Astrolabe Maps of a Solar System

The Age of Odds is kind of my dream campaign, it is the culmination of a large number of ideas that have been floating around my head for years.

I describe the setting as "Spacesuits and Sorcery."  It takes place an uncertain time in the far future, after post-human gods abandoned the rest of the universe and fled into their own domains, leaving the interstellar societies they managed to collapse in an event known as the Schism.

The Eridu solar system is the focus of the campaign.  After the Schism, the High Ways, which allowed for faster than light transit, were closed to mortals.  Due to this, there is no FTL travel in the setting.  This means that I had to cram what would normally be a sector's worth of complexity into a single star system.



This is my method for making a map of a single star system.  It is somewhat limited to the setting, since it assumes a solar system, where the planets have been moved or constructed in a way that produces more habitable planets than could be expected.

Planets, asteroids, and habitats are grouped into Orbitals.  Each Orbital is then divided into a number of sectors, which correspond to a dice size.  This assumes a sun with a similar mass and luminosity to Earth's.  The size of the planet or habitat shouldn't affect the orbital period too much.




Planet
Dice/sectors
Semimajor Axis (au)
Mass (earths)
Year Ratio
Rotation Rate
1
1d4
.825
1
.667
90
2
1d6
1
1
1
60
3
1d8
1.21
1
1.333
45
4
1d10
1.41
1
1.667
36
5
1d12
1.59
400
2
30

Clusters of Asteroids and Habitats are grouped at the Lagrange Points in the solar system.  The Wikipedia article gives a good summary of them.  https://en.wikipedia.org/wiki/Lagrangian_point 
The short story is that most things will cluster around L4 and L5 in an oribtal.  I also put a lot of things at L3, even though it's just a meta-stable point.

All of these planets should be approximately in the sun's habitat zone.  I explain the discrepancies with a series of solar shields and reflectors.  In fact, Nona's solar shield broke down and the planet is slowly frying.  It's a major plot point.

The outer solar system is modeled as static.  If 20 in game years pass I might have to change that, but it really doesn't matter for me.

Working with a solar system that was engineered by god-like beings in a past age makes tracking numbers very easy.  Planets in this system have a number of days that match up with their years, with no leap years, and a simple year ratio based on nice whole numbers.  These numbers also tie into dice sizes, so you can actually generate random locations in the solar system with ease.

SO, here's the kicker.  You can make a map like this orbit pretty easily, here's the trick.

Put the planets of each orbital onto a different layer in your preferred image editing software, then PUT THE PLANETS OF EACH ORBITAL INTO A SEPARATE LAYER.  Every two in game months (1/6 of a year on the earth-like planet with a 1AU orbit) I then rotate each layer by the rotation rate in the chart.  This will mean than the planets change position relative to each other at a fairly reasonable rate.

I'm using Stars Without Number for this campaign, so this actually has been having an effect in the faction system minigame.  For instance, the Hela Cluster is close to the Sorrel Cluster right now, which allowed the pirates located in the Hela Cluster to easily mount raids against Alewold Heavy Industries trade routes originating from New Akad in the Sorrel Cluster.

Travel between areas in the solar system is measured by the number of sectors, with each sector taking 30 days at speed 1 in Stars Without Number.  A faster ship can cut this time in half for each level of engine it has.

This sort of turned into a stream of consciousness post, but I hope it is of use to somebody.  Just remember that the end goal is to get useful emergent gameplay from the position of planets with a minimum of effort on the part of the GM rather than to accurately model the behavior of a solar system.

I'll probably do another post about the Age of Odds setting at some point in the future, I am very proud of it.



Addendum: A lot of what I did was inspired by this stellar map, in fact the background layer I'm using was made by it's creator.
https://www.reddit.com/r/SWN/comments/em5te0/a1sized_stellar_chart_for_my_own_stars_without/

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