What time is it? Telling time is the oldest practical application of
astronomy. Today's lecture is the first of a 2-part lecture on the
astronomical origins of our methods of keeping time and making
calendars. This lecture reviews the divisions of the year into the
solstices, equinoxes, and cross-quarter days, the division of the year
into months by moon phase cycles, months into weeks, and the division
of the day into hours by marking the location of the Sun in the sky
Recorded 2007 Oct 2 in 1000 McPherson Lab on the Columbus
campus of The Ohio State University.