WEBVTT FILE 1 00:00:00.010 --> 00:00:02.130 2 00:00:02.150 --> 00:00:12.490 [music] 3 00:00:12.510 --> 00:00:17.380 A series of Landsat satellites have surveyed the Earth's surface since 1972. 4 00:00:17.400 --> 00:00:22.119 In that time, Landsat data have become a vital reference worldwide, 5 00:00:22.140 --> 00:00:27.230 used for understanding scientific issues related to land use and natural resources. 6 00:00:27.250 --> 00:00:28.080 7 00:00:28.100 --> 00:00:31.900 However, some Landsat images are simply striking to look at, 8 00:00:31.920 --> 00:00:37.580 presenting spectacular views of mountains and valleys, forests and farms. 9 00:00:37.600 --> 00:00:41.900 To celebrate the 40th anniversary of Landsat, the U.S. Geological Survey 10 00:00:41.920 --> 00:00:48.130 and NASA asked for your help in selecting the top five Earth As Art images. 11 00:00:48.150 --> 00:00:49.930 12 00:00:49.950 --> 00:00:53.030 Number Five – Lake Eyre 13 00:00:53.050 --> 00:00:57.680 Patches of shallow water in Australia's Lake Eyre resemble a skull. 14 00:00:57.700 --> 00:01:02.180 This ephemeral feature occurs in a flat, often parched landscape. 15 00:01:02.200 --> 00:01:06.260 Lake Eyre is Australia's largest lake – when it's full. 16 00:01:06.280 --> 00:01:10.940 However, in the last 150 years, Lake Eyre has only been full three times. 17 00:01:10.960 --> 00:01:11.679 18 00:01:11.700 --> 00:01:14.930 Number Four – Algerian Abstract 19 00:01:14.950 --> 00:01:18.330 What looks like pale yellow streaks of paint 20 00:01:18.350 --> 00:01:22.479 slashing through a mosaic of mottled colors are ridges of wind-blown sand 21 00:01:22.500 --> 00:01:28.990 that make up a sea of sand extending from Algeria into Mauritania, in northwestern Africa. 22 00:01:29.010 --> 00:01:32.980 In this area of ever-shifting sand, one of several in the Sahara, 23 00:01:33.000 --> 00:01:36.480 individual dunes often surpass 500 meters – 24 00:01:36.500 --> 00:01:39.860 nearly a third of a mile – in both width and height. 25 00:01:39.880 --> 00:01:46.580 The light blue areas in the image are salt crusts left behind from the evaporation of the valley's water. 26 00:01:47.600 --> 00:01:48.580 27 00:01:48.600 --> 00:01:52.410 Number Three – Meandering Mississippi 28 00:01:52.430 --> 00:01:56.580 Small blocky shapes of towns, fields, and pastures 29 00:01:56.600 --> 00:02:00.740 surround the graceful swirls and whorls of the Mississippi River. 30 00:02:00.760 --> 00:02:04.850 Numerous oxbow lakes and cutoffs run along the 31 00:02:04.870 --> 00:02:06.900 meandering river south of Memphis, Tennessee, 32 00:02:06.920 --> 00:02:09.979 on the border between Arkansas and Mississippi. 33 00:02:10.000 --> 00:02:11.060 34 00:02:11.080 --> 00:02:16.140 The "Mighty Mississippi" is the largest river system in North America. 35 00:02:16.160 --> 00:02:17.780 36 00:02:17.800 --> 00:02:21.190 Number Two – Yukon Delta 37 00:02:21.210 --> 00:02:25.240 Beginning in British Columbia and flowing through Yukon, in Canada, 38 00:02:25.260 --> 00:02:29.410 the Yukon River crosses Alaska before emptying into the Bering Sea. 39 00:02:29.430 --> 00:02:33.090 Countless lakes, sloughs, and ponds 40 00:02:33.110 --> 00:02:35.770 are scattered throughout this scene of the Yukon Delta. 41 00:02:35.790 --> 00:02:41.950 The sinuous, branching waterways resemble blood vessels reaching out to enclose an organ. 42 00:02:41.970 --> 00:02:46.130 It is one of the largest river deltas in the world, 43 00:02:46.150 --> 00:02:50.310 and is protected as part of the Yukon Delta National Wildlife Refuge. 44 00:02:50.330 --> 00:02:51.690 45 00:02:51.710 --> 00:02:55.480 Number One – Van Gogh From Space 46 00:02:55.500 --> 00:02:58.670 In the style of Van Gogh's painting "Starry Night," 47 00:02:58.690 --> 00:03:03.540 massive congregatinos of greenish phytoplankton swirl in the dark water around Gotland, 48 00:03:03.560 --> 00:03:07.020 a Swedish Island in the Baltic Sea. 49 00:03:07.040 --> 00:03:13.160 Phytoplankton are microscopic marine plants that form the first link in nearly all ocean food chains. 50 00:03:13.180 --> 00:03:18.470 Population explosions, or blooms of phytoplankton, like the one shown here, 51 00:03:18.490 --> 00:03:22.680 occur when deep currents bring nutrients up to sunlit surface waters, 52 00:03:22.700 --> 00:03:29.709 fueling the growth and reproduction of these tiny plants. 53 00:03:29.730 --> 00:03:32.709 54 00:03:32.730 --> 00:03:37.709 [beep] 55 00:03:37.730 --> 00:03:45.940