|
|
Phoebe's Radiation
| Description |
Phoebe's Radiation |
| Full Description |
This image shows thermal radiation from the day and night sides of Saturn's moon Phoebe, taken by the composite infrared spectrometer onboard Cassini 1.8 hours before the spacecraft's closest approach to Phoebe on June 11, 2004. The left-hand panel displays the image in grayscale format, showing the brightness of Phoebe's radiation in the wavelength range 15-17 microns, which is about 25 times the longest wavelength visible to the naked eye. In the middle panel this brightness is used to estimate the surface temperature distribution across Phoebe. Temperatures are given in degrees Kelvin, and vary from a relatively toasty 107 Kelvin (-267 Fahrenheit), in the late morning near the equator (white, lower right), to less than 75 Kelvin (-324 Fahrenheit) in the northern hemisphere in the pre-dawn hours (dark blue, upper left). The "ragged edge" of Phoebe in this region is an instrumental artifact. Temperatures are affected strongly by topography, as can be seen by comparison with the visible-wavelength image (right). Some of the coldest temperatures are found in the shadowed region inside the large depression in the northern hemisphere (upper right). The Cassini-Huygens mission is a cooperative project of NASA, the European Space Agency and the Italian Space Agency. The Jet Propulsion Laboratory, a division of the California Institute of Technology in Pasadena, manages the Cassini-Huygens mission for NASA's Office of Space Science, Washington, D.C. The Cassini orbiter and its two onboard cameras were designed, developed and assembled at JPL. The composite infrared spectrometer team is based at NASA's Goddard Space Flight Center, Greenbelt, Md. For more information about the Cassini-Huygens mission, visit http://saturn.jpl.nasa.gov and the Cassini composite infrared spectrometer home page at http://cirs.gsfc.nasa.gov/ . Image Credit: NASA/JPL/Goddard Space Flight Center |
|
Phoebe Temperature Maps
| Description |
Phoebe Temperature Maps |
| Full Description |
A montage of maps of Saturn's moon Phoebe shows surface temperatures at various times of day as determined by the composite infrared spectrometer onboard Cassini during the June 11, 2004, Phoebe flyby. The asterisk on each map shows the location of the subsolar point, where the Sun is directly overhead. This point moves across the surface as Phoebe rotates. It is morning in regions to the left of the subsolar point, and afternoon in regions to the right. Like a newspaper weather map, different colors indicate different temperatures, though Phoebe's temperatures are distinctly cooler than even the coldest January day on Earth. Equatorial temperatures peak in the early afternoon near 112 Kelvin (-257 Fahrenheit), plunging to 78 Kelvin (-319 Fahrenheit) before dawn, and are even colder at higher latitudes. The large day/night temperature contrasts imply that Phoebe's surface is covered in loose dust or ice particles that store little heat and thus cool off rapidly at night. Regions of Phoebe's surface that were not observed are shown in black. Most of the maps show the effect on surface temperatures of the large crater-like depression seen in Cassini's visible-wavelength images of Phoebe, which is located just left of center in these maps. Crater walls that are shadowed and cold in the early morning in the first map are sunlit and warm in the late afternoon in the final map. The Cassini-Huygens mission is a cooperative project of NASA, the European Space Agency and the Italian Space Agency. The Jet Propulsion Laboratory, a division of the California Institute of Technology in Pasadena, manages the Cassini-Huygens mission for NASA's Office of Space Science, Washington, D.C. The Cassini orbiter was designed, developed and assembled at JPL. The composite infrared spectrometer team is based at NASA's Goddard Space Flight Center, Greenbelt, Md. For more information about the Cassini-Huygens mission, visit http://saturn.jpl.nasa.gov and the Cassini composite infrared spectrometer home page at http://cirs.gsfc.nasa.gov/ . Image Credit: NASA/JPL/Goddard Space Flight Center |
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Landsat Witnesses the Destru
…
| Title |
Landsat Witnesses the Destruction of Mesopotamian Ecosystem |
| Abstract |
In one of the greatest ecological disasters of our time, the ancient marshlands of Mesopotamia are systematically being converted to dry salt flats as a result of human mismanagement of the region's water resources. Landsat satellite imagery reveals that in the last 10 years, wetlands that once covered as much as 20,000 square km in parts of Iraq and Iran have been reduced to a small fraction of their original size. The authors of a new report released by the United Nations Environment Programme (UNEP) at the 11th Stockholm Water Symposium on August 13, 2001, warn that the marshlands could completely disappear within the next 3-5 years unless dramatic steps are taken immediately to reverse the damage being done. The UNEP Executive Director described the wetlands' condition as 'a major environmental catastrophe that will be remembered as one of humanity's worst engineered disasters.' He noted that 'the tragic loss of this rare wetland has occurred in approximately the same period since world leaders pledged to safeguard the environment at the United Nations Conference on Environment and Development (the Earth Summit) held in Rio de Janeiro in 1992.' Regarded by historians as one of the cradles of civilization, the Mesopotamian Fertile Crescent has supported Marsh Arab society for millennia. But through the damming and siphoning off of waters from the Tigris and Euphrates Rivers, the countries of Iran, Iraq, Turkey, and Syria have decimated the ecosystem and, with it, a culture rooted in the dawn of human history (dating back to ancient Sumeria about 5,000 years ago). |
| Completed |
2000-08-14 |
|
Landsat Witnesses the Destru
…
| Title |
Landsat Witnesses the Destruction of Mesopotamian Ecosystem |
| Abstract |
In one of the greatest ecological disasters of our time, the ancient marshlands of Mesopotamia are systematically being converted to dry salt flats as a result of human mismanagement of the region's water resources. Landsat satellite imagery reveals that in the last 10 years, wetlands that once covered as much as 20,000 square km in parts of Iraq and Iran have been reduced to a small fraction of their original size. The authors of a new report released by the United Nations Environment Programme (UNEP) at the 11th Stockholm Water Symposium on August 13, 2001, warn that the marshlands could completely disappear within the next 3-5 years unless dramatic steps are taken immediately to reverse the damage being done. The UNEP Executive Director described the wetlands' condition as 'a major environmental catastrophe that will be remembered as one of humanity's worst engineered disasters.' He noted that 'the tragic loss of this rare wetland has occurred in approximately the same period since world leaders pledged to safeguard the environment at the United Nations Conference on Environment and Development (the Earth Summit) held in Rio de Janeiro in 1992.' Regarded by historians as one of the cradles of civilization, the Mesopotamian Fertile Crescent has supported Marsh Arab society for millennia. But through the damming and siphoning off of waters from the Tigris and Euphrates Rivers, the countries of Iran, Iraq, Turkey, and Syria have decimated the ecosystem and, with it, a culture rooted in the dawn of human history (dating back to ancient Sumeria about 5,000 years ago). |
| Completed |
2000-08-14 |
|
Landsat Witnesses the Destru
…
| Title |
Landsat Witnesses the Destruction of Mesopotamian Ecosystem |
| Abstract |
In one of the greatest ecological disasters of our time, the ancient marshlands of Mesopotamia are systematically being converted to dry salt flats as a result of human mismanagement of the region's water resources. Landsat satellite imagery reveals that in the last 10 years, wetlands that once covered as much as 20,000 square km in parts of Iraq and Iran have been reduced to a small fraction of their original size. The authors of a new report released by the United Nations Environment Programme (UNEP) at the 11th Stockholm Water Symposium on August 13, 2001, warn that the marshlands could completely disappear within the next 3-5 years unless dramatic steps are taken immediately to reverse the damage being done. The UNEP Executive Director described the wetlands' condition as 'a major environmental catastrophe that will be remembered as one of humanity's worst engineered disasters.' He noted that 'the tragic loss of this rare wetland has occurred in approximately the same period since world leaders pledged to safeguard the environment at the United Nations Conference on Environment and Development (the Earth Summit) held in Rio de Janeiro in 1992.' Regarded by historians as one of the cradles of civilization, the Mesopotamian Fertile Crescent has supported Marsh Arab society for millennia. But through the damming and siphoning off of waters from the Tigris and Euphrates Rivers, the countries of Iran, Iraq, Turkey, and Syria have decimated the ecosystem and, with it, a culture rooted in the dawn of human history (dating back to ancient Sumeria about 5,000 years ago). |
| Completed |
2000-08-14 |
|
Landsat Witnesses the Destru
…
| Title |
Landsat Witnesses the Destruction of Mesopotamian Ecosystem |
| Abstract |
In one of the greatest ecological disasters of our time, the ancient marshlands of Mesopotamia are systematically being converted to dry salt flats as a result of human mismanagement of the region's water resources. Landsat satellite imagery reveals that in the last 10 years, wetlands that once covered as much as 20,000 square km in parts of Iraq and Iran have been reduced to a small fraction of their original size. The authors of a new report released by the United Nations Environment Programme (UNEP) at the 11th Stockholm Water Symposium on August 13, 2001, warn that the marshlands could completely disappear within the next 3-5 years unless dramatic steps are taken immediately to reverse the damage being done. The UNEP Executive Director described the wetlands' condition as 'a major environmental catastrophe that will be remembered as one of humanity's worst engineered disasters.' He noted that 'the tragic loss of this rare wetland has occurred in approximately the same period since world leaders pledged to safeguard the environment at the United Nations Conference on Environment and Development (the Earth Summit) held in Rio de Janeiro in 1992.' Regarded by historians as one of the cradles of civilization, the Mesopotamian Fertile Crescent has supported Marsh Arab society for millennia. But through the damming and siphoning off of waters from the Tigris and Euphrates Rivers, the countries of Iran, Iraq, Turkey, and Syria have decimated the ecosystem and, with it, a culture rooted in the dawn of human history (dating back to ancient Sumeria about 5,000 years ago). |
