Jovian planets, the planets Jupiter, Saturn, Uranus, and Neptune. They are all larger and more massive than the earth. Since they rotate faster, they are more flattened at the poles than are the terrestrial planets. They are less dense than the earth, as they are composed of gaseous matter, predominantly hydrogen.
The Columbia Electronic Encyclopedia, 6th ed. Copyright © 2012, Columbia University Press. All rights reserved.
See more Encyclopedia articles on: Astronomy: General