Eris is the second-largest known dwarf planet in our solar system, with a diameter slightly smaller than Pluto. It was one of the factors that led to the reclassification of Pluto as a dwarf planet.
Eris is in the outer solar system, more precisely in the scattered disc region beyond Neptune. Dysnomia is the moon of Eris. Eris takes approximately 557 Earth years to complete one orbit around the Sun.