Desert Diary
May 11, 2004

Physics/Green

     

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In a way, it's kind of ironic that we tie together in our minds the color green and the process of photosynthesis, the capture of light and its conversion into chemical energy. The irony is that we see plant leaves as green because the plants AREN'T using the green wavelengths of light for photosynthesis. Except when we're looking at something that emits light or passes light through it, the colors we see are those that are reflected rather than being absorbed. And to capture the energy of light, plant pigments have to absorb the light; the green light is, so to speak, the discard.

In school, often a big fuss is made about white not being a color. Although this is really only a matter of semantics, teachers are trying to make the point that white light is made up of the wavelengths of all of the colors we can see. The reflected sunlight from an object perceived as being of a given color is such because the other sunlight colors have been absorbed, and we're seeing the leftovers.

Contributor: Arthur H. Harris, Laboratory for Environmental Biology, Centennial Museum, University of Texas at El Paso.

Desert Diary is a joint production of the Centennial Museum and KTEP National Public Radio at the University of Texas at El Paso.

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