The Moon is our closest astronomical companion. Its orbit around the Earth gave us a basic unit of time: the month. Over the course of a month, the moon gradually changes from complete darkness to complete illumination. These phases give rise to a simple method for estimating the local time of day. Once we understand why the phases occur, and we notice where the moon is in relation to the horizon, we can estimate the time with coarse accuracy. Join us to learn from astronomical observer and math instructor at Coconino Community College, Dr. Lisa Foley, just how to tell the time by observing the moon.