Great Salt Desert, Iran. ike poster paints run wild, this image reveals an eclectic montage of landscapes in Iran's largest desert, the Dasht-e Kavir, or Great Salt Desert. The word kavir is Persian for salt marsh. The almost-uninhabited region covers an area of more than 77,000 square kilometers [29,730 square miles] and is a mix of dry streambeds, desert plateaus, mudflats and salt marshes. Extreme heat, dramatic daily temperature swings, and violent storms are the norm in this inhospitable place. Taken by Landsat 7 on Feb. 10, 2003.

Belcher Islands, Canada. Like sweeping brushstrokes of pink and green, the Belcher Islands meander across the deep blue of Canada's Hudson Bay. The islands' only inhabitants live in the small town of Sanikiluaq, near the upper end of the middle island. Despite the green hues in this image, these rocky islands are too cold to sustain more than a smattering of low-growing vegetation. Taken by Landsat 5 on Sep. 21, 2001.

Mississippi River. Small, blocky shapes of towns, fields, and pastures surround the graceful swirls and whorls of the Mississippi River. Countless oxbow lakes and cutoffs accompany the meandering river south of Memphis, Tennessee, on the border between Arkansas and Mississippi. The "mighty Mississippi" is the largest river system in North America. Taken by Landsat 7 on May 28, 2003.

Gotland, Sweden. 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. Phytoplankton are microscopic marine plants that form the first link in nearly all ocean food chains. 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 by Landsat 7 on July 13, 2005.

Eyjafjorour Fjord, Iceland. This stretch of Iceland's northern coast resembles a tiger's head complete with stripes of orange, black and white. The tiger's mouth is the great Eyjafjorour, a deep fjord that juts into the mainland between steep mountains. The name means "island fjord," derived from the tiny, tear-shaped Hrisey Island near its mouth. The ice-free port city of Akureyri lies near the fjord's narrow tip, and is Iceland's second largest population center after the capital, Reykjavik. Taken by Landsat 7 on Oct. 21, 1999.

Erg Iguidi, Algeria. 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 one-third of a mile — in both width and height. Taken by Landsat 5 on Apr. 8, 1985.

Byrd Glacier, Antarctica. Truly a river of ice, Antarctica's relatively fast-moving Byrd Glacier courses through the Trans-Antarctic Mountains at a rate of 0.8 kilometers [0.5 miles] per year. More than 180 kilometers [112 miles] long, the glacier flows down from the polar plateau (left) to the Ross Ice Shelf (right). Long, sweeping flow lines are crossed in places by much shorter lines, which are deep cracks in the ice called crevasses. The conspicuous red patches indicate areas of exposed rock. Taken by Landsat 7 on Jan. 11, 2000.

Yukon Delta, Alaska. After beginning in northern British Columbia and flowing through Yukon in Canada, the Yukon River crosses Alaska before emptying into the Bering Sea. Countless lakes, sloughs, and ponds are scattered throughout this scene of the Yukon Delta. The river's sinuous, branching waterways seem like blood vessels branching out to enclose an organ. It is one of the largest river deltas in the world, and currently protected as part of the Yukon Delta National Wildlife Refuge. Taken by Landsat 7 on Sep. 22, 2002.

Rocky Mountains, Canada. What appears to be a stroke of thick red paint is actually a remarkable interplay of light and cloud in the Canadian Rockies. Angling through them is part of the Rocky Mountain Trench, a valley that extends from Montana to just south of the Yukon. Low clouds filled a part of the trench near the border between the Canadian provinces of Alberta and British Columbia. The light-reflecting nature of the clouds coupled with low sun elevation resulted in this startling effect. Taken by Landsat 5 on Feb. 1, 2007.

Great Barrier Reef, Australia. What might be mistaken for dinosaur bones being unearthed at a paleontological dig are some of the individual reefs that make up the Great Barrier Reef, the world's largest tropical coral-reef system. The reef stretches more than 2,000 kilometers [1,240 miles] along the coast of Queensland, Australia. It supports astoundingly complex and diverse communities of marine life and is the largest structure on the planet built by living organisms. Taken by Landsat 7 on Aug. 8, 1999.

Empty Quarter, Saudi Arabia–Yemen Border. White pinpricks of cloud cast ebony shadows on the Rub' al Khali, or Empty Quarter, near the border between Saudi Arabia and Yemen. The lines of wind-sculpted sand are characteristic of immense sand deserts, or sand seas, and the Rub' al Khali is the largest desert of this type in the world. A highland ridge is just high enough to disturb the flow of the lines. In the center of that interruption lies the Saudi Arabian town of Sharurah. Taken by Landsat 7 on Feb. 1, 2003.

