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Science, Evolution, and Creationism, by the National Academies, focuses on teaching evolution in today's classrooms. Check out the other publications in our online store.
These two photographs of a flower show how the evening primrose looks in two different wavelengths. The upper panel shows the flower as humans see it in visible light. The lower panel shows the primrose in UV, and reveals the "honey guides" (the dark areas) invisible to the human eye but seen by insects. The dark lines and patches guide the insect to the collection of nectar stored in the center and to the pollen on the anthers.
Image courtesy Dr. Jeremy Burgess, Science Source/Photo Researchers.

Ultraviolet (UV) Radiation

Some kinds of "light" are invisible to us. Ultraviolet (UV) "light" is one kind of "invisible light". UV is a type of electromagnetic radiation. Some light waves are shorter than others. Short light waves look purple or violet to our eyes. UV waves are even shorter than purple waves. If we could see UV light, it would look "more purple than purple". That's why it is called ultra-violet, or "beyond violet", light.

UV light from the Sun can cause sunburns. Fortunately, our atmosphere blocks most UV radiation from space. The ozone layer of Earth's atmosphere blocks a lot of the UV.

UV radiation carries more energy than normal light. X-rays have even more energy than UV light. X-rays come after UV along the electromagnetic spectrum.

Last modified May 17, 2010 by Randy Russell.

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Windows to the Universe, a project of the National Earth Science Teachers Association, is sponsored in part by the National Science Foundation and NASA, our Founding Partners (the American Geophysical Union and American Geosciences Institute) as well as through Institutional, Contributing, and Affiliate Partners, individual memberships and generous donors. Thank you for your support! NASA AGU AGI NSF