Eris is the most massive known dwarf planet — about 27% more massive than Pluto — orbiting in the scattered disc at an average distance of 68 AU. Its discovery in 2005, along with the revelation that it is larger than Pluto, directly triggered the International Astronomical Union's 2006 redefinition of 'planet' and the creation of the dwarf-planet category. Eris's small moon Dysnomia, discovered in 2005, orbits at roughly 37,000 km and allows precise mass measurements through Kepler's third law. Eris's highly inclined, eccentric orbit suggests Neptune's early outward migration scattered it from the primordial Kuiper Belt into its current distant path.