1913: The history of the modern projection planetarium started with Oskar von Miller (1855-1934), the founder of the Deutsches Museum in Munich, searching for an attraction for its astronomical section. He turned to the astronomer Max Wolf (1863-1932) in Heidelberg who suggested a public show that demonstrated the motions in the sky. Originally, Wolf thought of a rotating sphere of stars with the visitor in the centre while the happenings occurred in time lapse. The antetype was the Atwood Globe presented just in the previous year. Miller approached the Carl Zeiss Company in Jena with this thought.

1926: While the engineers at Zeiss still worked on the first model, a next generation was conceived. It should be free of constraints like invariable latitute. Instead, it would be an all-purpose device for any place on Earth and easily swing to Southern skies, for example. The objects below the local horizon would be masked by a bezel. The idea envisaged two separate star spheres, one for each hemisphere. It was realised by the dumbbell-design, the so-called "Mark-II". Each sphere scaled 75 centimeters in diameter and was connected by a bridge that enclosed the planetary projectors. This bridge was also the main axis mounted on a pivot. The design of the Mark-II should coin the appearance of the planetarium projectors for the next decades.

1926: In the first year after the opening in Munich, a boom set in. Many cities wanted to have a planetarium and competed against each other for priority. Leipzig was the second city to open, but delays occured because of long negotiations about the location and construction. Zeiss already manufactured the better model, Mark-II, and they could not meet the demands. When the first Mark-II was ready for installation, the dome in Leipzig was not. So, the company decided to deliver it to the next one on its long list, and this was Barmen (today: Wuppertal). It opened on 18th May, 1926, and had a huge dome of 24.6 meters (image). Just two days later, Leipzig inaugurated its facility with the next copy of the Mark-II. Dusseldorf was also eager to get the honour of being among the first ones, and it had its dome already finished, but its booking of the projector was later. The mayor urged and asked the previous cities to cede their priority. As this failed, Zeiss gave its second copy of the Model-I temporarily to Dusseldorf. So, it opened 5 days after Barmen with the largest dome of almost 30 meters. Alone in 1926, six new planetaria were inaugurated.

1937: The first projector not manufactured by Zeiss was constructed by the brothers Frank and John Korkosz in Springfield, Massachusetts. It was a sphere of 1 meter and displayed 7150 stars down the the 5th magnitude but no planets. The star fields were arranged on 41 individual plates. The projector went into service on October 10th, 1937. It exhibits an incredible robustness and is one of the oldest still operating machines in the world. While John handled the technical details about the instrument, Frank devoted himself to the public presentations. In the course of the following two decades he conducted more than 10,000 shows and gained a widely known reputation. His brilliant star demonstrations reached nearly 1 million people. In 1958, Frank became director of the Springfield Museum of Natural History.

1919: The first technical draft of a star projection on a dome is credited to Wilhelm Finke (1884-1950) in Bremen. He obtained the first patent on the idea in 1919. He wrote letters to seven companies asking for a cooperation, including Zeiss in Jena. Unfortunately, he did not find partners to build the device. One year later, Walther Bauersfeld brought the planetarium into life while following the former request of the Deutsches Museum: Instead of revolving the large sphere as in the Atwood Globe, a small sphere in the centre would display the stars on the inner surface of the larger one. The smaller sphere would be equipped with tiny projectors and rotate parallel to the axis of the World. This is the planetarium with the opto-mechanical projector we know today. His patent contained the technical realisation, but not the idea which was already attributed to Finke. The technical details of Bauersfeld's script accumulated to more than 600 pages. A large staff of engine builders, opticians and electricians was commissioned for its realisation.