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Sunglint reflections reveal details of Chesapeake Bay and the great bend of the Potomac River. Cities are difficult to detect from space during daylight hours, so the sickle-shaped bend of the river is a good visual guide for astronauts trying to photograph the nation’s capital, Washington D.C. The farm-dominated Piedmont Plateau is the light-toned area between the mountains and the bay.
The Appalachian Mountains appear striped because the ridges are forested, providing a dense and dark canopy cover, while the valleys are farmed with crops that generally appear as lighter-toned areas. (Farmland is even lighter than usual in this image because the fields are fallow after the harvest.) Geologically, the valleys are the softer, more erodible rock layers, much the preferred places for human settlement. Not only do the larger rivers occupy the valley floors, but the soils are thicker, the slopes are gentler, and the valleys are better protected from winter winds.
The rocks that form this valley-and-ridge province, as it is known, are relatively old (540 to 300 million years old) and were laid down in horizontal layers when North America was attached to Europe in the ancient supercontinent of Laurasia. During this time Gondwanaland—an ancient supercontinent that included present-day Africa, India, South America, Australia, and Antarctica—was approaching Laurasia under the influence of plate tectonics. The northwest coastline of modern Africa was the section of Gondwanaland that “bumped up” against modern North America over a long period (320 to 260 million years ago).
The net result of the tectonic collision was the building of a major mountain chain, much higher than the present Appalachian range. In the process, the flat-lying rock layers were crumpled up into a series of tight folds, at right angles to the advance of Gondwanaland. The collision also formed the singular supercontinent of Pangaea. Over the following 200 million years, Pangaea broke apart; the modern Atlantic Ocean formed; and erosion wore down the once-high mountains. What is left 200 million years later are the coastline of North America and the eroded stumps of the relatively low, but visually striking mountain chain.
ISS033-E-21663=Dallas Metropolitan Area at Night: Most metropolitan areas of the western United States are spread over large areas with regular street grid patterns that are highly recognizable from space (particularly at night). The northern Dallas metro area in Texas exhibits this pattern in this astronaut photograph from the International Space Station.The north-south and east-west grid of major streets is highlighted by orange lighting, which lends a fishnet-like appearance to the urban area. Smaller residential and commercial buildings give green-gray stipple patterns to some blocks. The airplane terminals of Dallas-Fort Worth International Airport are lit with golden-yellow lights and surrounded by relatively dark runways and fields. Likewise, the runways of Dallas Love Field are recognizable by their darkness.
Other dark areas within the metro region are open space, parks, and water bodies. Larger commercial areas, as well as public and industrial facilities, appear as brilliantly lit regions and points. For comparison, a day-time view of Dallas is available here.
Dallas is part of the larger Dallas-Fort Worth-Arlington Metropolitan Statistical Area (population 6,526,548 in 2011), as recognized by the U.S. Census Bureau. To most Texans, it is simply “DFW” or “the Metroplex.” Several of the larger urban areas within DFW are visible in this image; Dallas, Garland, and Richardson all have populations above 100,000 according to the North Central Texas Council of Governments. While the economy of Dallas was historically based in the oil and cotton industries, today commerce, technology, healthcare, and transportation are the major economic drivers.
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Aso formed during four explosive eruptions that took place between 300,000 and 90,000 years ago. These eruptions produced pyroclastic flows and airfall tephra that covered much of Kyushu. As the eruptions emptied the magma chambers beneath those ancient volcanoes, they collapsed and formed the caldera.
Volcanic activity continued after the formation of the caldera, as evidenced by 17 younger volcanoes in the area, including Naka-dake—one of Japan’s most active volcanoes and the site of ash plumes as recently as June 2011. The nearby Kusasenri crater is the site of the Aso Volcano Museum and of pastureland for cows and horses.
The floor of Aso caldera is largely occupied by urban and agricultural land uses that present a gray to white speckled appearance. Fields and cities surround the younger volcanic structures to the north, west, and south. Tan to yellow-brown regions along the crater rim—and along the lower slopes of the younger volcanic highlands in the central caldera—are lacking the dense tree cover of some of the greener areas in the image.
