 Because Eris was initially thought to be larger than Pluto, it was described as the "tenth planet" by NASA and in media reports of its discovery.In response to the uncertainty over its status, and because of ongoing debate over whether Pluto should be classified as a planet, the IAU delegated a group of astronomers to develop a sufficiently precise definition of the term "planet" to decide the issue.This was announced as the IAU's "Definition of a Planet in the Solar System," adopted on August 24, 2006.