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Potential number of Star Systems in a map SECTOR?

How many potential star systems might be found in a single SECTOR from the STA map of the Alpha and Beta Quadrants? Particularly how many (average) systems in a Shackleton Expanse sector ?

Average stellar density is 0.004 stars per cubic LY…

Now, that’s theoretical ideals, but…

As for how big the expanse is? Well, the gridlines are, based upon the distance to Alpha Centauri, about 20 LY blocks. Assuming the grid shown is a 20 LY deep block, each square represents 8000 LYÂł, so, 32 stars per block.

If we instead use the 112 LY to the RNZ, we get 50 LY cubes… but then lots of the worlds are wrong.

But it’s probably not a 20 LY thick. And I suspect that the artist really had zero clue about the sizes involved. Romulus is further from the RNZ than Alpha C is from Earth, but Alpha C is supposed to be 4.26 LY, while Romulus is 3.2 LY from the border. Likewise, the scale is inconsistent for the 5.26 LY between Bajor and Cardassia.

And let’s not forget… Qonos is only 4 days away at warp 4.5… (Ent. Broken Bow) using WF^3.1 =C (rough fit to the TNG Tech Manual), that puts it 1.16 LY away from Earth…

Ignoring Enterprise’s stupidly bad math…

if we go with the upper bound of 50 LY implied by the RNZ… each grid is then about 500 stars.

So, in the end, however many you want, because the map is nonsense. Pretty nonsense, but nonsense none the less


I like this answer. Thank you!

However many you need for your storytelling purposes. :slight_smile:


There is actually a rough estimate in one of the stellar cartography books…

And for the speed/distance discrepancies - it was never explained what the “Vulcan Star Charts” offered that weren’t available via the Hubble Telescope. I’ve gone with the theory that warp speed actually varies according to the subspace field density in a given region - which can up the maximum speed by over a 1000 times… The star charts showed channels where this was the case, effectively forming high speed bypasses (without the destruction of minor suburbs like Earth).

Although I still love First Contact’s implication that the Romulan Neutral Zone is half-way between Alpha Centauri and Earth (based on 3 hours for the Enterprise’s journey) :slight_smile:


I always use this idea as well - astrometrics and astronavigation are more than just charting where stars and planets, etc., physically are, but also mapping subspace, gravitational, and other spatial variations that can influence Warp travel. There are places where warp travel is faster or slower than the “baseline” values (Warp Factor cubed in ENT and TOS; approx. Warp Factor *[10/3] in TNG onwards), but these places shift over time (space isn’t static), so they need to be regularly charted. This also allows for worlds to be in strategically important locations, and for standard routes to exist between important worlds.

Technically, Warp Factor itself isn’t a constant measure of speed. Rather, it’s a shorthand unit of reference for the intensity of a propulsive subspace distortion field. Warp Factor can be considered roughly analogous to the Mach number used in supersonic aviation - Mach 1, Mach 2, etc., isn’t a speed, it’s a ratio of the speed of an object to the speed of sound in a particular medium, as the speed of sound itself varies.

At the time of Broken Bow, there was a “highway” of sorts between Earth and Qo’noS, a confluence of various spatial and subspatial phenomena that allowed extremely fast travel for relatively low levels of subspace distortion. Conditions like that don’t happen often, and tend not to last very long, but any warp-capable culture monitors for these conditions because they can be extremely advantageous for trade, exploration, and military matters, even if only for a short while.


@Modiphius-Nathan thank you! The reason I asked the original question is because, in addition to discovering new star systems in the Shackleton Expanse, I’d like my PCs to use their stellar cartography and astrometrics labs onboard their ship to detect and plot/define/map those gravimetric distortions and electromagnetic disturbances with a Shackleton Expanse sector. An option is to use graph paper ( or grid graphic on a computer ) with a 2D x-y coordinate or 3D x-y-z coordinate to define the boundaries of such anomalies thus creating optimal “lanes” for warp travel in the Expanse. Of course those anomalies might not be static and also there could be surge or temporary distortions which appear and fade.
Thank you for you post !

