I mentioned in my July State of the Frontier post that I was working on putting together a way to generate star systems. This is a sample of the data you can expect to see for each system. This particular system isn’t tied to any specific system on the map but is more for demonstration purposes. This is also not the final formatting or colors, but rather the default colors from the programs. Once I figure out exactly what I want, I’ll update the code to make the output match. So let’s look at what we have.

System Data

First up is the system data. This is generated using a program called StarGen. It’s a bit old and doesn’t work exactly for the smallest or largest stars but it is good start for most of the more interesting systems that might have habitable planets. I also don’t think it takes into account much of the new exoplanet data but we’re making system for a science fiction game so that’s okay. I’ll probably tweak things as I go along.

This generates a lot of data for each planet including thinks like average, min, and max temperatures, orbital characteristics, rotational characteristics, atmospheric composition (if present) and more.

Test System
12 Planets (size proportional to Sqrt(Radius)) See Key
Stellar characteristics
Stellar mass	1.08 solar masses
Stellar luminosity	1.48
Age	1.146 billion years (6.183 billion left on main sequence)
Habitable ecosphere radius	1.216 AU (0.990 – 1.755 AU)

Planetary Overview
#	Type			Dist.	Mass	Radius
1		Rock		0.363 AU	0.353 EM	0.711 ER
2		Rock		0.677 AU	0.151 EM	0.538 ER
3		Venusian		0.968 AU	0.582 EM	0.838 ER
4		Terrestrial		1.393 AU	1.114 EM	1.036 ER
5		Sub-Jovian		1.881 AU	5.356 EM	2.810 ER
6		Sub-Jovian		3.087 AU	3.734 EM	2.636 ER
7		Jovian		4.684 AU	626.589 EM	12.161 ER
8		Sub-Jovian		8.294 AU	8.347 EM	3.620 ER
9		Jovian		15.114 AU	54.383 EM	6.573 ER
10		Rock		24.112 AU	0.293 EM	0.893 ER
11		Jovian		29.693 AU	26.864 EM	5.661 ER
12		Rock		44.468 AU	0.218 EM	0.810 ER

Planet #1 Statistics
Planet type	Rock Resonant Spin Locked Low-G, Hot, Airless, 1-Face
Distance from primary star	5.4E+07 KM	0.363 AU
Mass	2.1E+24Kg	0.353 Earth masses
Surface gravity	685.0 cm/sec2	0.70 Earth gees
Surface pressure	0 millibars	0.000 Earth atmospheres
Surface temperature	217.9° Celcius 424.2° Fahrenheit	+203.9° C Earth temperature +367.0° F Earth temperature
Normal temperature range	Night Day -174.6° C -282.3° F – 426.4° C 799.5° F Min Max -188.9° C -308.1° F – 430.6° C 807.0° F
Equatorial radius	4535.9 Km	0.71 Earth radii
Density	5.40 grams/cc	0.98 Earth densities
Eccentricity of orbit	0.215
Escape Velocity	7.9 Km/sec
Molecular weight retained	136.8 and above
Axial tilt	14°
Planetary albedo	0.07
Exospheric Temperature	14259.02° K	+12986.02° C Earth temperature
Length of year	76.84 Earth days	1.55 Local days
Length of day	1191.81 hours
Boiling point of water	-273.1° Celcius -459.7° Fahrenheit
Hydrosphere percentage	0.0
Cloud cover percentage	0.0
Ice cover percentage	0.0

