When Anton Pannekoek left Dutch astronomy in 1905, he left a stagnating, uninspiring research community. When he returned a decade later, things started to change in the Dutch astronomical community. By the mid-1920s, De Sitter, Hertzsprung, Oort, Minnaert, and Pannekoek had built a flourishing discipline. Through their work and students, they shaped Dutch astronomy for the rest of the twentieth century. This paper focuses on Pannekoek’s return to astronomy and his role in Dutch astronomy in the Interwar period. First, I will provide a detailed reconstruction of his failed appointment at Leiden Observatory in 1918-1919. After that, I will analyse how he could play an influential role, even though he had little staff, students, or facilities at the University of Amsterdam.

Professor M.G J. Minnaert director of the observatory at Sonnenborgh, Utrecht, from 1937 to 1963, died on October 26, 1970, at the age of seventyseven.

A deserted tower at the Uithof Campus of Utrecht University used to be an astronomical observatory, purpose-built for Marcel Minnaert’s famous undergraduate course in practical astronomy. The tower, which was opened in 1964, has hardly been used, however. This was in part because of unforeseen campus development, but also because of shifting teaching priorities. This paper reconstructs the history of Minnaert’s ‘Sterrentoren’, which illustrates how failed observatories can shed as much light on the history of astronomy as successful ones.