| Completed |
2000-08-14 |
|
Landsat Witnesses the Destru
…
| Title |
Landsat Witnesses the Destruction of Mesopotamian Ecosystem |
| Abstract |
In one of the greatest ecological disasters of our time, the ancient marshlands of Mesopotamia are systematically being converted to dry salt flats as a result of human mismanagement of the region's water resources. Landsat satellite imagery reveals that in the last 10 years, wetlands that once covered as much as 20,000 square km in parts of Iraq and Iran have been reduced to a small fraction of their original size. The authors of a new report released by the United Nations Environment Programme (UNEP) at the 11th Stockholm Water Symposium on August 13, 2001, warn that the marshlands could completely disappear within the next 3-5 years unless dramatic steps are taken immediately to reverse the damage being done. The UNEP Executive Director described the wetlands' condition as 'a major environmental catastrophe that will be remembered as one of humanity's worst engineered disasters.' He noted that 'the tragic loss of this rare wetland has occurred in approximately the same period since world leaders pledged to safeguard the environment at the United Nations Conference on Environment and Development (the Earth Summit) held in Rio de Janeiro in 1992.' Regarded by historians as one of the cradles of civilization, the Mesopotamian Fertile Crescent has supported Marsh Arab society for millennia. But through the damming and siphoning off of waters from the Tigris and Euphrates Rivers, the countries of Iran, Iraq, Turkey, and Syria have decimated the ecosystem and, with it, a culture rooted in the dawn of human history (dating back to ancient Sumeria about 5,000 years ago). |
| Completed |
2000-08-14 |
|
Landsat Witnesses the Destru
…
| Title |
Landsat Witnesses the Destruction of Mesopotamian Ecosystem |
| Abstract |
In one of the greatest ecological disasters of our time, the ancient marshlands of Mesopotamia are systematically being converted to dry salt flats as a result of human mismanagement of the region's water resources. Landsat satellite imagery reveals that in the last 10 years, wetlands that once covered as much as 20,000 square km in parts of Iraq and Iran have been reduced to a small fraction of their original size. The authors of a new report released by the United Nations Environment Programme (UNEP) at the 11th Stockholm Water Symposium on August 13, 2001, warn that the marshlands could completely disappear within the next 3-5 years unless dramatic steps are taken immediately to reverse the damage being done. The UNEP Executive Director described the wetlands' condition as 'a major environmental catastrophe that will be remembered as one of humanity's worst engineered disasters.' He noted that 'the tragic loss of this rare wetland has occurred in approximately the same period since world leaders pledged to safeguard the environment at the United Nations Conference on Environment and Development (the Earth Summit) held in Rio de Janeiro in 1992.' Regarded by historians as one of the cradles of civilization, the Mesopotamian Fertile Crescent has supported Marsh Arab society for millennia. But through the damming and siphoning off of waters from the Tigris and Euphrates Rivers, the countries of Iran, Iraq, Turkey, and Syria have decimated the ecosystem and, with it, a culture rooted in the dawn of human history (dating back to ancient Sumeria about 5,000 years ago). |
| Completed |
2000-08-14 |
|
Mercury transit of the Sun
| Title |
Mercury transit of the Sun |
| Completed |
2003-05-07 |
|
Mercury transit of the Sun
| Title |
Mercury transit of the Sun |
| Completed |
2003-05-07 |
|
Mercury transit of the Sun
| Title |
Mercury transit of the Sun |
| Completed |
2003-05-07 |
|
Mercury transit of the Sun
| Title |
Mercury transit of the Sun |
| Completed |
2003-05-07 |
|
Mercury transit of the Sun
| Title |
Mercury transit of the Sun |
| Completed |
2003-05-07 |
|
Mount St. Helens
| Title |
Mount St. Helens |
| Description |
Hot lava had broken through the surface of the growing lava dome on Mount St. Helens when the MASTER sensor took this image in the early morning hours of October 13, 2004. MASTER, which stands for MODIS/ASTER Airborne Simulator, is an aircraft- mounted remote sensing device built to simulate the Moderate Resolution Imaging Spectroradiometer (MODIS [ http://modis.gsfc.nasa.gov/ ]) and Advanced Spaceborne Thermal Emission and Reflection Radiometer [ http://asterweb.jpl.nasa.gov/ ] (ASTER) instruments on NASA's Terra [ http://terra.nasa.gov/ ] satellite. The top image was made from MASTER's thermal sensitive bands, and shows the heat in the volcano's crater. A brilliant white spot on the southwest side of the crater is hot lava bubbling to the surface. Smaller, less intense hot spots around the crater have formed where magma near the surface has heated the rock above it. The dark area around the lava dome is the crater. Shielded from the sun and covered with snow, the dark crater floor is cooler than the surrounding landscape, which appears red. A plume of steam rising from the lava dome (colored purple) drifts southeast in this image. The plume and crater floor are more visible in the lower, true color image. Acquired just after dawn, the image has few shadows and low contrast. An image composed of thermal infrared and visible light wavelengths reveals more details around the mountain. The volcanic plume is bright cyan, the cool crater is purple, and snow is light blue. To the north of the volcano, two bright red lines extend from south to north. These are warm-water streams, possibly heated by the active volcano. NASA images courtesy Jeff Myers, MASTER [ http://masterweb.jpl.nasa.gov/ ] instrument team, NASA Ames Research Center |
|
Mount St. Helens
| Title |
Mount St. Helens |
| Description |
Hot lava had broken through the surface of the growing lava dome on Mount St. Helens when the MASTER sensor took this image in the early morning hours of October 13, 2004. MASTER, which stands for MODIS/ASTER Airborne Simulator, is an aircraft- mounted remote sensing device built to simulate the Moderate Resolution Imaging Spectroradiometer (MODIS [ http://modis.gsfc.nasa.gov/ ]) and Advanced Spaceborne Thermal Emission and Reflection Radiometer [ http://asterweb.jpl.nasa.gov/ ] (ASTER) instruments on NASA's Terra [ http://terra.nasa.gov/ ] satellite. The top image was made from MASTER's thermal sensitive bands, and shows the heat in the volcano's crater. A brilliant white spot on the southwest side of the crater is hot lava bubbling to the surface. Smaller, less intense hot spots around the crater have formed where magma near the surface has heated the rock above it. The dark area around the lava dome is the crater. Shielded from the sun and covered with snow, the dark crater floor is cooler than the surrounding landscape, which appears red. A plume of steam rising from the lava dome (colored purple) drifts southeast in this image. The plume and crater floor are more visible in the lower, true color image. Acquired just after dawn, the image has few shadows and low contrast. An image composed of thermal infrared and visible light wavelengths reveals more details around the mountain. The volcanic plume is bright cyan, the cool crater is purple, and snow is light blue. To the north of the volcano, two bright red lines extend from south to north. These are warm-water streams, possibly heated by the active volcano. NASA images courtesy Jeff Myers, MASTER [ http://masterweb.jpl.nasa.gov/ ] instrument team, NASA Ames Research Center |
|
Severe Floods Sweep Across H
…
| Title |
Severe Floods Sweep Across Haiti and the Dominican Republic |
| Description |
Over the past week, both Haiti and the Dominican Republic, the two countries on the island of Hispaniola, have been ravaged by severe flooding after several days of heavy rain. Hundreds have perished in the two countries as a direct result of mud slides and flash flooding. The hardest hit area was in and around the town of Jimani in the southwestern part of the Dominican Republic near the border with Haiti. The Soliel River overflowed its banks before dawn on the morning of the 25th of May 2004 catching the town by surprise. A trough of low pressure across the central Caribbean provided the impetus for the numerous showers and heavy rains. The effect was amplified as moisture-laden low-level southerly winds from the Caribbean interacted with the topography of the island. The Dominican weather service reported that 10 inches of rain fell near Jimani in just 24 hours. The Tropical Rainfall Measuring Mission satellite which was launched in November of 1997 uses both passive and active sensors to measure rainfall over the global tropics from space. The TRMM-based, near-real time Multi-satellite Precipitation Analysis (MPA) at the NASA Goddard Space Flight Center provides quantitative rainfall estimates over the global tropics. The above images show rainfall accumulation between May 18 and May 25, 2004. The first lower shows MPA rainfall totals over the northern Caribbean. The red areas indicate rainfall totals in excess of 14 inches over most of Hispaniola. Darker red areas along the border between Haiti and the Dominican Republic show rainfall totals for the period approaching 24 inches. The second image provides a close-in view of rainfall contours over the same period. It shows that the highest totals are right along the border between Haiti and the Dominican Republic and over the northeastern part of the Dominican Republic and exceed 550 mm (21.7 inches). The above animations show that the bulk of the rain appears to have fallen in a single day on May 23. This graph confirms what the animations show in more detail. It shows the instantaneous average rainfall over a 250-km radius centered at 19N 72W (near the center of the border between Haiti and the Dominican Republic) over the period. It reveals that most of the rain did, in fact, fall on the 23rd of May although significant amounts fell on May 22 and 24 as well. The dates begin at 00Z (midnight Greenwich Mean Time, or 7 pm local time). This graph shows the accumulated rainfall with time for the same area and period. By 00Z on the 25th, an average of 300 mm (11.8 inches) of rain had fallen over the area with a maximum single point accumulation of 598 mm (23.5 inches).TRMM [ http://trmm.gsfc.nasa.gov/ ] is a joint mission between NASA and the Japanese space agency JAXA. Images produced by Hal Pierce (SSAI/NASA GSFC) and caption by Steve Lang |
