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Bering Sea

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Four hundred miles above the Earth’s surface, for nearly 40 years, Landsat satellites have collected data for the U.S. Geological Survey, for use in scientific research. “Earth as Art 3,” an exhibit on display at the Library of Congress in Washington, D.C., offers an opportunity to celebrate the more dramatic images for their artistic value rather than their data value.

The latest satellite, Landsat 7, uses an instrument that collects seven images at once, with each image showing a specific part of the electromagnetic spectrum, called a band. Humans cannot see light outside the visible spectrum, but satellites are able to detect wavelengths into the ultraviolet and infrared. The original images are acquired in black and white, so color must be assigned via computer. The three primary colors of light are red, green and blue, and each color is given a different band/image. Once the three images are combined, you will have what is called a “false color image.” One common combination shows green, healthy vegetation as bright red, which is handy in forestry and agricultural applications. Landsat images are used to gather all kinds of geological and hydrological data and for other types of environmental monitoring.

The Erongo Massif, an isolated, sheer-walled mountain that rises 1,200 meters (3,937 feet) above arid Namibian plains. The massif is a remnant of a gigantic volcano that was active roughly 150 million years ago. At some point, the volcano’s center collapsed in upon itself under the weight of overlying lava. Eons of erosion by wind and wind-blown sand gradually exposed the long-dead volcano’s core of granite and basalt.

Oxbow lakes and cutoffs accompany the Mississippi river south of Memphis, Tennessee, on the border between Arkansas and Mississippi, USA.

Much of Oman is desert, but the Arabian Sea coast in the Dhofar region represents a marked difference. This coastal region catches the monsoon rains, or khareef, during the summer months. Drenching rains fall primarily on the mountainous ridge that separates the lush, fertile areas along the coast from the arid interior, feeding streams, waterfalls, and springs that provide water in the fertile lowlands for the remainder of the year.

Massive congregations of greenish phytoplankton swirl in the dark water around Gotland, a Swedish island in the Baltic Sea. Phytoplankton are microscopic marine plants that form the first link in nearly all ocean food chains.

After beginning in northern British Columbia and flowing through Yukon in Canada, the Yukon River crosses Alaska, USA, before emptying into the Bering Sea.

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