The Heidelberg Joint Astronomical Colloquium this summer semester takes place on Tuesdays at 16:30 in the Grand Lecture Hall of Philosophenweg 12. The colloquium is organised jointly by the Center for Astronomy at Heidelberg University (ZAH), the Max Planck Institute for Astronomy (MPIA), the Max Planck Institute for Nuclear Physics (MPIK), and the Heidelberg Institute for Theoretical Studies (HITS).