Essentially a small room with a dome ceiling.
The lights get turned off, the globe is turned on to show the stars on the roof (paint a light-bulb black and scratch spots to get the same effect). Then for the next hour, someone will talk about some of the constellations and other objects in the sky, along with a few Greek myths.
This is something that was built in the 50's or 60's and hasn't been updated or upgraded since. On their site they show fabulous pictures of star systems, galaxies, and planets but you see none of this when you're there (false advertising?).
Oh I forgot the also have an old projector I think.
I've been to the planetarium in New York, that was cool, this was naff at best.