Trans-Neptunian object

Eris and its moon Dysnomia are both Trans-Neptunian Objects

Trans-Neptunian object or TNO is a name astronomers give to any minor planet in the Solar System which orbits (goes around) the Sun beyond the planet Neptune. There are over a thousand of them.^[1] Many are in the Kuiper belt.

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v t e The Solar System

Sun • Heliosphere	Planets ☾ = moon(s) ∅ = rings		Mercury	Venus	Earth ☾	Mars ☾

			Jupiter ☾ ∅	Saturn ☾ ∅	Uranus ☾ ∅	Neptune ☾ ∅

	Dwarf planets		Ceres	Pluto ☾	Haumea ☾	Makemake

			Eris ☾

	Small Solar System bodies	Asteroids (minor planets)	Groups and families: Vulcanoids · Near-Earth asteroids · Asteroid belt Jupiter Trojans · Centaurs · Neptune Trojans · Asteroid moons · Meteoroids · Pallas · Juno · Vesta · Hygiea · Interamnia · Europa
		Asteroids (minor planets)	See also the list of asteroids.

		Trans- Neptunians	Kuiper belt – Plutinos: Orcus · Ixion – Cubewanos: Varuna · Quaoar · Huya
		Trans- Neptunians	Scattered disc: Sedna

		Comets	Periodic comets and non-periodic comets Damocloids · Oort cloud
See also the list of solar system objects