My protagonist is an astronomer in a fantasy world.

Ideally, what I want is software where I can specify some properties of this planet, e.g. orbital and rotation period, nearby stars, number of moons, and then visualise what someone would see from the planet's surface.

All the software I've found while searching visualises the real universe, whereas I want some kind of sandbox mode.

If this doesn't exist, can anyone guess what kind of tech stack I could use to build something basic myself? I am a Python engineer, but very inexperienced.

  • 1
    $\begingroup$ doesn't universe sandbox allow you to do what you want? $\endgroup$
    – Kepotx
    Commented Jul 11, 2018 at 15:30
  • $\begingroup$ When you say, "visualizes the real universe" is a problem, I assume you mean you want to visualize the sky from a custom planet arbitrarily located in the real galaxy, not that you want software to randomly create star fields. Am I right? Or are you OK with random star fields? $\endgroup$
    – JBH
    Commented Jul 11, 2018 at 15:33
  • $\begingroup$ While I think the question is good as is, I can't even imagine a scenario where this would be useful for a story. Are you role-playing as an astronomer, observing randomly generated stars? Perhaps if you could describe what you actually want to accomplish at the end of the day, there are other solutions to get there if no suitable software exists $\endgroup$
    – Raditz_35
    Commented Jul 11, 2018 at 15:50
  • 2
    $\begingroup$ JBH: a custom planet in a real galaxy would be better than nothing. And Raditz_35: what we (in the real world) see in the sky contributes much to our religions and myths. That's why it's important to worldbuilding, in my world at least. $\endgroup$
    – K--
    Commented Jul 11, 2018 at 16:07
  • $\begingroup$ @daisy Yes but why do you need an actual simulation for that? I find this approach very interesting. Do you plan to specify the exact position and sizes and brightness and so on on all the stars you use in your stories? There are a lot of stars out there. Perhaps btw it would help if you wrote what kind of parameters you want to specify yourself $\endgroup$
    – Raditz_35
    Commented Jul 12, 2018 at 16:05

3 Answers 3


Maybe, the most similar software to that specification and free, is Digital Universe developed by Hayden Planetarium. This software is available for Windows, Mac and Linux.
Download here and look for tutorial and guide here.
This package is the most accurate in visualization but is not sandboxed (you can not simulate specific conditions).
Using Universe Sandbox 2 you are free to simulate many celestial events (for example, generate your star, planets and moons with realistic conditions of gravity force -not custom periods-) but if you can compare with an actual sky this is not the best option, thus you need to recreate many bodies in the near universe. You need to pay for Universe Sandbox.
My last recommendation is Stellarium if you choose a real body in the solar system. You can change specific position (local coordinates) in the body and time of observation (past, present or future, with custom velocity to see changes in the sky). This is free.


Astrosynthesis is a nice generator that could fit your needs. It's a paid-for program, but it also has a 14-day trial so you can see what it has.

It lets you generate stars as well as show them on a number of map types. I've fiddled around with it before, and I think you can do things to make constellations, too? There's definitely a "Celestial Sphere" sort of display mode, and you can set a lot of things up with it, too.


I'm thinking Kerbal Space Program maybe?

It's a game about launching rockets and exploring space from a fictional planet named Kerbin. Kerbin has two moons and exists in a different solar system than our own, complete with made-up planets some of which have their own made-up moons.

I know that people have made mods to make change the in-game solar system from the fictional one to a model of our own solar system. If the solar system can be changed like that, then you can make a mod (there may even be modding tools to help you) that puts your desired solar system into the game. You could make your own planet, moons, sister planets, comets, and your own skybox for the stars. When I say a mod I don't think it'd be a big overhaul or anything. You'd probably just have to define the parameters of the solar system in some file and load it in.

Then you could walk or fly a Kerbal astronaut around in the game and see what your protagonist would see. There are mods to turn off the HUD for better screen-captures.


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