Adelphos

In the summer of 2011 I created the planet Adelphos, located 11.3 lightyears from Earth in the EZ Aquarii System. Although Adelphos is fictionalTechnically we have yet to prove that it doesn't exist. I have tried to add enough detail to make it feel real.

Mass	1.23E+25 kg (2.06 M🜨)
Equatorial Radius	8,204 km (1.29 R🜨)
Orbital Distance	128,00 km
Equatorial Gravity	12.18 m/s2 (0.44 g0)
Surface Pressure	112.294 kpa (1.11 atm)
Length of Day	42.78 hr, or 1 dayEarth day 18 hr 46 min 40 s
Length of Year	29 daysAgain, Earth days, or 29 days 20 hr 25 min 11 sec

The roots of Adelphos can be traced back to TVTropes. One of my theatre friends introduced me to the site and I began browsing it during my commute home on the busI still love that smartphones make this possible.. Like anyone who encounters TVTropes for the first time, I was hooked. It was very entertaining to see plotholes and inaccuracies exposed in the most popular works of art. In particular, I really enjoyed reading Space Does Not Work That Way. The more I read about how Hollywood could never get space right, the more interested I became in showing them how it's done. With all of these new tools at my disposal, I endeavored to write a science fiction story that was as scientifically realistic as possible. The following ordeal consumed much of my summer and a good portion of my free time over the next 2.5 years. Once it was over, I had learned two lessons:

1. I love creating things (settings, characters, plots, etc.).
2. I am a lousy writer.

I spent so much time worldbuildingLiterally, that I never managed to create a story that did the world justice. I still hope to write a story for Adelphos one day. I may even write more than one. But until then, I just want to share my creation with the world.

Planet Building 101

As many science fiction writers know, you can't just write a story about aliens. You need humans to relate to the audience and to highlight how the aliens are differentBecause it would be weird if the aliens were constantly explaining to one another how they were different from humans. So, obviously my planet had to be reachable from Earth. I looked at the list of nearest stars and chose one almost at random. EZ Aquarii was the closest triple-star system and I thought that would make things interestingIt didn't actually change the semantics much, but the other two stars do add some color to the sky. But what really made things interesting was the type of stars in the system.

All three stars were Red Dwarfs. Red Dwarf stars are very small and glow dim red. Because they are so dim, the habitable zone (region in which liquid water can exist) is correspondingly closer to the stars. In other words, I would have to place my planet very close to its sunBetween 0.07447AU and 0.10728AU in order for it to be warm enough for life to exist. But there is a problem with tight orbits like that. At such a distance, the gravitational force between the planet and its sun is so strong that the planet stops spinning. This is called tidal locking. There has been a lot of speculation about what sort of life could evolve/exist on a planet with perpetual day on one side and perpetual night on the other. But as interesting as this was, I didn't want to get into it. Maybe it was just too outlandish and I needed my setting to be more familiar. So I did what any self-respecting writer would do: I came up with a ham-handed solution that conveniently avoided the issue altogether.

Instead of putting my planet in direct orbit around its sun, it would be the moon of a larger planet. This larger planet would be tidally locked to the sun while the smaller moon orbits. This way, my planet would get a day/night cycle similar to that of Earth. I don't know if this would actually work. I did enough calculations to put my mind at ease, but I have the feeling such a system would not be stable. But either way, I just went with it. So here is my star system so far: If you remember, EZ Aquarii consists of three stars. They are creatively designated A, B, and C. Stars A and C are locked together in a tight orbit and star B is off on its own so I positioned my planet around EZ Aquarii B.

But how big is my moon? If I made it bigger than Earth, the aliens would have to be correspondingly stronger to support their own weight. I liked this idea because giving the aliens super-strength would make them more intimidating. After playing with a few numbers, I settled on 12.18 m/s² for the surface gravity. With an average density of 5314 kg/m³ this resulted in a radius of 8.204 km, almost five times the radius of Earth. But if the moon was bigger than Earth, the planet it orbits would have to be bigger still. I didn't want it to be too much bigger though, so I decided to make it 5.12Because I like powers of 2. times the size of the moon. I ended up having to condense things a lot to prevent the moon's orbit from leaving the habitable zone. The planet and moon are so close in size that they are considered a binary systemLike Pluto and Charon, and they orbit close enough that both experience strong tidal forces3.15E24 Newtons as compared to Earth's 2E20 Newtons from the Moon..

So now I had a established the basic properties of my planet. The next step, was the mapping process.

Mapping a New World

I have always loved drawing maps. As early as 8th grade, I would sketch maps based on tectonic plate boundaries. Where the plates came together, I drew mountain ranges. Where they went apart, I drew flat planes, and so on. I used the same method to map Adelphos. But mapping an entire planet is more complicated. I encountered the classic problem of mapping a 3-D object on a 2-D surface. True, I could have just drawn the map in a rectangle, but I that would mean regions around the poles would be distorted when projected onto a sphere. So I decided to draw the tectonic plate boundaries directly onto a sphere instead.

I sketched latitude and longitude lines on the surface of a basketballIt helped that many of those lines are already there.. Then I drew the tectonic plate boundaries and assigned a random direction for each one to move. To get the map into two dimensions, I drew the same latitude longitude lines on a large sheet of paper and copied the plate boundaries over by hand. I made lots of smaller plates, especially around the equator, to indicate higher geological activity as a result of the strong tidal forces.

