Serving Astronomy: the Aim of the IAU

The IAU was founded in 1919 “to facilitate the relations between astronomers of different countries where international co-operation is necessary or useful” and “to promote the study of astronomy in all its departments.” These aims have led the IAU throughout the century of its existence, but the way it has tried to fulfill them has changed. Johannes Andersen, Claus Madsen and I have tried to trace the changing role of the IAU in the international astronomical community through the twentieth century and into the twenty-first. The IAU has striven – occasionally struggled – to protect international scientific cooperation across the deep political divides that characterized the 20th century, while maintaining an important function in the context of the rapidly evolving science itself and the changing fabric of institutions involved in astronomy. We especially argue how the emphasis of the IAU’s activities has shifted from the first aim – facilitating collaboration by organizing meetings and defining common standards – to the second aim: promoting astronomy by outreach and development programs.