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Images of Namibia and Goddard Space Flight Center (GSFC)
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Floods in Southern Africa
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Floods in Southern Africa |
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A black web of water surrounds the Zambezi River in the top image, captured by the Moderate Resolution Imaging Spectroradiometer (MODIS [ http://modis.gsfc.nasa.gov ]) on NASA's Terra [ http://terra.nasa.gov/ ] satellite on February 10, 2007. Mozambique was experiencing its worst floods in six years when the Zambezi flowed over its banks in January and February 2007, reported the United Nations Office for the Coordination of Humanitarian Affairs (OCHA [ http://www.reliefweb.int/rw/RWB.NSF/db900SID/YZHG-6YCQR4?OpenDocument&rc=1&emid=FL-2007-000011-ZMB ]). As of February 12, an estimated 29 people had died and 60,000 had been evacuated from the river's banks. Early and heavy rains fell over the entire Zambezi Basin, pushing the Zambezi and many of its tributaries into flood stage. The floods are likely to worsen as the 2,574-kilometer-long river receives water from its swollen tributaries in Angola, Namibia, Zambia, and Malawi. Releases from the massive Cahora Bassa Reservoir, [ http://earthobservatory.nasa.gov/NaturalHazards/natural_hazards_v2.php3?img_id=14110 ] which is reaching its capacity, are also expected to make flooding worse along the lower Zambezi. These images show the lower Zambezi where it meets the Shire River flowing south from Malawi, one of the most severely affected regions in Mozambique. The top image provides a remarkably cloud-free view of the floods, while the lower image, taken on December 31, 2006, shows the region before the rains started in January. The images were made with a combination of infrared and visible light to highlight the presence of water on the ground. Water is black or dark blue, while plant-covered land is green. Bare earth is tan and pink, and clouds are pale blue and white. Fires are outlined in red. Images such as these and photo-like, true-color images are provided by the MODIS Rapid Response Team [ http://rapidfire.sci.gsfc.nasa.gov/subsets/?FAS_SMozambique/2007041 ] on a daily basis. NASA image courtesy the MODIS Rapid Response Team [ http://rapidfire.sci.gsfc.nasa.gov ] at NASA GSFC. |
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Floods in Southern Africa
| Title |
Floods in Southern Africa |
| Description |
A black web of water surrounds the Zambezi River in the top image, captured by the Moderate Resolution Imaging Spectroradiometer (MODIS [ http://modis.gsfc.nasa.gov ]) on NASA's Terra [ http://terra.nasa.gov/ ] satellite on February 10, 2007. Mozambique was experiencing its worst floods in six years when the Zambezi flowed over its banks in January and February 2007, reported the United Nations Office for the Coordination of Humanitarian Affairs (OCHA [ http://www.reliefweb.int/rw/RWB.NSF/db900SID/YZHG-6YCQR4?OpenDocument&rc=1&emid=FL-2007-000011-ZMB ]). As of February 12, an estimated 29 people had died and 60,000 had been evacuated from the river's banks. Early and heavy rains fell over the entire Zambezi Basin, pushing the Zambezi and many of its tributaries into flood stage. The floods are likely to worsen as the 2,574-kilometer-long river receives water from its swollen tributaries in Angola, Namibia, Zambia, and Malawi. Releases from the massive Cahora Bassa Reservoir, [ http://earthobservatory.nasa.gov/NaturalHazards/natural_hazards_v2.php3?img_id=14110 ] which is reaching its capacity, are also expected to make flooding worse along the lower Zambezi. These images show the lower Zambezi where it meets the Shire River flowing south from Malawi, one of the most severely affected regions in Mozambique. The top image provides a remarkably cloud-free view of the floods, while the lower image, taken on December 31, 2006, shows the region before the rains started in January. The images were made with a combination of infrared and visible light to highlight the presence of water on the ground. Water is black or dark blue, while plant-covered land is green. Bare earth is tan and pink, and clouds are pale blue and white. Fires are outlined in red. Images such as these and photo-like, true-color images are provided by the MODIS Rapid Response Team [ http://rapidfire.sci.gsfc.nasa.gov/subsets/?FAS_SMozambique/2007041 ] on a daily basis. NASA image courtesy the MODIS Rapid Response Team [ http://rapidfire.sci.gsfc.nasa.gov ] at NASA GSFC. |
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Dust blowing off Namibia
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Dust blowing off Namibia |
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Tendrils of dust swept off the west coast of Namibia and spread over the Atlantic in early July 2005. The Moderate Resolution Imaging Spectroradiometer (MODIS) on the Aqua satellite took this picture on July 10, 2005. In this image, faint plumes of dust that stretch over several hundred kilometers blow in a southwesterly direction off the coast. To the north and east of the dust is the Etosha Pan, a low expanse of land filled with clay, silt, and mineral salts. In this image it appears as a white rectangular shape. NASA image created by Jesse Allen, Earth Observatory, using data obtained from the MODIS Rapid Response team. |
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Dust Plumes off Namibia
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Dust Plumes off Namibia |
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Many plumes of desert dust (tan pixels) were streaming westward off the coasts of Angola (top) and Namibia (bottom) in southwestern Africa on June 9, 2004. Notice the dark green color of the ocean beneath the dust plumes, indicating the presence phytoplankton thriving in the surface waters there. The frequent influx of iron-rich desert dust settling into the ocean here?together with cold, nutrient-rich waters upwelling from the depths?make these some of the most biologically productive ocean waters on Earth. This true-color image was acquired on June 9, 2004, by the Moderate Resolution Imaging Spectroradiometer (MODIS) aboard NASA?s Terra satellite. The high-resolution image available here is 500 meters per pixel, but the image is also available at additional resolutions. [ http://rapidfire.sci.gsfc.nasa.gov/gallery/?2004161-0609/Namibia.A2004161.0930 ] Image courtesy Jacques Descloitres, MODIS Rapid Response Team, NASA-Goddard Space Flight Center |
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Dust Plumes off Namibia
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Dust Plumes off Namibia |
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Whisps of white dust sweep off of northern Namibia?s Skeleton Coast in this Moderate Resolution Imaging Spectroradiometer [ http://modis.gsfc.nasa.gov ] (MODIS) image, acquired on June 9, 2004 by NASA?s Terra [ http://terra.nasa.gov/ ] satellite. The image has been draped over data from the Shuttle Radar Topography Mission [ http://www2.jpl.nasa.gov/srtm/ ] to show changes in elevation. The resulting 3-D image could help pinpoint the source of blowing dust, though in this image, the source is not entirely clear. In the lower right corner are the peaks of the Kaokoveld Mountains. The view of the coast shown here is similar to one a person might have standing (or flying) over Namibia's northern border looking south-southwest. Image by Frank Eckardt, Department of Environmental Science, University of Botswana, based on data from the MODIS Rapid Response Team [ http://rapidfire.sci.gsfc.nasa.gov ] at NASA GSFC and SRTM data courtesy NASA/JPL/NIMA/USGS, SRTM [ http://www2.jpl.nasa.gov/srtm/ ] Science Team. |
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Dust Plumes off Namibia
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Dust Plumes off Namibia |
| Description |
