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
15810 Arawn resonance with Neptune, similarly to dwarf planet Pluto, the largest known plutino. It measures approximately in diameter, based on an absolute magnitude of 7.6, and estimated albedo of 0.1. In April 2016, a rotation period of 5.47 hours was determined for this minor planet. In 2012, Arawn was hypothesized to be in a quasi-satellite loop around Pluto, as part of a recurring pattern, becoming a Plutonian quasi-satellite every 2 Myr and remaining in that phase for nearly 350,000 years. Measurements made by the "New Horizons" probe in 2015 made it possible to calculate the motion of Arawn much more accurately.