planet in the Solar System beyond the orbits of the its Main-belt asteroids
The outer planets are planets in the Solar System that are beyond the asteroid belt. The four planets; Jupiter, Saturn, Uranus and Neptune are gas giants. All four of these planets have planetary rings which are made up of dust and other particles.
- ↑ Wolf, Portia. "The Outer Planets". Laboratory For Atmosphere And Space Physics. University of Colorado. Archived from the original on 30 December 2011. Retrieved 2 April 2012.
- Outer Planets Assessment Group (NASA)
- Planetary Science Decadal Survey Mission & Technology Studies Archived 2017-12-18 at the Wayback Machine
- Dwayne Day – Exploration of the Outer Planets – U.S. Centennial of Flight Commission Archived 2011-04-13 at the Wayback Machine ~2003