, primarily found in the region between Mars and Jupiter (the asteroid belt), but also elsewhere in the solar system. This term is a broad category that includes most asteroids and distant objects, but traditionally excludes comets and the major planets.

Usage

The term "minor planet" is used in formal astronomical contexts to classify and discuss these bodies. - Astronomers discovered a new minor planet beyond the orbit of Neptune. - Ceres was the first minor planet to be identified in the asteroid belt.

Advanced Usage

• Historical and Evolving Classification: The term "minor planet" was historically used interchangeably with "asteroid." However, with modern classifications, some objects traditionally called minor planets (like Ceres) are now also classified as "dwarf planets." The formal designation system for minor planets is managed by the International Astronomical Union's Minor Planet Center.
  • Pluto was once considered a planet, then reclassified as a minor planet (specifically, a dwarf planet), before the dwarf planet category was formally defined.

Variants and Related Words

• Asteroid (n): Often used synonymously for minor planets found in the inner solar system, especially within the asteroid belt. An asteroid is a type of minor planet.
  • The spacecraft will visit a metal-rich asteroid.
• Dwarf Planet (n): A subcategory of minor planets that are massive enough to be rounded by their own gravity but have not cleared their orbital neighborhood. Pluto and Ceres are dwarf planets.
  • Eris is a dwarf planet located in the scattered disc.
• Planetoid (n): A less formal term sometimes used as a synonym for a minor planet or asteroid.
• Small Solar System Body (SSSB) (n): A modern formal term defined by the International Astronomical Union that encompasses most objects classified as minor planets, but specifically excludes planets and dwarf planets.

Synonyms

• Asteroid (for most rocky bodies within the asteroid belt)
• Planetoid (general synonym)

Related Terms and Contexts

• Comet: A different type of small solar system body characterized by a visible coma (atmosphere) and tail when near the Sun, due to sublimating ices. Comets are generally not called minor planets.
• Meteoroid: A much smaller particle from a minor planet or comet.
• Orbit: The path a minor planet follows around the Sun.
• Minor Planet Center (MPC): The official organization responsible for collecting observational data and designating minor planets.

Noun

1. any of numerous small celestial bodies that move around the sun