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.

Trans-Neptunian Object Media

Pluto imaged by New Horizons
Distribution of trans-Neptunian objects
Euler diagram showing the types of bodies in the Solar System.
Looking back at Pluto, the largest visited KBO so far
Colors of trans-Neptunian objects. Mars and Triton are not to scale. Phoebe and Pholus are not trans-Neptunian.
Illustration of the relative sizes, albedos and colours of some large TNOs
Size comparison between the Moon, Neptune's moon Triton, Pluto, several large TNOs, and the asteroid Ceres. Their respective shapes are not represented.
Kuiper belt object 486958 Arrokoth, in images taken by the New Horizons spacecraft
Overview of trans-Neptunian objects with extreme TNOs grouped into three categories at the top.
Sedna's orbit takes it far beyond even the Kuiper belt (30–50 au), out to nearly 1,000 au (Sun–Earth distance)

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