Centaur (minor planet) in the context of Centaur

The asteroid belt is a torus-shaped region in the Solar System, centered on the Sun and roughly spanning the space between the orbits of the planets Jupiter and Mars. It contains a great many solid, irregularly shaped bodies called asteroids or minor planets. The identified objects are of many sizes, but much smaller than planets, and, on average, are about one million kilometers (or six hundred thousand miles) apart. This asteroid belt is also called the main asteroid belt or main belt to distinguish it from other asteroid populations in the Solar System.

The asteroid belt is the smallest and innermost circumstellar disc in the Solar System. Classes of small Solar System bodies in other regions are the near-Earth objects, the centaurs, the Kuiper belt objects, the scattered disc objects, the sednoids, and the Oort cloud objects. About 60% of the main belt mass is contained in the four largest asteroids: Ceres, Vesta, Pallas, and Hygiea. The total mass of the asteroid belt is estimated to be 3% that of the Moon.

A small Solar System body (SSSB) is an object in the Solar System that is neither a planet, a dwarf planet, nor a natural satellite. The term was first defined in 2006 by the International Astronomical Union (IAU) as follows: "All other objects, except satellites, orbiting the Sun shall be referred to collectively as 'Small Solar System Bodies'".

This encompasses all comets and all minor planets other than those that are dwarf planets. Thus SSSBs are: the comets; the classical asteroids, with the exception of the dwarf planet Ceres; the trojans; and the centaurs and trans-Neptunian objects, with the exception of the dwarf planets Pluto, Haumea, Makemake, Quaoar, Orcus, Sedna, Gonggong and Eris and others that may turn out to be dwarf planets.

A formal minor-planet designation is, in its final form, a number–name combination given to a minor planet (asteroid, centaur, trans-Neptunian object and dwarf planet but not comet). Such designation always features a leading number (catalog or IAU number) assigned to a body once its orbital path is sufficiently secured (so-called "numbering"). The formal designation is based on the minor planet's provisional designation, which was previously assigned automatically when it had been observed for the first time. Later on, the provisional part of the formal designation may be replaced with a name (so-called "naming"). Both formal and provisional designations are overseen by the Minor Planet Center (MPC), a branch of the International Astronomical Union.

Currently, a number is assigned only after the orbit has been secured by four well-observed oppositions. For unusual objects, such as near-Earth asteroids, numbering might already occur after three, maybe even only two, oppositions. Among more than half a million minor planets that received a number, only about 20 thousand (or 4%) have received a name. In addition, approximately 700,000 minor planets have not been numbered, as of November 2023.

A distant minor planet, or distant object, is any minor planet found beyond Jupiter in the outer Solar System that is not commonly thought of as an "asteroid". The umbrella term is used by IAU's Minor Planet Center (MPC), which is responsible for the identification, designation and orbit computation of these objects. As of January 2025, the MPC maintains 6101 distant objects in its data base.

Most distant minor planets are trans-Neptunian objects and centaurs, while relatively few are damocloids, Neptune trojans or Uranus trojans. All distant objects have a semi-major axis (average distance from the Sun) greater than 6 AU. This threshold, which is just beyond the orbit of Jupiter (5.2 AU), ensures that the vast majority of "true asteroids" – such as the near-Earth, Mars-crosser, main-belt and Jupiter trojan populations – are excluded from the distant minor planets.

944 Hidalgo /hɪˈdælɡoʊ/ is a centaur and unusual object on an eccentric, cometary-like orbit between the asteroid belt and the outer Solar System, approximately 52 kilometers (32 miles) in diameter. Discovered by German astronomer Walter Baade in 1920, it is the first member of the dynamical class of centaurs ever to be discovered. The dark D-type object has a rotation period of 10.1 hours and likely an elongated shape. It was named after Mexican revolutionary Miguel Hidalgo y Costilla.

31824 Elatus (/ˈɛlətəs/; provisional designation 1999 UG₅) is a very red centaur from the outer Solar System, approximately 48 kilometers (30 miles) in diameter. It was discovered on 29 October 1999, by astronomers of the Catalina Sky Survey at Mount Lemmon Observatory in Arizona, United States. The minor planet was named after Elatus, a centaur from Greek mythology.

This is a list of trans-Neptunian objects (TNOs), which are minor planets in the Solar System that orbit the Sun at a greater distance on average than Neptune, which means all of their orbits have a semi-major axis greater than 30.1 astronomical units (AU). The Kuiper belt, scattered disk, and Oort cloud are three conventional divisions of this volume of space. As of October 2025, the catalog of minor planets contains 1,037 numbered TNOs. In addition, there are 4,518 unnumbered TNOs, which have been observed since 1993.

This list consists of all types of TNO subgroups: classical Kuiper belt objects, also known as "cubewanos", the resonant trans-Neptunian objects with their main and higher-order resonant subgroups, the scattered disc objects (SDOs), and the extreme trans-Neptunian objects including the ESDOs, EDDOs, and sednoids, which have a semi-major axis of at least 150 AU and a perihelion (closest approach to the Sun) greater than that of Neptune. The list also contains several centaurs, if the object's orbit has a sufficiently large semi-major axis (a). Centaurs have unstable orbits in which the perihelion (q) is well inside of Neptune's orbit but the farthest point (aphelion, Q) is very distant.

This is a list of periodic comets that were numbered by the Minor Planet Center after having been observed on at least two occasions. Their orbital periods vary from 3.2 to 366 years. As of November 2025, there are 513 numbered comets (1P–513P). There are 440 Jupiter-family comets (JFCs), 50 Encke-type comets (ETCs), 15 Halley-type comets (HTCs), five Chiron-type comets (CTCs), and one long-period comet (153P). 79 bodies are also near-Earth comets (NECs). In addition, eight numbered comets are principally classified as minor planets – five main-belt comets, two centaurs (CEN), and one Apollo asteroid – and display characteristics of both an asteroid and a comet.

Occasionally, comets will break up into multiple chunks, as volatiles coming off the comet and rotational forces may cause it to break into two or more pieces. An extreme example of this is 73P/Schwassmann–Wachmann, which broke into over 50 pieces during its 1995 perihelion.

(636872) 2014 YX₄₉ (provisional designation 2014 YX₄₉) is a centaur and Uranus co-orbital, approximately 77 kilometers (48 miles) in diameter. Discovered by the Mount Lemmon Survey on November 21, 2006, it is the second known centaur on a tadpole orbit with Uranus, and the fourth Uranus co-orbital discovered after 83982 Crantor, (687170) 2011 QF99 and (472651) 2015 DB216.

A Saturn-crosser is a minor planet whose orbit crosses that of Saturn. The known numbered Saturn-crossers (as of 2005) are listed below. There is only one inner-grazer (944 Hidalgo) and no outer-grazers or co-orbitals known; most if not all of the crossers are centaurs. (15504) 1999 RG33 is a damocloid.

A Uranus-crosser is a minor planet whose orbit crosses that of Uranus. The numbered Uranus-crossers (as of 2005) are listed below. Most, if not all, are centaurs.