|
Severe Floods Sweep Across H
…
| Title |
Severe Floods Sweep Across Haiti and the Dominican Republic |
| Description |
Over the past week, both Haiti and the Dominican Republic, the two countries on the island of Hispaniola, have been ravaged by severe flooding after several days of heavy rain. Hundreds have perished in the two countries as a direct result of mud slides and flash flooding. The hardest hit area was in and around the town of Jimani in the southwestern part of the Dominican Republic near the border with Haiti. The Soliel River overflowed its banks before dawn on the morning of the 25th of May 2004 catching the town by surprise. A trough of low pressure across the central Caribbean provided the impetus for the numerous showers and heavy rains. The effect was amplified as moisture-laden low-level southerly winds from the Caribbean interacted with the topography of the island. The Dominican weather service reported that 10 inches of rain fell near Jimani in just 24 hours. The Tropical Rainfall Measuring Mission satellite which was launched in November of 1997 uses both passive and active sensors to measure rainfall over the global tropics from space. The TRMM-based, near-real time Multi-satellite Precipitation Analysis (MPA) at the NASA Goddard Space Flight Center provides quantitative rainfall estimates over the global tropics. The above images show rainfall accumulation between May 18 and May 25, 2004. The first lower shows MPA rainfall totals over the northern Caribbean. The red areas indicate rainfall totals in excess of 14 inches over most of Hispaniola. Darker red areas along the border between Haiti and the Dominican Republic show rainfall totals for the period approaching 24 inches. The second image provides a close-in view of rainfall contours over the same period. It shows that the highest totals are right along the border between Haiti and the Dominican Republic and over the northeastern part of the Dominican Republic and exceed 550 mm (21.7 inches). The above animations show that the bulk of the rain appears to have fallen in a single day on May 23. This graph confirms what the animations show in more detail. It shows the instantaneous average rainfall over a 250-km radius centered at 19N 72W (near the center of the border between Haiti and the Dominican Republic) over the period. It reveals that most of the rain did, in fact, fall on the 23rd of May although significant amounts fell on May 22 and 24 as well. The dates begin at 00Z (midnight Greenwich Mean Time, or 7 pm local time). This graph shows the accumulated rainfall with time for the same area and period. By 00Z on the 25th, an average of 300 mm (11.8 inches) of rain had fallen over the area with a maximum single point accumulation of 598 mm (23.5 inches).TRMM [ http://trmm.gsfc.nasa.gov/ ] is a joint mission between NASA and the Japanese space agency JAXA. Images produced by Hal Pierce (SSAI/NASA GSFC) and caption by Steve Lang |
|
Severe Floods Sweep Across H
…
| Title |
Severe Floods Sweep Across Haiti and the Dominican Republic |
| Description |
Over the past week, both Haiti and the Dominican Republic, the two countries on the island of Hispaniola, have been ravaged by severe flooding after several days of heavy rain. Hundreds have perished in the two countries as a direct result of mud slides and flash flooding. The hardest hit area was in and around the town of Jimani in the southwestern part of the Dominican Republic near the border with Haiti. The Soliel River overflowed its banks before dawn on the morning of the 25th of May 2004 catching the town by surprise. A trough of low pressure across the central Caribbean provided the impetus for the numerous showers and heavy rains. The effect was amplified as moisture-laden low-level southerly winds from the Caribbean interacted with the topography of the island. The Dominican weather service reported that 10 inches of rain fell near Jimani in just 24 hours. The Tropical Rainfall Measuring Mission satellite which was launched in November of 1997 uses both passive and active sensors to measure rainfall over the global tropics from space. The TRMM-based, near-real time Multi-satellite Precipitation Analysis (MPA) at the NASA Goddard Space Flight Center provides quantitative rainfall estimates over the global tropics. The above images show rainfall accumulation between May 18 and May 25, 2004. The first lower shows MPA rainfall totals over the northern Caribbean. The red areas indicate rainfall totals in excess of 14 inches over most of Hispaniola. Darker red areas along the border between Haiti and the Dominican Republic show rainfall totals for the period approaching 24 inches. The second image provides a close-in view of rainfall contours over the same period. It shows that the highest totals are right along the border between Haiti and the Dominican Republic and over the northeastern part of the Dominican Republic and exceed 550 mm (21.7 inches). The above animations show that the bulk of the rain appears to have fallen in a single day on May 23. This graph confirms what the animations show in more detail. It shows the instantaneous average rainfall over a 250-km radius centered at 19N 72W (near the center of the border between Haiti and the Dominican Republic) over the period. It reveals that most of the rain did, in fact, fall on the 23rd of May although significant amounts fell on May 22 and 24 as well. The dates begin at 00Z (midnight Greenwich Mean Time, or 7 pm local time). This graph shows the accumulated rainfall with time for the same area and period. By 00Z on the 25th, an average of 300 mm (11.8 inches) of rain had fallen over the area with a maximum single point accumulation of 598 mm (23.5 inches).TRMM [ http://trmm.gsfc.nasa.gov/ ] is a joint mission between NASA and the Japanese space agency JAXA. Images produced by Hal Pierce (SSAI/NASA GSFC) and caption by Steve Lang |
|
Severe Floods Sweep Across H
…
| Title |
Severe Floods Sweep Across Haiti and the Dominican Republic |
| Description |
Over the past week, both Haiti and the Dominican Republic, the two countries on the island of Hispaniola, have been ravaged by severe flooding after several days of heavy rain. Hundreds have perished in the two countries as a direct result of mud slides and flash flooding. The hardest hit area was in and around the town of Jimani in the southwestern part of the Dominican Republic near the border with Haiti. The Soliel River overflowed its banks before dawn on the morning of the 25th of May 2004 catching the town by surprise. A trough of low pressure across the central Caribbean provided the impetus for the numerous showers and heavy rains. The effect was amplified as moisture-laden low-level southerly winds from the Caribbean interacted with the topography of the island. The Dominican weather service reported that 10 inches of rain fell near Jimani in just 24 hours. The Tropical Rainfall Measuring Mission satellite which was launched in November of 1997 uses both passive and active sensors to measure rainfall over the global tropics from space. The TRMM-based, near-real time Multi-satellite Precipitation Analysis (MPA) at the NASA Goddard Space Flight Center provides quantitative rainfall estimates over the global tropics. The above images show rainfall accumulation between May 18 and May 25, 2004. The first lower shows MPA rainfall totals over the northern Caribbean. The red areas indicate rainfall totals in excess of 14 inches over most of Hispaniola. Darker red areas along the border between Haiti and the Dominican Republic show rainfall totals for the period approaching 24 inches. The second image provides a close-in view of rainfall contours over the same period. It shows that the highest totals are right along the border between Haiti and the Dominican Republic and over the northeastern part of the Dominican Republic and exceed 550 mm (21.7 inches). The above animations show that the bulk of the rain appears to have fallen in a single day on May 23. This graph confirms what the animations show in more detail. It shows the instantaneous average rainfall over a 250-km radius centered at 19N 72W (near the center of the border between Haiti and the Dominican Republic) over the period. It reveals that most of the rain did, in fact, fall on the 23rd of May although significant amounts fell on May 22 and 24 as well. The dates begin at 00Z (midnight Greenwich Mean Time, or 7 pm local time). This graph shows the accumulated rainfall with time for the same area and period. By 00Z on the 25th, an average of 300 mm (11.8 inches) of rain had fallen over the area with a maximum single point accumulation of 598 mm (23.5 inches).TRMM [ http://trmm.gsfc.nasa.gov/ ] is a joint mission between NASA and the Japanese space agency JAXA. Images produced by Hal Pierce (SSAI/NASA GSFC) and caption by Steve Lang |
|
Severe Floods Sweep Across H
…
| Title |
Severe Floods Sweep Across Haiti and the Dominican Republic |
| Description |
