Einstein Science Reporting for Kids
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American Association for the Advancement of Science

What do butterfly wings and TV screens have in common?

Dr. Peter Vukusic with several butterflies that each have special structures in their wing scales to reflect light in beautiful ways.
Click here for a high resolution photograph.

Many of the gadgets we use every day work by controlling the movement of light waves. CD and DVD players use lasers to read information off disks, allowing us to listen to music or watch movies. Optical fibers carry information signals long distances, in the form of light, allowing telephones and other devices to "talk" to each other.

Three different Papilio nireus.
Click here for a high resolution photograph.

As scientists are learning, nature has figured out how to control light in ways that rival some of the most sophisticated technologies made by humans. For example, researchers in the United Kingdom have discovered that the beautifully colored wings swallowtail butterflies of eastern and central Africa reflect and direct light using tricks similar to the ones used in TV and computer screens.

These swallowtail butterflies, whose scientific name is Papilio nereus, are black with patches of fluorescent greens and blues. Peter Vukusic and Ian Hooper of Exeter University report in the 18 November issue of the journal Science that this color comes from tiny structures in the scales that cover the wings.

These structures, called photonic crystals, have layers of atoms that are spaced precisely so that only certain wavelengths of light can travel through. The scales also contain mirror-like structures that help control the direction the light travels. When sunlight hits the wings, it's transformed into brilliant fluorescent blue and green light.

As Vukusic and Hooper discovered, the structures in these butterfly wings are quite similar to human-made technologies called "high-efficiency light emitting devices," which also precisely reflect and direct light. Light emitting devices, or "LEDs" are found in computer and television screens, street lights, and many other objects that light up but don't need conventional light bulbs.