Oskar von Miller, founder of the Deutsches Museum, was looking for a solution to illustrate the motions of celestial objects to visitors. Until then, various sized mechanical constructions had served to illustrate the motions of the Earth, Moon, and other planets. These models had the disadvantage that viewers were always on the outside. It would be better to illustrate the laws of celestial motion to visitors from an inside view, just as one would see space from the surface of the Earth. 

This wish was fulfilled by the Carl Zeiss Jena company with the development of the Copernican Planetarium in parallel with the development of the projection planetarium. Constructed in 1924 this room filling exhibit marked the end of the development of mechanical planetariums. 

Attached to the center of the room’s 12 m diameter ceiling are the objects of the solar system. The planets, represented as spheres of varying sizes, are moved around the central Sun by an electrically driven carriage with respective periods of revolution proportional to those in nature. Just below the Earth a platform moves along the floor in uniform motion with the Earth. An observer on the platform can view the room through a periscope that widens the angle of vision. As the platform moves with the observer along the Earth’s simulated orbit, the apparent motions of the planets against the background constellations of the zodiac can be observed. These zodiacal constellations are depicted on a cylindrical wall with small lamps representing the brightest stars.