Researchers use different wavelengths to reveal features not visible in white light.
"Do you see what I see?": A lesson about the astronomical imaging, how to build a color wheel, and online activities seeing the Crab Nebula at different wavelengths. -light-science.html
"Star Light, Star Bright" activity has good background information on waves and excellent electromagnetic spectrum diagram. ace/lfs/emspectr.html
Explains the electromagnetic spectrum through puzzles and question and answer format in easy to understand terms. ience/know_l1/emspectrum.html
Excellent background information on the electromagnetic spectrum with links to activities and a quiz on the electromagnetic spectrum.
NASA's Infrared Processing and Analysis Center's Infrared Astronomy: a terrific site providing background information on infrared astronomy from the days of Herschel to the present. Great infrared images! c/EMSpec.html
Great graphic on the electromagnetic spectrum, and interesting at home experiment on infrared radiation using a TV remote.