The Volga River drains much of western Russia’s industrial region as it travels southward to empty into the Caspian Sea. Over thousands of years, the river has built a tremendous delta that forms the northwestern shoreline of the Caspian Sea. The delta channels provide transportation between the heartland of Russia and the oil-rich Caspian Sea. The Volga’s extensive distributaries (branches to the sea) harbor habitat and rich fishing grounds for Russia’s famous beluga sturgeon, the source of beluga caviar. The delta’s wetlands, parts of which are designated as the Astrakhanskiy Biosphere Reserve, are important stopping points and breeding grounds for migrating water birds. This detailed astronaut photograph zooms in on a shipping channel in the western part of the delta.
Published Oct 23, 2006
Har Nuur (“Black Lake”) is located in western Mongolia’s Valley of Lakes, part of a system of closed basins stretching across central Asia. These basins are the remnants of larger paleolakes (paleo- means “ancient”) that began to shrink approximately five thousand years ago as regional climate became drier. This oblique (looking at an angle) astronaut photograph captures the dynamic nature of the landscape of Har Nuur. The lake is encircled by sand dune fields that encroach on the lower slopes of the Tobhata Mountains to the west and south. Gaps in the mountains have been exploited by sand dunes moving eastward, indicating westerly winds. The most striking example is a series of dunes entering Har Nuur along its southwestern shoreline.
Published Oct 16, 2006
The Franz Josef Strauss, or Munich, International Airport served 29 million passengers in 2005, making it Germany’s second-busiest airport, after Frankfurt. This astronaut photograph, taken from the International Space Station, shows enough detail to distinguish individual airplanes on the terminal apron, and the dark gray-blue rooftop of Terminal 2.
Published Oct 9, 2006
In these images captured by International Space Station astronauts on August 27, 2006, bright sunlight glinting off the western Caribbean Sea reveals intersecting wave patterns and oily surfactants on the surface waters around Bajo Nuevo Reef. Bajo Nuevo is a collection of small islets arranged into two U-shaped cays, low islands made of coral or sand. This pair of images shows the easternmost of the two cays (also known as “keys”) and surrounding waters.
Published Oct 2, 2006
The Day Fire started in Los Padres National Forest north of Los Angeles on September 4, 2006. Easterly winds on September 17 blew the smoke westward, out to sea, and International Space Station astronauts observed this wind shift. In this astronaut photograph, the forested mountains north of Los Angeles appear dark green, and the smoke appears gray. Dense farmland appears at the south end of California’s Central Valley, in the upper left corner. Near top center, the western corner of the Mojave Desert is framed by a “V” of mountains. In the Mojave just beyond the top edge of the image (visible in the large version) are dry lakes that appear as white patches; one of these lakes acts as a landing site for the Space Shuttle.
Published Sep 25, 2006
Crater Lake is formed from the caldera of Mount Mazama. Part of the Cascades volcanic chain, Mount Mazama sits between the Three Sisters volcanoes to the north and Mount Shasta to the south. The catastrophic eruption of Mount Mazama that occurred approximately 7,700 years ago destroyed the volcano while simultaneously forming the basin for Crater Lake. Eruptive activity continued in the region for perhaps a few hundred years after the major eruption. Evidence of this activity lingers in volcanic rocks, lava flows, and domes beneath the lake surface; the small cone of Wizard Island is the only visible portion of these younger rocks. Although considered a dormant volcano, Crater Lake is part of the United States Geological Survey Cascades Volcano Observatory seismic monitoring network.
Published Sep 18, 2006
One of the main reasons that rainless regions like the Sahara Desert are interesting from the perspective of landscape science is that the work of flowing water—mainly streams and rivers—becomes less important than the work of wind. Over millennia, if enough sand is available, winds can generate dunes of enormous size, arranged in regular patterns. Long, linear dunes stretch generally north to south across much of northeast Algeria, covering a vast tract (~140,000 square kilometers) of the Sahara Desert known as the Erg Oriental. Erg means “dune sea” in Arabic, and the term has been adopted by modern geologists. Spanning this image from a point on the southwest margin of the erg (image center point: 28.9°N 4.8°W) are a series of 2-kilometer-wide linear dunes, comprised of red sand. The dune chains are more than 100 meters high. The “streets” between the dunes are grayer areas free of sand.
