Infrared waves are just like visible light, except longer . . . too long for our eyes to see. Our eyes see light waves that are not too short, not too long, but just right within a tiny range of sizes. Infrared waves are too long for our eyes to see, but warm objects are sending them out all the time. So we see light from a lightbulb, but we don't see the heat from the lightbulb. As you can see, things "look" very different in infrared. All we need is a special infrared-detecting instrument. If we could put such an instrument in orbit around Earth, we could find out all kinds of useful things. ASTER (which stands for Advanced Spaceborne Thermal Emission and Reflection Radiometer) was launched into orbit on December 18, 1999. Information from ASTER will be used to . . .   study oceans, lakes, and rivers observe volcanos, especially ones near cities and villages look for things in the ground, such as metals, oil, water, and earthquake faults help keep track of glaciers, which are like rivers of solid ice. ASTER will show whether they are melting, growing, or moving. This picture of Lake Tahoe (on the California/Nevada border) was taken from an aircraft. But the colorful part of the lake is an infrared image that has been color-enhanced. Purple and blue show the coldest parts of the lake, while yellow and red are the warmest.

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