Gas Giants

We have four gas giant planets in our Solar System: Jupiter, Saturn, Uranus, and Neptune.

A gas giant is a large planet that contains over ten times the mass of Earth, are made up of mostly gases such as hydrogen, and have small percentages of rocky materials mostly located at their cores.

Gas giants are also called Outer Planets or Jovian.

Our Solar System

In our Solar System, the ice and gas giant planets are located at the outer perimeters and they take longer to orbit the Sun due to their distances.

The rocky, terrestrial planets have higher densities than the gas giants, but the gas giants aren’t made up of all gas.

Under the atmospheres of Saturn and Jupiter are layers of liquid metallic hydrogen and molecular hydrogen.

Neptune has a mantle overlaying its rocky core of water-ammonia, and Uranus has a solid rock core with an icy layer surrounded by a gaseous atmosphere.

Saturn and Jupiter have the distinction of having metallic hydrogen layers that conduct electricity.

The Core

The gas giant cores are under incredibly high pressures crushing the core and making them extremely hot.

During the Kepler space mission, we have found that gas giants exist around over one thousand stars.

These are large “exoplanets” and are sometimes given names such as Super Jupiters, Hot Jupiters, or Giant Neptunes.

Ice Giants

Scientists refer to Uranus and Neptune as “ice giants.”

These are defined as planets that have at least ten times the Earth’s mass and have a higher percentage of the “ices” of volatile elements heavier than helium and hydrogen.

Astronomers are continuing to study other exoplanets and believe some of them could be ice giants.

Ring System

The gas giants in our Solar System all have some sort of ring system. The rings are made up of a number of elements including material chunks, dust, and ice in the outer areas of the Solar System.

The planet Saturn has the largest ring system in our Solar System and at least one asteroid is believed to have a small ring.

Astronomers believe that the gas giants were originally a combination of rocky and ice planets when they first formed, however, their core sizes gave them the ability to snag helium and hydrogen from the gas clouds that were formed when the Sun was condensing.

This occurred before the Sun blew out most of the gas. The most distant gas giants had a more difficult time collecting helium and hydrogen, and this might be part of the explanation for the smaller sizes of Saturn and Jupiter.

Facts about the Gas Giants

  • In other star systems, the gas giants are closer to their parent stars than in our Solar System.
  • Jupiter and Saturn’s atmospheres contain a higher percentage of heavier elements such as ammonia and methane and are therefore referred to as being more “polluted.”
  • It’s believed that many of the moons of the gas giants may have been celestial travelers that were caught by the gravity of each gas giant.
  • Jupiter is believed to have almost been a star.
  • In the science fiction book and movie, “2010: Odyssey 2”, Jupiter becomes the second star in our Solar System, with the moon Europa as a potential orbiting planet to hold life.
  • The NASA Cassini space mission learned many new things about Saturn, Jupiter, and their moons.

Gas Giants Quiz

  • Astronomy for Kids