What is light? Most astronomical objects are too far away to measure

directly. Light is the messenger of the Universe, carrying with it

information about objects as near as the Moon and as far away as the

most distant objects in the visible Universe. In this lecture we will

review the basic properties of light, the electromagnetic spectrum, the

inverse square law of brightness, and the Dopper Effect. Recorded 2007

Oct 22 in 1000 McPherson Lab on the Columbus campus of The Ohio State

University.