Once I had my map imported into Photoshop, the possibilities were endless. I began by painting a bump mapAn elevation profile where white is the highest elevation and black is the lowest. over the scan. Starting with medium gray, I figured out elevation based on the plate tectonics and darkened or lightened the areas accordingly. I placed little spikes along the plate boundaries (especially the divergent ones) to indicate volcanoes. At the poles, I generated noise in order to shred the landscape up the way glaciers do. Finally, I applied a generated cloud texture to the whole thing to make it look more random. Although I had the boundaries as guidelines, I ended up making a lot of this up. I'm no geology expert so I just went with what felt right. Come to think of it, most of what I know about plate tectonics comes from Bill Nye. Now that I had a bump map, drawing coastlines would be very easy. All I had to do was create a blue layer and tell it to show up only where the bump map was dark. The darker the threshold, the lower sea level would be. I played with the slider until I found a sea level I liked. I exposed a larger portion of the land because it created cool coastlines and archipelagos. It was pretty cool to have a world map for my planet, but I wanted to see how it would look on a sphere. To this end, I found a very cool application called Celestia. Celestia is a space simulator of staggering proportions. At first glance, it appears to include just Earth and the other planets. But as you explore, you see that it contains all of the moons, asteroids, dwarf planets, comets, and spacecraft in the Solar System. Plus, Celestia maps every star that has a name (even if it's just a bunch of numbers) as well as the exoplanets around those stars. It even includes all of the galaxies in the Local Group and beyond. But what really made Celestia useful for my purposes was its extendibility. You can add new planets or stars by just writing a config file and dropping it in the right directory. Include the right information plus a few textures and Celestia will simulate the appearance and movement of the planets and stars. This is how I brought Adelphos to life.

Before I get into how Adelphos was brought into the third dimension, let me explain where the name came from. While working out the technicalities of my planet, I was simultaneously inventing aliens and a story to go with it. I liked how a lot of celestial bodies in the Solar System have Latin names. There's something very official about such an influential language. So I started researchingVia online dictionaries. possible Latin names for my planet. I wanted it to have a meaning that was true to the concept of another planet with life. I also wanted it to make sense in-universe and sound like something the astronomy community would realistically settle on. After brainstorming a few possibilities, I decided on something that expressed the feeling of kinship between the only two planets in the universe known to nurture life. Words like friend, ally, and comrade came to mind. But my favorite word was brother.

The more I thought about it, the more the word seemed to click. Brother. Brothers are similar in many ways, but very different in others. Brothers love each other, but they disagree and fight, especially when they are young. But through thick and thin, brothers will always be there for each other. It seemed to me that this was a perfect template for Earth's relationship with my planet I considered sister, but Earth already has a sister planet..

So I looked up the Latin word for brother... and it was Frater. Of course. From Fraternity. That was not at all the kind of connotation I wanted for my planet's name. I kept looking at other meanings and other Latin names, but I had been really happy with a name derived from brother. So I investigated some other languages. I soon settled on Greek. It had the same sort of cultural significance as Latin while also sounding more foreign. The Greek word for brother is αδελφός. Rendered in the Latin alphabet, this is Adelphos. The volcanic, yellow planet that Adelphos orbits was named Aura, from the Latin word for GoldDue to it's golden color. I later renamed Aura ChrysosThe Greek word for gold. in order to both remain consistent with the Greek names and to avoid having two planets whose names start with the same letter. The three red dwarf stars were named after Nona, Decima, and Morta, the three fates from Roman mythology. I chose Nona to be the name of the star that Adelphos and Aura orbit around because Morta sounds too depressing and decima sounds too "mathy".

So now that I had the essential information about my planet, I set out to create it in Celestia. The internet provided all the information I needed about Nona, aka. Gliese 866B. I had to ignore a few error bars, though, in order to have specific enough values.

Now that Adelphos was in Celestia, it needed some real textures. I had coastlines and an elevation profile, but I still hadn't figured out what the land would actually look like. I remembered reading a cool article in Scientific American about what color plants might be on alien worlds. In particular, the article speculated about how photosynthesis would work with stars of different colors. For instance, plants that live beneath a blue giant star would probably have evolved to absorb ultraviolet light and would appear blue or purple to our eyes. Plants under a red dwarf star would similarly shift their absorption spectrum downward toward infrared. This means that the vegetation on Adelphos would be dark red or black.

So I knew what color the plants would be, but where would they grow? To answer this question I read up on climate and how it is determined by geography. Using an Atlas as my guide, I read about different climate classifications and where they existed on Earth. To map Adelphos's climate, I adopted a simplified version of the Koppen climate classification. Since Adelphos's axis of rotation is almost perfectly vertical, it does not experience dramatic seasonal changes the way Earth does. As a result, some of the climate classifications did not apply.

Naturally, vegetation on Adelphos would grow more abundantly in humid climates so I filled in dark vegetation spots in the humid regions. The rest of the surface was given the same dull, dirt hue that we see in satellite pictures of Earth. Regions around the poles or above certain elevations were automatically colored white to reflect the snow and ice present in an arctic climate. The sea, I gave a more greenish blue color. There wasn't a scientific reason for this, I just really like that shade of green. In the end, I was pretty happy with the results. One day I may write a story for Adelphos, but I doubt it. This kind of manual planet creation just isn't necessary anymore. Now we can create far more realistic planets on the fly with procedural generation software like Space Engine and Elite Dangerous.

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