Building a Better Star Map

I like my star map – but I recognize it’s not “perfect”. For one thing, since Earth is off-center and then the entire development of human space is kind of biased towards Trailing (where the Empire expanded), human space occupies the center and right part of the map, leaving the left part empty. The reason is simple – it wasn’t planned out when I started to build it.

So I thought I’d do a draft of what human space “should” look like. I’ll take the written history as a basis – but I will fix what needs fixing.

Some data points:

  1. The first FTL mission was in 2174, to Alpha Centauri
  2. Hyperdrive speeds continually improved over the course of the history of the Federated Nations
  3. “Leapfrog 2”, launched in 2278, founded Eureka in 2308, circa 1100 light-years towards Center and Spinward.
  4. Regular explorers from the FN arrived at Eureka in 2390 – meaning that human space had expanded less than 1100 light years by 2390; let’s say 1000 light years maximum.

Do note that the galactic disc is “only” about 1000 light-years thick. At this point, it’s safe to assume that human space covers the disc’s entire width in at least the center 500ly radius.

Human Space in 2380AD
Human Space in 2380AD

Ignore the second set of circles “south east” of Earth – I added them just to have a second set, roughly in the direction of Empire.

In 2547, the System States Alliance secedes from the Federated Nations. They are located on the “outer Rimward fringe” of human space. But how big is human space 160 years later?

Rate of expansion from 2174 to 2390 was about 5 light-years per year. However, hyperdrives increased greatly in speed during the 24th Century – so the rate of expansion speeds up; but of course it covers more volume. If we stick to 5ly/year, human space expands another 800 light-years until 2547. That seems to be way too much.

Let’s do the math. Human space, at 1000ly, contained 3141592654 cubic light years of volume. That’s an incredible 15250449 cubic light years per year! Clearly, the Federated Nations did not settle or probably even visit every star system in its space.

If that rate stays constant, human space should expand by 15250449*160=2440071964 cubic light years by 2547, for a total of 5581664617 cubic light years. Or, to put this into terms we can actually use, Human Space in 2547 should be a cylindrical volume with a radius of 1332.93 light-years – a little more if you consider that it likely flattens towards the edge. Let’s round it up to 1400 light-years.

Human Space in 2547AD
Human Space in 2547AD

This also gives us a good indicator for the distance of Home – the future Imperial Capital – from Earth. It was settled in 2580 – in other words, it should be located just outside the 1400 light-years circle. As you can see, I placed it nearly 1000 light-years too far away – careless worldbuilding. (That said, there is a plausible explanation for the greater distance. More on that later.)

The next data point is Excalibur, the first of the Sword Worlds. It was settled in 2634 by refugees from one of the FN enclaves after interstellar society breaks down. Human space still expands at this point – mostly due to inertia – but direction and amount are hard to predict. At most, human space should be ~1500light years in radius at this point.

As you see, I actually underestimated the distance of Excalibur from Terra. Let’s assume that these refugees went just as far as they had to to get out of harm’s way – maybe they went to a habitable world for which the colonization project had been cancelled. Any location within the 1500ly ring is actually quite reasonable; I’ll move the world just outside it.

Human Space in 2634AD
Human Space in 2634AD

But what about Empire?

Home was bombed in 2632; it took them until 3445 to rediscover the hyperdrive. In 3482, a religious sect set out to find a better place to live. They founded the colony “Heaven” in 3491 – “900 light years” from Home. They would set out more or less away from what they knew to be occupied territory.

Empire was founded in 3498 – 54 years after Home returned to the stars. If Empire had expanded as quickly as the Federated Nations at their prime, it would have had a radius of 500ly at this point. However, it almost certainly did not – not only would they have to expand more carefully; they also waged at least one interstellar war in between which would have slowed them down.

Empire in 3498AD
Empire in 3498AD

..And The Federation

Tanith Base was established deep in what used to be FN territory in 3045. The Alliance with Marduk was signed in 3057. The Terran Federation was established in 3181.

The problem with Federation expansion is that it’s very “erratic” – The TF mostly aimed at reuniting human space. We do know that Empire and Federation make contact in 3918. Let’s see if we can decide where that happens.

First, 800 years is a long, long time. The FN rose and fell in a little more than half that time. Again, the FN moved in a vacuum (no pun intended) – there were no established colony worlds that desired freedom, and there were no alien species that might have impaired expansion. Both Federation and Empire had to work harder to expand. At FN rates, 800 years would mean a territory of 2000 light-years radius!

One of the TF’s earlier pushes was the journey to Earth herself. They arrived in circa 3230. Federation had over 200 years to expand and consolidate territory before Home undertook its first Hyperdrive voyage.

Since we can’t really calculate the point of contact, it’s perhaps time to guesstimate. Let’s mark off the half-way point between Earth and Home:

Guesstimating a future frontline
Guesstimating a future frontline

Since the Federation had a headstart, the actual meeting point between the two is probably closer to the yellow 1000ly circle. That works for me.


As I hinted at above, there is one way to explain a more irregularly shaped human space: Project Leapfrog.

Leapfrog is a variation of the old “sleeper ship” idea – except these travelled at FTL speeds, and instead of taking hundreds of years to reach a nearby star, these ships travelled several decades until they were outside human space, found a suitable world and set up a colony. By the time regular explorers reached them, they were well established and could serve as a base of operations. Or, in practical terms, they would accelerate exploration and colonization in the long term.

Human Space should, reasonably, expand further in the general direction of the Leapfrog colonies. This would let me place Home further away.

At the same time, Spinward/Trailing of Earth the next rift between arms is much closer than in the other directions. This could either slow down exploration (harder to find suitable worlds, thus giving less incentive to invest in the region) or speed it up (more territory gets covered for the same number of colony worlds).

However, since scale is another problem I have, a somewhat smaller human space is probably a good thing. It will let me create more detailed maps. I’ll keep these matters in mind when I move on to creating the actual map.

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