Planet #2 Statistics
Planet type	Rock Low-G, Hot, Airless
Distance from primary star	1E+08 KM	0.677 AU
Mass	9.1E+23Kg	0.151 Earth masses
Surface gravity	513.8 cm/sec2	0.52 Earth gees
Surface pressure	0 millibars	0.000 Earth atmospheres
Surface temperature	86.6° Celcius 187.9° Fahrenheit	+72.6° C Earth temperature +130.7° F Earth temperature
Normal temperature range	Night Day -23.5° C -10.2° F – 187.7° C 369.9° F Min Max -59.1° C -74.4° F – 217.4° C 423.3° F
Equatorial radius	3428.6 Km	0.54 Earth radii
Density	5.36 grams/cc	0.97 Earth densities
Eccentricity of orbit	0.260
Escape Velocity	5.9 Km/sec
Molecular weight retained	69.5 and above	SO3, Kr, Xe
Axial tilt	24°
Planetary albedo	0.07
Exospheric Temperature	4108.54° K	+2835.54° C Earth temperature
Length of year	195.39 Earth days	53.18 Local days
Length of day	88.17 hours
Boiling point of water	-273.1° Celcius -459.7° Fahrenheit
Hydrosphere percentage	0.0
Cloud cover percentage	0.0
Ice cover percentage	0.0

Planet #3 Statistics
Planet type	Venusian Hot, Arid, Cloudy, Boiling ocean, Unbreathably thick atmosphere
Distance from primary star	1.4E+08 KM	0.968 AU
Mass	3.5E+24Kg	0.582 Earth masses
Surface gravity	812.6 cm/sec2	0.83 Earth gees
Surface pressure	44300 millibars	43.721 Earth atmospheres
Surface temperature	288.7° Celcius 551.7° Fahrenheit	+274.7° C Earth temperature +494.5° F Earth temperature +210.0° C greenhouse effect (GH)
Normal temperature range	Min Max 281.3° C 538.4° F – 295.1° C 563.2° F
Equatorial radius	5344.0 Km	0.84 Earth radii
Density	5.44 grams/cc	0.99 Earth densities
Eccentricity of orbit	0.101
Escape Velocity	9.3 Km/sec
Molecular weight retained	13.8 and above	N, O, CH4, NH3, H2O, Ne, N2, CO…
Axial tilt	21°
Planetary albedo	0.52
Exospheric Temperature	2007.71° K	+734.71° C Earth temperature
Length of year	334.30 Earth days	463.35 Local days
Length of day	17.32 hours
Boiling point of water	244.9° Celcius 472.8° Fahrenheit
Hydrosphere percentage	0.0
Cloud cover percentage	100.0
Ice cover percentage	0.0

Planet #4 Statistics
Planet type	Terrestrial Cold, Few clouds (N2, O2 – breathable)
Distance from primary star	2.1E+08 KM	1.393 AU
Mass	6.7E+24Kg	1.114 Earth masses
Surface gravity	1018.0 cm/sec2	1.04 Earth gees
Surface pressure	1161 millibars	1.145 Earth atmospheres
Surface temperature	6.2° Celcius 43.2° Fahrenheit	-7.8° C Earth temperature -14.0° F Earth temperature
Normal temperature range	Night Day 2.1° C 35.8° F – 10.1° C 50.1° F Min Max -20.1° C -4.2° F – 31.0° C 87.9° F
Equatorial radius	6607.3 Km	1 Earth radii
Density	5.51 grams/cc	1 Earth densities
Eccentricity of orbit	0.108
Escape Velocity	11.6 Km/sec
Molecular weight retained	4.3 and above	N, O, CH4, NH3, H2O, Ne, N2, CO… Nitrogen  63.0%  731 mb  (ipp: 692)   Oxygen  36.9%  428 mb  (ipp: 405)   Argon  0.1%  1 mb  (ipp: 1)
Axial tilt	22°
Planetary albedo	0.20
Exospheric Temperature	969.62° K	-303.38° C Earth temperature
Length of year	577.04 Earth days	920.22 Local days 1.58 Earth years
Length of day	15.05 hours
Boiling point of water	104.0° Celcius 219.2° Fahrenheit
Hydrosphere percentage	54.6
Cloud cover percentage	24.2
Ice cover percentage	6.2

