"Why are there so many songs about rainbows?" sings Kermit the Frog in a song (about rainbows) called "Rainbow Connection" from 1979's "The Muppet Movie." And it's not just songs that feature rainbows ...

It is important to point out that we are not so much interested in dispersive prisms that split a beam of white light into its spectrum of colors, although they make great album covers.