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First: I love this idea!
Second: Have you thought about doing this in full 3D on a computer? This was the first thought that came to my mind when I thought on how I would do this.

Second thought: several layers of (semi-)transparent paper (one for each coordinate on the z-axis) could do the job as well. :slight_smile:

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In general, we play games in theater of the mind. I think it is best if we not get too tied down to 3D maps in a 2D game environment. It sounds like a lot of complication I don’t need. On the other hand, if you’re doing a lot of star mapping and your players just need to have the reassurance their efforts are not in vain, then have at it! Then we have to come up with timey whimey explanations of space-time to cover our inability to actually map this environment. But if someone could talk more about the 3D option in a computer…I might be tempted - oh wait I am falling into the IT ZONE aaaaaAAAAAAHHHHHH!

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Aramis, I only wished my knowledge was that detailed about the ST universe.

I use a good bit of augmentation to get things correct. That said, I also have a good memory for relationships. (In other words, I’ve enough of a memory to recall what to look for, then google it to make certain.)

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What follows is the stuff I found when I too asked this question a few months ago. BLUF: A “realistic” answer for our neighborhood is Aramis’ 0.004 system per cubic LY. " Any number you need for your story" is as also good an answer as any.

It looks like Modiphius followed Star Trek Star Charts very closely which uses 20 ly cubes as the Sector size…at least in the tiny part of the Galaxy mapped by the Federation. Since the galactic disk is ~thousand LY “thick”, the 20 LY “deep” cubes still work (around here). So Aramis’ “32” math is good for ST:A. In Real Life (tm.) there are apparently 33 stars in a 12.5 LY radius of Sol as shown here:

The Universe within 12.5 Light Years The Nearest Stars (This site is awesome by the way. There’s quite a few maps.

I queried real star data in a 3d mapping program (Astrosynthesis) just to mess around with using real stars for making sector maps for ST:A and got 23 stars within 10 LY of Sol. There was no straightforward way for me to search a cube though…so…to be sure I hit Google, confident that some crazy person with more astronomy knowledge than I had also asked this question before. Turns out … someone did.

Shocking :slight_smile:

This site is a (very cool) star mapper that combines real star data from a number of catalogs and includes an option to map about 100 systems from Star Trek.
More details on how the site was made are here:

So I made a 10x10 LY cube centered on Sol and counted the stars manually (there’s no list function except in the selection menu at the right). There are 26.
20 x 20 LY cube centered on Sol

If you want to see out towards Shakleton-a-ways, you’ve got to fiddle with the coordinates an then squint a lot. There are a couple of things to know so that you can do this for yourself.

  1. The coordinate system is conveniently centered on Sol. So 0, 0, 0 is here.
  2. -Y is “Galactic East” or right on the Modiphius game map.
  3. +X is “Galactic North” or up on the Modiphius game map (towards center of the galaxy).
  4. The galactic disk is ~50 sectors “deep” at our position on this scale. So the Z axis matters. I kept it set at 10 or 20 but I note that the website’s author had to put Romulus 86 LY from the plane of the galaxy to match it to a known star at roughly its 2D location on the Star Charts maps.
  5. “Magnitude Limit” is how bright of a star the website will show you on the map. MAGNITUDE GETS LARGER AS STARS GET DIMMER. So set it low if you want to filter out stars. This becomes important when you want to map larger areas and try to see relationships.
  6. This program was made with our current star data which is more complete the closer you are to Sol. So there’s naturally fewer stars on the maps farther away from Earth. So you have more creative freedom the farther away you are from Sol.

So…there…if you want to try to use real stars to make your sector maps…you too can drive yourself utterly and completely mad trying to take Star Trek’s 2D map and make it fit our 3D universe. And have fun doing it!


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