Our universe is an inconceivably vast space that contains billions of heavenly bodies, and even then, most of outer space is completely empty! In our solar system, for example, there are 8 planets: Mercury is the closest to sun and hot as hell. There is also Venus, the brightest planet in the solar system, as well as Earth, “the blue planet” – the only planet which sustains life, and our precious home. There is also the “red planet”, called Mars, where astronauts hope to someday find life. We’ve found water there, so we seem to be getting somewhere!
Beyond these inner planets, however, there are four larger planets known as the “Giant Planets“, obviously named because they are massive in comparison to the other four planets. These four giants are Jupiter, Saturn, Uranus, and Neptune.
Giant planets are also called “Jovian Planets”. The term Jovian comes from Jove, the king of the gods in Roman mythology, and also the early name of Jupiter. Therefore, Jovian describes the other giant planets as being Jupiter-like. All Jovian planets were also once known as “Gas Giants”, but Uranus and Neptune were later classified as “Ice Giants“.
Why are these planets called gas giants and ice giants?
What are Gas Giants?
The name ‘gas giant’ was coined in 1952 by science fiction writer James Blish to refer to all the giant planets. The four giant planets are huge gas balls, which is quite different than Earth and and other three rocky inner planets. Gas giants are primarily composed of gases, such as hydrogen and helium, and a much thicker layer of metallic hydrogen, along with a molten rocky core.
Unlike rocky planets, gas giants do not have a well-defined surface, and there is no clear boundary between where the atmosphere ends and the surface begins. In other words, you wouldn’t be able to land on these planets, as their atmospheres simply become gradually denser towards the core, perhaps with liquid or liquid-like states somewhere in between.
Until 1990, there were four gas giant planets, but in the 1990s, it was discovered that Uranus and Neptune were composed of different substances than Saturn and Jupiter. As of now, there are only two gas giants in our solar system – Saturn and Jupiter. Uranus and Neptune are now known as “ice giants”.
What are Ice Giants?
Ice giants are massive planets composed mainly of substances that are heavier than helium and hydrogen. The ice giants, Uranus and Neptune, are primarily made up of oxygen, nitrogen, carbon, and sulfur – the next most abundant elements in the Sun after hydrogen and helium.
Both Uranus and Neptune lack the deep metallic hydrogen mantles that are found on Jupiter and Saturn, and they are mostly ice that lacks a deep hydrogen mantle. As a result, these majestic planets are known as ice giants, in order to distinguish them from the gas giants: Jupiter and Saturn.
The more we learn about space and our solar system, the closer we are to understanding how we came to exist on this planet. It’s a slow process, and names occasionally have to be changed, but it’s all worth it in the end!
- Outer Planets – Lunar & Planetary Institute
- About Gas Giants – Lunar & Planetary Institute
- Ice Giant – Wikipedia
- Gas Giant – Wikipedia