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The town of Suibing stands out as a larger gray patch on the banks of the river. A significant 300 meter-high hill south of the river throws midmorning shadows. The region is one of the most heavily cultivated in northeastern China, with corn, soybeans, and sorghum being major crops. The areas of varying whiteness cover may correlate with zones of different crops and forest cover (for example, on the hill in the center part of the image). The degree to which fallow fields are cleared of vegetation may also affect the apparent snow brightness.
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University sectors stand out with different street and light patterns, including the King Saud University campus—which houses the Arabic Language Institute—and the Princess Nora Bint Abdul Rahman University—which is the largest all-female university in the world. Highways and various ring roads also stand out due to bright, regular lighting. Lighted developments beyond the ring roads mark the growth of the city (image lower left and lower right). Newer neighborhoods, set further from the city center, are recognizable by blue-gray lightning.
By contrast with night images, detail within the urban area is far less distinct in daylight images such as this one.
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Because of the high levels of volcanic activity on the Kamchatka Peninsula, the Kamchatka Volcanic Eruption Response Team (KVERT) monitors the activity levels of several volcanoes and issues updates including aviation alerts and webcams. KVERT reported moderate seismic activity at Karymsky between November 2–9, 2012. Such activity can indicate the movement of magma beneath or within a volcanic structure and that an eruption may be imminent. The Tokyo Volcanic Ash Advisory Center (VAAC) subsequently reported an explosive eruption at Karymsky on November 9 at 22:15 Universal Time.
This astronaut photograph of the resulting ash plume was taken approximately 1 hour and 35 minutes after the eruption began. The plume extends from the summit of Karymsky to the southeast, with brown ash deposits darkening the snow cover below the plume.
The Akademia Nauk caldera—now filled with water to form the present-day Karymsky Lake—is located to the south of Karymsky volcano. Calderas are formed by explosive eruption and emptying of a volcano’s magma chamber, leading to collapse of the structure to form a crater-like depression. Akademia Nauk last erupted in 1996.
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Directly to the north and northeast of Bezymianny, the much larger and taller stratovolcanoes Kamen (4,585 meters above sea level) and Klyuchevskaya (also Kliuchevskoi) (4,835 meters) are visible. Klyuchevskaya is Kamchatka’s most active volcano; it last erupted in 2011, whereas Kamen has not erupted during the recorded history of the region. The most recent activity at the volcanic massif of Ushkovsky (3,943 meters) was an explosive eruption in 1890.
To the south of Bezymianny, the peaks of Zimina (3,081 meters above sea level) and Udina (2,923 meters) volcanoes are just visible above the cloud deck; no historical eruptions are known from either of them. While the large Tobalchik volcano to the southwest is largely formed from a basaltic shield volcano, its highest peak (3,682 meters) is formed from an older stratovolcano. Tobalchik last erupted in 1976.
While this image may look like it was taken from a passenger airplane, in fact it was taken from the considerably higher altitude of the International Space Station (ISS). At the time the image was taken, the ISS was located approximately 417 kilometers above the Sea of Okhotsk and more than 700 kilometers to the southwest of the volcanoes. The combination of the low viewing angle, the shadows, the height, and the distance from the volcanoes contributes to the appearance of a topographic relief map.
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The brightest group of lights at image center is the capital city, Doha, with the neighboring smaller ports of Ad-Dahira and Umm Sa’id to the north and south. (Note that north is to the left, due to the path of the ISS orbit.) Highways are clearly visible leading west from the capital to the Dukhan oil fields, to Saudi Arabia, and to the north of the country where—judging by the lack of night lights—the population is probably very low. The relatively minor coast road between the oil fields and the Saudi frontier also stands out.
Almost the entire island nation of Bahrain appears at lower left, with the capital city of Manama nearly as bright as the lights of Doha. The difference in light intensity reflects a difference in population; Doha has 1.45 million inhabitants, while the dense Manama metro area has a population of 1.2 million.