Published Sep 11, 2006
The Golden Gate of San Francisco Bay is one of the most recognizable straits in the world due to the Golden Gate Bridge that spans it. This high-resolution astronaut photograph is a nearly cloud-free view of the northern part of the San Francisco metropolitan area.
Published Sep 4, 2006
The crew of Expedition 13 recently passed a major milestone: as of late August 2006, more than one quarter of a million images of Earth had been taken from the International Space Station. The 250,000th image is an oblique view (a photograph taken from a side angle) of the city of Christchurch, New Zealand. This view provides a sense of perspective and accents topography, in contrast to nadir (directly downwards) views. Snow highlights the peaks of the Banks Peninsula to the southeast of the city. The peninsula has a radically different landscape compared to the adjoining, flat Canterbury Plains, where Christchurch (gray patch to the north) is located. The Banks Peninsula is formed from the overlapping cones of the extinct Lyttelton and Akaroa volcanoes. Subsequent erosion of the cones formed the heavily dissected terrain visible in the image, and sea level rise led to the creation of several harbors around the Peninsula. Erosion continues unabated today, as evidenced by the apron of greenish blue, sediment-laden waters surrounding the Banks Peninsula.
Published Aug 28, 2006
Subduction of the Nazca tectonic plate along the western coast of South America forms the high Peruvian Andes. The subduction (movement of one plate beneath another) also produces magma, feeding a chain of historically active volcanoes along the western front of the mountains. The most active of these volcanoes in Peru is Ubinas. A typical, steep-sided stratovolcano comprised primarily of layers of silica-rich lava flows, it has a summit elevation of 5,672 meters (18,609 feet). At 1.4 kilometers (0.87 miles) across, the volcano’s caldera gives it a truncated profile. Hardened lava flows from past eruptions linger on the volcano’s flanks. This oblique image (looking at an angle) from the International Space Station (ISS) captures an ash cloud first observed on satellite imagery at 11:00 GMT on August 14, 2006. An ISS astronaut took this picture one hour and 45 minutes later.
Published Aug 21, 2006
One of the most consistently active volcanoes in the world, Sicily’s Mount Etna has a historical record of eruptions dating back to 1500 BC. This astronaut photograph captures plumes of steam and possibly ash originating from summit craters on the mountain: the Northeast Crater and Central Crater, which includes two secondary craters (Voragine and Bocca Nuova).
Published Aug 14, 2006
While the Great Lakes region of North America is well known for its importance to shipping between the United States, Canada, and the Atlantic Ocean, it is also the location of an impressive structure in the continent’s bedrock: the Michigan Basin. Formed during the Paleozoic Era (approximately 540–250 million years ago) the Basin looks much like a large bullseye defined by the arrangement of exposed rock layers that all tilt inwards, forming a huge bowl-shaped structure. The outer layers of the Basin include thick deposits of carbonates—rocks containing carbon and oxygen, such as limestone—deposited over millions of years when a shallow sea covered the region. These carbonate rocks are mined throughout the Great Lakes region using large open-pit mines. The largest carbonate mine in the world, Calcite Quarry, appears in this astronaut photograph.
Published Aug 7, 2006
This astronaut photograph captures a northbound convoy of cargo ships entering the Mediterranean Sea from the Suez Canal in Egypt.
Published Jul 31, 2006
The Permian Basin of west Texas and southeastern New Mexico is one of the most productive petroleum provinces of North America. The area holds one of the thickest deposits of rock from the Permian Period, which lasted from approximately 290 to 251 million years ago. The Basin is a large depression in the bedrock surface along the southern edge of the North American craton, an ancient core of continental crust. The Basin filled with thick layers of sediment during the Paleozoic Era (about 545 to 251 million years ago) as the region was alternately covered by shallow oceans, or exposed as coastal salt flats. The sediments hardened into primarily organic-rich carbonate and minerals such as common table salt. Later activity in the Earth’s crust caused folding of the sedimentary layers, creating ideal conditions for the formation, trapping, and storage of petroleum. In this astronaut photograph, numerous white well locations and petroleum drilling structures mark the Yates Oil Field in the layered sedimentary rocks of the Permian Basin.