Whisps of white dust sweep off of northern Namibia?s Skeleton Coast in this Moderate Resolution Imaging Spectroradiometer [ http://modis.gsfc.nasa.gov ] (MODIS) image, acquired on June 9, 2004 by NASA?s Terra [ http://terra.nasa.gov/ ] satellite. The image has been draped over data from the Shuttle Radar Topography Mission [ http://www2.jpl.nasa.gov/srtm/ ] to show changes in elevation. The resulting 3-D image could help pinpoint the source of blowing dust, though in this image, the source is not entirely clear. In the lower right corner are the peaks of the Kaokoveld Mountains. The view of the coast shown here is similar to one a person might have standing (or flying) over Namibia's northern border looking south-southwest. Image by Frank Eckardt, Department of Environmental Science, University of Botswana, based on data from the MODIS Rapid Response Team [ http://rapidfire.sci.gsfc.nasa.gov ] at NASA GSFC and SRTM data courtesy NASA/JPL/NIMA/USGS, SRTM [ http://www2.jpl.nasa.gov/srtm/ ] Science Team. |
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Hydrogen Sulfide Eruption Al
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Hydrogen Sulfide Eruption Along the Coast of Namibia |
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A milky green cloud of water off the Namib Desert coast of Namibia in southern Africa is a tell-tale sign of sulfur rising to the surface. The yellowish clouds of sulfur come from hydrogen sulfide gas produced by anaerobic bacteria (bacteria that can live without oxygen) at the ocean floor. In this region, strong currents bring abundant food from the bottom of the ocean to nurture large plant and animal populations. As the surface life dies, it sinks to the bottom of the ocean, where it becomes food for anaerobic bacteria.. The bacteria release hydrogen sulfide gas, which produces pure sulfur when it reacts with oxygen near the surface. In the first stages of the reaction, the sulfur appears white, and in this image creates a milky-green green tinge to the water. When the transformation is more complete, the yellowish sulfur and the blue water will combine to make the plume appear very green. The hydrogen sulfide gas is highly toxic to fish. Periodic die-offs of whole populations of fish and other commercial seafood are ongoing concerns for the regional fishing industry. This true-color Moderate Resolution Imaging Spectroradiometer [ http://modis.gsfc.nasa.gov ] (MODIS) image was acquired by the Terra [ http://terra.nasa.gov/ ] satellite on March 5, 2004. The diagonal stripes that run across the image mark the beginning and end of the rotation of MODIS' double-sided scan mirror. The scan lines are caused by small differences between the two sides of the scan mirror. The high-resolution image provided above is at MODIS? maximum resolution of 250 meters per pixel. The image is available in additional resolutions [ http://rapidfire.sci.gsfc.nasa.gov/gallery/?2004065-0305/Namibia.A2004065.0930 ]. Image courtesy Jacques Descloitres, MODIS Rapid Response Team [ http://rapidfire.sci.gsfc.nasa.gov ] at NASA GSFC |
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Hydrogen Sulfide Eruption Al
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Hydrogen Sulfide Eruption Along the Coast of Namibia |
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*Hydrogen Sulfide Eruption Along the Coast of Namibia* Bright colors in the ocean waters off the coast of Namibia tell a story of marine life and death. In this region of the South Atlantic, winds push the warm surface water westward, and cold waters from the bottom of the ocean rush up in their place. The cold water carries with it the nutrients that have sunk to the ocean floor, providing a boon to ocean life. In particular, microscopic plants called phytoplankton thrive on the added nutrients. In turn, these tiny plants are a source of food for many other ocean dwellers. In this Moderate Resolution Imaging Spectroradiometer [ http://modis.gsfc.nasa.gov ] (MODIS) image acquired on April 10, 2004, by the Terra [ http://terra.nasa.gov/ ] satellite, a dark green swirl of water in the ocean shows where a colony of phytoplankton bloom. The individual plants grow quickly, then die after a few days. Their remains sink to the ocean floor where bottom-dwelling bacteria break them down. Eventually, the bacteria use all of the oxygen, and a second form of bacteria take over. These bacteria, anaerobic bacteria, release toxic hydrogen sulfide gas as they consume the decomposing plants. The gas rises to the surface along the Namibian coast, where it turns to pure sulfur in reaction to oxygen in the water. The yellow sulfur tints the blue water a bright green in this satellite image. Called hydrogen sulfide eruptions, the phenomenon has only been observed along the Namibian coast. Sadly, the decomposing plants are lethal to the life they once supported. Hydrogen sulfide gas can kill large populations of fish and other marine life. As a result, the waters off the coast of Namibia are closely monitored by the regional fishing and aquaculture industry. Image courtesy Jacques Descloitres, MODIS Rapid Response Team [ http://rapidfire.sci.gsfc.nasa.gov ] at NASA GSFC |
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Hydrogen Sulfide Eruption of
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Hydrogen Sulfide Eruption off Namibia |
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The brilliant burst of neon blue and green that hugs the shore of Namibia in this photo-like image might be beautiful from space, but it is deadly on the ground. The color is caused by hydrogen sulfide erupting to the surface. The foul-smelling gas is toxic by itself, but it also robs the water of oxygen when it erupts to the surface, leading to large fish kills. Ironically, it is the ocean's productivity in this region that causes the deadly eruptions. Strong ocean currents sweep nutrient-rich water to the sunlit surface of the Atlantic Ocean off the coast of Namibia. The ample supply of nutrients allows tiny free-floating plants (phytoplankton) to proliferate. When the large phytoplankton blooms die, the plants sink to the ocean floor, where bacteria break them down. The anaerobic bacteria that complete the decay process release toxic hydrogen sulfide into the ocean. The gas builds near the ocean floor until a bubble erupts to the surface. As it rises, the hydrogen combines with oxygen to form water molecules, leaving solid, yellow sulfur. The sulfur scatters yellow light, lending the water a brilliance that can range from milky white to electric blue. This particular eruption surrounds Walvis Bay and stretches north along the Skeleton Coast and south to the orange dune fields of the Namib Desert. The city of Walvis Bay is a faint gray discoloration on the southern shore of the bay. The Moderate Resolution Imaging Spectroradiometer (MODIS [ http://modis.gsfc.nasa.gov ]) flying on NASA's Aqua [ http://aqua.nasa.gov/ ] satellite captured this image on July 25, 2007. The large image provided above has a resolution of 250 meters per pixel. The MODIS Rapid Response System provides the image in additional resolutions. Image courtesy Jeff Schmaltz, MODIS Rapid Response Team [ http://rapidfire.sci.gsfc.nasa.gov ] at NASA GSFC |
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Hydrogen Sulfide Eruptions a
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Hydrogen Sulfide Eruptions along the Coast of Namibia |
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On April 18, 2004, the Moderate Resolution Imaging Spectroradiometer [ http://modis.gsfc.nasa.gov ] (MODIS) on the Aqua [ http://aqua.nasa.gov/ ] satellite detected several bright green hydrogen sulfide eruptions along the coast of Namibia. The eruptions, which are deadly to fish, occur when bacteria release hydrogen sulfide gas as they break down dead plants and animals that have sunk to the sea floor. As the gas rises to the surface, it interacts with oxygen to form solid white sulfur, which tints the water the bright green color seen here. Hydrogen sulfide eruptions happen frequently off the shore of Namibia because of patterns in the ocean currents called upwelling. In this region, cold water pushes nutrients from the ocean floor to the surface, where ocean life thrives. In particular, large colonies of microscopic ocean plants, phytoplankton, grow in the nutrient rich water, forming the dark green swirls seen in this image. As the plants use all of the nutrients, they die and sink to the sea floor where bacteria consume them. The bacteria release toxic hydrogen sulfide gas into the soil. Eventually, the toxic gas erupts from the soil. In addition to the bright waters seen by satellites, the event is marked by massive fish die-offs and a strong smell that resembles rotten eggs. To date, hydrogen sulfide eruptions have only been observed off the shore of Namibia. Additional eruptions can be seen further down the coast at 250 meters per pixel in the high-resolution image provided above. The image is also available in additional resolutions [ http://rapidfire.sci.gsfc.nasa.gov/gallery/?2004109-0418/Namibia.A2004109.1235 ]. The MODIS instrument on the Terra [ http://terra.nasa.gov/ ] satellite captured an earlier phase of the eruption on April 17, 2004 [ http://rapidfire.sci.gsfc.nasa.gov/gallery/?2004108-0417/Namibia.A2004108.0915 ]. Image courtesy Jacques Descloitres, MODIS Rapid Response Team [ http://rapidfire.sci.gsfc.nasa.gov ] at NASA GSFC |
