Monday (July 23) marked the 40th anniversary of NASA's Landsat satellites, a series of earth observation satellites intended to inform scientists about land use and natural resources.
They also capture some impressive images, made even more eye-popping when enhanced with color. For the anniversary, folks at the U.S. Geological Service took 120 images from 40 years of satellite fly-bys, applied a "digital palette" and asked the public to pick their favorites. Below are the top 5, with descriptions by NASA:
Fifth place: The scary face in this image is actually inundated patches of shallow Lake Eyre (pronounced "air") in the desert country of northern South Australia. An ephemeral feature of this flat, parched landscape, Lake Eyre is Australia's largest lake when it's full. However in the last 150 years, it has filled completely only 3 times. Taken Aug. 5, 2006.
Fourth place: What look like pale yellow paint streaks slashing through a mosaic of mottled colors are ridges of wind-blown sand that make up Erg Iguidi, an area of ever-shifting sand dunes extending from Algeria into Mauritania in northwestern Africa. Erg Iguidi is one of several Saharan ergs, or sand seas, where individual dunes often surpass 500 meters (nearly a third of a mile) in both width and height. Taken April 8, 1985.
Third place: Small, blocky shapes of towns, fields and pastures surround the graceful swirls and whorls of the Mississippi River, the largest river system in North America. Countless oxbow lakes and cutoffs accompany the meandering river south of Memphis, Tennessee, on the border between Arkansas and Mississippi. Taken May 28, 2003.
Second place: Lakes, sloughs and ponds are scattered throughout this scene of the Yukon Delta in southwest Alaska. One of the world's largest river deltas, and protected as part of the Yukon Delta National Wildlife Refuge, the river's sinuous waterways seem like blood vessels branching out to enclose an organ. Taken Sept. 22, 2002.
First place: In the style of Van Gogh's painting "Starry Night," massive congregations of greenish phytoplankton swirl in the dark water around Gotland, a Swedish island in the Baltic Sea. Population explosions, or blooms, of phytoplankton, like the one shown here, occur when deep currents bring nutrients up to sunlit surface waters, fueling the growth and reproduction of these tiny plants. Taken July 13, 2005.
Photo credits: NASA's Goddard Space Flight Center/USGS. Descriptions by Ellen Gray of NASA's Earth Science News Team.