Michael had a long-time interest in archaeoastronomy, which is the study of how ancient civilizations used astronomy (often called "the oldest science") to understand the world around them and bring meaning to their lives. Numerous examples exist of structures or buildings which have special alignments for solar (solstice, equinox) or lunar calendar events.
Perhaps the most famous of these is Stonehenge, in southern England. Shown at left is a photo of Michael's children (Rachel and David) standing next to Stonehenge in 1971 (in the days when one could still really stand next to and touch the stones), when we made a special trip from London, where Michael was on sabattical at Imperial College.
Michael's interest in these was far more than a modern "Gee whiz!" reaction, but one of an astronomer who wished to truly understand what these works represented. He wrote articles and gave lectures (colloqia and for general audiences) about archaeoastronomy.
There were some interesting facets to these. I (David) can remember his describing the positions at Stonehenge, for which some of the markings were for events in 54 year cycles, remarkable because (a) this was longer than the average lifespan at the time and (b) this for a society with no written records. [Writing this from teen-age memory; apologies for any inaccuracies in this. Errors are mine not his.]
As one can see from the Public Talks and Lectures page elsewhere on this site, he was giving talks on archaeastronomy at least as early as 1978 and as late as 2013 (two years before health matters curtailed his availability for public talks). His interest in archaeastronomy also led him to join the Wash U Center for Archaeometry in 1976, described here.
In addition, in 1985 he published a freshman astronomy text titled "Astronomy: From Stonehenge to Quasars." (See link below.) Most colleges require a science course as a "distribution requirement," "core," or "general education" curriculum, and astronomy is one of the most popular such offerings. The unusual aspect of this textbook was indeed its emphasis on archaeoastronomy, which was woven in throughout the book.
Astronomy of the Ancients
Washington University Magazine, Spring 1980
Astronomy: From Stonehenge to Quasars
Prentice-Hall, 1985, 589 pages.
Freshman astronomy text
The Cahokia Sun Circles
The Wisconsin Archeologist
2007 vol 88, pp 78-90