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Hydrogen Sulfide Eruptions A
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Hydrogen Sulfide Eruptions Along the Coast of Namibia |
| Description |
People living along Namibia?s desert coast have long been familiar with the rotten egg smell that periodically emanates from the Atlantic Ocean. With an economy that is largely based on fishing, the locals are also used to seeing millions of fish die whenever the unpleasant scent fills the air. The smell and the fish die-off are caused by hydrogen sulfide erupting from decaying plants on the sea floor. In the southeast Atlantic Ocean, strong ocean currents carry nutrient-rich deep-ocean water to the surface. The waters nourish free-floating microscopic plants, called phytoplankton, and other sea life. When the plants die, they sink to the ocean floor where bacteria begin to break them down. The oxygen is quickly used in the decay process, and anaerobic bacteria take over. These bacteria emit hydrogen sulfide gas as a by-product. The gas builds on the ocean floor until it erupts suddenly. When it reaches the surface, the hydrogen combines with oxygen to form water, allowing solid white sulfur to precipitate into the ocean. Of itself, hydrogen sulfide gas is toxic to fish, but this reaction with oxygen also creates deadly low-oxygen conditions in the ocean. The reaction at the surface also makes hydrogen sulfide eruptions visible in satellite imagery. The white sulfur reflects light, tinting the water bright green along the Namibian coast. On May 12, 2004, the Moderate Resolution Imaging Spectroradiometer [ http://modis.gsfc.nasa.gov ] (MODIS) on NASA?s Terra [ http://terra.nasa.gov/ ] satellite captured this image of a hydrogen sulfide eruption in progress. Along the coast, milky green sections of ocean show where hydrogen sulfide gas is coming up. Offshore, a phytoplankton bloom forms a bright green swirl in the ocean water, proof of the productivity that triggers the deadly eruptions. Both the image above and the full image are at MODIS? maximum resolution of 250 meters per pixel. The image is available in additional resolutions [ http://rapidfire.sci.gsfc.nasa.gov/gallery/?2004133-0512/Namibia.A2004133.0905 ]. NASA GSFC image courtesy Jacques Descloitres, MODIS Rapid Response Team [ http://rapidfire.sci.gsfc.nasa.gov ] |
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Namibia
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Namibia |
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On the southwest coast of Africa, the soft orange sands of Namibia's coastal desert rise to a rugged interior plateau, with outcroppings of colorful rocks and pale green vegetation. The large coastal desert is one of the oldest in the world, and is caused by a cool ocean current, called the Benguela Current, snaking its way up from the south along southern Africa's Atlantic Coast. The cold current suppresses rainfall, but contributes to a morning fog that becomes trapped on the surface of some dunes and provides enough moisture for sparse vegetation to grow in some places. The dunes, pushed up by strong onshore winds, are the highest sand dunes in the world—as high as 300 to 350 meters (1000 to 1167 feet) in places. Rows of linear sand dunes can be seen as alternating ripples of darker and lighter orange in the center of the image. The dune shapes become more chaotic surrounding the mud plain where a river runs down out of the plateau (left of center), but doesn't make it to the ocean. This image combines observations from the Moderate Resolution Imaging Spectroradiometer (MODIS) on June 8 and August 9, 2002, with topographic information provided by the U.S. Geological Survey's GTOPO30 Digital Elevation Model. The vertical scale has been exaggerated to show more detail of the topography. For another look at the area, check out Astronaut Photo STS103-732-5. Image by Frank Eckardt, Department of Environmental Science, University of Botswana, based on data from the MODIS Rapid Response Team at NASA GSFC |
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Phytoplankton and Hydrogen S
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Phytoplankton and Hydrogen Sulfide off the Coast of Namibia |
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Like neon signs against a black night sky, phytoplankton and hydrogen sulfide form brilliant green streaks in the ocean water off the coast of Namibia in southern Africa. Though the two splashes of color are caused by different things, they are connected. On the left, the cloud of green is formed by millions of microscopic plants growing on the surface of the ocean. In this part of the South Atlantic, deep, cold ocean water hits the coast of Africa and pushes to the surface. The cold water brings nutrients up from the ocean's depths, and this feeds a thriving marine ecosystem. Among the life nourished here is phytoplankton, the microscopic ocean plants that color the water on the left side of this image. Nutrients are so rich that dense blooms of phytoplankton often form off the southwest coast of Africa. As the plants die, they sink to the ocean floor. There, bacteria consume the plants, using up all of the oxygen in the water. Anaerobic bacteria that don't require oxygen take over the decay process, releasing hydrogen sulfide gas as they work on the phytoplankton. The gas accumulates until it erupts to the surface. On its way up, it interacts with oxygen in the upper layers of the ocean and releases pure sulfur, a powdery yellow solid. The yellow sulfur gives the water near the shore its distinctive green tint. The eruptions are accompanied by a strong smell—sulfur smells like rotting eggs—and fish kills. The Moderate Resolution Imaging Spectroradiometer (MODIS [ http://modis.gsfc.nasa.gov ]) flying on NASA's Aqua [ http://aqua.nasa.gov/ ] satellite captured this image on August 9, 2005. NASA image courtesy Jeff Schmaltz, MODIS Land Rapid Response Team [ http://rapidfire.sci.gsfc.nasa.gov ] at NASA GSFC |
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Fires in Central and Souther
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Fires in Central and Southern Africa |
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The southern Africa burning season is still underway as farmers and ranchers light fires to clear fields for planting and to renew rangeland vegetation. Numerous fires (red dots) were detected by the Moderate Resolution Imaging Spectroradiometer (MODIS) on NASA?s Terra satellite through Angola (top left quadrant) and Zambia (top right quadrant) and tapering off in Namibia (bottom left quadrant) and Botswana (bottom right quadrant). The green broomstick-shaped feature south of image center is the vegetation of the Okavango River Delta. The highly reflective area to its southeast is the Makgadikgadi Salt Pans. Another salt flat, called Etosha Pan, is visible south of the Angola-Namibia border. This image was acquired on September 12, 2002. Image by Jesse Allen, based on data from the MODIS Rapid Response Team at NASA-GSFC |
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Phytoplankton Bloom off Nami
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Phytoplankton Bloom off Namibia |
