Pluto was redefined as a dwarf planet by IAU.
It's 5.5x smaller than Earth, with orbit overlapping the Kuiper Belt, locating about 39 AU away. Its gravity is too small to clear its orbit. Plutoid atmosphere is thin and tenuous. When it is close to the Sun, the sublimation of surface ice generates a temporary atmosphere. As it travels away, the surface temperature becomes extremely cold and collapse the atmosphere into precipitation.
