A strange machine, not unlike a UFO, occupies the center of the domed auditorium. 69 comfortable seats accommodate the visitors. Having come in here out of broad daylight or pouring rain, they are now seeing stars appear above their heads as the room gets dark. It is just like sitting in an open-air theater under the nightly sky. More and more stars emerge in bewildering multitude, until an overlay projection of constellation figures provides orientation. Then the sky starts to move, and the narrator explains the laws and patterns governing their motions. The planetarium becomes a time-lapse machine carrying the audience through the planetary system. Special projectors demonstrate such events as a solar eclipse or afford a moon-bound astronaut's view of the Earth.
Quoted from the brochure "Travel through the Universe - The Osnabrueck Planetarium"