Published Jul 24, 2006
Tenerife is the largest of the Canary Islands, a Spanish possession located off the northwestern coast of Africa. The central feature of this astronaut photograph is the elliptical depression of the Las Cañadas Caldera that measures 170 square kilometers (about 65 square miles).
Published Jul 17, 2006
Located just north of the equator, this classically shaped atoll is part of the Caroline Islands, which stretch northeast of Papua New Guinea in the western Pacific. Nukuoro Atoll is one of 607 islands that make up the Federated States of Micronesia.
Published Jul 10, 2006
The largest airport in Texas, Dallas-Fort Worth International (DFW) is also the fourth largest in the world, and it occupies more surface area than the entire island of Manhattan in New York. This astronaut photograph captures the entire airport and portions of the surrounding Dallas-Fort Worth metropolitan area.
Published Jul 3, 2006
The city-state of Carthage in North Africa was founded by Phoenician settlers in 814 BC, and it subsequently became the seat of a trade empire that controlled much of the western Mediterranean region (including most of the former Phoenician lands). Carthage was completely destroyed by the Roman Republic during the Third (and final) Punic War (149-146 BC). The end of Carthage has been made notorious by the story that the Romans allegedly sowed the city with salt to ensure that no further rivals to their power would arise there. However, given the great value of salt at the time and the strategic importance of the city’s location, scholars dispute whether the event actually occurred. Following the destruction of Carthage, Roman dominance of the Mediterranean continued until the fall of the Western Empire in 476 AD.
Published Jun 26, 2006
Named Isla de Aves in Spanish, (meaning “Island of the Birds”) Aves Island lies west of the Lesser Antilles in the Caribbean. It provides a nesting site to green sea turtles (Chelonia mydas) and, of course, birds. Because the abundant bird droppings, known as guano, could be used in fertilizer and gunpowder, guano miners worked on the island until they depleted the supply. Since its discovery by Europeans, likely in the late 16th century, Aves Island was subsequently claimed by several European nations. The island is currently claimed by Venezuela, although disputes about ownership of the island, and the surrounding exclusive economic zone in the Caribbean, continue today.
Published Jun 19, 2006
Sunglint results when the Sun’s light bounces off the water’s surface and into the satellite sensor or camera. In this astronaut photograph, taken near noon on May 28th, 2006, sunglint highlights features on the surface of Lake Erie, about 50 kilometers (30 miles) west of Cleveland, Ohio. The angular water bodies along the river are likely marinas. The main part of the image shows numerous ship wakes in the zone of partial glint around the disk of the Sun’s reflection point. The wakes radiate from the mouth of the Vermilion River, with many of them heading northwest (towards the lower-right corner) in the direction of Detroit, Michigan.
Published Jun 12, 2006
The Phoenix, Arizona, metropolitan area is the largest in the southwestern United States. This astronaut photograph of the central metro region includes the boundary area between three of the municipalities included in the conurbation of Phoenix: the cities of Phoenix (left), Tempe (center and lower right), and Scottsdale (upper right).
Published Jun 5, 2006
Sunglint (reflection of sunlight from the water surface directly back to the camera or satellite sensor) off the Gulf of California gives the water a silver-gray appearance rather than the normal azure color in this astronaut photograph. The sunglint allows us to see several active features which wouldn’t be visible otherwise. The image captures a moment in time displaying very active and complex ocean wave dynamics. In this view of Punta Perihuete, Mexico, we can see three major features: biological orman-made oils floating on the surface; the out-going tidal current; and complex wave patterns. The oils on the surface are recognizable as light-grey, curved and variable-width streamers shaped by the local winds and currents. Plankton, fish, natural oil seeps, and boats dumping their bilges are all potential sources for these oils.
