It began with a basketball-sized bundle of technology called Sputnik 1. Launched by the Soviet Union on October 4, 1957, the world’s first artificial satellite was followed four months later by the first U.S. satellite, Explorer 1. The race into space was on, and with it came a new way of looking at the Earth. The first aerial photographs had been taken a century earlier by a French hot-air balloonist. Balloons were briefly used to gather military intelligence during the U.S. Civil War—until it became apparent that they were not immune to gunfire.

Other attempts to view the ground from on high included attaching tiny cameras to kites and even pigeons. But serious aerial photography didn’t begin until a passenger aboard an airplane piloted by co-inventor Wilbur Wright snapped the scene below in 1908.

By the end of the 20th century, more than 2,200 satellites were circling the planet, many of them providing steady streams of scientific data, along with views of the Earth never before imagined possible.

Satellites, combined with state-of-the-art imaging techniques, offer ordinary humans something heretofore found only among comic-book superheroes: the gift of super sight.

Remote sensing consists of using aerial photography and other methods to view what cannot be seen with the unaided eye. Various techniques allow the identification of soils, vegetation, mineral resources, seasonal crop growth, and changes brought about by storms and floods. Surface temperatures can be detected, revealing movements of groundwater, and even the nocturnal wanderings of animals by their heat shadows.

The key is the ability of remote-sensing devices to “see” energy in wavelengths not visible to the human eye, for example infrared bands. Different bands are arbitrarily assigned colors to produce “false-color” images—and new looks at an old world. Remote sensing, a stepchild of the space age, is prying out many of Earth’s innermost secrets.
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