Liverpool Bay, Canada. Skeletal extensions of land reach like bony fingers across a section of Liverpool Bay along the northern edge of Canada's Northwest Territories. Only small villages are thinly scattered in this remote and inhospitable region of Arctic tundra bordering the Beaufort Sea. The relatively flat landscape is dotted with shallow lakes during the extremely brief summer season. Taken by Landsat 5 on Jul. 26, 2007.

Aland Islands, Baltic Sea. Ethereal swirls of grease ice appear turquoise against the midnight blue of the northern Baltic Sea near the Aland Islands (red) between Finland and Sweden. An early stage of sea-ice formation, grease ice consists of a viscous mix of tiny ice crystals and resembles an oil slick on the ocean's surface. Wind and currents constantly shape and reshape grease ice into surreal, ghostly patterns. Taken by Landsat 7 on Apr. 19, 2003.

Okavango River, Botswana. Like a watercolor in which a brushstroke of dark green has bled into a damp spot on the paper, southern Africa's Okavango River spreads across the pale, parched landscape of northern Botswana to become the lush Okavango Delta. The delta forms where the river empties into a basin in the Kalahari Desert, creating a maze of lagoons, channels and islands where vegetation flourishes, even in the dry season, and wildlife abounds. Taken by Landsat 5 on Apr. 27, 2009.

Greenland Coast. Along the southeastern coast of Greenland, an intricate network of fjords funnels glacial ice to the Atlantic Ocean. During the summer melting season, newly calved icebergs join slabs of sea ice and older, weathered bergs in an offshore slurry that the southward-flowing East Greenland Current sometimes swirls into stunning shapes. Exposed rock of mountain peaks, tinted red in this image, hints at a hidden landscape. Taken by Landsat 7 on May 21, 2001.

Erg Chech, Algeria. Seen through the "eyes" of a satellite sensor, ribbons of Saharan sand dunes seem to glow in sunset colors. These patterned stripes are part of Erg Chech, a desolate sand sea in southwestern Algeria, where the prevailing winds create an endlessly shifting collage of large, linear sand dunes. The term erg is derived from an Arabic word for a field of sand dunes. Tken by Landsat 7 on Apr. 13, 2003

Mount Elgon, Uganda-Kenya Border. Clouds encircle the lofty rim of Africa's Mount Elgon, a huge, long-extinct volcano on the border between Uganda and Kenya. The solitary volcano has one of the world's largest intact calderas, a cauldron-like central depression. The caldera is about 6.5 kilometers [4 miles] across. It formed following an eruption, when the emptied magma chamber collapsed under the weight of volcanic rock above it. Taken by Landsat 5 on Aug. 9, 1984.

Dhofar Region, Oman. Much of Oman is desert, but the Arabian Sea coast in the Dhofar region represents a startling difference in climate. This coastal region catches the monsoon rains, or khareef, during the summer months. Drenching rains fall primarily on the mountainous ridge that separates the lush, fertile areas along the coast from the arid interior, recharging streams, waterfalls and springs that provide plentiful water supplies in the fertile lowlands for the remainder of the year. Taken by Landsat 5 on Apr. 2, 2005.

Chaunskaya Bay, Russia. Vivid colors and bizarre shapes come together in an image that could be an imaginative illustration for a fantasy story. This labyrinth of exotic features is present along the edge of Russia's Chaunskaya Bay (vivid blue half circle) in northeastern Siberia. Two major rivers, the Chaun and Palyavaam, flow into the bay, which in turn opens into the Arctic Ocean. Ribbon lakes and bogs are present throughout the area, created by depressions left by receding glaciers. Taken by Landsat 5 on June 15, 2005.

Meighen Island, Canada. A veil of blowing snow nearly obscures Meighen Island (left) off the northern coast of Canada. Across the Sverdrup Channel lies the much larger Axel Heiberg Island, where glaciers (blue) huddle among mountain peaks (yellow) and flow into deep fjords. No evidence of human occupation has ever been found on Meighen Island. Taken by Landsat 7 on June 14, 2000.

Waziristan Hills, Pakistan. Deep purple and green hues enhance the Waziristan Hills, a mountainous region of northwest Pakistan near the Afghanistan border. A formidable landscape, the Waziristan Hills are a hodgepodge of steep, rugged hills split by narrow passes and deep gorges. Rivers coursing down from the mountains provide water for agriculture in a region of scanty rainfall. Taken by Landsat 7 on Apr. 28, 2001.

Dardzha Peninsula, Turkmenistan. Looking like a monstrous ogre with something gooey in its mouth, the Dardzha Peninsula in western Turkmenistan lies among the shallow coastal terraces of the Caspian Sea. Strong winds create huge sand dunes near the water, some of which are partly submerged. Farther inland, the dunes transition to low sand plains. Taken by Landsat 7 on Feb. 11, 2001.