MAS April Monthly Meeting

Theory and Observation in the Pseudo-Annular Eclipse reported near Vienna on 17 June 1433

Prof. Michael Shank

This talk analyzes a solar eclipse that is described as annular, but that other reports and modern calculations show to have been very total. I explore the reasons for this odd state of affairs, since most eclipse observers are impressed by the darkness, not what’s happening immediately around the Sun. I argue that the report comes from a theoretically sophisticated observer with access to a 14th c. annular eclipse report that shaped his observation, which was then used to refute the concentric-sphere astronomy of al-Bitruji, an influential 12-13th century Arab astronomer.

Michael H. Shank is Professor emeritus in the now-defunct Department of the History of Science at the UW-Madison, specializing in 14-15th-c. natural philosophy and astronomy. Most recently, he was Visiting Professor in the Department of History of Science at Tsinghua University (Beijing; fall 2017, fall 2019) and Visiting Fellow at the Institute for Advanced Study in the Humanities and Social Sciences, Zhejiang University (Hangzhou; fall 2018).

The April meeting will be a virtual event, hosted with Zoom. Members will receive an email with a link and instructions to join a day or two before the event. Again this month we are opening the virtual meeting up to our followers who may want to join in. If you would like to attend the MAS virtual meeting, send an email to by noon Friday, April 9 to let us know of your interest. We will email you the Zoom link at 3pm that day which will get you into the meeting by 7:30 on Friday evening.