Pluto before Charon was discovered. Pluto is more than twice the diameter and a dozen times the mass of the dwarf planet Ceres, the largest object in the asteroid belt. It is less massive than the dwarf planet Eris, a trans-Neptunian object discovered in 2005, though Pluto has a larger diameter of 2376.6 km compared to Eris's approximate diameter of 2326 km. Determinations of Pluto's size had been complicated by its atmosphere, and hydrocarbon haze. In March 2014, Lellouch, de Bergh et al. published findings regarding methane mixing ratios in Pluto's atmosphere consistent with a Plutonian diameter greater than 2360 km,
Dwarf planet by an attempt by the IAU division III plenary session to reinstate Pluto as a planet in a second resolution. Indeed, the draft of Resolution 5A had called these median bodies "planetoids," but the plenary session voted unanimously to change the name to "dwarf planet." The second resolution, 5B, defined "dwarf planets" as a subtype of "planet", as Stern had originally intended, distinguished from the other eight that were to be called "classical planets". Under this arrangement, the twelve planets of the rejected proposal were to be preserved in a distinction between eight "classical planets" and four "dwarf planets". Resolution