Dwarf planet Fernández and Gonzalo Tancredi: they proposed an intermediate category for objects large enough to be round but which had not cleared their orbits of planetesimals. Dropping Charon from the list, the new proposal also removed Pluto, Ceres, and Eris, because they have not cleared their orbits. The IAU's final Resolution 5A preserved this three-category system for the celestial bodies orbiting the Sun. It reads: Although concerns were raised about the classification of planets orbiting other stars, the issue was not resolved; it was proposed instead to decide this only when such objects start to be observed. The term "dwarf planet"
Atmosphere of Pluto (but also changes in viewing geometry) results in appreciable changes of brightness and color of Pluto. Methane and carbon monoxide, despite their low abundance, are significant for thermal structure of the atmosphere: methane is a strong heating agent and carbon monoxide is a cooling one (although amount of this cooling is not completely clear). "New Horizons" discovered in the atmosphere of Pluto a multi-layered haze, which covers the entirety of the dwarf planet and reaches altitude over 200 km. The best images show about 20 layers of the haze. Horizontal extent of the layers is no less than 1000 km;