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[music]

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A series of Landsat satellites have surveyed the Earth's surface since 1972.

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In that time, Landsat data have become a vital reference worldwide,

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used for understanding scientific issues related to land use and natural resources.

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However, some Landsat images are simply striking to look at,

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presenting spectacular views of mountains and valleys, forests and farms.

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To celebrate the 40th anniversary of Landsat, the U.S. Geological Survey

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and NASA asked for your help in selecting the top five Earth As Art images.

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Number Five – Lake Eyre

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Patches of shallow water in Australia's Lake Eyre resemble a skull.

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This ephemeral feature occurs in a flat, often parched landscape.

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Lake Eyre is Australia's largest lake – when it's full.

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However, in the last 150 years, Lake Eyre has only been full three times.

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Number Four – Algerian Abstract

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What looks like pale yellow streaks of paint

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slashing through a mosaic of mottled colors are ridges of wind-blown sand

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that make up a sea of sand extending from Algeria into Mauritania, in northwestern Africa.

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In this area of ever-shifting sand, one of several in the Sahara,

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individual dunes often surpass 500 meters –

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nearly a third of a mile – in both width and height.

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The light blue areas in the image are salt crusts left behind from the evaporation of the valley's water.

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Number Three – Meandering Mississippi

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Small blocky shapes of towns, fields, and pastures 

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surround the graceful swirls and whorls of the Mississippi River.

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Numerous oxbow lakes and cutoffs run along the 

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meandering river south of Memphis, Tennessee,

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on the border between Arkansas and Mississippi.

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The "Mighty Mississippi" is the largest river system in North America.

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Number Two – Yukon Delta

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Beginning in British Columbia and flowing through Yukon, in Canada,

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the Yukon River crosses Alaska before emptying into the Bering Sea.

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Countless lakes, sloughs, and ponds

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are scattered throughout this scene of the Yukon Delta.

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The sinuous, branching waterways resemble blood vessels reaching out to enclose an organ.

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It is one of the largest river deltas in the world,

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and is protected as part of the Yukon Delta National Wildlife Refuge.

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Number One – Van Gogh From Space

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In the style of Van Gogh's painting "Starry Night,"

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massive congregatinos of greenish phytoplankton swirl in the dark water around Gotland,

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a Swedish Island in the Baltic Sea.

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Phytoplankton are microscopic marine plants that form the first link in nearly all ocean food chains.

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Population explosions, or blooms of phytoplankton, like the one shown here,

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occur when deep currents bring nutrients up to sunlit surface waters,

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fueling the growth and reproduction of these tiny plants.

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[beep]

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