MinorPlanet

Minor planet is a term used by the International Astronomical Union (IAU) to refer to small bodies in the solar system that orbit the Sun but are neither planets nor comets. The category encompasses a wide range of objects, including most asteroids, many dwarf planets, centaurs, Trojans, and trans-Neptunian objects. The term is often used interchangeably with small Solar System bodies, though some contexts distinguish “minor planets” from comets.

Most minor planets are rocky or icy; sizes range from tens of meters to thousands of kilometers. The majority reside in the main asteroid belt between Mars and Jupiter, but others orbit near-Earth, share an orbit with a planet as Trojans, or inhabit the outer solar system as centaurs and trans-Neptunian objects. The dwarf planets Pluto, Eris, Haumea, Makemake, and Ceres are included in this broad category; they are large enough for gravity to round them but have not cleared their orbital neighborhoods.

Discovery, designations, and naming: objects are first given provisional designations upon discovery, then receive a permanent number once their orbits are confirmed, and may be named subsequently by their discoverers under IAU guidelines. The Minor Planet Center assigns designations and tracks orbits.

Significance: studying minor planets informs models of solar system formation and evolution, and some objects are monitored for planetary defense as near-Earth objects. Ongoing surveys continue to discover and characterize new minor planets, revealing a dynamic and diverse population of small bodies in the solar system.