Atmospheres

So now for the fun stuff. Let’s start with atmospheres and exoplanets first, as atmospheric effects is something I specialize in. Atmospheres are the one thing keeping any life on any planet alive, so understanding how they work is important. Plus, depending on the elements in the atmosphere, the sky might be different colors.

The best references for offworld science you’re going to get are the various space agencies around the world. They have tons and tons of information for people who are interested in aliens, other worlds, and much more. However, sorting through that information is rather tricky. So here are some key ideas you’ll need to incorporate into your environments if you are creating a world beyond Earth.

Most planets have different atmospheres from Earth. We often hear about NASA and other space agencies looking for other planets that humans could exist on. But 99% or less of the universe isn’t human. So don’t plan for that in your story.

Most environments will be alien, uninhabitable, or slightly different from Earth. The atmosphere won’t be purely made of oxygen, nitrogen , and carbon. There might be more dominant elements in it as well. Or completely new elements that we haven’t discovered yet. But working within the science we know, let’s stick to the periodic table for this article.

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For a quick and easy example, let's take a look at Jupiter's atmosphere. Simply because gas giants have already been found to exist outside our solar system, and we know for sure humans cannot survive on that planet.

Jupiter has an extremely dry and dense atmosphere. The dominant elements in its atmosphere are hydrogen, helium, methane, and ammonia. These elements are also the main elements that make up our Sun, so understandably, they can be very toxic.

Most of the hydrogen that exists within Jupiter is liquid. This hydrogen liquid also exists in the planet's atmosphere. The extreme gravity on Jupiter draws the atmosphere towards its tiny core. It is speculated that because of the huge gravitational pull, that there is no clear distinction between the surface of Jupiter and the atmosphere.

Because of its gravitational compression. The surface of Jupiter is considered to be over 36,000 degrees F in temperature. But due to Jupiter being just too tiny in size, it can never become a star. Even if its internal temperatures get somewhat close to starting that process.

Jupiter also contains massive amounts of storms that are driven by its rotation, and surrounding motion. Most of its storms are driven by internal heat, as it is too far away from the sun to have solar flares or extra heat affect it. The winds in these storms have clocked at over 400 miles per hour.

Now for another planetary example, let’s take a look at Mercury. Which is literally the solar system opposite of Jupiter. Mercury has a very thin atmosphere that does not protect it from the Sun and surrounding space. There are no clouds in the atmosphere, and it is almost invisible.

The reason the atmosphere is like this is for many different reasons. The first being, is that Mercury is incredibly close to the Sun. The solar flares and heat from the star have helped heat up the planet, and greatly erode its atmosphere. The atmosphere is primarily made up of oxygen, sodium and hydrogen.

There is no clear weather system on mercury. Because of its long solar days, and faster than average rotation, Mercury also has very extreme temperature fluctuations. More than any other planet in our solar system.

If you were to stand on the surface of Mercury, the sky would appear black, and the sun would stretch over almost all parts of the sky.

So taking some main information away for this for world building:

The larger the planet, the greater the gravitational pull.
The closer to a star a planet is, the wilder the temperature patterns. The farther away it is, the colder it will be. But this also depends on size.
The greater the gravitational pull towards the center of the planet, the hotter and more compressed the atmosphere will be.
The closer to a star the planet is, the less of an atmosphere.
Large gas giants often have elements in liquid form in their atmosphere.

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What this might translate as in VFX is:

Objects will be heavier on planets with a lot of gravity.
Hotter temperatures mean warmer colors. This might mean more heat distortion, fire, and volcanic activity.
Less clouds the hotter the planet is. More clouds if the planet is large, and dense.
The colder the planet is, the more rocky and icy it will become.

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Now let’s jump into exoplanet atmospheres.

Because exoplanets exist far beyond our solar system, we don’t have too much specific information about specific planets. But here are some highlights of what we have found so far.

We have discovered common elements from our home planet in other ones across the galaxy. Such as sodium in planet HD 209458 b, water, carbon monoxide, carbon dioxide and methane in planet HD 189733 b as well.

NASA has also discovered gas giants with cloud free atmospheres as well. HAT-P-11b is a Neptune sized planet first discovered in 2014. They were also able to detect various water molecules in the planet’s atmosphere. They have also detected atmospheric layers in exoplanets. In June 2015, NASA reported that planet WASP-33b has a stratosphere. They found these layers as Ozone and other hydrocarbons absorb large amounts of radiation. Which in turn heats up parts of the atmosphere.Which makes this layer detectable through different spectrums of light. This planet is also the hottest exoplanet known, and the stratosphere is thought to be caused by large deposits of titanium oxide.

Winds reaching over 2km per second have also been detected on exoplanets. This is equal to seven times the speed of sound.

So when designing an atmosphere for a planet, it is very important to pick and choose your elements wisely. Simply because your life forms will be consuming those elements, and might be dependent on them. Or will be primarily made up of those breathable elements. The environment around them will also change with regards to the weather, and chemical changes.

It is thought that composition of atmospheres form through gasses being emitted through the planet’s forming crust. Primitive atmospheres mainly contain carbon dioxide, methane, ammonia, sulfur dioxide and hydrochloric acid. Water and oxygen atoms are only present in the atmosphere if their chemical compounds are starting to form on the surface, and if the star outside the planet has enough energy to heat up its interior.

As mentioned at the beginning of the article, elements appear in different colors. Our sky looks blue, because the water molecules in the air refract blue light. However, Helium will appear pink, Neon will have a red and orange color, and Argon will appear blue. You can’t make every atmosphere blue, and have the plot describe the planet as having a methane rich atmosphere. That is just not fair.

The last thing you need to know about habitable planets is that NASA looks for life on other worlds by the amount of methane in their atmosphere. It is considered a way of possibly tracing life on other worlds. Methane is also a major resource when it comes to powering rockets and other propellants. Methane in its natural state is both colorless and odorless. So visually it's very hard to detect.However, it can be detected through infrared techniques.

Methane can be produced through decomposing life forms, and other extruded gasses from them. It can also be used to detect how long or when life might have existed on a planet.

So in summary, if you have a sky in the background of your world, take into consideration the elements that exist on that planet. That in turn will give you a better sky development, and lookdev.

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Some World Building Summaries:

Exoplanets share common elements with Earth
Some atmospheres are cloud free, while others have similar clouds you would see on Earth.
Exoplanets have cloud layers in their atmospheres. Such as Earth’s Stratosphere. Just like how Earth has high, Mid-Level, and Low Clouds. They also have cloud types as well.
Some Exoplanets have high wind levels.
Elements appear with different colors in their liquid, gas and solid states. So they have to be represented as such.
Methane is a hugely important feature, for having life existing in your offworld environment.
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