Planet #5 Statistics
Planet type	Sub-Jovian
Distance from primary star	2.8E+08 KM	1.881 AU
Mass	3.2E+25Kg	5.356 Earth masses 3.464 Earth masses dust 1.891 Earth masses gas
Equatorial radius	17923.5 Km	2.8 Earth radii
Density	1.33 grams/cc	0.24 Earth densities
Eccentricity of orbit	0.027
Escape Velocity	15.4 Km/sec
Molecular weight retained	1.3 and above	H2, He, N, O, CH4, NH3, H2O, Ne…
Axial tilt	25°
Planetary albedo	0.50
Exospheric Temperature	532.22° K	-740.78° C Earth temperature
Length of year	904.87 Earth days	1369.98 Local days 2.48 Earth years
Length of day	15.85 hours

Planet #6 Statistics
Planet type	Sub-Jovian
Distance from primary star	4.6E+08 KM	3.087 AU
Mass	2.2E+25Kg	3.734 Earth masses 2.431 Earth masses dust 1.304 Earth masses gas
Equatorial radius	16814.6 Km	2.6 Earth radii
Density	1.12 grams/cc	0.2 Earth densities
Eccentricity of orbit	0.057
Escape Velocity	13.3 Km/sec
Molecular weight retained	0.7 and above	H, H2, He, N, O, CH4, NH3, H2O…
Axial tilt	32°
Planetary albedo	0.54
Exospheric Temperature	197.52° K	-1075.48° C Earth temperature
Length of year	1903.08 Earth days	2564.73 Local days 5.21 Earth years
Length of day	17.81 hours

Planet #7 Statistics
Planet type	Jovian
Distance from primary star	7E+08 KM	4.684 AU
Mass	3.7E+27Kg	626.589 Earth masses 38.199 Earth masses dust 588.390 Earth masses gas
Equatorial radius	77565.0 Km	12 Earth radii
Density	1.92 grams/cc	0.35 Earth densities
Eccentricity of orbit	0.014
Escape Velocity	80.3 Km/sec
Molecular weight retained	0.0 and above	H, H2, He, N, O, CH4, NH3, H2O…
Axial tilt	20°
Planetary albedo	0.47
Exospheric Temperature	85.79° K	-1187.21° C Earth temperature
Length of year	3553.92 Earth days	13449.13 Local days 9.73 Earth years
Length of day	6.34 hours

Planet #8 Statistics
Planet type	Sub-Jovian
Distance from primary star	1.2E+09 KM	8.294 AU
Mass	5E+25Kg	8.347 Earth masses 2.726 Earth masses dust 5.621 Earth masses gas
Equatorial radius	23085.2 Km	3.6 Earth radii
Density	0.97 grams/cc	0.18 Earth densities
Eccentricity of orbit	0.177
Escape Velocity	17.0 Km/sec
Molecular weight retained	0.1 and above	H, H2, He, N, O, CH4, NH3, H2O…
Axial tilt	48°
Planetary albedo	0.46
Exospheric Temperature	27.37° K	-1245.63° C Earth temperature
Length of year	8380.04 Earth days	12298.07 Local days 22.94 Earth years
Length of day	16.35 hours

Planet #9 Statistics
Planet type	Jovian
Distance from primary star	2.3E+09 KM	15.114 AU
Mass	3.3E+26Kg	54.383 Earth masses 6.375 Earth masses dust 48.009 Earth masses gas
Equatorial radius	41923.0 Km	6.6 Earth radii
Density	1.05 grams/cc	0.19 Earth densities
Eccentricity of orbit	0.207
Escape Velocity	32.2 Km/sec
Molecular weight retained	0.0 and above	H, H2, He, N, O, CH4, NH3, H2O…
Axial tilt	50°
Planetary albedo	0.51
Exospheric Temperature	8.24° K	-1264.76° C Earth temperature
Length of year	20614.27 Earth days	42521.66 Local days 56.44 Earth years
Length of day	11.64 hours

