German astronomer (1898–1974), professor at the University of Munich and former director of the German Society for Space Research (1952–1955). Co-editor of Astronautica Acta, he was among the pioneers who helped institutionalize space research in Europe. A member of the Royal Astronomical Society, he published several popular works including Welcher Stern ist das? (1955) and Die Weltraumfahrt hat begonnen (1958), the first comprehensive treatment of astronautics in the German language. His research focused on astrometry and theoretical astronomy, where he developed new methods for observing stellar transits.