Centaur (small Solar System body) in the context of "944 Hidalgo"

According to the International Astronomical Union (IAU), a minor planet is an astronomical object in direct orbit around the Sun that is exclusively classified as neither a planet nor a comet. Before 2006, the IAU officially used the term minor planet, but that year's meeting reclassified minor planets and comets into dwarf planets and small Solar System bodies (SSSBs). In contrast to the eight official planets of the Solar System, all minor planets fail to clear their orbital neighborhood.

Minor planets include asteroids (near-Earth objects, Earth trojans, Mars trojans, Mars-crossers, main-belt asteroids and Jupiter trojans), as well as distant minor planets (Uranus trojans, Neptune trojans, centaurs and trans-Neptunian objects), most of which reside in the Kuiper belt and the scattered disc. As of October 2025, there are 1,472,966 known objects, divided into 875,150 numbered, with only one of them recognized as a dwarf planet (secured discoveries) and 597,816 unnumbered minor planets, with only five of those officially recognized as a dwarf planet.

The Kuiper belt (/ˈkaɪpər/ ) is a circumstellar disc in the outer Solar System, extending from the orbit of Neptune at 30 astronomical units (AU) to approximately 50 AU from the Sun. It is similar to the asteroid belt, but is far larger—20 times as wide and 20–200 times as massive. Like the asteroid belt, it consists mainly of small bodies or remnants from when the Solar System formed. While many asteroids are composed primarily of rock and metal, most Kuiper belt objects are composed largely of frozen volatiles (termed "ices"), such as methane, ammonia, and water. The Kuiper belt is home to most of the objects that astronomers generally accept as dwarf planets: Orcus, Pluto, Haumea, Quaoar, and Makemake. Some of the Solar System's moons, such as Neptune's Triton and Saturn's Phoebe, may have originated in the region.

The Kuiper belt is named in honor of the Dutch astronomer Gerard Kuiper, who conjectured the existence of a version of the belt in 1951. There were researchers before and after him who proposed similar hypoetheses, such as Kenneth Edgeworth in the 1930s. The most direct prediction of the belt was by astronomer Julio Ángel Fernández, who published a paper in 1980 suggesting the existence of a comet belt beyond Neptune which could serve as a source for short-period comets.

2018 AG₃₇ is a distant trans-Neptunian object and centaur that was discovered 132.2 ± 1.5 AU (19.78 ± 0.22 billion km) from the Sun, farther than any other currently observable known object in the Solar System. Imaged in January 2018 during a search for the hypothetical Planet Nine, the confirmation of this object was announced in a press release in February 2021 by astronomers Scott Sheppard, David Tholen, and Chad Trujillo. The object was nicknamed "FarFarOut" to emphasize its distance from the Sun.2018 AG₃₇ was discovered when it was near aphelion, the farthest point from the Sun in its elliptical orbit. The object is estimated to be at least 400 km (250 mi) in diameter. Because of its extreme distance, 2018 AG₃₇ appears extremely faint with an apparent magnitude of 25—only visible to the largest telescopes in the world.

2060 Chiron is a ringed small Solar System body in the outer Solar System, orbiting the Sun between Saturn and Uranus. Discovered in 1977 by Charles Kowal, it was the first-identified member of a new class of objects now known as centaurs—bodies orbiting between the asteroid belt and the Kuiper belt. Chiron is named after the centaur Chiron in Greek mythology.

Although it was initially called an asteroid and classified only as a minor planet with the designation "2060 Chiron", in 1989 it was found to exhibit behavior typical of a comet. Today it is classified as both a minor planet and a comet, and is accordingly also known by the cometary designation 95P/Chiron. More recently, a series of occultation events through the 2010s and early 2020s revealed that Chiron hosts rings, making it one of four minor planets known to have rings (the three others being 10199 Chariklo, Haumea, and Quaoar) and the only known comet to do so.

10199 Chariklo /ˈkærəkloʊ/ is a ringed asteroid or centaur in the outer Solar System. It is the largest known centaur, with a diameter of about 250 km (160 mi). It orbits the Sun between Saturn and Uranus with an orbital period of 62.5 years. It was discovered on 15 February 1997 by the University of Arizona's Spacewatch project at Kitt Peak National Observatory. Chariklo has a dark, reddish surface composed of water ice, silicate minerals, amorphous carbon, and various complex organic compounds (also known as tholins).

Chariklo's ring system consists of two narrow rings of icy particles in orbit around the object. The rings of Chariklo were discovered in 2013, when astronomers observed Chariklo occulting or passing in front of a star. Chariklo was the first minor planet discovered to have rings, and as of 2025, it is one of the four minor planets known to have rings (the three others being 2060 Chiron, Haumea, and Quaoar). It is unknown what keeps Chariklo's rings stable, as it has been predicted that they should decay within a few million years. Astronomers have hypothesized that Chariklo's rings might be maintained by the gravitational influence of yet-undiscovered shepherd moons orbiting Chariklo. The origin of Chariklo's rings is uncertain, with various possible explanations including ejection of surface material via outgassing or tidal disruption of a moon around Chariklo.

The centaur 10199 Chariklo, with a diameter of about 250 kilometres (160 mi), is the second-smallest celestial object with confirmed rings (with 2060 Chiron being the smallest), and the fifth ringed celestial object discovered in the Solar System, after the gas giants and ice giants. Orbiting Chariklo is a bright ring system consisting of two narrow and dense bands, 6–7 km (4 mi) and 2–4 km (2 mi) wide, separated by a gap of 9 kilometres (6 mi). The rings orbit at distances of about 400 kilometres (250 mi) from the center of Chariklo, a thousandth the distance between Earth and the Moon. The discovery was made by a team of astronomers using ten telescopes at various locations in Argentina, Brazil, Chile and Uruguay in South America during observation of a stellar occultation on 3 June 2013, and was announced on 26 March 2014.

The existence of a ring system around a minor planet was unexpected because it had been thought that rings could only be stable around much more massive bodies. Ring systems around minor bodies had not previously been discovered despite the search for them through direct imaging and stellar occultation techniques. Chariklo's rings should disperse over a period of at most a few million years, so either they are very young, or they are actively contained by shepherd moons with a mass comparable to that of the rings. The team nicknamed the rings Oiapoque (the inner, more substantial ring) and Chuí (the outer ring), after the two rivers that form the northern and southern coastal borders of Brazil. A request for formal names will be submitted to the IAU at a later date.

The following is a collection of lists of asteroids of the Solar System that are exceptional in some way, such as their size or orbit. For the purposes of this article, "asteroid" refers to minor planets out to the orbit of Neptune, and includes the dwarf planet Ceres, the Jupiter trojans and the centaurs, but not trans-Neptunian objects (objects in the Kuiper belt, scattered disc or inner Oort cloud). For a complete list of minor planets in numerical order, see List of minor planets.

Asteroids are given minor planet numbers, but not all minor planets are asteroids. Minor planet numbers are also given to objects of the Kuiper belt, which is similar to the asteroid belt but farther out (around 30–60 AU). Asteroids are mostly between 2–3 AU from the Sun or at the orbit of Jupiter, 5 AU from the Sun. Comets are not typically included under minor planet numbers, and have their own naming conventions.