In 1912, Oskar von Miller had the idea of projecting an artificial starry sky onto a dome to demonstrate astronomical principles to the public. Despite initial skepticism from the Carl Zeiss company, engineer Walther Bauersfeld created a groundbreaking planetarium projector. The projector displayed the stars, planets, and constellations in realistic movements. The Zeiss Model I projector was demonstrated in 1923 and officially opened in 1925 at the Deutsches Museum. This innovation quickly spread worldwide, with planetariums becoming popular tools for science education. The Zeiss company continued to develop advanced planetarium technology, with over 4,000 planetariums now in operation globally.
https://spectrum.ieee.org/planetarium-history