If you're a sci-fi world builder, then you'd love this software. This is a Work-In-Progress program to generate realistic galaxies. Generate a planetary system around a star, select a planet in that system, and you can get realistic views of the night sky as seen from that planet. You can use it to map constellations and develop a mythology for a constructed culture on that planet.
That's the idea at least.
Next step is to amp up the number of stars in the rendering. I'm putting together some scene management concepts that will allow me to have up to a billion stars, and yet still be able to render the galaxy from a distance with a decent frame-rate.
I'm also attempting to co-opt the Accrete Algorithm for procedurally generating planetary systems. Unfortunately, there isn't a decent description of the algorithm aside from 30-year-old papers, utilising astronomy jargon that I can't even begin to understand. There are other possible approaches, and I'll bet there are a couple of open-source solar system generation algorithms out there that will be of use.
Keep an eye out for a download.