4.3.2026
On February 28th, we celebrated the retirement of Prof. Joachim Wambsganss, long-serving director of the Astronomisches Rechen-Institut (ARI) and a deeply valued member of the Department of Physics and Astronomy at Heidelberg University.
In the historic Alte Aula, the ARI organized a truly memorable Festkolloquium entitled “Gravitational Lensing” in his honor — a fitting title for a scientist whose name has become known worldwide with microlensing research and the study of quasars. Right at the beginning of his Heidelberg years, Joachim also participated in the founding of the ‚Zentrum für Astronomie der Universität Heidelberg‘ (ZAH), which has grown into Germany’s largest university center for astronomy — a remarkable structural legacy.
Joachim has always believed that science should be shared with the general public. It was therefore especially meaningful to recall his role in establishing the now widely appreciated “Akademische Mittagspause” by launching the so-called “Halbe Heidelberger Sternstunden”, a series of 70 short public lunchtime talks held at Heidelberg’s Peterskirche, presenting current topics in astronomy to a broad audience. This initiative reflects what has always defined him: intellectual generosity, accessibility, and genuine enthusiasm for discovery.
From 2014 to 2020, he served first as Vice President and then as President of the Astronomische Gesellschaft (AG, German Astronomical Society), strengthening international collaboration and representing the astronomical community with dedication and integrity. A particularly moving highlight came at the end of the ceremony: Prof. Stefanie Walch-Gassner, current President of the Astronomische Gesellschaft, appointed Joachim Wambsganss an Honorary Member of the society — a rare distinction and a powerful sign of the esteem in which he is held across the community.
For over two decades, Joachim Wambsganss and Prof. Eva Grebel jointly led the ARI with vision, steadiness, and a deep commitment to excellence. The event was thoughtfully organized and nicely introduced by Prof. Dominika Wylezalek, who now succeeds him in co-leadership at the ARI, and wonderfully moderated by Dr. Mark McCaughrean (MPIA Heidelberg), creating an atmosphere that was both celebratory and heartfelt.
Joachim’s scientific achievements and his impact as a mentor, collaborator, and leader were warmly acknowledged by an impressive group of international colleagues, many former postdoctoral researchers and doctoral students, and long-time companions, including Prof. Shude Mao (Westlake University, China), Prof. Paul Schechter (MIT), Prof. Eva Grebel (ARI/ZAH), Prof. Martin Roth (Leibniz Institute for Astrophysics Potsdam, AIP), Prof. Hans Zinnecker (Universidad Autónoma de Chile), Prof. Timo Anguita (Universidad Andrés Bello, Chile), Dr. Janine Fohlmeister (AIP), Dr. Robert Schmidt and Dr. Markus Hundertmark (ARI/ZAH), and Prof. Ralf Klessen (ITA/ZAH).
From the Faculty’s perspective we express our sincere gratitude. Joachim Wambsganss is not only an outstanding scientist, but also an inspiring leader and a truly cherished colleague. His legacy will continue to shape astronomy in Heidelberg and far beyond. We thank him wholeheartedly and wish him all the very best for this new chapter - officially starting on 1st of April.
