Short version first:
I believe that your fictional world deserves its own night sky. To that end, I have put together a tool to help you create one for your campaign. Make a copy of the Google Sheet and see what you can come up with.
Look, I know. A spreadsheet. But it’s the most accessible I can make this thing, and all of the pain-in-the-ass work was on my end. If you use it, let me know how it goes.
So much of the D&D-ish game relies on a world that runs parallel to the one we know. You could do anything, anything, but the practical limits show up real quick. We rely so much on things that are normal, but for certain exceptions, because every change calls for an explanation. And referee explanation isn’t any fun for anyone.
But, pause. How many constellations can you name? (There are eighty-eight.) How many stars can you name? (There are more than 9,000 visible to the naked eye under dark skies, across the world, but not all have agreed-upon, non-gibberishy names. I mean actual names, like Regulus and Deneb and Antares.) What can you identify on a night with patchy clouds, disrupting the familiar patterns? For folks playing the game, those answers could run the full spectrum.
For the characters, though, in a world without mechanical timepieces and all of our modern conveniences, one should assume a familiarity with the night sky. In addition to being more visible with little light pollution, the celestial sphere has served as an exceptionally reliable clock and calendar for thousands of years. At least. Everyone has a passing familiarity at minimum. The myths and tales of imagined order in the skies tell us a great deal about the societies that created them.
So should your skies not be a mirror of those here on Earth – which is, honestly, plenty interesting enough – consider this an opportunity to quietly expand the lore and richness if your campaign.
Or just have fun and doof about. I’ll explain how this works, and how I imagine using it for my own purposes. Follow the link above, make a copy that you can edit, and if it works for you, awesome!
This is built on an Earth analogue, using algorithms provided by the U.S. Naval Observatory for sidereal time and by NASA for solar position and time. (I have the code and my notes, but can’t find the website for a link. Apologies.) There are a lot of terms to calculate, lots of corrections and adjustments, and hidden sheets so you don’t have to look under the hood if you’re not inclined. So: same year, axial tilt, planet-star distance, orbital eccentricity, etc.
Also the same starting day of the year, so if you’re using a different trigger for rolling over the calendar – like the vernal equinox, maybe – take that into account.
You’ll need a latitude and longitude for your observer, though longitude mostly doesn’t matter here. When nightfall arrives, the stars look the same. You might get some weirdness in the auto-generated star charts approaching the poles, once the Sun no longer either rises or sets.
A year and a reference year, the latter only important if you plan to examine changes over extended historical time. Shifts over thousands of years can have big changes, and maybe you can work with that. What vestiges of the past have changed, such that the long-lived elves never quite adapted?
A time: day of the year, with hour and minute. The sky at nightfall is different than at midnight, and moreso when twilight first glows in the morning. For when you need specifics. The spreadsheet gives you sunrise and sunset times on the selected date if you need them.
Feel free to change the year length, too. It might break everything, or throw in some weird artifacts, but if you want to?
The last is a random seed. Pick a number, any number. It powers a pseudorandom algorithm that the spreadsheet uses as inputs for all of those stars. Write down that number, and it’ll produce an identical “random” sky every time. Go ahead and type in different seeds until you generate something you like.
What you get, then, is a bunch of charts showing dots. Dark backgrounds with white dots to look sky-like; inverted versions should you ever want to print and not hemorrhage toner. On the Sky View sheet, you’ll see a circle showing the entire sky, projected flat, horizon to horizon. That’s the sky at the indicated time, with south at the bottom, north at the top.
Because you’re looking up, east is left and west is right. Change the time, and you change the stars. If you look closely, you’ll see rotation about a point in the north (or south, if you’re located in that hemisphere). If there’s a star there, it’s your pole star, and a selection of others will turn about it day and night, never falling below the horizon. These are your circumpolar stars. You can see them on every clear night.
The rest are seasonal stars, and only visible for a fraction of the year. They’ll be your timekeepers, the stars whose first and last appearances on the horizon align with annual events. Planting, harvests, the monsoon season, major religious cycles.