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A flash of blue and green lit the waters off Namibia in early November 2007 as a phytoplankton bloom grew and faded in the Atlantic Ocean. The Moderate Resolution Imaging Spectroradiometer (MODIS [ http://modis.gsfc.nasa.gov ]) on NASA's Aqua [ http://aqua.nasa.gov/ ] satellite captured this photo-like image on November 8, 2007. The bloom stretches from north to south along hundreds of kilometers, though it is brightest in the center of this image. Such blooms are common in the coastal waters off southwest Africa where cold, nutrient-rich currents sweep north from Antarctica and interact with the coastal shelf. At the same time, the easterly trade winds push surface water away from the shore, allowing water from the ocean's floor to rise to the surface, bringing with it iron and other material. The suffusion of nutrients from both the currents and upwelling water creates an environment where tiny surface-dwelling ocean plants (phytoplankton) thrive. Phytoplankton blooms are so abundant off Namibia that their death and decomposition often robs the water of dissolved oxygen. As the plants die, they sink to the ocean floor where bacteria consume them. There is so much plant material that the bacteria use all of the oxygen available int he water before they finish breaking down the plants, creating a dead-zone in the water where fish can't survive. Anaerobic bacteria, which don't require oxygen, take over in the decomposition process, releasing sulfur dioxide as a byproduct. The sulfur dioxide interacts with the ocean water to create solid sulfur and hydrogen sulfide, a poisonous gas, which eventually erupts to the surface, sometimes killing fish. Though no eruption is readily apparent in this image, hydrogen sulfide eruptions are often visible in satellite imagery because the solid sulfur colors the water a milky yellow-green. The bloom shown here persisted over several days. It first became distinct on October 28 [ http://rapidfire.sci.gsfc.nasa.gov/subsets/?NBenguela/2007301 ] (though clouds covered the region on previous days, so it may have developed earlier) and was just beginning to fade on November 14. [ http://rapidfire.sci.gsfc.nasa.gov/subsets/?NBenguela/2007318 ] The daily images [ http://rapidfire.sci.gsfc.nasa.gov/subsets/?NBenguela/2007312 ] provided by the MODIS Rapid Response System show the bloom growing and fading throughout that period. You can download a 250-meter-resolution KMZ file of the bloom [ http://earthobservatory.nasa.gov/NaturalHazards/Archive/Nov2007/namibia_amo_2007312.kmz ] suitable for use with Google Earth. [ http://earth.google.com/ ] NASA image courtesy the MODIS Rapid Response Team [ http://rapidfire.sci.gsfc.nasa.gov ] at NASA GSFC. |
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Seasonal floods along the Za
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Seasonal floods along the Zambezi River |
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Heavy rains through the month of March have pushed a section of Africa?s Zambezi River to its highest level since 1958. Just as the mighty river turns east in its path to the Indian Ocean, and immediately before it thunders over the Victoria Falls, it passes through the low-lying plains of Namibia?s Caprivi Strip. This section of the river floods often as the wet-season rains fill the river. This year, the floods have come earlier than normal, and are rising to levels not seen in nearly 50 years. The Namibian government expects to evacuate 40,000 to 50,000 people from the region as the flood waters continue to rise, though only 20,000 have been affected as of April 1. In comparison, last year?s floods, which at the time were declared the worst the region had seen since 1958, forced 12,000 people from their homes. On March 31, 2004, the waters reached 6.89 meters, surpassing the peak of last year?s flood, 6.64 meters. So far, two people have died in this year?s floods. The Moderate Resolution Imaging Spectroradiometer [ http://modis.gsfc.nasa.gov ] (MODIS) on the Aqua [ http://aqua.nasa.gov/ ] satellite captured this view of the flood in the Caprivi Strip on March 30, 2004. The false color image shows the flood water in an inky black in sharp contrast to the bright green vegetation. Bare ground is tan and clouds are light blue. The image is available in true-color [ http://rapidfire.sci.gsfc.nasa.gov/gallery/?2004090-0330/Caprivi.A2004090.1205 ] and additional resolutions [ http://rapidfire.sci.gsfc.nasa.gov/gallery/?2004090-0330/Caprivi.A2004090.1205.721 ]. The Zambezi River forms at a spring in northern Zambia, and flows south through Zambia and Angola before turning east in Namibia?s Caprivi Strip and flowing through Zimbabwe, Zambia, and Mozambique to the Indian Ocean. It is Africa?s fourth largest river system after the Nile, Zaire, and Niger Rivers. The high-resolution image also shows floods along the northern section of the river in Zambia at MODIS maximum resolution of 250 meters per pixel. Image courtesy Jesse Allen, based on data from the MODIS Rapid Response Team [ http://rapidfire.sci.gsfc.nasa.gov ] at NASA GSFC |
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Seasonal floods along the Za
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Seasonal floods along the Zambezi River |
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Officials in Namibia worked quickly to evacuate more people in the southern Caprivi Strip as a second wave of flooding on the Zambezi River pushed south toward Lake Liambezi. The lake has been dry since 1985, and the flood waters are expected to spread quickly as the lake fills. The Caprivi Strip began to flood in early February, far earlier than the typical rainy season floods. This year?s floods have affected some 50,000 people and are being called the worst floods the region has seen since 1958. The Moderate Resolution Imaging Spectroradiometer [ http://modis.gsfc.nasa.gov ] (MODIS) on the Terra [ http://terra.nasa.gov/ ] satellite acquired this image on April 17, 2004. At 250 meters per pixel, the image shows how wide-spread the black flood waters are against the tan and green land. In places, the dark channel of the Zambezi River can be seen as a thin line cutting diagonally across the flood plain. Image courtesy Jesse Allen, based on data from the MODIS Rapid Response Team [ http://rapidfire.sci.gsfc.nasa.gov ] at NASA GSFC |
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Seasonal floods along the Za
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| Title |
Seasonal floods along the Zambezi River |
| Description |
On April 12, 2004, the clouds that typically shroud Western Zambia this time of year cleared long enough to give the Moderate Resolution Imaging Spectroradiometer [ http://modis.gsfc.nasa.gov ] (MODIS) on the Terra [ http://terra.nasa.gov/ ] satellite this clear view of the flooded Zambezi River. The river floods during the rainy season every year, but this year, the waters are higher than usual. Recent news reports say that 21,000 households in Western and Northwestern Zambia have been affected by the Zambezi floods so far. The flooding began in December 2003, and increased as the region received far more rain than normal. Now the river is covering most of the plains that line its banks, limiting access to the schools and health centers that are not submerged. Fields of maize and rice have also been covered by the floods. The high waters on this stretch of the Zambezi are also troubling to the already water-logged communities downstream. As these flood waters have moved down into northeast Namibia?s Caprivi Strip, they have affected 20,000 people, killing six. Now officials expect the river to continue to expand in the coming weeks. This image shows the Zambezi River in Zambia just north of the Namibian border. Flowing down across the lower left corner of the image is the Cuando River, which also appears to be flooded with black water surrounding the green lines that mark the river?s usual banks. This section of the Cuando River runs along the border of Zambia and Angola. In this false color image, water is black, and vegetation is bright green. A few white and light blue clouds skirt the edges of the scene. The high-resolution image provided above is at MODIS? maximum resolution of 250 meters per pixel. Image courtesy Jesse Allen, based on data from the MODIS Rapid Response Team [ http://rapidfire.sci.gsfc.nasa.gov ] at NASA GSFC |
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South Africa
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South Africa |
| Description |
