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Did you know that even the most colorful butterfly actually has NO COLOR? Most objects that we see have color because it contains pigments that reflect the color. Butterfly wings are made of transparent chitin molecules. The colors come about because it bends the light to reflect in different ways. The spacing and stacking pattern of the chitin determines the color that is reflected. This is called STRUCTURAL COLOR (as opposed to pigmented color) It is much like colors you see on a soap bubble. The bubble is transparent, yet you can see colors on the bubble… only on a butterfly it’s on a much smaller scale.... and there are millions of them.
How can sunlight turn into so many different colors? It’s the same concept as a rainbow. Sunlight looks white, but is made up of seven colors. When the light passes through water or a prism, the light bends. Some colors bend faster than others so they bend at different angles, thereby causing the light to split into the seven colors, creating a rainbow. With the butterfly, the light is bent in many different directions and angles that it cancels out some colors. Light is basically made of energy that travels in waves. When the top of the wave meets the bottom of a wave of equal size, the cancel each other out. The chitin bends the light this way and that, and cancelling out some colors. What is left is the color that you see. Because the angle of that the light hits the wings changes when the butterfly is flying, the colors slightly shift while the butterfly is in flight. This is called iridescence. This color shift throws of predators thereby adding protection to the butterfly.
Some butterflies, such as the glass wing butterfly truly look transparent. In the picture on the left, you can see it does look transparent. The chitin is arranged in such a way that no cancellation of light is occurring.
So next time you see a butterfly, take a good look at its shifting colors.. but don’t touch!