Dwarf planet be discovered, and the number of planets would start growing quickly if Pluto were to remain a planet. Eris (then known as ) was discovered in January 2005; it was thought to be slightly larger than Pluto, and some reports informally referred to it as the "tenth planet". As a consequence, the issue became a matter of intense debate during the IAU General Assembly in August 2006. The IAU's initial draft proposal included Charon, Eris, and Ceres in the list of planets. After many astronomers objected to this proposal, an alternative was drawn up by the Uruguayan astronomers Julio Ángel
Eris (dwarf planet) outer belt. Inner-belt objects are expected to be generally more massive than outer-belt objects, and so astronomers expect to discover more large objects like Eris in high-inclination orbits, which planetary searches have traditionally neglected. 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