While some night views are informative about a landscape, they can also be difficult and confusing to locate. Astronauts learn to recognize where they are at night by flying over populated places repeatedly. Coastlines—one of their best geographic indicators—are generally lost to view because water surfaces and unpopulated land surfaces look the same without illumination such the full moon.
Thus, the thumb-shaped Qatari peninsula, so well-known in Middle Eastern geography, does not show up at all in this nighttime photograph. However, the low-light imaging bands of the Visible Infrared Imaging Radiometer Suite on the Suomi NPP satellite showed the Qatari peninsula and the long arm of the Gulf of Bahrain (lower image) on a moonlit night. The image was acquired during the early morning hours of September 30, 2012, two weeks before the astronaut photograph.
A detailed, daylight view of Doha is available here.
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Highways and large arterial streets appear as bright yellow-orange lines extending outwards into the surrounding suburbs (light violet and reddish brown regions of diffuse lighting). Dark areas beyond the suburban zone are rural or, to the southeast, indicate the waters of Chesapeake Bay. Small, dark patches are open spaces, including parks, cemeteries, and the Baltimore Zoo (within Druid Hill Park). Two large, brightly-lit areas along Chesapeake Bay are commercial/industrial regions and include the major port facilities for Baltimore.
The City of Baltimore was incorporated in 1796, after serving as the de facto capital of the nascent United States of America during the Second Continental Congress (December 20, 1776, to March 4, 1777). Today, the Baltimore metropolitan area (as defined by the Baltimore Metropolitan Council) includes more than 2.5 million people and parts of five Maryland counties—Anne Arundel, Baltimore, Carroll, Harford, and Howard. The region is also a focus of urban ecological research through the Baltimore Ecosystem Study that is part of the National Science Foundation’s Long Term Ecological Research network.
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Isla Santiago itself was formed from a shield volcano (also called Santiago). This type of volcanic structure is recognized by low, flat summits surrounded by extensive flow fields of lava; the lava is not very viscous, so it can flow for great distances from the source vents. Several dark lava flow fields are visible in this astronaut photograph, the largest along the eastern, western, and southern coastlines. The small Isla Rábida to the south is the peak of another, mostly submerged shield volcano. (Note that the image is rotated so that south is to the top left.)
In addition to the lava flows, other volcanic features known as tuff cones are visible on the eastern and western sides of the island. These cones are formed by the rapid interaction of hot flowing lava and water. The water underneath the lava flow flashes to steam explosively, and this both fragments the lava and rapidly cools it, leading to the formation of cones of glassy, relatively fine-grained volcanic material. The most recent volcanic activity on Isla Santiago occurred during 1904–1906.
The summit ridge of the Santiago shield volcano is located in the northwestern part of the island. Also at image center is a large but isolated region of green vegetation on the south-facing slope, below the summit ridge. This image was taken during the dry, or garúa, season that lasts from June to November. The season is dominated by cooler air transported by southeast trade winds and cooler waters from the Humboldt and Cromwell currents. The combination of cool air and water results in rain falling only in the island highlands, with south- and east-facing slopes receiving the most precipitation. Despite the favorable location, the yellow-green color of the vegetation may indicate water (or other) stress.
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Immediately to the west of the summit peak (but still on the upper slopes of Shasta) lies the Shastina lava dome complex, reaching 3,758 meters (12,330 feet) above sea level. Two dark lava flows that originated from the Shastina complex and flowed downslope (toward the northwest) are visible in the lower center of this image. The flows contrast sharply with the surrounding vegetated lower slopes and the barren upper slopes of Shasta. The Black Butte lava dome complex forms another isolated hill on the lowermost slopes of Shasta, near the town of Weed, California.
Geologists have mapped prehistoric pyroclastic flow and mudflow deposits (or lahars) from Hotlum cone and the Shastina and Black Butte lava dome complexes to distances of 20 kilometers (12 miles) from the summit of Shasta. As Mount Shasta has erupted within the past 250 years and several communities are within this hazard radius, the U.S. Geological Survey’s California Volcano Observatory actively monitors the volcano for signs of activity.