Over the past week, both Haiti and the Dominican Republic, the two countries on the island of Hispaniola, have been ravaged by severe flooding after several days of heavy rain. Hundreds have perished in the two countries as a direct result of mud slides and flash flooding. The hardest hit area was in and around the town of Jimani in the southwestern part of the Dominican Republic near the border with Haiti. The Soliel River overflowed its banks before dawn on the morning of the 25th of May 2004 catching the town by surprise. A trough of low pressure across the central Caribbean provided the impetus for the numerous showers and heavy rains. The effect was amplified as moisture-laden low-level southerly winds from the Caribbean interacted with the topography of the island. The Dominican weather service reported that 10 inches of rain fell near Jimani in just 24 hours. The Tropical Rainfall Measuring Mission satellite which was launched in November of 1997 uses both passive and active sensors to measure rainfall over the global tropics from space. The TRMM-based, near-real time Multi-satellite Precipitation Analysis (MPA) at the NASA Goddard Space Flight Center provides quantitative rainfall estimates over the global tropics. The above images show rainfall accumulation between May 18 and May 25, 2004. The first lower shows MPA rainfall totals over the northern Caribbean. The red areas indicate rainfall totals in excess of 14 inches over most of Hispaniola. Darker red areas along the border between Haiti and the Dominican Republic show rainfall totals for the period approaching 24 inches. The second image provides a close-in view of rainfall contours over the same period. It shows that the highest totals are right along the border between Haiti and the Dominican Republic and over the northeastern part of the Dominican Republic and exceed 550 mm (21.7 inches). The above animations show that the bulk of the rain appears to have fallen in a single day on May 23. This graph confirms what the animations show in more detail. It shows the instantaneous average rainfall over a 250-km radius centered at 19N 72W (near the center of the border between Haiti and the Dominican Republic) over the period. It reveals that most of the rain did, in fact, fall on the 23rd of May although significant amounts fell on May 22 and 24 as well. The dates begin at 00Z (midnight Greenwich Mean Time, or 7 pm local time). This graph shows the accumulated rainfall with time for the same area and period. By 00Z on the 25th, an average of 300 mm (11.8 inches) of rain had fallen over the area with a maximum single point accumulation of 598 mm (23.5 inches).TRMM [ http://trmm.gsfc.nasa.gov/ ] is a joint mission between NASA and the Japanese space agency JAXA. Images produced by Hal Pierce (SSAI/NASA GSFC) and caption by Steve Lang |
|
Severe Floods Sweep Across H
…
| Title |
Severe Floods Sweep Across Haiti and the Dominican Republic |
| Description |
Over the past week, both Haiti and the Dominican Republic, the two countries on the island of Hispaniola, have been ravaged by severe flooding after several days of heavy rain. Hundreds have perished in the two countries as a direct result of mud slides and flash flooding. The hardest hit area was in and around the town of Jimani in the southwestern part of the Dominican Republic near the border with Haiti. The Soliel River overflowed its banks before dawn on the morning of the 25th of May 2004 catching the town by surprise. A trough of low pressure across the central Caribbean provided the impetus for the numerous showers and heavy rains. The effect was amplified as moisture-laden low-level southerly winds from the Caribbean interacted with the topography of the island. The Dominican weather service reported that 10 inches of rain fell near Jimani in just 24 hours. The Tropical Rainfall Measuring Mission satellite which was launched in November of 1997 uses both passive and active sensors to measure rainfall over the global tropics from space. The TRMM-based, near-real time Multi-satellite Precipitation Analysis (MPA) at the NASA Goddard Space Flight Center provides quantitative rainfall estimates over the global tropics. The above images show rainfall accumulation between May 18 and May 25, 2004. The first lower shows MPA rainfall totals over the northern Caribbean. The red areas indicate rainfall totals in excess of 14 inches over most of Hispaniola. Darker red areas along the border between Haiti and the Dominican Republic show rainfall totals for the period approaching 24 inches. The second image provides a close-in view of rainfall contours over the same period. It shows that the highest totals are right along the border between Haiti and the Dominican Republic and over the northeastern part of the Dominican Republic and exceed 550 mm (21.7 inches). The above animations show that the bulk of the rain appears to have fallen in a single day on May 23. This graph confirms what the animations show in more detail. It shows the instantaneous average rainfall over a 250-km radius centered at 19N 72W (near the center of the border between Haiti and the Dominican Republic) over the period. It reveals that most of the rain did, in fact, fall on the 23rd of May although significant amounts fell on May 22 and 24 as well. The dates begin at 00Z (midnight Greenwich Mean Time, or 7 pm local time). This graph shows the accumulated rainfall with time for the same area and period. By 00Z on the 25th, an average of 300 mm (11.8 inches) of rain had fallen over the area with a maximum single point accumulation of 598 mm (23.5 inches).TRMM [ http://trmm.gsfc.nasa.gov/ ] is a joint mission between NASA and the Japanese space agency JAXA. Images produced by Hal Pierce (SSAI/NASA GSFC) and caption by Steve Lang |
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Thunderstorms above the Sier
…
| Title |
Thunderstorms above the Sierra Nevada |
| Description |
On June 14, 2004, a series of thunderstorms swept over the southern Sierra Nevada. Storms during the summer are frequent in the area. Warm air rises up the flanks of the mountains, cooling as it gains altitude. Moisture in the air then condenses, creating clouds and rainfall. This image was acquired by the National Oceanic and Atmospheric Administration?s Geostationary Operational Environmental Satellite Program (GOES)-West satellite on June 14, 2004, at 4:00 PDT. The animations include data from dawn until dusk. Image and animation by Robert Simmon, based on data provided by the GOES Project Science [ http://rsd.gsfc.nasa.gov/goes/ ] office |
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Thunderstorms above the Sier
…
| Title |
Thunderstorms above the Sierra Nevada |
| Description |
On June 14, 2004, a series of thunderstorms swept over the southern Sierra Nevada. Storms during the summer are frequent in the area. Warm air rises up the flanks of the mountains, cooling as it gains altitude. Moisture in the air then condenses, creating clouds and rainfall. This image was acquired by the National Oceanic and Atmospheric Administration?s Geostationary Operational Environmental Satellite Program (GOES)-West satellite on June 14, 2004, at 4:00 PDT. The animations include data from dawn until dusk. Image and animation by Robert Simmon, based on data provided by the GOES Project Science [ http://rsd.gsfc.nasa.gov/goes/ ] office |
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Total solar eclipse over Ant
…
| Title |
Total solar eclipse over Antarctica |
| Description |
The moon cast a long shadow over Antarctica on November 23, 2003, in a total solar eclipse. The sun typically hangs low on the horizon during the southernmost continent's almost-summer months, so when the Moon moved between the Sun and the Earth, its shadow fell in a roughly 500-kilometer long oval like the long shadows of a early summer dawn. At the time this image was taken, the sun was at approximately 15 degrees above the horizon. The shadow's long circular shape is the same pattern a flashlight casts an the floor when held at a similar angle. The moon's shadow has two parts: the fuzzy outer shadow, the penumbra, and the dark inner shadow, the umbra. Within the umbra, the sun is completely blocked. A person standing on the ground sees a glowing black disk in front of the sun?the disk is the moon, and the glow is the sun's corona. In the penumbra, the ground observer sees the moon covering part of the sun. Both the penumbra and the umbra are visible in this true-color image. The Moderate Resolution Imaging Spectroradiometer [ http://modis.gsfc.nasa.gov ] (MODIS) on the Aqua [ http://aqua.nasa.gov/ ] satellite captured this image of the eclipse between 23:15 and 23:20 UTC. The Terra [ http://terra.nasa.gov/ ] satellite captured a similar image [ http://rapidfire.sci.gsfc.nasa.gov/gallery/?2003327-1123/Antarctica.A2003327.2255 ] of the eclipse. The eclipse started at 22:08 UTC, and the shadow passed from the surface of the earth a little over an hour later at 23:20 UTC. The sun's light was completely blocked at 22:49 for one minute and 55 seconds. At the time this image was taken, the sun was just rising over Antarctica, tinting the mountains a delicate pink, even within the shadow of the eclipse. Beyond the dark upper left corner, the sun has not yet driven away night's darkness. The bluish tones of the snow reveal how Antarctica appears from space without atmospheric correction. The shadow covers Queen Maud Land, Antarctica, with its tip pointing towards Africa. The South Pole is just beyond the right corner of the image. The moon is not the only thing throwing shadows across the landscape in this image. On the top left, the Pensacola Mountains make long horizontal shadows on the ice. Patches of low cloud along the left side of the umbra are also leaving a dark smudge on the surface. This image is available in multiple resolutions [ http://rapidfire.sci.gsfc.nasa.gov/gallery/?2003327-1123/Antarctica2.A2003327.2320 ]. Image courtesy Jacques Descloitres, MODIS Rapid Response Team [ http://rapidfire.sci.gsfc.nasa.gov ] at NASA GSFC |
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Total solar eclipse over Ant
…
| Title |
Total solar eclipse over Antarctica |
| Description |
