THE LIGHT DOCTOR 3: Clockwork Blue

Chapter 3 reveals that a narrow band of blue light has been the key day-night signal ever since life began deep in the oceans.

The light that illuminates us, whether it is sunlight, or from electric light or a candle, is composed of a rainbow mix of colors which fuse together to form the white or yellowish color we normally observe. We only get to see the beautiful array of the separated colors of the rainbow when sunlight falls on a piece of crystal, or on raindrops in the sky…