This article serves as Earthshots' introduction. Earthshots introduces remote sensing by showing before/after image pairs of various environmental events. It explains the events themselves, and how we see them from satellites. The example shown here is the multiplication of "center pivot" irrigation-- essentially enormous sprinkler systems-- in Kansas between 1972 and 1988.
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This image shows the area around Garden City, Kansas in 1972. To see the same area 16 years later, click on the "1988" in the caption below the image. Try switching between 1972 and 1988. Try the map. Try zooming in (click inside the yellow brackets) and zooming out (click outside/without the yellow brackets).
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As this chart shows, Landsat images show how much energy from the sun (electromagnetic radiation) was reflecting off the Earth's surface when the image was taken. Clear water reflects little radiation, so it looks black. Pavement and bare ground reflect a lot of radiation, so they look bright. Urban areas usually look light blue-gray. Vegetation absorbs visible light but reflects infrared, so it looks red. This is a customary way to show satellite images.
(Some images have black "zero fill" at the corners, because the Landsats do not fly straight north-south. Most images are color-adjusted and reduced-resolution.)
For more details, read the help article on EMR represented by RGB.
These Landsat images center on Finney County, in southwestern Kansas. Garden City is centered in the brackets, with Lake McKinney west of town, and the Arkansas River just south of town flowing eastward. From 1972 to 1990 Garden City's population grew from about 15,000 to about 24,000.1
Much of the former shortgrass prairie of western Kansas is now irrigated cropland. Common crops in this area are corn, wheat and sorghum. Red areas in the images are healthy vegetation. Light-colored cultivated fields in the images are fallow or recently harvested wheat fields.
These images show center-pivot irrigation systems (the small circles) multiplying between 1972 and 1988. From 1969 to 1987, irrigated acreage in Kansas increased by 62%, from 1.5 million acres to 2.4 million acres. In only the years 1984-1988, Kansas farms with center-pivot irrigation systems increased 19%, from 2,630 farms to 3,122 farms. As of 1987, Finney County led the state in irrigated acreage, with 184,177 acres.2
This area utilizes irrigation water from the Ogallala Aquifer, which underlies an area from Wyoming to Texas. Landsat images are useful for measuring irrigated crop acreage, a key component of modeling aquifer response to changes in water use.
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1. The population figures are estimated from these data for the town of Garden City: Merriam Webster's New Geographical Dictionary, 1980: 1970c est. 14,790. Encyclopedia Britannica, 15th edition, 1988: 1982 est. 20,082. U.S. Census: 1990 24,097.
2. Rajinder S. Bajwa and others, 1992, Agricultural irrigation and water use: Washington, D.C., USDA Economic Research Service, Agriculture information bulletin no. 638.
Billard, Jules B., and Blair, James, P., 1970, The revolution in American agriculture: National Geographic Magazine, vol. 137, no. 2, February, p. 147-185.
The Exploratorium. Electromagnetic Spectrum (San Francisco: The Exploratorium, 1991), 85 x 61 cm color chart.
N. M. Short, P. D. Lowman Jr., S. C. Freden and W. A. Finch Jr. Mission to Earth: Landsat Views the World Washington, D.C.: National
Aeronautics and Space Administration, NASA SP-360, 1976) 459 pp.
Linda Spizzirri, ed. An Educational Coloring Book of Satellites (Medinah, Illinois: Spizzirri Publishing Co., Inc., 1986), 30 pp.
Thelin, Gail P. and Heimes, Frederick J., 1987, Mapping irrigated cropland from Landsat data for determination of water use from the High Plains Aquifer in parts of Colorado, Kansas, Nebraska, New Mexico, Oklahoma, South Dakota, Texas, and Wyoming: U.S. Geological Survey Professional Paper 1400-C.
U. S. Geological Survey. Historical Landsat data comparisons; illustrations of the Earth's changing surface (1995) 45 p.
U. S. Geological Survey. Landsat Data Users Handbook (1979) 207 pp.
U. S. Geological Survey, and National Oceanic and Atmospheric Administration. Landsat 4 Data Users Handbook (1984) 244 pp.
Zwingle, Erla, and Richardson, Jim, 1993, Ogallala aquifer: wellspring of the high plains: National Geographic Magazine, vol. 183, no. 3, March, p. 80-109.
LM1032034007222990 (Landsat 1 MSS, 16 August 1972)
LM5030034008822890 (Landsat 5 MSS, 15 August 1988)
The world mosaic used in Earthshots was compiled at USGS EROS from AVHRR scenes acquired 21-30 June 1992 by the NOAA 11 satellite. The band combination is AVHRR 2 1 1, to approximate the band combination MSS 4 2 1. Antarctica was added to the image later as a plain white mask.
U.S. Geological Survey, 1984 (compiled in 1961, edition of 1984), State of Kansas: scale 1:500,000.
Mosaicked maps: U.S. Geological Survey, 1975 (1955, revised 1975), Scott City, Kansas: scale 1:250,000. U.S. Geological Survey, 1975 (1955, revised 1975), Dodge City, Kansas: scale 1:250,000.
The maps in Earthshots labeled "commercial maps" are from Digital Wisdom Inc., 1995, Mountain High Maps: Tappahannock, Va., Digital Wisdom. Copyright 1995 Digital Wisdom Inc. (The use of any trade, product, or firm name in this work is for descriptive purposes only and does not imply endorsement by the U.S. Government.)
The photographs for this article were taken on 12 March 1998 by Robb Campbell, USGS, with Peter Devincentis, USGS.
Campbell, Robert Wellman, ed. 2000. "Garden City, Kansas: 1972, 1988." Earthshots: Satellite Images of Environmental Change. U.S. Geological Survey. http://earthshots.usgs.gov. This article was first released 14 February 1997, and last revised 14 August 2000.
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