Definition of planet
Videos
Source: "IAU 2006 General Assembly: Resolutions 5 and 6". IAU. August 24, 2006. Archived from the original on June 20, 2009. Retrieved June 23, 2009.
Sketch of the heliocentric model of the Solar System by Copernicus
Proteus, a moon of Neptune, is irregular, despite being larger than the spheroidal Mimas.
The brown dwarf Gliese 229B in orbit around its star, later found to be binary
The solitary Cha 110913-773444 (middle), a possible sub-brown dwarf, set to scale against the Sun (left) and the planet Jupiter (right)
Pluto
Videos
Pluto is a dwarf planet in the Kuiper belt, a ring of bodies beyond the orbit of Neptune. It is the ninth-largest and tenth-most-massive known object to directly orbit the Sun. It is the largest known
Clyde Tombaugh, in Kansas
Sputnik Planitia is covered with churning nitrogen ice "cells" that are geologically young and turning over due to convection.
A multispectral Visual Imaging Camera image of Pluto in enhanced color to bring out differences in surface composition
Regions where water ice has been detected (blue regions)