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Earth as Art

02.12.04

Satellites in space have a great view of Earth. They take pictures that scientists use to study our planet. Many of these pictures are also just fun to look at. Earth as Art is a Web site that has a lot of cool pictures taken by NASA satellites. Like this one of mountains in China.

 Mountains in China

And this one of sand and seaweed in the Bahamas.

 Sand and Seaweed in Bahamas

But why do these pictures look more like paintings than what we would see with our own eyes? Well, because satellites don't see light like we do.

Just like sound, light travels as waves of different sizes. The size of a wave is determined by its wavelength. Wavelength is the distance from one wave crest to the next. For example, red light has a larger wavelength than blue light. Different objects on Earth (plants, soil, water, etc.) reflect different wavelengths of light.

 A Wavelength Cycle

Satellites can't see colors of light like we can. But they can measure the amount of light reflected at different wavelengths. These measurements are sent back to Earth as numbers.

Computers then use these numbers to create several pictures in black and white. Each picture is of the exact same area. But each one shows the amount of light reflected at a different wavelength. The more light an object reflects, the brighter that spot is in the picture.

There are three steps left to making an Earth as Art picture. First, three of the black-and-white pictures are chosen. Then, each one is shaded in a different color -- red, green or blue. And last, the pictures are combined.

Poof! ... A work of art!

 A Sample of Images Shaded in Red, Green, and Blue and then Combined to Make a New Picture

Earth as Art Web site
http://landsat.gsfc.nasa.gov/earthasart

Related Resources
Imagers
http://imagers.gsfc.nasa.gov/student.html

Alaska: A Bird's Eye View
http://www.uaf.edu/asgp/k12

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