Eris and Dysnomia

Explanation: Eris was discovered in January 2005 by a Palomar Observatory-based team led by Mike Brown. It is a trans-Neptunian object (TNO) and a member of a high-eccentricity population known as the scattered disc. It has one known moon, Dysnomia. Eris is the most massive known TNO, estimated to be about 2,326 km across and 27% more massive than Pluto.

Pluto

Image credit: NASA, ESA, and M. Brown.