This true-color image of South Africa was acquired on May 14, 2000, by NASA's Moderate-resolution Imaging Spectroradiometer, or MODIS. The image was produced using a combination of the sensor's 250-m and 500-m resolution visible wavelength bands. As part of the opening ceremony to begin the joint U.S.-South Africa SAFARI Field Experiment, NASA presented print copies of this image as gifts to Dr. Ben Ngubane, Minister of Arts, Science & Technology, and Honorable Advocate Ngoaka Ramathlodi, Premier of the Northern Province, South Africa. The area shown in this image encompasses seven capital cities and a number of the region's distinctive geological features can be seen clearly. Toward the northern (top) central part of the image, the browns and tans comprise the Kalahari Desert of southern Botswana. The Tropic of Capricorn runs right through the heart of the Kalahari and the Botswanan capital city of Gaborone sits on the Limpopo River, southeast of the Kalahari. Along the western coastline of the continent is the country of Namibia, where the Namib Desert is framed against the sea by the Kaokoveld Mountains. The Namibian capital of Windhoek is obscured by clouds. Looking closely in the center of the image, the Orange River can be seen running from east to west, demarcating the boundary between Namibia and South Africa. On the southwestern corner of the continent is the hook-like Cape of Good Hope peninsula and Cape Town, the parliamentary capital of South Africa. Running west to east away from Cape Town are the Great Karroo Mountains. The shadow in this image conveys a sense of the very steep grade of the cliffs along the southern coast of South Africa. Port Elizabeth sits on the southeasternmost point of South Africa, and a large phytoplankton bloom can be seen in the water about 100 miles east of there. Moving northward along the east coast, the Drakensberg Mountains are visible. The two small nations of Lesotho and Swaziland are in this region, completely contained within South Africa's boundaries. In the upper righthand corner of the image is the Bay of Maputo, where sits Maputo, the capital of Mozambique. Fires are visible in the northeast corner of the image, near Maputo. Just north of Maputo is where the Limpopo River empties into the Indian Ocean. Tracing the Limpopo inland back toward the west, this river defines the northern boundary of South Africa with both Zimbabwe and Botswana. Johannesburg, the commercial capital of South Africa, can be seen as the greyish pixels in the northeastern region of the country. The country's legislative capital, Pretoria, is about 50 miles north of Johannesburg and 250 miles west of Maputo, in the heart of the Northern Province (formerly known as Transvaal). (Image courtesy Jacques Descloitres, MODIS Land Group, NASA Goddard Space Flight Center) |
|
Streamers of Dust off Namibi
…
| Title |
Streamers of Dust off Namibia |
| Description |
On June 24, 2003, the Sea-viewing Wide Field-of-View Sensor (SeaWiFS) captured this image of southern Africa showing numerous dust plumes streaming oceanward from the Namibia coastline— a pattern that previously collected SeaWiFS imagery indicates is common in this part of the world at this time of the year. Image courtesy the SeaWiFS Project, NASA Goddard Space Flight Center, and ORBIMAGE |
|
Streamers of Dust off Namibi
…
| Title |
Streamers of Dust off Namibia |
| Description |
Streamers of dust were hanging in the air over the Atlantic Ocean off the coast of Namibia on June 24, 2003. This image was captured by the Moderate Resolution Imaging Spectroradiometer (MODIS) on the Aqua satellite. The high-resolution image provided above is 500 meters per pixel. The MODIS Rapid Response System provides this image at MODIS' maximum spatial resolution of 250 meters. Image courtesy Jeff Schmaltz, MODIS Rapid Response Team, NASA GSFC |
|
Sulfur Plume along Namibian
…
| Title |
Sulfur Plume along Namibian Coast |
| Description |
Along Namibian coast, off southwest Africa, a cold, deep current snakes northward past the Namib Desert carrying icy waters from deep in the Southern Ocean. Year-round southerly winds cause the warmer surface waters near the coast to be deflected westward away from shore, and the cold waters of the Benguela Current rise up from the depths to replace them. In the ocean, the welling up of cold water has a positive influence on living organisms. As ocean organisms grow and reproduce in the surface waters of the ocean, they use up the nutrients there. Cold waters welling up from deep in the ocean replenish those nutrients and often result in a rapid increase in marine plant life, called a bloom. The individual, microscopic plants, called phytoplankton, live just a few days, and when they die their remains sink to the bottom of the ocean, where they build up in the mud on the coastal floor. Bottom-dwelling bacteria chew through this rich belt of coastal mud, decomposing the phytoplankton remains. The result of this decomposition can be seen in this true-color Moderate Resolution Imaging Spectroradiometer (MODIS) image from the Aqua satellite, acquired on October 16, 2003, in which the coastal waters appear milky-green. (A similar event occurred on Jan. 9, 2003. [ http://earthobservatory.nasa.gov/NaturalHazards/natural_hazards_v2.php3?img_id=5383 ]) Some bacteria consume oxygen as they break down the plant remains, giving off carbon dioxide and water as by-products. But eventually, all the oxygen is used up. At that point, other bacteria take over the decomposition. These bacteria use a form of sulfur when they decompose the organic matter, and give off hydrogen sulfide gas as a by- product. The hydrogen sulfide gas periodically bubbles up from the ocean bottom, and when it encounters more oxygen-rich water near the surface, a chemical reaction occurs that transforms the sulfide gas into pure sulfur. In the first stages of the reaction, the sulfur appears white, and in this image creates a milky-green green tinge to the water. When the transformation is more complete, the plume will look very green?a mixture of the yellow sulfur and blue water. Ironically, the region?s high productivity is also one of its greatest threats, since the hydrogen sulfide gas resulting from such an explosion of life and its inevitable decay is highly toxic to the fish and other marine animals that feed off the phytoplankton. Periodic die-offs of whole populations of fish and other commercial seafood are ongoing concerns for the regional fishing industry. Image courtesy Jacques Descloitres, MODIS Rapid Response Team at NASA GSFC |
|
Sulfur Plume Off Namibia
| Title |
Sulfur Plume Off Namibia |
| Description |
Off the coast of Namibia in southwest Africa, a cold, deep current snakes northward past the Namib Desert carrying icy waters from deep in the Southern Ocean off Antarctica. Year-round southerly winds cause the warmer surface waters near the coast to be deflected westward away from shore, and the cold waters of the Benguela Current rise up from the depths to replace them. In the ocean, the welling up of cold water has a positive influence on living organisms. As ocean organisms grow and reproduce in the surface waters of the ocean, they use up the nutrients there. Cold waters welling up from deep in the ocean replenish those nutrients and often result in a rapid increase in marine plant life, called a bloom. The individual, microscopic plants, called phytoplankton, live just a few days, and when they die their remains sink to the bottom of the ocean, where they build up in the mud on the coastal floor. Bottom-dwelling bacteria chew through this rich belt of coastal mud, decomposing the phytoplankton remains. The result of this decomposition can be seen in this true-color Moderate Resolution Imaging Spectroradiometer (MODIS) image from the Terra satellite on January 9, 2003, in which the coastal waters appear milky-green. Some bacteria consume oxygen as they break down the plant remains, giving off carbon dioxide and water as by-products. But eventually, all the oxygen is used up. At that point, other bacteria take over the decomposition. These bacteria use a form of sulfur when they decompose the organic matter, and give off hydrogen sulfide gas as a by- product. The hydrogen sulfide gas periodically bubbles up from the ocean bottom, and when it encounters more oxygen-rich water near the surface, a chemical reaction occurs that transforms the sulfide gas into pure sulfur. In the first stages of the reaction, the sulfur appears white, and in this image creates a milky-green green tinge to the water. When the transformation is more complete, the plume will look very green?a mixture of the yellow sulfur and blue water. Ironically, the region?s high productivity is also one of its greatest threats, since the hydrogen sulfide gas resulting from such an explosion of life and its inevitable decay is highly toxic to the fish and other marine animals that feed off the phytoplankton. Periodic die-offs of whole populations of fish and other commercial seafood are ongoing concerns for the regional fishing industry. Image courtesy Jacques Descloitres, MODIS Rapid Response Team at NASA GSFC |
