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Our Glaciers: Then and Now activity kit helps you see the changes taking place in glaciers around the world. See all our activity kits and classroom activities.
On average, people in the U.S.A. are exposed to about 3.6 milliSieverts of radiation each year.
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Windows to the Universe original artwork using data from the National Council on Radiation Protection and Measurements.


Radiation comes in two basic types: electromagnetic radiation transmitted by photons, and particle radiation consisting of electrons, protons, alpha particles, and so forth.

Electromagnetic radiation, transmitted as photons, includes everything from relatively benign radio waves to dangerous and powerful X-rays and gamma rays. Energy levels across the electromagnetic spectrum vary inversely with wavelength.

Particle radiation involves fast-moving sub-atomic particles, such as electrons, protons, and nuclei (ions) of Helium and heavier elements.

Exposure to too much radiation of various types can be harmful to humans and other living things. Radiation can also fry the electronics in spacecraft, disabling them.

Last modified October 27, 2006 by Randy Russell.

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Our online store includes fun classroom activities for you and your students. Issues of NESTA's quarterly journal, The Earth Scientist are also full of classroom activities on different topics in Earth and space science!

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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