How do we make calendars? This lecture explores the astronomical
origins of our calendars. We start by discussing lunar and solar
calendars and their hybrids in history and tradition (for example, the
Islamic Lunar Calendar and the Hebrew Luni-Solar Calendar), and then
describe the Julian and Gregorian Calendar reforms that attempt to align
the calendar with the seasons of the year with greater degrees of
precision. Recorded 2007 Oct 3 in 1000 McPherson Lab on the Columbus
campus of The Ohio State University.