The International Astronomical Union (IAU) was founded in 1919, in the wake of the First World War, together with its sister Unions in related natural sciences. It will thus turn 100 years in 2019. Written by a mixed team of insiders and outsiders, this book presents the IAU in the changing context of the historical, scientific and technological development of astronomy during the past 100 years. While much important scientific progress took place already before 1945, the book naturally focuses on the accelerating evolution during the second half of the century. In the past few decades, the previously narrow IAU focus on organising professional astronomy has broadened to include societally relevant activities such as addressing the hazard of asteroid impacts, the planetary status of Pluto in the Solar System, and the hugely successful International Year of Astronomy. Most recently, it is spearheading a combination of science literacy and public outreach. The book will be of interest to professional astronomers as well as an astronomically interested general audience. The book features live personal interviews with as many of the key actors as still possible.

Authored by ESO senior advisor Claus Madsen, the present book comprises 576 action-packed pages of ESO history and dramatic stories about the people behind the organisation. This is the ultimate historical account about ESO and its telescopes in the southern hemisphere, but also about a truly remarkable European success story in research. Spanning the range from the first telescopes to the future platforms of the next generation, it shows how the improvement of the telescopes leads to a continuously changing view of the Universe. With 150 photos and illustrations. Produced especially for ESO's 50th anniversary.