Today in the history of astronomy, a groundbreaking planetarium opens in Germany. The world's first modern planetarium projector, the Zeiss Model I was made by German optics manufacturer the Carl Zeiss Company in 1923-24. Credit: Deutsches Musuem May 7, 1925, saw the debut of the projection planetarium at the Deutsches Museum in Munich, Germany. The first planetarium of its kind, it featured the Zeiss Model I projector, a triumph of engineering that projected 4,500 stars onto the dome – plus the Milky Way, the Sun, the Moon, and five of the planets. Its movements were driven by gears and motors operated by the educator narrating the program, giving it the ability to replicate the changing of the skies based on seasons and Earth rotation. The projection planetarium revolutionized astronomy education, helping the public standing inside the dome at the Deutsches Museum better understand the systems that made up the heavens.…