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  • Writer's pictureRaelyn Teague

Worldbuilding Sun and Stars |Worldbuilding 3|

Spoiler alert for Avatar: The Last Airbender, Horizon: Zero Dawn

I promised we’d dive deeper into the minutia of creating a new world for your characters to inhabit, and today’s episode is going to be the first splash.

For those out there who really want to flex those worldbuilding muscles, these videos shouldn’t be your sole workout program. I will be doing an overview of things you may want to consider, but I won’t be diving too deep into the nitty gritty science of it all. If your story depends on making sure the world you designed is completely, flawlessly within the realm of scientific plausibility, use these videos as a springboard to brainstorm some neat ideas before you do more in-depth research.

On a related note, much of what I present is going to be focused on how an Earth-like world and universe function. For any speculative fiction writers out there, know you don’t have to design an Earth-like world, but understanding how Earth works may help you decide the ways in which you want your world to be different, and what consequences those differences might have. Again, use these episodes as a springboard to help you brainstorm ideas for whatever new kind of world you want to make.


Let’s start worldbuilding a place for your characters to live by talking about the source of all life as we know it. Despite all evidence contained in the crayon doodles of three-year-olds everywhere, that burning ball of plasma in the sky (or the “sun,” as plebs call it) is not yellow in colour. If you look at the sun when it’s high in the sky (please don’t do this), it would look closer to its true, white colour. When low in the sky, however, the sun can appear any number of shades between yellow, orange, and crimson, but this is due to a phenomenon known as atmospheric scattering. When light from the sun collides with Earth’s atmosphere, that light scatters. Our atmosphere is better at scattering light wavelengths on the blue, violet, and indigo side of the visible light spectrum, and since white light is a combination of the whole light spectrum, knocking those colours out of the equation leaves us with the light wavelengths on the yellow to red side of the spectrum. When atmospheric conditions change, such as when there’s a lot of dust or smoke in the air, the sun may look even more vibrantly orange or even red. Summers where I live tend to be sunny and dry, and wildfires are an unfortunate reality, so I’m well-familiar with blood-red sunsets.

Under the Morgan-Keenan system, the sun is classified as a G2V star. I said I wasn't going to go too deep into the science, so what does this mean and why do we care? In short, the “G2” refers to our sun’s “spectral class,” or how hot it is. In an economy based on solar heat, our “G2” sun would be fairly middle class. The roman numeral “V” tacked on at the end, however, refers to the sun’s luminosity and means our sun is what’s called a “main-sequence” star. This separates our sun from giant stars (such as hypergiants) from dwarf stars (like white dwarfs).

Okay. But what does all this really mean?

In order to have life as we know it exist, the kind of sun you have is actually very, very important.

You see, you can’t have a sun that’s too big or hot that would give too much radiation for orbiting planets to have liquid water or maintain life. On the other hand, if you have a sun that’s too small, an inhabitable planet would have to orbit the sun much closer. No big deal, right? Except that when a planet orbits that close, they tend to become tidally locked, meaning the same side of the planet is always facing the sun, and that just doesn’t work for life as we understand it.

You also need to have a sun that is in a stable part of its life cycle. Eventually, as our sun ages, it will expand, overtaking the orbits of Mercury and Venus, making life impossible on Earth. But don’t worry, humankind will murder our planet long, long before that ever happens. Something to cheer up.

Currently our sun is in the most stable part of its life cycle. Which, as mentioned, is important, but you also need to have a sun whose stable period is long. Like, really long. Like, many billions of years long. Because one of the things needed for life to flourish on a planet is time.

According to current understanding, the earliest signs of any kind of life on Earth are about 4.2 billion years old. Which was a mere few trillion years after Earth had come into existence. It took billions of years for that early life to evolve into anything more complex than microscopic organisms, and human life has only existed for about 200,000 years. All this is to say that, unless the main characters in your story are microscopic organisms or you have an in-world explanation for super fast evolution, without having a sun with a long stable period, life doesn’t have the chance to begin and to evolve.

