Eris was first discovered in January 2005 during further analysis of images originally taken at the Mount Palomar observatory in 2003. Initially called the Tenth Planet, it was reclassified, along with Pluto as a Dwarf Planet in 2006.
More massive than Pluto, it is currently at a distance of 96 AU (3 times the distance to Pluto) but it’s highly elliptical 557 year orbit will bring it as close as 37 AU. Along with some of the comets it is one of the most remote objects in the Solar system.
This two frame animation shows two pictures taken 24 hours apart. Eris appears to move about 21″ in this time (about 0.88″/hour).
