The new building of the Deutsches Museum in Munich opened on May 7, 1925. The building is located on the Museum Island and is a visitor attraction today as it was then. The concept of museum founder Oskar von Miller was new. He wanted an international museum for all areas of technology and natural sciences including celestial science, so the museum also needed to have a planetarium. It even got two. The first was the Copernican Planetarium. It was a cylindrical chamber simulating the movements of the planets, including the Earth, around the Sun. The second, the so called Ptolemaic Planetarium was totally new. It was based on the projection of the celestial bodies onto a white dome. The apparatus to make this possible was developed by the Carl Zeiss Jena company with Walther Bauersfeld as its managing director and leading designer. Even before the opening of the new museum building the first demonstration of the Zeiss projection planetarium took place in Munich on October 21, 1923. The projector was fully functional, but not yet finished.

This photo shows the projector in 1925 after completion. The view is from the “east” side in the Deutsches Museum’s 10 m planetarium dome. It allowed the display of 4500 stars, the Milky Way band and the names of important constellations. The projectors in the cylindrical part reproduced the Sun, Moon and the planets Mercury, Venus, Mars, Jupiter and Saturn on the dome. Motors and gears allowed for the simulation of daily rotation in increments of 50 seconds, 2 minutes or 4 minutes. The change in positions of the sun, moon and planets in the sky, the so-called annual motion, could also be illustrated using the planetarium projector. A year ran in only 7 seconds, in one or in four minutes. The design of the projector was intended for viewing the starry sky from the latitude of Munich. Later models also allowed changing the apparent position on the Earth and showed the complete starry sky.

The projector was in operation until 1960, with interruptions due to World War II and building renovations, and has been on exhibition ever since.