When I was a kid I bought a big set of glow-in-the-dark adhesive stars and decorated the ceiling of my room with them. The ceiling was sloped on the sides because it was right under the apex of the roof. It really was like having my own personal planetarium, although I didn't bother to arrange the stars as they actually appear in the night sky.

I spent many nights reading great books, then turning off the lights and thinking over the stories under those phosphorescent stars... What bliss!