Eris is the new official name for the Kuiper Belt object formerly known as 2003 UB313 or Xena. Relatively little is known about this object, partly due to its great distance from us, and also due to the fact that it was only discovered as recently as October 2003. However, it has been found to be slightly larger than Pluto and is in fact the largest of the KBOs whose sizes have been determined with any degree of accuracy.