Gas giants are large planets that contain more than 10 times the mass of Earth, they are also known as the Jovian or Outer Planets. Their compositions are mostly gases, such as hydrogen, and small amounts of rocky material (mostly at their cores). The four gas giants in our solar system are Jupiter, Saturn, Uranus, and Neptune.
Gas Giant Sizes
|Name||Diameter||Distance from the Sun||Orbit Period|
|Jupiter||139,822 km||778,340,821 km (5.20 AU)||11.9 years
|Saturn||116,464 km||1,426,666,422 km (9.58 AU)||29.5 years
|Uranus||50,724 km||2,870,658,186 km (19.22 AU)||84.0 years
|Neptune||49,244 km||4,498,396,441 km (30.10 AU)||164.8 years
Facts about the Gas Giants
- The gas and ice giant planets take longer to orbit the Sun because of their great distances. The farther away they are, the more time it takes to make one trip around the Sun.
- The densities of the gas giants are much less than the densities of the rocky, terrestrial worlds of the solar system.
- Gas giants are not all gas. Beneath the heavy atmospheres of these Jupiter and Saturn are layers of molecular hydrogen and liquid metallic hydrogen.
- Uranus has an icy layer over its solid rock core, and covered with a gaseous atmosphere. Neptune has a water-ammonia ocean for a mantle overlying its rocky core.
- The metallic hydrogen layers in Jupiter and Saturn conduct electricity.
- The cores of the gas giants are crushed under tremendously high pressures and they are very hot (up to 20,000 K), while the cores of the ice giants Uranus and Neptune are at 5000K and 5,400K respectively.
- Gas giants have been found around more than a thousand stars by the Kepler mission. These large exoplanets are often referred to by such names as Hot Jupiters, SuperJupiters, and Giant Neptunes.
An ice giant planet is one that is at least ten times the mass of Earth, and contains a higher percentage of what planetary scientists refer to as “ices”. These are volatile elements heavier than hydrogen and helium, and were in ice form (mainly water) when the planets first formed. In our solar system, Uranus and Neptune are often referred to as “ice giants” due to the higher amounts of such volatile they contain. Astronomers have also determined that some exoplanets could be ice giants, as well.
A ring system around a planet or asteroid is a disk made up of dust, chunks of material (ice, in the outer solar system), and small moons. This material forms a ring (or rings) around its parent body. The largest ring system in the solar system is the one around Saturn. Jupiter, Uranus and Neptune also have rings, and at least one asteroid is known to have a small ring as well.
The Outer Planets
Find out more about the outer planets by selecting one below.