Planet #10 Statistics
Planet type	Rock Low-G, Cold, Airless
Distance from primary star	3.6E+09 KM	24.112 AU
Mass	1.8E+24Kg	0.293 Earth masses
Surface gravity	360.2 cm/sec2	0.37 Earth gees
Surface pressure	0 millibars	0.000 Earth atmospheres
Surface temperature	-214.0° Celcius -353.1° Fahrenheit	-228.0° C Earth temperature -410.3° F Earth temperature
Normal temperature range	Night Day -220.6° C -365.0° F – -207.3° C -341.2° F Min Max -237.0° C -394.6° F – -191.8° C -313.3° F
Equatorial radius	5693.4 Km	0.89 Earth radii
Density	2.26 grams/cc	0.41 Earth densities
Eccentricity of orbit	0.161
Escape Velocity	6.4 Km/sec
Molecular weight retained	0.1 and above	H, H2, He, N, O, CH4, NH3, H2O…
Axial tilt	54°
Planetary albedo	0.15
Exospheric Temperature	3.24° K	-1269.76° C Earth temperature
Length of year	41539.68 Earth days	39480.41 Local days 113.73 Earth years
Length of day	25.25 hours
Boiling point of water	-47.6° Celcius -53.7° Fahrenheit
Hydrosphere percentage	0.0
Cloud cover percentage	0.0
Ice cover percentage	0.1

Planet #11 Statistics
Planet type	Jovian
Distance from primary star	4.4E+09 KM	29.693 AU
Mass	1.6E+26Kg	26.864 Earth masses 3.276 Earth masses dust 23.587 Earth masses gas
Equatorial radius	36103.9 Km	5.7 Earth radii
Density	0.81 grams/cc	0.15 Earth densities
Eccentricity of orbit	0.089
Escape Velocity	24.4 Km/sec
Molecular weight retained	0.0 and above	H, H2, He, N, O, CH4, NH3, H2O…
Axial tilt	60°
Planetary albedo	0.52
Exospheric Temperature	2.14° K	-1270.86° C Earth temperature
Length of year	56765.41 Earth days	95559.79 Local days 155.41 Earth years
Length of day	14.26 hours

Planet #12 Statistics
Planet type	Rock Low-G, Cold, Airless
Distance from primary star	6.7E+09 KM	44.468 AU
Mass	1.3E+24Kg	0.218 Earth masses
Surface gravity	325.5 cm/sec2	0.33 Earth gees
Surface pressure	0 millibars	0.000 Earth atmospheres
Surface temperature	-229.6° Celcius -381.3° Fahrenheit	-243.6° C Earth temperature -438.5° F Earth temperature
Normal temperature range	Night Day -234.6° C -390.3° F – -224.5° C -372.1° F Min Max -249.8° C -417.7° F – -209.6° C -345.2° F
Equatorial radius	5165.8 Km	0.81 Earth radii
Density	2.25 grams/cc	0.41 Earth densities
Eccentricity of orbit	0.030
Escape Velocity	5.8 Km/sec
Molecular weight retained	0.0 and above	H, H2, He, N, O, CH4, NH3, H2O…
Axial tilt	39°
Planetary albedo	0.15
Exospheric Temperature	0.95° K	-1272.05° C Earth temperature
Length of year	104035.23 Earth days	93990.83 Local days 284.83 Earth years
Length of day	26.56 hours
Boiling point of water	-53.4° Celcius -64.1° Fahrenheit
Hydrosphere percentage	0.0
Cloud cover percentage	0.0
Ice cover percentage	0.1

There is an alternate output for the system view at the top. Instead of the images, it can make a simple system diagram that looks like this:

This shows the relative positions of the planets on a log scale as well as the range of their orbits (the gray bars) based on the generated eccentricities. The blue bar is the habitable zone for the system and the numbers above the gray bars are the masses of the planets in Earth masses. I’m leaning toward using this one. What do you think?

