Quaoar in the context of Dwarf planet

A natural satellite is, in the most common usage, an astronomical body that orbits a planet, dwarf planet, or small Solar System body (or sometimes another natural satellite). Natural satellites are colloquially referred to as moons, a derivation from the Moon of Earth.

In the Solar System, there are six planetary satellite systems, altogether comprising 419 natural satellites with confirmed orbits. Seven objects commonly considered dwarf planets by astronomers are also known to have natural satellites: Orcus, Pluto, Haumea, Quaoar, Makemake, Gonggong, and Eris. As of January 2022, there are 447 other minor planets known to have natural satellites.

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.

The number of dwarf planets in the Solar System is unknown. Estimates have run as high as 200 in the Kuiper belt and over 10,000 in the region beyond.However, consideration of the surprisingly low densities of many large trans-Neptunian objects, as well as spectroscopic analysis of their surfaces, suggests that the number of dwarf planets may be much lower, perhaps only nine among bodies known so far. The International Astronomical Union (IAU) defines dwarf planets as being in hydrostatic equilibrium, and notes six bodies in particular: Ceres in the inner Solar System and five in the trans-Neptunian region: Pluto, Eris, Haumea, Makemake, and Quaoar. Only Pluto and Ceres have been confirmed to be in hydrostatic equilibrium, due to the results of the New Horizons and Dawn missions. Eris is generally assumed to be a dwarf planet because it is similar in size to Pluto and even more massive. Haumea and Makemake were accepted as dwarf planets by the IAU for naming purposes and will keep their names if it turns out they are not dwarf planets. Smaller trans-Neptunian objects have been called dwarf planets if they appear to be solid bodies, which is a prerequisite for hydrostatic equilibrium: planetologists generally include at least Gonggong, Orcus, and Sedna. Quaoar was labelled as a dwarf planet in a 2022–2023 annual report, though it does not appear to be in hydrostatic equilibrium. In practice the requirement for hydrostatic equilibrium is often loosened to include all gravitationally rounded objects, even by the IAU, as otherwise Mercury would not be a planet.

Weywot (formal designation (50000) Quaoar I) is the only known moon of the trans-Neptunian dwarf planet Quaoar. It was discovered by Michael Brown and Terry-Ann Suer using images taken by the Hubble Space Telescope on 14 February 2006. It is named after the Tongva sky god and son of Quaoar. Weywot is about 165 km (103 mi) in diameter and orbits Quaoar every 12.4 days at an average distance of 13,300 km (8,300 mi). Weywot is thought to play a role in maintaining Quaoar's outer ring by gravitationally influencing it in an orbital resonance.

The following is a list of Solar System objects by orbit, ordered by increasing distance from the Sun. Most named objects in this list have a diameter of 500 km or more.

• The Sun, a spectral class G2V main-sequence star
• The inner Solar System and the terrestrial planets
  • Mercury
    • Mercury-crossing minor planets
  • Venus
    • Venus-crossing minor planets
      • Zoozve, Venus' quasi-satellite
  • Earth
    • Moon
    • Near-Earth asteroids
      • 2021 PH27
      • Apophis
      • Eros
    • Earth trojans (2010 TK7)
    • Earth-crosser asteroids
      • Earth's quasi-satellites
  • Mars
    • Deimos
    • Phobos
    • Mars trojans
    • Mars-crossing minor planets
  • Asteroids in the asteroid belt, between the orbits of Mars and Jupiter
    • Ceres, a dwarf planet
    • Vesta
    • Pallas
    • Hygiea
    • Europa (asteroid)
    • Davida
    • Sylvia
    • Asteroids number in the hundreds of thousands. For longer lists, see list of exceptional asteroids, list of asteroids, or list of Solar System objects by size.
      • Asteroid moons
  • A number of smaller groups distinct from the asteroid belt
• The outer Solar System with the giant planets, their satellites, trojan asteroids and some minor planets
  • Jupiter
    • Rings of Jupiter
    • Complete list of Jupiter's natural satellites
      • Galilean moons
        • Io
        • Europa (moon)
        • Ganymede
        • Callisto
    • Jupiter trojans
    • Jupiter-crossing minor planets
  • Saturn
    • Rings of Saturn
    • Complete list of Saturn's natural satellites
      • Mimas
      • Enceladus
      • Tethys (trojans: Telesto and Calypso)
      • Dione (trojans: Helene and Polydeuces)
      • Rhea
        • Rings of Rhea (largely disproven)
      • Titan
      • Hyperion
      • Iapetus
      • Phoebe
      • Shepherd moons
    • Saturn-crossing minor planets
  • Uranus
    • Rings of Uranus
    • Complete list of Uranus's natural satellites
      • Miranda
      • Ariel
      • Umbriel
      • Titania
      • Oberon
    • Uranus trojan (2011 QF99)
    • Uranus-crossing minor planets
  • Neptune
    • Rings of Neptune
    • Complete list of Neptune's natural satellites
      • Proteus
      • Triton
      • Nereid
    • Neptune trojans
    • Neptune-crossing minor planets
  • Non-trojan minor planets
    • Centaurs
      • Chiron
      • Chariklo
    • Damocloids
  • Trans-Neptunian objects (beyond the orbit of Neptune)
    • Kuiper-belt objects (KBOs)
      • Plutinos
        • Orcus, a dwarf planet
          • Vanth
        • Pluto, a dwarf planet
          • Complete list of Pluto's natural satellites
            • Charon
        • Ixion
        • Achlys
      • Twotinos
      • Cubewanos (classical objects)
        • Haumea, a dwarf planet
          • Namaka
          • Hiʻiaka
        • Quaoar, a dwarf planet
          • Weywot
        • Makemake, a dwarf planet
          • S/2015 (136472) 1
        • Máni
        • Salacia
          • Actaea
        • Aya
        • Varda
          • Ilmarë
        • Varuna
        • Ritona
        • Arrokoth
    • Scattered-disc objects
      • Gonggong, a dwarf planet
        • Xiangliu
      • Eris, a dwarf planet
        • Dysnomia
      • Chiminigagua
      • (84522) 2002 TC302
      • (87269) 2000 OO67
      • 2015 TH367/V774104
    • Detached objects
      • (612911) 2004 XR190
      • 2012 VP113 (possibly inner Oort cloud)
      • Sedna, a dwarf planet (possibly inner Oort cloud)
    • Oort cloud (hypothetical)
      • Hills cloud/inner Oort cloud
      • Outer Oort cloud

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.

Weywot (formal designation (50000) Quaoar I) is the largest known moon of the trans-Neptunian dwarf planet Quaoar. It was discovered by Michael Brown and Terry-Ann Suer using images taken by the Hubble Space Telescope on 14 February 2006. It is named after the Tongva sky god and son of Quaoar. Weywot is about 165 km (103 mi) in diameter and orbits Quaoar every 12.4 days at an average distance of 13,300 km (8,300 mi). Weywot is thought to play a role in maintaining Quaoar's outer ring by gravitationally influencing it in an orbital resonance.