Karl Andreas Groß sells a scientifically correct starfield skydome on the Market.
This is a Starfield Environment ready to use for Blender Cycles World. This World Setup uses both,a high resolution Image and a procedural Sky Texture to achieve a photorealistic Background as well as a good Global illumination. The Starfield Image Map contains more than 2.4 Million Stars of the visible universe! By simply adjusting one Value you will get either a light filled Skydome, or an overwhelming amount of stars that even shows the structure of the milky way.
Starfield Skydome sells for $15.00