100 years ago today, on May 10, 1925 (April 18, 1925 lunar calendar), the world's first planetarium was completed and opened in Munich, Germany. On May 10, 1925, the world's first planetarium was completed and opened in Munich, Germany. This planetarium is part of the Deutsches Museum. The Deutsches Museum is one of the largest science and technology museums in Europe and one of the first in the world. The museum contains about 28,000 exhibits in 50 fields of science and technology, attracting about 1.50 million visitors every year. The planetarium on the top floor is the world's first planetarium and the world's first projection planetarium. The projector used is a masterpiece of technology at the time. It can display constellations, galaxies and nebulae that can be seen in the northern and southern hemispheres. This part describes in detail the development process from ancient Greek astronomy represented by geocentric theory to new astronomy represented by heliocentric theory in the era of Copernicus and Galileo. There is a Zeiss telescope with an aperture of 30 cm and a focal length of 5 meters. It is the place that attracts the most children.