This program uses mathematical models to explain how light produces color in rainbows. Models developed by Aristotle, Newton, and others calculate the angle in which light travels. Bacon’s model establishes the reflection of light at a fixed 42-degree exit angle from the rainbow’s arch; a later model shows how light refracts within color “cones” to produce the spectrum, and how the colors are conveyed to observers by angles of elevation. Calculations by Newton and Descartes explain the dark band observed in mid-spectrum. Produced by the Open University. (25 minutes)