The Outer Planets

Science, Grade 6


Table Of Contents: The Outer Planets

1. What Are the Outer Planets?
The outer planets beyond Mars are the gas giant planets, Jupiter, Saturn, Uranus and Neptune. They are also known as the Jovian planets. These planets are much larger and spaced further apart than the inner planets. They are primarily composed of hydrogen and helium.
2. Jupiter
Jupiter, the fifth planet from the Sun, is the largest planet in the solar system. Although primarily composed of gases, its magnetic field indicates that it may have a rocky core. It has a giant red spot that is actually an enormous storm in its atmosphere. There are 64 known moons that orbit Jupiter.
3. Saturn
Saturn, the sixth planet from the Sun, is the second largest planet in the solar system. Winds can blow as fast as 1,800 km on this planet. Saturn's rings are primarily composed of ice particles with some dust and rock particles mixed in. There are 62 known moons that orbit Saturn.
4. Uranus
Uranus, the seventh planet from the Sun, is the first planet to be discovered with the use of a telescope. Its cloudy atmosphere is primarily made of helium and hydrogen, but also has higher concentrations of frozen ammonia, water and methane. Uranus is sometimes referred to as an ice giant. This planet has two sets of rings and 27 known orbiting moons.
5. Rotation and Tilt of Uranus
Similar to Venus, Uranus spins on its axis in a clockwise direction, called retrograde rotation. It also has a rotation axis that is tilted almost parallel to its orbital plane. This makes it appear that Uranus is rotating on its side.
6. Neptune
Neptune is the furthest planet from the Sun. This gas giant is similar to Uranus in that it has a higher amount of frozen gases like methane, water and ammonia, and therefore it is also called an ice giant. The highest known wind speeds in the solar system, measuring up to 2,100 kilometers per hour, are found on Neptune. Thirteen moons orbit Neptune.