Hey all! It has been a while.
I have decided to try and participate in something I saw referenced on social media—I can’t remember which one—called #galaxy24. This is a spin on #dungeon23 where you were supposed to build a mega-dungon with one room a day or a smaller dungeon with one room a week.
Mine is simultaneously more and less ambitious. I am endeavoring to create one system a month in a video on the channel, so only 12 systems by the end of the year unless I throw in an extra here or there. However, one way in which this will be more ambitious is that I will be making each system with a different Star System generator system each time. Some of them will be stand-alone generators while others will be from science fiction TTRPGs like Traveler and Mindjammer.
System #1 - Liber Astarte
For our first system, we will be using Liber Astarte. This was an unofficial fan creation to be used with the various Warhammer 40K TTRPGs, specifically as an extension to the Rogue Trader system generator. I am afraid I do not know who wrote it or exactly where I got it from as it has sat on my hard drive unused for more than half a decade. So while I will normally provide links, I am afraid that I can’t do that today.
The first part of the process we did on the Youtube Channel. This was generating the star, determining orbits and habitable zones, and then what type of planets were in each orbit.
Below is a picture of the sheet that I made based on the one included in the text to record the results as well as a link to the video.
A Quick Tour
For simplicity’s sake, let’s call this star system Astarte. As you might have noted in the video or system sheet, we have two, technically three stars.
Astarte Aa is a Sun-like star
Astarte Ab is a brown dwarf that orbits Astarte Aa It is not quite big enough to fuse mass and is therefore technically a massive, gas giant potentially still somewhat luminous in the visible wavelengths due to thermal energy collected in its creation.
Astarte B is a “red” main sequence star.
Orbiting Astarte B, we have Astarte Bb, which is a habitable, but mostly frozen world gripped in an deep ice age. There is likely some life here, but is either not very complex or highly adapted to a cold environment. Survival for non-specialized life like humans would be difficult except in the warmest parts of the planet.
Orbiting Astarte Aa, we have an interesting collection.
Astarte Ac
Astarte Ad
Astarte Ae is a small rocky body with a tenuous or non-existent atmosphere along the lines of Mercury or the Moon.
Astarte Af is an Earth-like planet.
Astarte Ag is a ringed gas giant with a Saturn-like appearance and 2 moons the size of a rocky planets.
Astarte Ab is the brown dwarf we mentioned previously. I labeled it Ab instead of Ag like the 5th planet normally would be because I imagine this one will have discovers first due to its large size
Astarte Ah is a super-Jupiter. I expect that Ag and Ah are likely around the same diameter with Ah’s much larger mass making it more dense rather than bigger. It also has many moons of considerable size.
Continuing the Process
Liber Astarte also has rules for detailing out planets, so that will explore them to detail the seemingly quite habitable Astarte Af. To do this, the system has us go through the following checklist, determining the results with dice rolls and modifiers based on other statistics:
Planetary size and gravity
Atmospheric makeup
Hydrosphere, Cryosphere, and geological activity
Land area percentage
Relative humidity of the planet
Length of the day
Mean temperature and General Climate
Common minerals found and points of interest.
Size and Gravity
Getting started on this with size. The rules indicate that a standard terrestrial world like Astarte Af should be (1d10+5)x1000 km in diameter. My d10 result was 3, so our planet is 8,000 km. This is about halfway between Mars and Venus. If I chose to use their formula for gravity (Diameter/12), this would give our planet a gravity 2/3 that of Earth’s.
Atmosphere
For determining atmospheric makeup, there is less for us to do there today. For non-inhabitable planets, we have tables in the text for determining a primary gas for the atmosphere and a wide range of densities. However, for habitable planets, we simply roll to determine the density of a Nitrogen/Oxygen atmosphere.
For Astarte Af, I rolled a 6, which corresponds to a pressure equal to a standard Earth atmosphere at sea level.