Published May 29, 2006
ISS flight engineer Jeff Williams was the first to witness and then report an eruption at this Alaskan volcano in 2006.
Published May 25, 2006
George Washington not only served as the namesake for the capital city of the United States, he also chose its location, perhaps envisioning the transportation possibilities that the Potomac River flowing past the site would provide. Recognizable in this image are the Capitol Building, the Washington Monument (and its shadow), and the Lincoln Memorial, along the northeast bank of the Potomac River.
Published May 22, 2006
Much of the land surface is obscured in this oblique image of the North China Plain and parts of Inner Mongolia. In this image, a mass of gray smog—mainly industrial pollution and smoke from domestic burning—obscures Beijing and surrounding cities. Numerous plumes with their source points appear within the mass. Beijing suffers some of the worst air pollution in the world from these chronic sources, and the characteristic colors and textures of the smog can be easily seen through the windows of the International Space Station. The pale brown material in Bo Hai Bay, about 300 kilometers east of Beijing, is sediment from the Yellow River and other rivers.
Published May 15, 2006
The icefields of Patagonia, located at the southern end of South America, are the largest masses of ice in the temperate Southern Hemisphere (approximately 55,000 square kilometers).
Published May 8, 2006
Etosha Pan in northern Namibia is a large, dry lakebed in the Kalahari Desert. The 120-kilometer-long (75-mile-long) lake and its surroundings are protected as one of Namibia’s largest wildlife parks. About 16,000 years ago, when ice sheets were melting across Northern Hemisphere land masses, a wet climate phase in southern Africa filled Etosha Lake. Today, Etosha Pan is seldom seen with even a thin sheet of water covering the salt pan. This astronaut photograph shows the point where the Oshigambo River runs into the salt lake during an unusually wet summer in southern Africa, in March 2006.
Published May 1, 2006
Lake Poopó sits high in the Bolivian Andes, catching runoff from its larger neighbor to the north—Lake Titicaca (not shown)—by way of the Desaguadero River, which is the muddy area at the north end of the lake. Because Lake Poopó is very high in elevation (roughly 3,400 meters, or 11,000 feet above sea level), very shallow (generally less than 3 meters, or 9 feet), and the regional climate is very dry, small changes in precipitation in the surrounding basin have large impacts on the water levels and area of Lake Poopó. When the lake fills during wet periods, it drains from the south end into the Salar de Coipasa salt flat (not shown). Water levels in Lake Poopó are important because the lake is one of South America’s largest salt-water lakes, making it a prime stop for migratory birds, including flamingoes.
Published Apr 24, 2006
The Zagros Mountains in southwestern Iran present an impressive landscape of long linear ridges and valleys. Formed by collision of the Eurasian and Arabian tectonic plates, the ridges and valleys extend hundreds of kilometers. Stresses induced in the Earth’s crust by the collision caused extensive folding of the preexisting layered sedimentary rocks. Subsequent erosion removed softer rocks, such as mudstone and siltstone while leaving harder rocks, such as limestone and dolomite. This differential erosion formed the linear ridges of the Zagros Mountains. This astronaut photograph of the southwestern edge of the Zagros mountain belt includes another common feature of the region—a salt dome (Kuh-e-Namak or “mountain of salt” in Farsi).
Published Apr 17, 2006
If Lake Natron, in Africa’s Great Rift Valley, had a color theme, it would be pink. The alkali salt crust on the surface of the lake is often colored red or pink by the salt-loving microorganisms that live there. Also, the lake is the only breeding area for the 2.5 million Lesser Flamingoes that live in the valley. These flamingoes flock along saline lakes in the region, where they feed on Spirulina, a blue-green algae with red pigments. This mosaic of photographs of the southern portion of Lake Natron shows the largest open lagoon area, and island mud flat, and a large area of pink salt crust. The colors show the actual colors viewed by the astronauts. Each time the lake is photographed, there are differences in the pattern of its salt crust, and the red colors of the blue-green algae and bacteria on the surface of the crust.
Published Apr 10, 2006
