Done in Photoshop CS.
Alright, begin a new image with these settings:
Now, go to Filter>Texture>Stained Glass and have the setting like:
You should now have this:
Next go to Filter>Texture>Grain and set it up as follows:
And you’re done, you should now have a nice large image of a starry sky! And a plus, whist in game, when you look up at the stars and move some of them apear to flicker as in real life!
Here’s what mine produced:
Brave.