Eris and Dysnomia
Date: 30 Aug 2006
The Hubble Space Telescope and the Keck Observatory took images of Dysnomia's movement from which astronomer Mike Brown (Caltech) precisely calculated Eris to be 27 percent more massive than Pluto.
Last Update: 29 Mar 2011 (AMB)
Credit: NASA/ESA and M. Brown (Caltech)