Notice that the dots aren’t all the same size, and that tiny ones greatly outnumber those big stars. Size is an indicator of magnitude, the visual brightness. Of the 525 stars spread across the heavens, they’re loosely analogous to those seen from Earth, down to 4th magnitude. Lower magnitude means brighter (blame Hipparchus), and while you can see down to 6th with the naked eye, no one’s making stick figures in the sky with them.
Historically, most of the important stars have been the brightest. They’re the ones which get common names. In constellations, they’re often important to the imagined form. Aldebaran, the red eye of the angry bull, Taurus. Castor and Pollux, the heads of the twins in Gemini. Antares, the red eye of Scorpius, also traditionally known for not being Mars. That sort of thing.
(Reddish stars often stand in for anger or violence – Betelgeuse at Orion’s shoulder as he’s about to swing his club – and are distinctive. The original Python version of this included a B-V color index, but proved too fiddly to port into Google Sheets. You’ll have to introduce those aspects yourself, sorry.)
You also have charts showing the entire celestial sphere, stretched out to fit a rectangle, with the red dots marking the current horizon. See how that curve shifts with day and time, such that some stars are always visible, some occasionally, and some never? Wherever you are, there’s sky you can’t see; equator and poles give odd exceptions.
The second version of this chart includes a cyan or blue dotted line. (See the header image for an example.) This marks the ecliptic, the path the Sun traces across the heavens throughout the course of the year. This is the approximate area you’ll see the Moon and planets – assuming a flat disc structure like our solar system – and is the region of sky for the zodiac. Note: moons and planets not included.
If you’re looking for star signs in your campaign, one’s zodiac sign is where the Sun was at their birth. Note that the sign of the zodiac is 30°, even when none of the constellations associated with them are a nice, round, even number like that. If fudging the boundaries was good enough for the Babylonians, you may take that as license to play loose, too.
I’ve also included two sheets loaded up with a dozen snapshots of the sky throughout the year. Each is taken 90 minutes after sunset, more or less when twilight has faded, and can stand in well enough for a month-by-month survey of what’s visible. Export, print, make notes as is useful for you.
If you’re going to make the most of all this, print out a full sky on paper. Consider that the Babylonians divided the ecliptic band into a dozen constellations, and see how you feel about size. Keep in mind that this will map onto the inside of a sphere, so the top and bottom of this chart converge to a point.
Enormous constellations are unusual, but no one’s going to stop you from imagining an ourobouros forming a great circle across the entirety of the heavens. They can be tiny – Canis minor consists of two stars, both close together – or even made of disparate parts, as Serpens is bisected by Ophiuchus.
When in doubt, adjust the view in your star chart to see how things stack up.
Here’s a quick first pass at groups of stars that might make decent constellations, with the zodiac marked with Roman numerals I – XII, and a handful of other possibilities A – K. I’m not going through all of these – exercise for the reader! – but I’ll quickly point out three.
Zodiac I: Jirda, the Jumping Mouse
First rising at opposite the sunset in late summer, the bright star Aldylfhar at the tip of his long tail tells that the harvest season is not far away. Jirda and his kin grow active, hoarding seeds and grain for their winter burrows, knowing that the hot Sun is no excuse to put off preparations for winter.
Zodiac VIII: Hakiel, the Great Eagle
Rising at the beginning of the year, first appearing on the horizon around the winter solstice, Hakiel brings a promise from the gods that despite the winds and snow, humans are watched over, and that spring will come once again.
Zodiac X: The Shadow of Nyx
Following the First Cataclysm, the gods banished Nyx to her prison of eternal night. In revenge, she stole the stars once placed here, that she might have playthings in her seething solitude, and that humans would be reminded of her loss in the cold winter months. The elders say that when the Moon rises full within her shadow, she walks the world again for one night.
This post takes its title from a poem by Manny Loley, star poem. The original is untitled, and in Diné, and I doubt you’ll understand it untranslated any better than I do. Still: follow the link, read, and listen to it as intended. Every day could use a little poetry.
52 Monsters 
