Planet
Videos
A planet is a large, rounded astronomical body that is generally required to be in orbit around a star, stellar remnant, or brown dwarf, and is not one itself. The Solar System has eight planets by th
The eight planets of the Solar System with size to scale (up to down, left to right): Saturn, Jupiter, Uranus, Neptune (outer planets), Earth, Venus, Mars, and Mercury (inner planets)
A protoplanetary disk
Protoplanets colliding during planet formation
Earth's atmosphere
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)