h2g2 The Hitchhiker's Guide to the Galaxy: Earth Edition

Yellow appears to be the brightest chromatic hue even though there are no yellow sensitive cone cells in the retina because it is generated as a perception, rather than a sensation, when approximately equal numbers of red and green sensitive cones in the retina are stimulated simultaneously, producing approximately twice the neurological signal strength required for a simple sensation of red or green.

A similar mechanism makes cyan, or sky blue, the next brightest color, since its in a range where the sensitivities of the green and sensitive cones in the retina overlap.




A psychological observation, having to do with porta-potties, if they're crafted in a translucent yellow, they're much more cheerful inside, seem warmer and one notices the odor less than with the more common green and blue plastic porta-potties.

Metallic sheens in hair (or feather) color are due to diffraction effects which depend on scales on the surface of of the hair in resonant harmony with the given wave length of light.

Purplish overtones indicate a smaller scale size than blue, which is markedly smaller than
golden or red sheens.

Greens of the character are much more common with birds and insects than with mammals.

The yellow of the common yellow oxalis flower is due to a flavinoid.

If one makes a ball of the yellow petals, kneading them together and rolls it across blotting paper or filter paper saturated in neutral purple anthoxanthin, say from a red cabbage, the ball will turn a vivid crimson.

The red color of rhubarb is a similar flavonoid produced by similar variations in ph.