The moon cast a long shadow over Antarctica on November 23, 2003, in a total solar eclipse. The sun typically hangs low on the horizon during the southernmost continent's almost-summer months, so when the Moon moved between the Sun and the Earth, its shadow fell in a roughly 500-kilometer long oval like the long shadows of a early summer dawn. At the time this image was taken, the sun was at approximately 15 degrees above the horizon. The shadow's long circular shape is the same pattern a flashlight casts an the floor when held at a similar angle. The moon's shadow has two parts: the fuzzy outer shadow, the penumbra, and the dark inner shadow, the umbra. Within the umbra, the sun is completely blocked. A person standing on the ground sees a glowing black disk in front of the sun?the disk is the moon, and the glow is the sun's corona. In the penumbra, the ground observer sees the moon covering part of the sun. Both the penumbra and the umbra are visible in this true-color image. The Moderate Resolution Imaging Spectroradiometer [ http://modis.gsfc.nasa.gov ] (MODIS) on the Aqua [ http://aqua.nasa.gov/ ] satellite captured this image of the eclipse between 23:15 and 23:20 UTC. The Terra [ http://terra.nasa.gov/ ] satellite captured a similar image [ http://rapidfire.sci.gsfc.nasa.gov/gallery/?2003327-1123/Antarctica.A2003327.2255 ] of the eclipse. The eclipse started at 22:08 UTC, and the shadow passed from the surface of the earth a little over an hour later at 23:20 UTC. The sun's light was completely blocked at 22:49 for one minute and 55 seconds. At the time this image was taken, the sun was just rising over Antarctica, tinting the mountains a delicate pink, even within the shadow of the eclipse. Beyond the dark upper left corner, the sun has not yet driven away night's darkness. The bluish tones of the snow reveal how Antarctica appears from space without atmospheric correction. The shadow covers Queen Maud Land, Antarctica, with its tip pointing towards Africa. The South Pole is just beyond the right corner of the image. The moon is not the only thing throwing shadows across the landscape in this image. On the top left, the Pensacola Mountains make long horizontal shadows on the ice. Patches of low cloud along the left side of the umbra are also leaving a dark smudge on the surface. This image is available in multiple resolutions [ http://rapidfire.sci.gsfc.nasa.gov/gallery/?2003327-1123/Antarctica2.A2003327.2320 ]. Image courtesy Jacques Descloitres, MODIS Rapid Response Team [ http://rapidfire.sci.gsfc.nasa.gov ] at NASA GSFC |
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Venus and Comet Pojmanski
| Title |
Venus and Comet Pojmanski |
| Explanation |
Shining brightly in the east at dawn, Venus [ http://antwrp.gsfc.nasa.gov/apod/ap060201.html ] dominates the sky in this view over a suburban landscape from Bursa, Turkey. An otherwise familiar scene for astronomer Tunc Tezel, his composite picture of the morning sky recorded on March 2nd also includes a surprise visitor to the inner solar system, Comet [ http://www.windows.ucar.edu/tour/link=/comets/ comets.html&edu=high ] Pojmanski. Cataloged as C/2006 A1 [ http://www.aerith.net/comet/catalog/2006A1/ 2006A1.html ], the comet was discovered on January 2nd by Grzegorz Pojmanski of Warsaw University Astronomical Observatory [ http://www.astrouw.edu.pl/ ] in Poland. At the time very faint [ http://www.aerith.net/pictures/comet.html#2006A1 ] and tracking through southern skies [ http://www.yp-connect.net/~mmatti/ ], the comet has now moved north and grown just bright enough to be a good target for early-rising [ http://astroblogger.blogspot.com/2006/02/ hunting-comet-pojmanski.html ] skygazers with binoculars. Enhanced and framed in this picture, the comet's tail [ http://antwrp.gsfc.nasa.gov/apod/ap000413.html ] has also grown to a length of several degrees. The comet will be at its closest approach to planet Earth, just over 100 million kilometers away, on March 5. For northern hemisphere observers in the next few days, the beginning of morning twilight really will be the best time to spot Comet Pojmanski [ http://skyandtelescope.com/observing/objects/comets/ article_1684_1.asp ]. |
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Sky and Planets
| Title |
Sky and Planets |
| Explanation |
On February 10th, an evocative [ http://www.jps.net/ssumner/ ] evening sky above Rocklin, California, USA inspired astrophotographer Steve Sumner to record this remarkable sight - five planets and the Moon. Near its first quarter phase, the bright Moon [ http://lunar.arc.nasa.gov/ ] was intentionally overexposed but Saturn [ http://www.jpl.nasa.gov/cassini/ ], Jupiter [ http://galileo.jpl.nasa.gov/ ], Mars [ http://mars.jpl.nasa.gov/ ], and Mercury [ http://sd-www.jhuapl.edu/MESSENGER/ ] (and, of course, planet Earth's [ http://www.earth.nasa.gov/ ] horizon) are all clearly visible in the deepening twilight. Notably absent in this grouping of naked-eye planets is Venus [ http://antwrp.gsfc.nasa.gov/apod/ap990903.html ] which is still putting in an early appearance as the morning star [ http://ispec.scibernet.com/station/morn_star.html ]. This month, Mercury has joined Venus in the dawn twilight while Saturn, Jupiter, and Mars still shine brightly in the western sky at nightfall [ http://www.skypub.com/sights/sights.shtml ] making another gorgeous close grouping with the crescent Moon [ http://www.inconstantmoon.com/ ]. |
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Messier Marathon
| Title |
Messier Marathon |
| Explanation |
Gripped by an astronomical spring fever [ http://www.zzotto.com/rfc/CFTrip.htm ], it's once again time for many amateur stargazers to embark on a Messier Marathon [ http://www.seds.org/messier/xtra/marathon/marathon.html ]! The Vernal Equinox [ http://antwrp.gsfc.nasa.gov/apod/ap960922.html ] occurs March 20, marking the first day of Spring for the Northern Hemisphere. It also marks a favorable celestial situation [ http://www.reflector.org/MESSIER.HTM ] for potentially viewing all the objects in 18th century French astronomer Charles Messier's catalog [ http://www.seds.org/messier/xtra/history/biograph.html ] in one glorious dusk to dawn [ http://www.seds.org/messier/xtra/marathon/hall.html ] observing run. This year [ http://www.seds.org/messier/xtra/marathon/mm2000.html ] a bright full moon will interfere with dark skies near the actual equinox, so good nights near new moon for weekend marathoners are March 11/12 and April 1/2. (As an added bonus all the planets [ http://antwrp.gsfc.nasa.gov/apod/ap000310.html ] in the solar system can be viewed on these dates.) Astronomer Paul Gitto has created this masterful Messier Marathon [ http://www.cometman.com/messier.html ] grid with 11 rows and 10 columns of Messier catalog objects [ http://www.seds.org/messier/xtra/history/m-cat.html ]. In numerical order, the grid begins with M1, the Crab Nebula, [ http://antwrp.gsfc.nasa.gov/apod/ap960626.html ] at upper left and [ http://www.seds.org/messier/m/m102.html ] ends with M110 [ http://www.seds.org/messier/m/m110.html ], a small elliptical galaxy in Andromeda (lower right). Gitto's images were made with a digital camera and a 10-inch diameter reflecting telescope. |
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Comet Meets Ring Nebula: Par
…
| Title |
Comet Meets Ring Nebula: Part I |
| Explanation |
As dawn approached on May 8, astronomer Stefan Seip carefully watched Fragment C of broken [ http://neo.jpl.nasa.gov/cgi-bin/db?name=73P ] comet 73P/Schwassmann-Wachmann 3 [ http://skyandtelescope.com/observing/objects/comets/ article_1704_1.asp ] approach M57 [ http://seds.lpl.arizona.edu/messier/m/m057.html ] - the Ring Nebula, and faint spiral galaxy IC 1296 [ http://www.skyhound.com/sh/archive/jul/IC_1296.html ]. Of course, even though the trio seemed to come close together in a truly cosmic photo opportunity, the comet [ http://antwrp.gsfc.nasa.gov/apod/ap060504.html ] is in the inner part of our solar system, a mere 0.5 light-minutes [ http://en.wikipedia.org/wiki/Light-minute ] or so from Seip's telescope located near Stuttgart, Germany, planet Earth [ http://science.nasa.gov/headlines/y2006/ 24mar_73p.htm?list237669 ]. The Ring Nebula (upper right) is more like 2,000 light-years distant, well within our own Milky Way Galaxy [ http://antwrp.gsfc.nasa.gov/apod/ap050825.html ]. At a distance of 200 million light-years, IC 1296 (between comet and ring) is beyond even the Milky Way's boundaries. Because the comet is so close, it appears to move relatively rapidly against the distant stars. This dramatic telescopic view [ http://www.photomeeting.de/astromeeting/comets/ 060508SchwWas_a_d.htm ] was composited from two sets of images, one compensating [ http://www.ewellobservatory.com/ccd/ comet.cfm ] for the comet's apparent motion and one recording the background stars and nebulae [ http://antwrp.gsfc.nasa.gov/apod/ap030516.html ]. |
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M4: The Closest Known Globul
…
| Title |
M4: The Closest Known Globular Cluster |
| Explanation |
M4 is a globular cluster [ http://www.seds.org/messier/glob.html ] visible in dark skies about one degree west of the bright star Antares [ http://antwrp.gsfc.nasa.gov/apod/ap980726.html ] in the constellation [ http://www.astro.wisc.edu/~dolan/constellations/extra/constellations.html ] Scorpius [ http://www.astro.wisc.edu/~dolan/constellations/constellations/Scorpius.html ]. M4 is perhaps the closest globular cluster [ http://antwrp.gsfc.nasa.gov/apod/globular_clusters.html ] at 7000 light years [ http://www.treasure-troves.com/astro/Light-Year.html ], meaning that we see M4 [ http://www.seds.org/messier/m/m004.html ] only as it was 7000 years ago, near the dawn of recorded human history [ http://www.hyperhistory.com/online_n2/History_n2/a.html ]. Although containing hundreds of thousands of stars and spanning over 50 light-years, M4 [ http://adsabs.harvard.edu/cgi-bin/nph-bib_query?bibcode=1993MNRAS.265..395D ] is one of the smallest and sparsest globular clusters [ http://ast.leeds.ac.uk/research/gcs.html ] known. A particularly unusual aspect for a globular cluster is M4 [ http://www.astr.ua.edu/gifimages/m4v.html ]'s central bar of stars. M4, pictured above [ http://www.noao.edu/image_gallery/html/im0598.html ], is one of the oldest objects for which astronomers can estimate age directly. Cluster white dwarfs [ http://antwrp.gsfc.nasa.gov/apod/ap971102.html ] appear to be at least nine billion years old - so ancient they limit the youth of our entire universe [ http://www.astro.ucla.edu/~wright/cosmology_faq.html ]. |
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Ceres: Asteroid or Planet?