But more than simply being in the stable period, our sun is also pretty non-violent. It gets the occasional solar flare or sun spot, which can affect life on Earth, but it’s not so violent as to render our struggle for survival a wasted effort. Any world you create with a more violent star than ours will need to have life that has found a way to adapt to the effects of regular solar flares or other attacks from the sun.

What about creating a world that has more than one sun?

The world of Thra in The Dark Crystal has three suns. Tatooine famously has two. But is that just made-up fantasy and sci-fi nonsense from a time when people didn’t care about plausibility? Well, not entirely.

You can have planets that orbit more than one star. These are called binary stars, and to have this kind of planetary system work, it would probably take the form of a smaller star orbiting a larger star or of two equally-sized stars orbiting each other. Any planets would then orbit both stars. Life on such a planet is theoretically possible, and it even brings with it some neat worldbuilding to consider such as eclipses where one sun blocks the other, temporarily cooling the planet, or sunrises and sunsets where the two stars get closer or farther apart each day. Cool!


While the earlier episodes in this series will focus more on building the physical aspects of the world—designing creatures, races, or social and economic worldbuilding will come later—I wanted to mention that now is a good time to start thinking about how those physical aspects of your world may impact or intertwine with your world’s cultures, history, or evolution.

A great example of how the sun can affect the history of an invented world comes from Avatar: The Last Airbender. I know, I know. You’re super shocked I would bring up this show, aren’t you?

In the world of Avatar, we know that fire benders’ power is affected and strengthened by the sun. And also by comets. In many ways, the power of the Fire Nation itself stems from the sun. In the episode The Library, Team Avatar learns that a total solar eclipse in the Fire Nation’s history left their benders temporarily without the ability to bend their element. In a world that includes water, earth, and air benders whose bending capabilities are not tied to the sun, an eclipse leaves the Fire Nation incredibly vulnerable. While we don’t know exactly what happened on that historic day of the eclipse, we do know it was bad for the Fire Nation.

You can also use the sun to show differences in culture. If you’ve played Horizon: Zero Dawn, you probably noticed how the sun is a major focus in the Carja people’s government, religion, and language. You can barely get two sentences out of one of these people without them using an idiom that speaks of the sun, of light, or of the absence of it: shadow. It’s really easy to do something like this in a way that comes off as cheesy (and, while it worked for me, I could even see people arguing that Horizon: Zero Dawn is a little too one-note about this), but when done right it adds a sense of history and culture. So think about how the world you’re building might impact the people who live there and the systems those people create.


Now that you know a little more about our sun and have maybe chosen a sun or two to be the centre of a solar system of your own, what about the other stars in your galaxy?

This is one of those things a lot of people skip in worldbuilding, which is understandable. If you’ve got deadlines or more important details to build for your story, stars are less risky to put on the chopping block than other aspects of worldbuilding.

It certainly isn’t necessary to know the name and location of every star in your world. In fact, I’d normally advise against spending that much time on this. However, sometimes, as long as you’re thoughtful about how you include it and don’t go overboard, a simple allusion or two to a very specific star in your sky might add another level of detail to your world. It might help your world feel a little more real. A little more lived in. A little less like a set of wood and glue you designed for the play your characters perform on the page.

Maybe a character going on a long trek in your dangerous fantasy world prays to the star associated with her goddess for protection each night. Or maybe a teen in your sci-fi sees a particular star and instantly misses their dad who’s working on a space station out that way.


There’s still a lot more to a solar system than the sun, so I’m going to save any discussion on Project: Noveljutsu for a future video. In the meantime, your challenge for this episode is simply to think about how you might use the sun or stars to make the worldbuilding in your novels feel a little more complete. Maybe try writing a short scene. Sci-fi or fantasy writers might try a scene set on a world with two suns during an eclipse. Maybe the characters in your romance novel are forced to take shelter from wildfire smoke together as a blood red sun sets. That's it for this post! I'll see you next time with another worldbuilding topic.


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