Grand Prismatic Spring, Yellowstone

Credit: Image by Robert Simmon, SSAI/NASA GSFC, based on data copyright Space Imaging, Posted on: Saturday, 29 May 2004, 06:00 CDT Download full size image

Yellowstone National Park contains the most concentrated array of hot springs and geysers in the world. The largest, and one of the most spectacular, springs in the park is the Grand Prismatic Spring. It is 90 meters (300 feet) across and 50 meters (160 feet) deep. In the center of the pool the water is 87° C (188° F)—too hot to support life. In the cooler water along the edges of the pool, however, colonies of thermophilic (heat-loving) cyano-bacteria and algae thrive. Yellow, orange, and red pigments are produced by the bacteria as a natural sunscreen. As a result, the pool displays a spectrum of colors from the bright blue of the center to the orange, red, and brown alagal mats along the edges. NASA scientists study Yellowstone’s hot springs because they may be similar to the environments where life first evolved on Earth.

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