Off topic(?):
One day in college I walked into class while the prof was still cleaning up from the previous class. He had a spin-top laying on a table and I joked about how hard his other class must be. The top had a black and white checkered patern on it. He told me to spin it. The rainbows that appeared blew me away. When I asked what caused this he said no one really knew. He went on to say that if a picture of that was shown on a black & white TV, the rainbows appeared in full color.
Neat, huh?
John