| Title |
Ceres: Asteroid or Planet? |
| Explanation |
Is Ceres [ http://en.wikipedia.org/wiki/Ceres_%28asteroid%29 ] an asteroid [ http://www.nineplanets.org/asteroids.html ] or a planet? Although a trivial designation to some, the recent suggestion by the Planet Definition Committee [ http://www.iau2006.org/mirror/www.iau.org/iau0601/iau0601_committee.html ] of the International Astronomical Union [ http://www.iau2006.org/mirror/www.iau.org/NEWS.55.0.html ] would have Ceres reclassified from asteroid to planet. A change in taxonomy might lead to more notoriety for the frequently overlooked world. Ceres [ http://www.pantheon.org/articles/c/ceres.html ], at about 1000 kilometers across, is the largest object in the main asteroid belt [ http://www.solstation.com/stars/asteroid.htm ] between Mars and Jupiter. Under the newly proposed criteria [ http://www.iau2006.org/mirror/www.iau.org/iau0601/iau0601_release.html ], Ceres would qualify as a planet because it is nearly spherical and sufficiently distant from other planets. Pictured above [ http://hubblesite.org/newscenter/newsdesk/archive/releases/2005/27/image/a ] is the best picture yet of Ceres, taken by the Hubble Space Telescope [ http://antwrp.gsfc.nasa.gov/apod/ap010806.html ] as part of a series of exposures ending in 2004 January. Currently, NASA's Dawn mission [ http://dawn.jpl.nasa.gov/ ] is scheduled to launch in 2007 June to explore Ceres and Vesta [ http://antwrp.gsfc.nasa.gov/apod/ap060820.html ], regardless of their future designations. |
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Moon And Venus Share The Sky
| Title |
Moon And Venus Share The Sky |
| Explanation |
July is drawing to a close and in the past few days, some early morning risers [ http://antwrp.gsfc.nasa.gov/apod/ap990714.html ] could have looked east and seen a crescent Moon sharing the pre-dawn [ http://science.nasa.gov/headlines/y2000/ast25jul_1m.htm ] skies with planets Jupiter and Saturn. Planet Mercury will also pass about 2 degrees from the thin waning crescent Moon [ http://aa.usno.navy.mil/AA/faq/docs/moon_phases.html ] just before sunrise near the eastern horizon on Saturday, July 29. And finally, on the evening of July 31st, Venus will take its turn near the crescent Moon [ http://antwrp.gsfc.nasa.gov/apod/ap991108.html ]. But this time it will be a day-old crescent Moon near the western horizon, shortly after sunset [ http://antwrp.gsfc.nasa.gov/apod/ap000507.html ]. In fact [ http://pages.prodigy.net/pam.orman/JoeAlmanac2000.html ], on July 31 (August 1 Universal Time) the Moon will occult [ http://www.skypub.com/sights/occultations/lunar/ 0001lunarocc.html ] (pass in front of) Venus for northwestern observers [ http://www.skypub.com/sights/images2000/ 0008moonvenus_big.jpg ] in North America. This telescopic picture taken on 31 December 1997, shows a lovely young crescent Moon and brilliant crescent Venus in [ http://antwrp.gsfc.nasa.gov/apod/ap990903.html ] the early evening sky near Bursa, Turkey [ http://www.mersina.com/Turkey/Marmara/Bursa/index.html ]. And what about the Sun? On Sunday, July 30, a partial eclipse of the Sun [ http://sunearth.gsfc.nasa.gov/eclipse/extra/ PSE2000Jul31.html ] will be visible from some locations [ http://sunearth.gsfc.nasa.gov/eclipse/OH/ PSE2000Jul.gif ] in North America. |
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A Perseid Meteor
| Title |
A Perseid Meteor |
| Explanation |
This weekend, the annual Perseid Meteor Shower [ http://spacescience.com/headlines/y2000/ast08aug_1.htm ] reaches its maximum. Grains of cosmic sand and gravel shed from Comet Swift-Tuttle [ http://antwrp.gsfc.nasa.gov/apod/ap960219.html ] will streak across the sky as they vaporize during entry into Earth's atmosphere [ http://liftoff.msfc.nasa.gov/academy/space/atmosphere.html ]. The Perseids [ http://antwrp.gsfc.nasa.gov/apod/ap960809.html ] result from the yearly crossing of the Earth through Comet Swift-Tuttle's orbit. The Perseids [ http://comets.amsmeteors.org/meteors/showers/ perseids.html ] are typically the most active meteor shower [ http://www.imo.net/index.html ] of the year. In a clear dark sky, an observer might see a meteor a minute near peak times [ http://antwrp.gsfc.nasa.gov/apod/ap991124.html ], but this year a bright moon will overwhelm the glow from many perseid meteors until moonset [ http://tycho.usno.navy.mil/srss.html ] in the early morning hours. Pictured above [ http://aibn47.astro.uni-bonn.de/~gallery/atmosphere/perseide.html ] is a Perseid meteor from 1993. The colors are representative but digitally enhanced. As the meteor [ http://www.seds.org/nineplanets/nineplanets/meteorites.html ] streaked across the night sky, different excited atoms emitted different colors of light. The origin of the green tinge visible at the right is currently unknown, however, and might result from oxygen [ http://pearl1.lanl.gov/periodic/elements/8.html ] in Earth's atmosphere. Perseid meteors can best be seen from a relaxing position, away from lights, just before the dawn twilight. |
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Comet SWAN Brightens
| Title |
Comet SWAN Brightens |
| Explanation |
A newly discovered comet has brightened enough to be visible this week with binoculars. The picturesque comet [ http://antwrp.gsfc.nasa.gov/apod/ap050904.html ] is already becoming a favored target for northern sky imagers. Pictured above [ http://www.astrostudio.at/Astrofotos/astrofotos.php?k_id=69 ] just last week, Comet SWAN showed a bright blue-green coma and an impressive tail. Comet C/2006 M4 (SWAN) [ http://cometography.com/lcomets/2006m4.html ] was discovered in June in public images from the Solar Wind Anisotropies [ http://www.fmi.fi/research_space/space_7.html ] (SWAN) instrument of NASA and ESA [ http://en.wikipedia.org/wiki/ESA ]'s Sun-orbiting SOHO [ http://sohowww.nascom.nasa.gov/ ] spacecraft. Comet [ http://en.wikipedia.org/wiki/Comet ] SWAN, near magnitude six, will be visible with binoculars in the northeastern sky not far from the Big Dipper over the next few days before dawn. The comet [ http://www.aerith.net/comet/catalog/2006M4/2006M4.html ] is expected to reach its peak brightness this week. Passing its closest to the Sun two days ago, Comet SWAN [ http://ssd.jpl.nasa.gov/sbdb.cgi?ID=dK06M040;orb=1;cov=0#orb ] and will be at its closest to the Earth toward the end of this month. Comet SWAN's unusual orbit [ http://cfa-www.harvard.edu/cfa/ps/mpec/K06/K06S89.html ] appears to be hyperbolic [ http://adsabs.harvard.edu/abs/1992A&A...259..692K ], meaning that it will likely go off into interstellar space [ http://antwrp.gsfc.nasa.gov/apod/ap020210.html ], never to return. |
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NGC 6960: The Witch's Broom
…
| Title |
NGC 6960: The Witch's Broom Nebula |
| Explanation |
Ten thousand years ago, before the dawn of recorded human history [ http://news.bbc.co.uk/hi/english/sci/tech/newsid_334000/334517.stm ], a new light must suddenly have appeared in the night sky and faded after a few weeks. Today we know this light was an exploding star [ http://imagine.gsfc.nasa.gov/docs/science/know_l1/supernovae.html ] and record the colorful expanding cloud as the Veil Nebula [ http://nineplanets.org/twn/cygnusx.html ]. Pictured above [ http://robgendler.astrodigitals.com/Nebulas.html ] is the west end of the Veil Nebula [ http://www.astropix.com/HTML/E_SUM_N/VEIL.HTM ] known technically as NGC [ http://www.ngcic.com/dss/dss_images.htm ] 6960 but less formally as the Witch's Broom Nebula. The rampaging gas gains its colors by impacting and exciting existing [ http://antwrp.gsfc.nasa.gov/apod/ap960307.html ] nearby gas. The supernova remnant [ http://antwrp.gsfc.nasa.gov/apod/supernova_remnants.html ] lies about 1400 light-years away towards the constellation of Cygnus [ http://www.multimania.com/cdadfs/constellation/cygne/cygnus.htm ]. This Witch's Broom actually spans over three times the angular size of the full Moon [ http://antwrp.gsfc.nasa.gov/apod/moon.html ]. The bright blue star 52 Cygnus [ http://www.seds.org/Maps/Stars_en/Fig/cygnus.html ] is visible with the unaided eye from a dark location but unrelated to the ancient supernova [ http://www.chapman.edu/oca/benet/intro_sn.htm ]. |
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3D Mercury Transit
| Title |
3D Mercury Transit |
| Explanation |
Mercury is now [ http://www.astronomy.com/ASY/CS/forums/314872/ ShowPost.aspx ] visible shortly before dawn, the brightest "star" just above the eastern horizon. But almost two weeks ago Mercury [ http://antwrp.gsfc.nasa.gov/apod/ap061114.html ] actually crossed the face of the Sun for the second time in the 21st century. Viewed with red/blue glasses [ http://photojournal.jpl.nasa.gov/Help/VendorList.html ], this stereo anaglyph combines space-based images of the Sun and innermost planet in a just-for-fun 3D [ http://www.sungazer.net/3dtransit.html ] presentation of the Mercury transit [ http://www.transitofvenus.org/mercury.htm ]. The solar disk image is from Hinode [ http://solarb.msfc.nasa.gov/index.html ]. (sounds like "hee-no-day", means sunrise). A sun-staring observatory, Hinode was launched from Uchinoura Space Center and viewed the transit [ http://solar-b.nao.ac.jp/news_e/20061109_e.shtml ] from Earth orbit. Superimposed on Mercury's dark silhouette is a detailed image [ http://antwrp.gsfc.nasa.gov/apod/ap011124.html ] of the planet's rugged surface based on data from the Mariner 10 [ http://nssdc.gsfc.nasa.gov/nmc/tmp/1973-085A.html ] probe that flew by Mercury in 1974 and 1975. |
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Minotaur Dawn
| Title |
Minotaur Dawn |
| Explanation |