Planetary Maps

For each system, I want to do planetary maps for at least the habitable planets and possibly some of the ones classified as Venusian, Martian, Water, or Ice by StarGen. I haven’t found a program that will make good maps of the airless worlds (putting craters everywhere).

I also haven’t found a program that I’m completely happy with as far as generating the maps go. I have two that each do a bit of what I like.

Worldbuilder

The first is a program called Worldbuilder. It creates the world using plate tectonics it figure out mountain ranges, subduction zones, and the like and then has an atmospheric circuation model to figure out rainfall and temperatures and such. I like all that. It also can do a lot of different map projections, including on a globe and allow you to zoom in on any part of the map. Strangely, it only does a hex grid across the map and not lattitude and longitude lines.

It has a lot of knobs you can turn to adjust things like the water percentage, heat level, number of techtonic plates, and so on. And it does ice caps quite nicely.

One of the major downsides is that it is not supported anymore and the last development on it was in 2015. And while I have the code, it is in Lua, a languate I know nothing about so its a bit hard to read and edit. Another issue is that there is no key that I have been able to find to explain the colorings on the various maps (temperature, elevation, biomes). I’m sure its in the code but I’m still trying to figure it out.

Here are some maps for a sample world from that system. You might recognize the map style from other maps I’ve posted on the blog for locations and adventures on Pale. I used this program to generate the planetary map I used for that.

I really like the way this program generates the worlds, I just wish there was a little more documentation on what the program knobs do, and a key to the maps. In looking at the code, the biomes seem to be fairly generic: ice, water, rock, sand, etc.

Planet Map Generator

The other program is just called Planet, although the web page calls it Planet Map Generator. This one doesn’t have as many things you can adjust in the planet generation and just make maps based on an algorithm that generates the elevations on the map. The maps can look very fractally or smoother depending on the coloring scheme you use. It is a fractal generation method so you can zoom in as much as you want and it has some projections that I like that Worldbuilder including an icosohedral projection that is great for gaming.

You can tweak the water level and colors used but not much else. Addtionally, the developer also just added biome generation based on a simple air flow and rain model for given terrains. And the biome list has 11 different biomes, so that is nice.

Here are a few maps from that program. These are all elevation maps.

I really like the look of these maps. The one thing it doesn’t do is show ice caps or really do any weather patterns.

Which to choose?

I want to be consistent so I probably need to choose one of the map programs over the other. While i love the look of the maps coming from the Planet Map Generator, it isn’t quite as versatile for creating different types of worlds with different characteristics and I’m leaning more toward the Worldbuilder program for that reason.

There is an interesting option. The Planetary Map builder does have the option to import a low resolution (24×12) map of symbols as a seed for it’s map generation. So if I take that sample elevation map from Worldbuilder and convert it into the format Planetary Map Builder needs for input, I get a map that looks like this (with the original map below it).

Some of the details are lost and the terrain is a bit different, the Planetary Map Builder tends to put the moutains in the middle of the contients while the Worldbuilder does it on tectonic boundaries.

I could also create the biome map in Planetary Map Builder.

So while I can make the nicer looking maps from the Worldbuilder seed maps, I don’t think I like the way that changes the terrain. So I’m leaning toward the Worldbuilder maps as I like the terrain features better. I just need to figure out how to color them like the Planetary Map Builder maps and get better biome information.

What I probably need to do is learn Lua and translate the Worldbuilder code into C/C++ and then merge it with the relevant code from Planetary Map Builder. But that’s a bit of work. We’ll see if I can find time. Until then, I think I’ll use the Worldbuilder maps as is. The nice thing is that it is reproduceable and if I do make code upgrades later, I can rerun the programs to produce the same worlds with upgraded maps.

Final Thoughts

I still haven’t decided how to format these or where to host them but that’s a small matter. I can always start as blog posts like this one and then move them somewhere later.

What do you think about the different maps and style? Which do you prefer? Share your thoughts in the comments below.

And if you like the things I’m working on and want to encource me to spend more time on it, consider supporting me on Patreon.