If you're lucky enough to see the secondary fainter rainbow just above the first, you might wonder why it's colours are reversed?

Transcript -- The colours of the rainbow

For centuries the rainbow has been an object of wonder for scientists and mathematicians. It has taken 2000 years to discover many of its secrets. This five track album uses 3D imagery to explain exactly how light is deflected off rain droplets to form the bow like shape we see. This material forms part of The Open University course MU120 Open mathematics.