|
Sulfur Upwelling off the Afr
…
| Title |
Sulfur Upwelling off the African Coast |
| Description |
Though these aquamarine clouds in the waters off the coast of northern Namibia may look like algae blooms, they are in fact clouds of sulfur produced by anaerobic bacteria on the ocean's floor. This image of the sulfur-filled water was taken on April 24, 2002, by the Sea-viewing Wide Field-of-View Sensor (SeaWiFS), flying aboard the Orbview-2 satellite. The anaerobic bacteria (bacteria that can live without oxygen) feed upon algae carcasses that exist in abundance on the ocean's floor off of Namibia. As the bacteria ingest the algae husks, they produce hydrogen sulfide, which slowly builds up in the sea-floor sediments. Eventually, the hydrogen sulfide reaches the point where the sediment can no longer contain it, and it bubbles forth. When this poisonous chemical reaches the surface, it combines with the oxygen in the upper layers of the ocean to create clouds of pure sulfur. The sulfur causes the Namibian coast to smell like rotten eggs, and the hydrogen sulfide will often kill fish and drive lobsters away. For more information, read: A Bloom By Any Other Name [ http://earthobservatory.nasa.gov/cgi-bin/redirect?http://daac.gsfc.nasa.gov/CAMPAIGN_DOCS/OCDST/sulfur_plume.html ] A high-resolution (250 meters per pixel) image earlier on the 24th taken from the Moderate-Resolution Imaging Spectroradiometer (MODIS) shows additional detail in the plumes. Image courtesy the SeaWiFS Project, [ http://earthobservatory.nasa.gov/cgi-bin/redirect?http://seawifs.gsfc.nasa.gov/SEAWIFS.html ] NASA/Goddard Space Flight Center, and ORBIMAGE. MODIS image courtesy Jacques Descloitres, MODIS Land Rapid Response Team [ http://rapidfire.sci.gsfc.nasa.gov/ ] at NASA GSFC |
|
Sulfur Upwelling off the Afr
…
| Title |
Sulfur Upwelling off the African Coast |
| Description |
Though these aquamarine clouds in the waters off the coast of northern Namibia may look like algae blooms, they are in fact clouds of sulfur produced by anaerobic bacteria on the ocean's floor. This image of the sulfur-filled water was taken on April 24, 2002, by the Sea-viewing Wide Field-of-View Sensor (SeaWiFS), flying aboard the Orbview-2 satellite. The anaerobic bacteria (bacteria that can live without oxygen) feed upon algae carcasses that exist in abundance on the ocean's floor off of Namibia. As the bacteria ingest the algae husks, they produce hydrogen sulfide, which slowly builds up in the sea-floor sediments. Eventually, the hydrogen sulfide reaches the point where the sediment can no longer contain it, and it bubbles forth. When this poisonous chemical reaches the surface, it combines with the oxygen in the upper layers of the ocean to create clouds of pure sulfur. The sulfur causes the Namibian coast to smell like rotten eggs, and the hydrogen sulfide will often kill fish and drive lobsters away. For more information, read: A Bloom By Any Other Name [ http://earthobservatory.nasa.gov/cgi-bin/redirect?http://daac.gsfc.nasa.gov/CAMPAIGN_DOCS/OCDST/sulfur_plume.html ] A high-resolution (250 meters per pixel) image earlier on the 24th taken from the Moderate-Resolution Imaging Spectroradiometer (MODIS) shows additional detail in the plumes. Image courtesy the SeaWiFS Project, [ http://earthobservatory.nasa.gov/cgi-bin/redirect?http://seawifs.gsfc.nasa.gov/SEAWIFS.html ] NASA/Goddard Space Flight Center, and ORBIMAGE. MODIS image courtesy Jacques Descloitres, MODIS Land Rapid Response Team [ http://rapidfire.sci.gsfc.nasa.gov/ ] at NASA GSFC |
|
Flooding In Namibia
| Title |
Flooding In Namibia |
| Description |
In early May 2003, heavy rains in south central Africa led to flooding along Namibia?s Caprivi Strip. High waters along the Zambezi River and its tributaries displaced 25,000 people. The floodwaters can be seen in this false-color image (right) acquired on May 14, 2003, by the Moderate Resolution Imaging Spectroradiometer (MODIS) aboard NASA?s Terra spacecraft. The floodwaters resemble a lake in the center of the image. In March, the flooding was much less extensive (left, acquired on March 27, 2003). During the dry season, this lake would be completely absent and the Zambezi River would resemble a barely visible, thin line. In this false-color image, water is black. Clouds appear as pale blue and white, and vegetated land is green and yellow. Image by Jesse Allen, based on data from the MODIS Rapid Response Team at NASA-GSFC |
|
Flooding In Namibia
| Title |
Flooding In Namibia |
| Description |
In early May 2003, heavy rains in south central Africa led to flooding along Namibia?s Caprivi Strip. High waters along the Zambezi River and its tributaries displaced 25,000 people. The floodwaters can be seen in this false-color image (right) acquired on May 14, 2003, by the Moderate Resolution Imaging Spectroradiometer (MODIS) aboard NASA?s Terra spacecraft. The floodwaters resemble a lake in the center of the image. In March, the flooding was much less extensive (left, acquired on March 27, 2003). During the dry season, this lake would be completely absent and the Zambezi River would resemble a barely visible, thin line. In this false-color image, water is black. Clouds appear as pale blue and white, and vegetated land is green and yellow. Image by Jesse Allen, based on data from the MODIS Rapid Response Team at NASA-GSFC |
|
Flooding in Namibia
| Title |
Flooding in Namibia |
| Description |
Several days of heavy rain triggered devastating floods in south-central Namibia at the end of February 2006. The rains filled the Hardap Dam, and on Saturday, February 25, the water flowed through the flood gates and flooded the city of Mariental. When the Moderate Resolution Imaging Spectroradiometer (MODIS [ http://modis.gsfc.nasa.gov ]) on NASA's Terra [ http://terra.nasa.gov/ ] satellite captured the top image on February 27, the overflow of water had swollen the Fish River south of the city. The bright green agricultural region around the city was also still flooded when this image was taken. According to the United Nations Office for the Coordination of Humanitarian Affairs, 122 houses and 80 businesses were submerged at the time of this image. Two people drowned in the floods. These images are shown in false color. Plant-covered land is green, with agricultural land much brighter than natural vegetation. Bare earth is tan and pink, water is blue, and clouds are pale blue and white. The lower image shows the Hardap region on February 15 before the rains started. NASA images created by Jesse Allen, Earth Observatory, using data obtained from the Goddard Earth Sciences DAAC. |
|
Flooding in Namibia
| Title |
Flooding in Namibia |
| Description |
Several days of heavy rain triggered devastating floods in south-central Namibia at the end of February 2006. The rains filled the Hardap Dam, and on Saturday, February 25, the water flowed through the flood gates and flooded the city of Mariental. When the Moderate Resolution Imaging Spectroradiometer (MODIS [ http://modis.gsfc.nasa.gov ]) on NASA's Terra [ http://terra.nasa.gov/ ] satellite captured the top image on February 27, the overflow of water had swollen the Fish River south of the city. The bright green agricultural region around the city was also still flooded when this image was taken. According to the United Nations Office for the Coordination of Humanitarian Affairs, 122 houses and 80 businesses were submerged at the time of this image. Two people drowned in the floods. These images are shown in false color. Plant-covered land is green, with agricultural land much brighter than natural vegetation. Bare earth is tan and pink, water is blue, and clouds are pale blue and white. The lower image shows the Hardap region on February 15 before the rains started. NASA images created by Jesse Allen, Earth Observatory, using data obtained from the Goddard Earth Sciences DAAC. |
|
Flooding on the Zambezi Rive
…
| Title |
Flooding on the Zambezi River |
| Description |