Hydrosphere/Cryosphere and Geological Activity
Again, with Astarte Af’s Hydrosphere (water volume) and Cryosphere (how much is frozen) we were limited to a range between 20-80% to ensure the planet is habitable and familiar. I rolled a 9 for our hydrosphere and 5 for our Cryosphere. This means we have a very wet planet with ~80% water coverage and about 50% of the surface experiences long-term freezing.
For Geological activity, they have us roll for Volcanism and Tectonic plate activity. A protoplanet is at 10 in both due to it not having a solid core and a Chthonian planet (inner core remnants of a gas giant) would have scores at 0. For a paradise planet, the formula for both was (1d10-6). since I rolled a 4 and an 8, this indicated that volcanism was practically unknown (0), but that tectonic activity was at a 2. In comparison, the author rated Earth as having a volcanism of 5 and tectonic activity of 4. I expect this means Astarte Af has a small number of large tectonic plates that move slowly and any volcanism is is limited to leaks expanding fault lines, likely under the ocean surface or ice caps.
Climate
Next, I did do some work on climate-related tables like relative humidity, length of day, and a planetary mean temperature.
The formula recommended for relative humidity was (1d10+Hydro)/2x10. Since our hydrosphere was 8 and I rolled a 7, so relative humidity would be 75%.
The planetary mean temperature is measured in this system using Fahrenheit (GASP!). It is recommended to be 100-(Cryosphere x 10) to that would be 50 degrees F for our planet or 10 degrees C. This is about 10 degrees F lower than Earth.
For day length, the system recommends 3d10 + (satellite sizes/1000)hours for the day. Since Astarte Af has two moonlets the size of asteroids, I assumed they would have very little baring on the orbit of the planet that could be measured in minutes or even seconds. instead, I simply rolled the 3d10, which resulted in a 20.
All this combined together means that we have a planet wetter and cooler than Earth. Many places likely have a climate similar to the temperate rainforests seen here on Earth in the Pacific Northwest or New Zealand. The evergreen rainforests still found in parts of Korea and Japan might be an even more apt comparison considering the high ocean volumes will have a smaller volume of landmass.
Mineral survey
Here again we are rolling for all terrestrial planets in the following categories to create a ranking on a scale from 0-9 in general abundance:
Industrial Minerals - 9
Common Metals - 6
Rare Metals - 8
Industrial Crystals - 9
Gemstones - 5
Radioactives - 6
The rules note that if a survey were to be conducted on the planet to find the following resources, then there would have a (rating x 10%) chance of finding a vein of the resource. so on Astarte Af, industrial minerals like clay, silica, gypsum and limestone as well as industrial crystals like silicon and aluminum oxides are quite ubiquitous. Non-radioactive rare earth elements and precious metals like gold, silver, and platinum-group metals would also be found with much more regularity than on Earth.
Imperium Rating
Finally, we come to the society that exists on this world. Considering it’s habitability and vast resource wealth, I have a hard time imagining that people would not be colonizing this world pretty extensively!
The Imperium rating has you roll a d100 on a table containing the following options:
Agri-world
Civilized World
Developing World
Dead World
Death World
Feral World
Feudal World
Forge World
Hive World
Quarantined World
Shrine World
I rolled a 41, which gave us a Developing World. This is described as a world divided in to different societies that may each possess widely different levels of technology and social development. Some of this may be due to access to the original technologies of the initial colonizers or variations in local resources. In this case, I would think that the pockets of habitable landmasses that are above the sea and not under the large ice shelves have likely created a large amount of cultural variation and may have also resulted in technological variation.
My assessment of Liber Astarte
I think this is an interesting resource! Not the most accurate, but also not overwhelming like some more advanced star system generators. Some of the rolls I did were either optional or would not be required if you wanted to flesh out a gas giant for example. It is just a pity that it is an unofficial resource that is so difficult to find now-a-days.
Feel free to comment which system you think I should use for February #galaxy24!