Dysnomia

Dysnomia is a natural satellite of the dwarf planet Eris, located in the outer Solar System. It is the only confirmed moon of Eris. The moon was discovered in 2005 during observations of Eris and was named after the Greek goddess Dysnomia, who in mythology is associated with lawlessness and is described as the daughter of Eris.

Dysnomia orbits Eris at a distance of tens of thousands of kilometers and completes an orbital period of about 15.8 days. Its size is not precisely known; estimates place its diameter in the range of a few tens of kilometers, making it small relative to Eris. The small size and faintness of the satellite make detailed measurements challenging.

In addition to its astronomical uses, the term dysnomia appears in linguistics and psychology as well. It is sometimes used to refer to word-finding difficulties, or anomia, a condition in which a person has trouble retrieving words despite intact language comprehension. This linguistic sense derives from the same Greek roots as the astronomical name, meaning “bad name” or “bad word.”

Dysnomia, as part of the Eris system, contributes to the study of trans-Neptunian objects and the formation of the outer Solar System. Its existence supports broader understanding of the population and characteristics of distant icy worlds.