Nearly every April, Africa's Zambezi River swells with seasonal rain, spreading across its broad flood plain in Angola and Namibia. Some of the people most seriously affected by the regular floods live in Namibia's Caprivi Strip. As of April 11, 2006, seven settlements in the flood-prone region were surrounded by water, reported the New Era, a Namibian newspaper. The region was clearly flooded in a false-color satellite image taken on April 11 (top), by the Moderate Resolution Imaging Spectroradiometer (MODIS [ http://modis.gsfc.nasa.gov ]) on NASA's Aqua [ http://aqua.nasa.gov/ ] satellite. In this image, water is black and dark blue, clouds are pale blue, plant-covered land is green, and bare earth is tan. In the three and a half weeks that passed between the time the top image was acquired and the time the lower image was acquired, the eastern tip of the Caprivi Strip turned into a vast shallow lake. Though the river was still rising, the floods were nowhere near the record-setting levels seen in 2004 [ http://earthobservatory.nasa.gov/NaturalHazards/natural_hazards_v2.php3?img_id=12081 ]. NASA image created by Jesse Allen, Earth Observatory, using data obtained courtesy of the MODIS Rapid Response [ http://rapidfire.sci.gsfc.nasa.gov/ ] team and the Goddard Earth Sciences DAAC. [ http://daac.gsfc.nasa.gov/ ] |
|
Flooding on the Zambezi Rive
…
| Title |
Flooding on the Zambezi River |
| Description |
Nearly every April, Africa's Zambezi River swells with seasonal rain, spreading across its broad flood plain in Angola and Namibia. Some of the people most seriously affected by the regular floods live in Namibia's Caprivi Strip. As of April 11, 2006, seven settlements in the flood-prone region were surrounded by water, reported the New Era, a Namibian newspaper. The region was clearly flooded in a false-color satellite image taken on April 11 (top), by the Moderate Resolution Imaging Spectroradiometer (MODIS [ http://modis.gsfc.nasa.gov ]) on NASA's Aqua [ http://aqua.nasa.gov/ ] satellite. In this image, water is black and dark blue, clouds are pale blue, plant-covered land is green, and bare earth is tan. In the three and a half weeks that passed between the time the top image was acquired and the time the lower image was acquired, the eastern tip of the Caprivi Strip turned into a vast shallow lake. Though the river was still rising, the floods were nowhere near the record-setting levels seen in 2004 [ http://earthobservatory.nasa.gov/NaturalHazards/natural_hazards_v2.php3?img_id=12081 ]. NASA image created by Jesse Allen, Earth Observatory, using data obtained courtesy of the MODIS Rapid Response [ http://rapidfire.sci.gsfc.nasa.gov/ ] team and the Goddard Earth Sciences DAAC. [ http://daac.gsfc.nasa.gov/ ] |
|
11 Hour Star Trails
| Title |
11 Hour Star Trails |
| Explanation |
Fix your camera to a tripod, lock the shutter open, and you can make an image of star trails [ http://www.astropix.com/HTML/I_ASTROP/I06/I0601/I0601.HTM ] - graceful concentric arcs traced by the stars as planet Earth rotates on its axis. Of course, the length of the star trails [ http://antwrp.gsfc.nasa.gov/apod/ap060901.html ] will depend on the exposure time. While exposures lasting just five minutes [ http://antwrp.gsfc.nasa.gov/apod/ap050707.html ] produce a significant arc, in about 12 hours a given star would trace out half a circle [ http://antwrp.gsfc.nasa.gov/apod/ap050714.html ]. But in any long exposure, the background glow from light-polluted skies [ http://www.universetoday.com/2006/08/30/ astrophoto-star-trails-over-namibia-by-josch-hambsch/ ] can build up to wash out the trails. Still, astronomer Josch Hambsch produced this stunning [ http://www.astronomie.be/hambsch/namibia06/startrails1.htm ] composite of star trails around the South Celestial Pole [ http://en.wikipedia.org/wiki/Celestial_pole ] with an effective "all night" exposure time of almost 11 hours. To do it, he combined 128 consecutive five minute long digital exposures recorded in very dark night skies above Namibia [ http://www.astronomie.be/hambsch/namibia06.htm ]. In his final image, the background glow on the right is due in part to the faint, arcing Milky Way [ http://antwrp.gsfc.nasa.gov/apod/ap040911.html ]. |
|
HESS Gamma-Ray Telescope
| Title |
HESS Gamma-Ray Telescope |
| Explanation |
Most ground-based telescopes [ http://www.seds.org/billa/bigeyes.html ] with lenses and mirrors are hindered by the Earth's nurturing, protective atmosphere [ http://antwrp.gsfc.nasa.gov/apod/ap000115.html ] that blurs images and scatters and absorbs light. But this telescope was designed to detect extreme gamma rays [ http://cossc.gsfc.nasa.gov/epo/vu/overview/ overview.html ] - photons with over 100 billion times the energy of visible light - and actually requires the atmosphere to operate. As the gamma rays [ http://antwrp.gsfc.nasa.gov/apod/ap000722.html ] impact the upper atmosphere they produce air showers of high-energy particles. Adorned with 382 separate mirrors each 60 centimeters in diameter and equipped with a fast camera, the telescope [ http://www.mpi-hd.mpg.de/hfm/HESS/public/telescope/ hn_telescopes.htm ] records in detail the brief flashes of optical light, called Cherenkov light [ http://imagine.gsfc.nasa.gov/docs/science/ how_l2/cerenkov.html ], created by the air shower particles. The telescope pictured here was inaugurated this week and is intended to operate as part of the High Energy Stereoscopic System [ http://www.mpi-hd.mpg.de/hfm/HESS/HESS.html ] (HESS) array under construction in Namibia [ http://www.cia.gov/cia/publications/factbook/geos/ wa.html ]. The initial phase of HESS will consist of four telescopes working in concert to provide multiple stereoscopic views of the air showers, relating them to the energies and directions of the incoming cosmic gamma rays [ http://www.mpi-hd.mpg.de/hfm/HESS/public/physics/ hessp.htm ]. |
|
2002 December 3 See Explanat
…
| Title |
2002 December 3 See Explanation. Clicking on the picture will download the highest resolution version available. |
| Explanation |
On December 4th [ http://sunearth.gsfc.nasa.gov/eclipse/TSE2002/ TSE2002.html ], for the second time in as many years, the Moon's shadow will track [ http://sunearth.gsfc.nasa.gov/eclipse/TSE2002/TSE2002txt/ T02animate.html ] across southern Africa bringing a total solar eclipse [ http://www.mreclipse.com/Special/SEprimer.html ] to African skies. Reaching Africa just before 6:00 Universal Time [ http://aa.usno.navy.mil/faq/ docs/UT.html ], the narrow path of totality - corresponding to the path of the Moon's umbra or dark central shadow - will run eastward through Angola, Namibia (Caprivi Strip), Botswana, Zimbabwe, South Africa's Kruger National Park [ http://profjohn.com/el/el2002/index.html ], and Mozambique. Moving out across the Indian Ocean it will ultimately cross onto the Australian continent at sunset (around 9:10 UT [ http://www.csiro.au/helix/eclipse/ ]). Observers directly in this path could catch at most a minute or so of the eclipse at its total phase, but at least a partial eclipse will be visible over much of Africa, Australia [ http://astronomy.swin.edu.au/solar_eclipse_2002/ ], some parts of Indonesia, and eastern Antarctica. While watching [ http://www.mreclipse.com/TSE01reports/ TSE01galleryA.html ] last year's June 21 eclipse, astronomer Fred Espenak recorded a series of exposures used to construct this dramatic composite image. The sequence follows the 2001 geocentric celestial event from start to finish above a thorny acacia tree [ http://www.blueplanetbiomes.org/ acacia_tortillis.htm ] near Chisamba, Zambia. |
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The Cat's Paw Nebula
| Title |
The Cat's Paw Nebula |
| Explanation |
As soon as we find out whose cat did this . . . Nebulae [ http://www.seds.org/billa/twn/ ] are as famous for being identified with familiar shapes as perhaps cats [ http://www.nationalgeographic.com/cats/ ] are for getting into trouble. No cat, though, could have created the vast Cat's Paw Nebula [ http://www.chapman.edu/oca/gallery2/htm-othr/ngc6334.htm ] visible in Scorpius [ http://www.astro.wisc.edu/~dolan/constellations/constellations/Scorpius.html ]. At 5500 light years distant, Cat's Paw [ http://www.aao.gov.au/local/www/dfm/uks011.html ] is an emission nebula [ http://fusedweb.pppl.gov/CPEP/Chart_Pages/5.Plasmas/Nebula/Emission.html ] with a red color that originates from an abundance of ionized hydrogen [ http://antwrp.gsfc.nasa.gov/apod/ap990312.html ] atoms. Alternatively known as the Bear Claw Nebula [ http://antwrp.gsfc.nasa.gov/apod/ap990406.html ] or NGC 6334 [ http://www.aao.gov.au/images/captions/uks010.html ], stars nearly ten times the mass of our Sun [ http://antwrp.gsfc.nasa.gov/apod/ap990615.html ] have been born there in only the past few million years. Pictured above [ http://www.spiegelteam.de/catpaw.htm ], the Cat's Paw nebula was photographed during an astrophotography expedition to Namibia [ http://www.cia.gov/cia/publications/factbook/geos/wa.html ]. |
