The names of the outer planets are Jupiter, Saturn, Uranus and Neptune. Jupiter is the largest planet in the Solar System. All four planets are considered gas giants, and Uranus and Neptune are considered by some astronomers to be ice giants as well.Continue Reading
Jupiter, Saturn, Uranus and Neptune are considered outer planets because their orbits are beyond the asteroid belt that separates Jupiter from Mars.
The outer planets are made largely of hydrogen and helium with additions of methane, ammonia and other compounds. Along with the Sun, Jupiter takes up about 99 percent of the total mass of the Solar System. It is so large that astronomers believe that it could have been a star if it had been more massive.
All of the outer planets have rings, but Saturn is famous for its complex and highly visible rings. The rings of the other planets are faint.
All of the outer planets have moons. Some of these moons are large and have atmospheres or are very geologically active. Astronomers believe that some of the moons might be able to support some forms of life. Jupiter's moon Europa, for example, might have an ocean of salt water beneath an ice crust.
Uranus is unusual because it rotates on its side and has an oddly inclined magnetic field.Learn more about Planets