Last Saturday [ http://www.wff.nasa.gov/news/story96.html ], some colorful dawn skies along the US east coast featured the Moon and a Minotaur rocket climbing [ http://www.sungazer.net/minotaur.html ] into low Earth orbit. The 7AM launch [ http://www.launchphotography.com/Minotaur_TacSat.html ] of the four stage Air Force Minotaur I rocket [ http://en.wikipedia.org/wiki/Minotaur_rocket ] took place at NASA's Wallops Flight Facility [ http://www.wff.nasa.gov/index.html ] on Virginia's eastern shore. Looking east, the rocket is visible beyond the top of the twisting exhaust plume in this wide angle view, with the waning crescent Moon at the upper right. The snapshot was taken from Alexandria, Virginia, some 100 miles northwest of Wallops Island. Orbital launches [ http://spaceplace.nasa.gov/en/kids/ds1_mgr.shtml ] from Wallops have so far been relatively rare, the last two taking place in 1995 and 1985. As a result, many early morning risers reported the unusual spectacle. The rocket's payload was the Air Force Research Laboratory's TacSat-2 [ http://www.wff.nasa.gov/tacsat2/ ] satellite and NASA's GeneSat-1 [ http://tia.arc.nasa.gov/genesat1/ ] microsatellite. |
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Three Planets in Dawn Skies
| Title |
Three Planets in Dawn Skies |
| Explanation |
Three children of the Sun [ http://antwrp.gsfc.nasa.gov/apod/ap061116.html ] rise in the east in this peaceful dawn skyview recorded December 7th near Bolu, Turkey. Inner planet Mercury [ http://kids.nineplanets.org/mercury.htm ], fresh from its second transit [ http://antwrp.gsfc.nasa.gov/apod/ap061114.html ] of the 21st century, stands highest in the bright sky at the top right. Gas giant Jupiter [ http://nssdc.gsfc.nasa.gov/planetary/factsheet/ jupiterfact.html ] lies below the cloud bank near picture center. A newsworthy Mars [ http://www.nasa.gov/mission_pages/mars/news/ mgs-20061206.html ] is also visible, right of Jupiter and just above the dark cloud bank. On Sunday, these planets will form a much tighter grouping [ http://skytonight.com/observing/ataglance ] before sunrise [ http://niteskys.com/mercury_mars_jupiter_120806.html ], while in the coming days the western sky after sunset will be ruled by brilliant planet Venus [ http://www.esa.int/SPECIALS/Venus_Express/ ], also known as the evening star. |
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NGC 6960: The Witch's Broom
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| Title |
NGC 6960: The Witch's Broom Nebula |
| Explanation |
Ten thousand years ago, before the dawn of recorded human history [ http://news.bbc.co.uk/hi/english/sci/tech/newsid_334000/334517.stm ], a new light must suddenly have appeared in the night sky and faded after a few weeks. Today we know this light was an exploding star [ http://imagine.gsfc.nasa.gov/docs/science/know_l1/supernovae.html ] and record the colorful expanding cloud as the Veil Nebula [ http://antwrp.gsfc.nasa.gov/apod/ap010928.html ]. Pictured above [ http://www.noao.edu/image_gallery/html/im0852.html ] is the west end of the Veil Nebula [ http://antwrp.gsfc.nasa.gov/apod/ap030204.html ] known technically as NGC [ http://en.wikipedia.org/wiki/New_General_Catalog ] 6960 but less formally as the Witch [ http://antwrp.gsfc.nasa.gov/apod/ap061211.html ]'s Broom [ http://www.broomshop.com/history/ ] Nebula. The rampaging gas gains its colors by impacting and exciting existing [ http://www.seds.org/billa/twn/cygnusx.html ] nearby gas. The supernova remnant [ http://antwrp.gsfc.nasa.gov/apod/supernova_remnants.html ] lies about 1400 light-years [ http://starchild.gsfc.nasa.gov/docs/StarChild/questions/question19.html ] away towards the constellation of Cygnus [ http://www.multimania.com/cdadfs/constellation/cygne/cygnus.htm ]. This Witch's Broom actually spans over three times the angular size [ http://imagine.gsfc.nasa.gov/YBA/HTCas-size/more-ang_size.html ] of the full Moon [ http://antwrp.gsfc.nasa.gov/apod/ap030810.html ]. The bright star 52 Cygnus [ http://www.seds.org/Maps/Stars_en/Fig/cygnus.html ] is visible with the unaided eye from a dark location but unrelated to the ancient supernova [ http://en.wikipedia.org/wiki/Supernova ]. |
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Comet McNaught Heads for the
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| Title |
Comet McNaught Heads for the Sun |
| Explanation |
Early morning risers with a clear and unobstructed eastern horizon can enjoy the sight of Comet McNaught (C/2006 P1) in dawn skies over the next few days. Discovered in August by R. H. McNaught (Siding Spring Survey [ http://www.mso.anu.edu.au/~rmn/ ]) the comet has grown bright enough to see with the unaided eye but will soon be lost in the glare of the Sun. Still, by January 11 sun-staring spacecraft SOHO should be able to offer web-based views [ http://sohowww.nascom.nasa.gov/data/realtime/c3/ 512/ ] as the comet heads toward [ http://neo.jpl.nasa.gov/cgi-bin/db_shm?name=c/2006+P1 ] a perihelion [ http://www.windows.ucar.edu/tour/ link=/physical_science/physics/mechanics/orbit/ perihelion_aphelion.html&edu=high ] passage inside the orbit of Mercury. This image captures [ http://www.astrostudio.at/Astrofotos/astrofotos.php?k_id=71 ] the new naked-eye comet [ http://www.nasa.gov/worldbook/comet_worldbook.html ] at about 2nd magnitude [ http://en.wikipedia.org/wiki/Apparent_magnitude ] in twilight skies near sunset on January 3rd. After rounding the Sun [ http://www.shadowandsubstance.com/ ] and emerging from the solar glare later this month, Comet McNaught [ http://www.aerith.net/comet/catalog/2006P1/2006P1.html ] could be even brighter. |
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Jupiter, Saturn and Messier
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| Title |
Jupiter, Saturn and Messier 45 |
| Explanation |
Brilliant Venus falls out [ http://antwrp.gsfc.nasa.gov/apod/ap990903.html] of the evening sky as March ends, but Jupiter and Saturn remain well up above the western horizon. Jupiter [ http://www.jpl.nasa.gov/galileo/jupiter/jupiter.html ] blazes forth above and to the left of a slightly fainter Saturn [ http://antwrp.gsfc.nasa.gov/apod/ap000212.html ] in this telephoto picture taken on January 19th. Near the top lies the lovely Pleiades [ http://antwrp.gsfc.nasa.gov/apod/ap000227.html ] star cluster with suggestions of its characteristic blue reflection nebulae [ http://antwrp.gsfc.nasa.gov/cgi-bin/apod/ apod_search?reflection+nebula ]. These planets and the Pleiades have a similar, easily recognizable orientation in the Spring night sky. Also known as M45 [ http://www.seds.org/messier/m/m045.html ], the 45th object in French astronomer Charles Messier's [ http://antwrp.gsfc.nasa.gov/apod/ap960626.html ] famous catalog, the Pleiades will likely soon be checked off many stargazers' tally lists. For northern hemisphere observers this weekend offers a prime opportunity to complete a Messier Marathon [ http://www.seds.org/messier/xtra/marathon/ marathon.html ] -- the viewing of all 110 Messier catalog objects [ http://www.seds.org/messier/data2.html ] in one glorious [ http://antwrp.gsfc.nasa.gov/apod/ap000311.html ] dusk to dawn observing run. This weekend it will also be possible to complete an all-planet marathon, observing all the solar system's [ http://space.jpl.nasa.gov/ ] planets in a single night. And if you still need something to look at, the International Space Station [ http://www.hq.nasa.gov/osf/station/viewing/ issvis.html ] could also be visible arcing through the skies depending on your location, but Mir will not [ http://www.russianspaceweb.com/ ]. |
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Shepard Flies Freedom 7
| Title |
Shepard Flies Freedom 7 |
| Explanation |
Forty years ago today (May 5, 1961 [ http://www.thespaceplace.com/history/mercury/ mercury03.html ]), at the dawn of the space age [ http://www.hq.nasa.gov/office/pao/History/sputnik/ index.html ], NASA controllers "lit the candle" and sent Alan Shepard arcing into space atop a Redstone rocket [ http://antwrp.gsfc.nasa.gov/apod/ap980404.html ]. The picture shows the pressure-suited Shepard before launch in his cramped space capsule [ http://www.hq.nasa.gov/office/pao/History/diagrams/ mercury.html ] dubbed "Freedom 7" [ http://images.jsc.nasa.gov/images/pao/MR3/ 10073523.htm ]. Broadcast live to a global television audience, the flight of Freedom 7 [ http://www.nasm.edu/galleries/attm/nojs/rm.ey.f7.1.html ] - the first space flight by an American - followed less than a month after the first human venture into space by Soviet Cosmonaut Yuri Gagarin [ http://antwrp.gsfc.nasa.gov/apod/ap010414.html ]. Freedom 7's historic flight [ http://www.hq.nasa.gov/office/pao/History/40thmerc7/ intro.htm ] was suborbital, lasting only about 15 minutes, but during it Shepard demonstrated manual control of his capsule. Naval aviator [ http://www.hq.nasa.gov/office/pao/History/40thmerc7/ shepard.htm ] Shepard was chosen as one of the original seven Mercury Program [ http://www.hq.nasa.gov/office/pao/History/SP-4201/ toc.htm ] astronauts. He considered this first flight [ http://www.hq.nasa.gov/office/pao/History/SP-4201/ch11-4.htm ] the greatest challenge and actively sought the assignment. Shepard's career as an astronaut spanned a remarkable period in human achievement and in 1971 he walked on the moon [ http://www.hq.nasa.gov/office/pao/History/alsj/a14/ a14.crew.html ] as commander of the Apollo 14 mission. A true pioneer and intrepid explorer, Alan Shepard died in 1998 [ http://www.nasa.gov/shepard.html ] at age 74. |
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Jupiter, Vesta, and the Milk
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| Title |
Jupiter, Vesta, and the Milky Way |
| Explanation |
In this gorgeous skyscape, gas giant Jupiter [ http://antwrp.gsfc.nasa.gov/apod/ap070329.html ] along with the stars and cosmic dust clouds of the Milky Way [ http://antwrp.gsfc.nasa.gov/apod/ap070330.html ] hang over the southern horizon in the early morning hours as seen from Stagecoach, Colorado, USA. Recorded on Thursday, Jupiter is the brightest object near picture center. Along with the stunning Milky Way, Jupiter is hard to miss, but a careful inspection of the view also reveals main belt [ http://www.solstation.com/stars/asteroid.htm ] asteroid Vesta [ http://antwrp.gsfc.nasa.gov/apod/ap060820.html ]. Of all the asteroids [ http://www.nineplanets.org/asteroids.html ] Vesta is the brightest and is now just bright enough to be visible to the naked eye from locations with very dark, clear skies. Vesta (as well as Jupiter) appears relatively bright now because it is near opposition, literally [ http://www.heavens-above.com/ gloss.asp?term=opposition ] opposite the Sun in planet Earth's sky and closest to Earth in its orbit. For Vesta [ http://dawn.jpl.nasa.gov/feature_stories/ Vesta_chart_descrip.asp ], this opposition offers the best viewing in many years. The year 2007 also coincides [ http://adsabs.harvard.edu/abs/1907Obs....30..103L ] with the 200th anniversary of the asteroid's discovery [ http://dawn.jpl.nasa.gov/DawnCommunity/ flashbacks/fb_06.asp ]. Starting late next month, NASA plans to launch the Dawn mission [ http://dawn.jpl.nasa.gov/index.asp ] intended to explore Vesta (and Ceres) and the main asteroid belt. |