|
Southern Cross Star Colors
| Title |
Southern Cross Star Colors |
| Explanation |
Fix your camera to a tripod, lock the shutter open, and you can easily record an image of star trails [ http://www.astropix.com/HTML/I_ASTROP/I06/I0601/ I0601.HTM ], the graceful concentric arcs traced by the stars as planet Earth [ http://antwrp.gsfc.nasa.gov/apod/ap021115.html ] rotates on its axis. Gradually change the focus of the camera lens during the exposure, and you could end up with a dramatic picture like this one where the out-of-focus portion of the trail shows off the star's color [ http://antwrp.gsfc.nasa.gov/apod/ap961202.html ]. In this case, the subject is one of the most famous constellations in the night sky, Crux [ http://www.hawastsoc.org/deepsky/cru/ ], the Southern Cross. Gacrux or gamma Crucis [ http://www.solstation.com/stars2/gacrux2.htm ] is the bright red giant star only 88 light-years distant that forms the top of the Cross seen here near top center. Acrux [ http://www.astro.uiuc.edu/~kaler/sow/acrux.html ], the hot blue star at the bottom of the Cross is about 320 light-years distant. Actually a binary star system, Acrux is the alpha star of the compact Southern Cross [ http://www.astro.uiuc.edu/~kaler/sow/ cru-t.html ] and lies along a line pointing from Gacrux to the South Celestial Pole [ http://antwrp.gsfc.nasa.gov/apod/ap000715.html ], off the lower right edge of the picture. Adding a separate short exposure to the end of the step-focussed trails to better show the positions of the stars themselves [ http://flagspot.net/flags/br_astro.html ], astronomer Stefan Seip recorded this remarkable image [ http://www.astromeeting.de/constellations/ 040523cruxa_d.htm ] last May in the dark night skies above Namibia. |
|
Zodiacal Light and the False
…
| Title |
Zodiacal Light and the False Dawn |
| Explanation |
An unusual triangle of light will be particularly bright near the eastern horizon before sunrise during the next two months for observers in Earth's northern hemisphere. Once considered a false dawn [ http://www.odysseymagazine.com/pages/Stargazer.html ], this triangle of light is actually Zodiacal Light [ http://home.wanadoo.nl/marco.langbroek/zodiac.html ], light reflected from interplanetary dust particles [ http://antwrp.gsfc.nasa.gov/apod/ap010813.html ]. The triangle is clearly visible in the left frame taken in Namibia [ http://www.cia.gov/cia/publications/factbook/geos/wa.html ] in May. Rolling the cursor [ http://www.ox.compsoc.net/~swhite/history/ ] over the image will bring up labels. Bright zodiacal light [ http://nightskylive.net/asterisk/viewtopic.php?p=170 ] can be seen nearly every clear moonless morning over the next few months on images taken by the Mauna Kea [ http://www.ifa.hawaii.edu/mko/ ], Hawaii [ http://www.state.hi.us/ ] fisheye CONCAM [ http://nightskylive.net/about.html ] of the Night Sky Live [ http://nightskylive.net/ ] project. Zodiacal dust [ http://coolcosmos.ipac.caltech.edu/cosmic_classroom/cosmic_reference/zodydust.html ] orbits the Sun [ http://www.nineplanets.org/sol.html ] predominantly in the same plane as the planets: the ecliptic [ http://antwrp.gsfc.nasa.gov/apod/ap001014.html ]. Zodiacal light [ http://www.as.wvu.edu/~jel/skywatch/skw9810h.html ] is so bright this time of year because the dust band [ http://antwrp.gsfc.nasa.gov/apod/ap000517.html ] is oriented nearly vertical at sunrise, so that the thick air near the horizon does not block [ http://www.earthsky.com/shows/shows.php?t=20040324 ] out relatively bright reflecting dust [ http://antwrp.gsfc.nasa.gov/apod/ap970825.html ]. Zodiacal light [ http://antwrp.gsfc.nasa.gov/apod/ap020915.html ] is also bright for people in Earth's northern hemisphere in March and April just after sunset. |
|
East of Antares
| Title |
East of Antares |
| Explanation |
East of Antares [ http://antwrp.gsfc.nasa.gov/apod/ap020526.html ], dark markings seem to sprawl through the crowded star fields toward the center of our Milky Way Galaxy. Cataloged in [ http://adsabs.harvard.edu/cgi-bin/ bib_query?1919ApJ....49....1B ] the early 20th century by astronomer E. E. Barnard [ http://astro.uchicago.edu/yerkes/virtualmuseum/ Barnardfull.html ], the obscuring interstellar dust clouds include [ http://www.saguaroastro.org/content/ Best-of-Barnards-Dark-Nebulae.htm ] B72 [ http://antwrp.gsfc.nasa.gov/apod/ap050521.html ], B77, B78, and B59, seen in silhouette [ http://antwrp.gsfc.nasa.gov/apod/ap001229.html ] against the starry background. Here, their combined shape suggests smoke rising from a pipe, and so the dark nebula's popular name is the Pipe Nebula. This gorgeous and expansive view [ http://panther-observatory.com/gallery/deepsky/doc/ Pipe_200mm.htm ] was recorded in very dark skies over Hakos, Namibia [ http://www.fallingrain.com/world/WA/40/Hakos.html ]. It covers a full 10 by 7 degree field in the pronounceable [ http://www.astronomyclub.org/learn/Say_What.htm ] constellation Ophiuchus. |
|
Flooding In Namibia: Natural
…
nasa, nasanaturalhazards
In early May 2003, heavy rai
…
namibia_14may03_721_3
| mediatype |
IMAGE |
| mediatype |
image |
| date |
2003-05-14 |
| creator |
NASA -- NASA Image Of The Day |
| identifier |
namibia_14may03_721_3 |
|
Flooding In Namibia: Natural
…
nasa, nasanaturalhazards
In early May 2003, heavy rai
…
namibia_14may03_721_3
| mediatype |
IMAGE |
| mediatype |
image |
| date |
2003-05-14 |
| creator |
NASA -- NASA Image Of The Day |
| identifier |
namibia_14may03_721_3 |
|
Phytoplankton Bloom off Nami
…
nasa, nasanaturalhazards
A flash of blue and green li
…
namibia_amo_2007312
| mediatype |
IMAGE |
| mediatype |
image |
| date |
2007-11-08 |
| creator |
NASA -- NASA Image Of The Day |
| identifier |
namibia_amo_2007312 |
|
Phytoplankton and Hydrogen S
…
nasa, nasanaturalhazards
Like neon signs against a bl
…
Namibia_AMO_2005221
| mediatype |
IMAGE |
| mediatype |
image |
| date |
2005-08-09 |
| creator |
NASA -- NASA Image Of The Day |
| identifier |
Namibia_AMO_2005221 |
|
Floods in Namibia: Natural H
…
nasa, nasanaturalhazards
* eoimages.gsfc.nasa.gov/ima
…
Namibia_TMO_2008085
| mediatype |
IMAGE |
| mediatype |
image |
| date |
2008-03-25 |
| creator |
NASA -- NASA Image Of The Day |
| identifier |
Namibia_TMO_2008085 |
|
Hydrogen Sulfide Eruption of
…
nasa, nasanaturalhazards
The brilliant burst of neon
…
Namibia_AMO_2007206
| mediatype |
IMAGE |
| mediatype |
image |
| date |
2007-07-25 |
| creator |
NASA -- NASA Image Of The Day |
| identifier |
Namibia_AMO_2007206 |
|
Floods in Southern Africa: N
…
nasa, nasanaturalhazards
* eoimages.gsfc.nasa.gov/ima
…
Mozambique_TMO_2007041
| mediatype |
IMAGE |
| mediatype |
image |
| date |
2007-01-10 |
| creator |
NASA -- NASA Image Of The Day |
| identifier |
Mozambique_TMO_2007041 |
|
Floods in Namibia: Natural H
…
nasa, nasanaturalhazards
* eoimages.gsfc.nasa.gov/ima
…
Namibia_TMO_2008075
| mediatype |
IMAGE |
| mediatype |
image |
| date |
2008-03-15 |
| creator |
NASA -- NASA Image Of The Day |
| identifier |
Namibia_TMO_2008075 |
|
Streamers of Dust off Namibi
…
nasa, nasanaturalhazards
On June 24, 2003, the seawif
…
NamibiaDust.OSW2003175
| mediatype |
IMAGE |
| mediatype |
image |
| date |
2003-06-24 |
| creator |
NASA -- NASA Image Of The Day |
| identifier |
NamibiaDust.OSW2003175 |
|
Dust Plumes off Namibia: Nat
…
nasa, nasanaturalhazards
Many plumes of desert dust (
…
Namibia_TMO2004161
| mediatype |
IMAGE |
| mediatype |
image |
| date |
2004-06-09 |
| creator |
NASA -- NASA Image Of The Day |
| identifier |
Namibia_TMO2004161 |
|
Dust Plumes off Namibia: Nat
…
nasa, nasanaturalhazards
Whisps of white dust sweep o
…
Namibia2_TMO_2004161
| mediatype |
IMAGE |
| mediatype |
image |
| date |
2004-06-09 |
| creator |
NASA -- NASA Image Of The Day |
| identifier |
Namibia2_TMO_2004161 |
|
Dust Plumes off Namibia: Nat
…
nasa, nasanaturalhazards
Whisps of white dust sweep o
…
Namibia2_TMO_2004161
| mediatype |
IMAGE |
| mediatype |
image |
| date |
2004-06-09 |
| creator |
NASA -- NASA Image Of The Day |
| identifier |
Namibia2_TMO_2004161 |
|
|
