Saturn, being a gas giant, does not have a solid structure but is instead composed of gaseous layers. Its atmosphere is a complex and overlapping mix of these layers and primarily consists of hydrogen and helium — the same elements that the Sun and the universe are made of.
Also seen in the atmosphere, in trace amounts, are methane, ammonia, and other gases.
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The outermost layers contain some interesting weather but Saturn’s innermost layer gives way to its molten, rocky core made of iron and nickel.
The table below shows the composition of the most common gases present on Saturn. Note how Hydrogen forms the vast bulk of the atmosphere.
Although Saturn is the second-largest planet in our solar system, its gaseous nature gives it a very low density, lower even than that of water.
Believe it or not, this means that Saturn would float in a bathtub full of water… if we could find one large enough.
How did Saturn evolve to this fascinatingly complex planet that we see today? What does each of its atmospheric layers look like?
Let’s find out.
4.5 billion years ago Saturn began forming along with other planets in our solar system.
In a process called disk instability, clumps of gas and dust began accumulating and Saturn’s massive core formed first. The core then gravitationally attracted lighter elements like methane and ammonia into a surrounding atmosphere before they could be blown away by solar winds.
Finally, 4 billion years ago, the complex planet that we observe today settled into orbit around the Sun.
What is Saturn Made Of?
Saturn’s atmospheric makeup is not distinct. Layers overlap onto one another, and the innermost layer smoothly gives way to the planet’s core (unlike Earth, Saturn does not have any surface to separate the core from the atmosphere).
Their composition differs among layers because as one goes deeper towards the core, the pressure from layers above forces lighter elements to fuse into heavier ones.
Saturn’s outermost layer is what we see from Earth with a telescope — a hazy yellow atmosphere. The color comes from ammonia ice crystals present in the upper atmosphere.
Methane is also present in this layer, and it interacts with incoming solar radiation in a process called methane photolysis. The products of this process, hydrocarbons, are carried away by winds of speeds 500 meters per second (in comparison, the strongest hurricanes on Earth travel at only 110 meters per second).
The temperature in this part of Saturn is a chilly -279 °F (-173 °C). The pressure varies between 0.5 to 2 bar. For comparison, 1 bar is the pressure we witness here on Earth at sea level.
Next Layer In
Below the outermost layer, the pressures hover at 2.5 to 9.5 bar, and water ice clouds materialize. The temperature here is -126 ℉ (-88 ℃), which provides a suitable environment for ammonium hydrosulfide ice to exist as well.
Deeper into the atmosphere, hydrogen steadily changes from existing in a gaseous state to becoming a liquid. This is the result of the pressure from the upper atmospheric layers, leading to pressures of 10-20 bars.
Moreover, since we are now nearing the core, the heat from it is felt here too. Both the pressure and temperature rise as we get closer to the core.
Since there is no clear distinction between the atmosphere and the core, the only hint that we’ve reached it is the high temperature, in thousands of kelvins, and the pressure that exceeds 1 million bar. Made of iron and nickel, this core itself is Earth’s size.
Does Saturn Have a Surface?
No. Since Saturn is a gas giant, it is made up of gases and liquids and does not have a surface like we see here on Earth. There is no place to stand or land on Saturn. The atmosphere itself directly leads to the planet’s molten core.
Saturn is a gas giant that is made up of a complex atmosphere and a solid molten core. The atmosphere majorly consists of hydrogen and helium, with trace amounts of ammonia, methane, and other elements.
Although clouds in their pure state are colorless, they are ‘contaminated’ by these chemicals, which is why Saturn looks a hazy yellow color when seen from Earth.
The atmosphere itself can be divided into three layers, but remember that this distinction is only based on their chemical composition. The layers by themselves are not distinct and overlap with each other.
The outermost layer is the only one visible from the outside. It contains ammonia ice crystals and a little bit of methane that undergoes photolysis when it interacts with sunlight. The inner layer contains water and ammonia ice clouds. The temperature and pressure increase steadily as we go deeper into the atmosphere.
In the innermost layer, hydrogen that has so far existed as gas is converted into a liquid because of the pressure.
All in all, Saturn sounds like an incredibly complicated planet, but in fact its nature is similar to other gas giants in our solar system.
Written by Sharmila Kunthuner