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Venus' Evening Loop
| Title |
Venus' Evening Loop |
| Explanation |
From September 2000 through March 2001, astronomer Tunc Tezel patiently photographed the planet Venus on 25 different dates as it wandered [ http://zebu.uoregon.edu/~js/ast221/lectures/ lec06.html ] through the evening twilight. The pictures were taken from the same spot on the campus of the Middle East Technical University near Ankara, Turkey, and timed so that for each photo the Sun was [ http://aa.usno.navy.mil/data/docs/RS_OneYear.html ] 7 degrees below the horizon. Carefully registering and combining the pictures, he produced this composite image -- a stunning demonstration of Venus' grand [ http://stoner.eps.mcgill.ca/~bud/craters/ FaceOfVenus.html ] looping sky motion [ http://sunra.colorado.edu/david/ch1.html ] during its recent stint as planet Earth's evening star [ http://www.library.utoronto.ca/utel/rp/poems/ longfe10.html ]. As indicated, the first picture, taken September 28, 2000, finds Venus [ http://www.windows.ucar.edu/cgi-bin/tour_def/venus/ morning_star.html ] close to the western horizon [ http://antwrp.gsfc.nasa.gov/apod/ap990619.html ] and drifting south (left) with the passing days. By December however, Venus [ http://nssdc.gsfc.nasa.gov/planetary/planets/ venuspage.html ] was climbing well above the horizon after sunset and in January 2001 it reached its maximum apparent distance (elongation [ http://astrosun.tn.cornell.edu/courses/astro201/ planet_view.htm ]) from the Sun. March found Venus [ http://antwrp.gsfc.nasa.gov/apod/ap010308.html ] falling from the evening sky while moving rapidly north, finally appearing (far right) as a faint dot against the sunset glow on March 24. This month, Venus rises before dawn as the brilliant morning star [ http://stardate.utexas.edu/resources/ faqs/049.html ]. |
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Small Worlds Ceres and Vesta
| Title |
Small Worlds Ceres and Vesta |
| Explanation |
Ceres [ http://www.planetary.org/explore/topics/asteroids_and_comets/ ceres.html ] and Vesta [ http://hubblesite.org/newscenter/archive/releases/ 1997/27 ] are, respectively, only around 950 kilometers and 530 kilometers in diameter - about the size of Texas and Arizona. But they are two of the largest of over 100,000 minor bodies [ http://nssdc.gsfc.nasa.gov/planetary/factsheet/ asteroidfact.html ] orbiting in the main asteroid belt [ http://www.solstation.com/stars/ asteroid.htm ] between Mars and Jupiter. These remarkably detailed Hubble Space Telescope images [ http://hubblesite.org/newscenter/archive/releases/ 2007/27/ ] show brightness and color variations across the surface of the two small worlds. The variations could represent large scale surface features or areas of different compositon. The Hubble image data will help astronomers plan for a visit by the asteroid-hopping Dawn spacecraft [ http://dawn.jpl.nasa.gov/index.asp ], scheduled for launch on July 7 and intended to orbit first Vesta [ http://antwrp.gsfc.nasa.gov/apod/ap070525.html ] and then Ceres [ http://antwrp.gsfc.nasa.gov/apod/ap060821.html ] after a four year interplanetary cruise. Though Shakespeare [ http://www.phrases.org.uk/meanings/305250.html ] might not have been impressed, nomenclature introduced by the International Astronomical Union in 2006 classifies nearly spherical Ceres as a dwarf planet [ http://en.wikipedia.org/wiki/Dwarf_planet ]. |
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A July Dawn
| Title |
A July Dawn |
| Explanation |
Those up before dawn in late July in the northern hemisphere could see planets, stars [ http://www.skypub.com/sights/sights.shtml ], and a spacecraft in a single quick glance before starting their day. Near the eastern horizon was bright Jupiter [ http://www.nineplanets.org/jupiter.html ], and not far above and to its right was the very bright Venus [ http://www.solarviews.com/eng/venus.htm ]. Connecting the dots will point you just right of Saturn [ http://antwrp.gsfc.nasa.gov/apod/saturn.html ]. Far in the distance but near the top right of the frame is the Pleiades [ http://antwrp.gsfc.nasa.gov/apod/ap010506.html ] star cluster. Orbiting the Earth [ http://antwrp.gsfc.nasa.gov/apod/ap001127.html ] well in the foreground, the International Space Station [ http://antwrp.gsfc.nasa.gov/apod/ap010509.html ] reflected sunlight to cause the faint line segment. In the very close foreground, the bright red and yellow lines were caused by a passing van. The above picture was taken on July 26 from Quebec [ http://www.gouv.qc.ca/ ], Canada [ http://www.cia.gov/cia/publications/factbook/geos/ca.html ]. Why are bushes visible [ http://www.skypub.com/sights/northern/0107skyn.shtml ] through the van? The van was present for only a few of the 25 seconds of the total exposure. |
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Zodiacal Light and the False
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| 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://en.wikipedia.org/wiki/Zodiacal_light ], 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 toward the left of the frame taken from the Paranal Observatory [ http://en.wikipedia.org/wiki/Paranal_Observatory ] in Chile [ http://en.wikipedia.org/wiki/Chile ] in July. 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 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. APOD editor to review best space pictures in Philadelphia tomorrow (Wednesday) night [ http://www.rittenhouseastronomicalsociety.org/ ] |
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Zodiacal Light and the False
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| 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 on the left of the above frame taken from Mauna Kea [ http://www.ifa.hawaii.edu/mko/ ] in Hawaii [ http://www.state.hi.us/ ] on August 30 by one of the developing global network of fisheye nighttime web cameras [ http://concam.net/ ] called CONCAMs [ http://concam.net/about.html ]. Zodiacal dust [ http://stardust.wustl.edu/IDPIntro.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 ]. Indeed, the triangle points to bright spots Jupiter and Saturn [ http://antwrp.gsfc.nasa.gov/apod/ap010807.html ], with Saturn [ http://antwrp.gsfc.nasa.gov/apod/ap010702.html ] nearer the center. 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/2000/es000327.html ] out relatively bright reflecting [ http://sirtf.jpl.nasa.gov/SciUser/C_PropKit/bgdoc_release/node3.html ] dust. Zodiacal light [ http://antwrp.gsfc.nasa.gov/apod/ap990613.html ] is also bright for people in Earth's northern hemisphere in March and April just after sunset. |
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Dawn Launch Mosaic
| Title |
Dawn Launch Mosaic |
| Explanation |
Shortly after sunrise [ http://www.nasa.gov/mission_pages/dawn/news/ dawn-20070927a.html ] on Thursday at Cape Canaveral [ http://www.nps.gov/nr/travel/aviation/cap.htm ] Air Force Station, the Dawn spacecraft [ http://www.nasa.gov/mission_pages/dawn/spacecraft/index.html ] began its journey to the asteroid belt, arcing eastward into a blue and cloudy sky. Dawn's voyage began on a conventional, chemically fueled [ http://exploration.grc.nasa.gov/education/rocket/ combst1.html ] Delta II rocket [ http://exploration.grc.nasa.gov/education/rocket/ bgmr.html ], but will continue with an innovative ion propulsion system [ http://dawn.jpl.nasa.gov/mission/ion_engine_interactive/ index.html ]. The spacecraft's extremely efficient ion engines [ http://science.nasa.gov/headlines/y2000/ast15jun_1.htm ] will use electricity derived from solar power to ionize xenon atoms and generate a gentle but continuous thrust. After a four year interplanetary cruise, Dawn will orbit two small worlds [ http://antwrp.gsfc.nasa.gov/apod/ap070622.html ], first Vesta and then Ceres. Vesta is one of the largest main belt asteroids, while nomenclature introduced by the International Astronomical Union in 2006 classifies nearly spherical Ceres as a dwarf planet [ http://solarsystem.nasa.gov/planets/ profile.cfm?Object=Dwarf&Display=OverviewLong ]. |
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Star Trails at Dawn
| Title |
Star Trails at Dawn |
| Explanation |
Just fix your camera to a tripod and you too can make an image of graceful trails traced by the stars [ http://www.astropix.com/HTML/I_ASTROP/TRIPOD/TRIPOD2.HTM ] as planet Earth rotates on its axis. Made on September 14 from Montlaux, France, this wide-angle view nicely shows [ http://www.koenvangorp.be/deepsky/startrails.html ] the stars near the celestial equator tracing nearly straight lines in projection, while stars north and south [ http://antwrp.gsfc.nasa.gov/apod/ap060901.html ] of the equator, respectively, appear to circle [ http://antwrp.gsfc.nasa.gov/apod/ap050714.html ] the north and south celestial poles [ http://en.wikipedia.org/wiki/Celestial_pole ]. Featured are the stars of Orion (right of center), brilliant Venus rising (left) as bright star Sirius rises in the south (bottom center), and a polar orbiting Iridium satellite [ http://antwrp.gsfc.nasa.gov/apod/ap060819.html ] (upper left). Beautiful dawn sky colors seem painted along the horizon. This remarkable picture was constructed from 477 consecutive 30 second digital exposures recorded over 4.3 hours and later combined [ http://www.startrails.de/html/software.html ]. |
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