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Earth and Moon and Sun of Goddard Space Flight Center (GSFC)
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Enceladus Temperature Map
| Description |
Enceladus Temperature Map |
| Full Description |
This image shows the surprise that startled Cassini scientists on the composite infrared spectrometer team when they got their first look at the infrared (heat) radiation from the south pole of Saturn's moon Enceladus. There is a dramatic warm spot centered on the pole that is probably a sign of internal heat leaking out of the icy moon. The data were taken during the spacecraft's third flyby of this intriguing moon on July 14, 2005. Based on data from previous flybys, which did not show the south pole well, team members expected that the south pole would be very cold, as shown in the left panel. Enceladus is one of the coldest places in the Saturn system because its extremely bright surface reflects 80 percent of the sunlight that hits it, so only 20 percent is available to heat the surface. As on Earth, the poles should be even colder than the equator because the sun shines at such an oblique angle there. The right hand panel shows a global temperature image made from measurements of Enceladus' heat radiation at wavelengths between 9 and 16.5 microns. Cassini made the observation from a distance of 84,000 kilometers (52,000 miles) on the approach to Enceladus, and the image shows details as small as 25 kilometers (16 miles). Equatorial temperatures are much as expected, topping out at about 80 degrees Kelvin (-315 degrees Fahrenheit), but the south pole is occupied by a well-defined warm region reaching 85 Kelvin (-305 degrees Fahrenheit). That is 15 degrees Kelvin (27 degrees Fahrenheit) warmer than expected. The composite infrared spectrometer data further suggest that small areas of the pole are at even higher temperatures, well over 110 degrees Kelvin (-261 degrees Fahrenheit). Evaporation of this relatively warm ice probably generates the cloud of water vapor detected above Enceladus' south pole by several other Cassini instruments. The south polar temperatures are very difficult to explain if sunlight is the only energy source heating the surface, though exotic sunlight-trapping mechanisms have not yet been completely ruled out. It therefore seems likely that portions of the polar region are warmed by heat escaping from the interior of the moon. This would make Enceladus only the third solid body in the solar system, after Earth and Jupiter's volcanic moon Io, where hot spots powered by internal heat have been detected. 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 mission for NASA's Science Mission Directorate, 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 . The composite infrared spectrometer team homepage is, http://cirs.gsfc.nasa.gov/ . Credit: NASA/JPL/GSFC |
| Date |
July 29, 2005 |
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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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Hubble Follows Rapid Changes
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| Title |
Hubble Follows Rapid Changes in Jupiter's Aurora |
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Spitzer and Hubble Capture E
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| Title |
Spitzer and Hubble Capture Evolving Planetary Systems |
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STEREO's Routes to Solar Orb
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| Title |
STEREO's Routes to Solar Orbits |
| Abstract |
The two STEREO spacecraft, A (red path) and B (yellow path), are launched from the Earth into a highly eccentric orbit with an apogee that reaches the orbit of the Moon. Once in this orbit, the trajectories are adjusted so they can receive gravity-assists from the Moon. The gravity assist will send them both into heliocentric orbits, one spacecraft ahead of the Earth and the other behind the Earth. This trajectory was generated using a spacecraft ephemeris generated shortly after launch. |
| Completed |
2007-02-05 |
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STEREO's Routes to Solar Orb
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| Title |
STEREO's Routes to Solar Orbits |
| Abstract |
The two STEREO spacecraft, A (red path) and B (yellow path), are launched from the Earth into a highly eccentric orbit with an apogee that reaches the orbit of the Moon. Once in this orbit, the trajectories are adjusted so they can receive gravity-assists from the Moon. The gravity assist will send them both into heliocentric orbits, one spacecraft ahead of the Earth and the other behind the Earth. This trajectory was generated using a spacecraft ephemeris generated shortly after launch. |
| Completed |
2007-02-05 |
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STEREO's Routes to Solar Orb
…
| Title |
STEREO's Routes to Solar Orbits |
| Abstract |
The two STEREO spacecraft, A (red path) and B (yellow path), are launched from the Earth into a highly eccentric orbit with an apogee that reaches the orbit of the Moon. Once in this orbit, the trajectories are adjusted so they can receive gravity-assists from the Moon. The gravity assist will send them both into heliocentric orbits, one spacecraft ahead of the Earth and the other behind the Earth. This trajectory was generated using a spacecraft ephemeris generated shortly after launch. |
| Completed |
2007-02-05 |
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STEREO's Routes to Solar Orb
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| Title |
STEREO's Routes to Solar Orbits |
| Abstract |
The two STEREO spacecraft, A (red path) and B (yellow path), are launched from the Earth into a highly eccentric orbit with an apogee that reaches the orbit of the Moon. Once in this orbit, the trajectories are adjusted so they can receive gravity-assists from the Moon. The gravity assist will send them both into heliocentric orbits, one spacecraft ahead of the Earth and the other behind the Earth. This trajectory was generated using a spacecraft ephemeris generated shortly after launch. |
| Completed |
2007-02-05 |
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STEREO's Routes to Solar Orb
…
| Title |
STEREO's Routes to Solar Orbits |
| Abstract |
The two STEREO spacecraft, A (red path) and B (yellow path), are launched from the Earth into a highly eccentric orbit with an apogee that reaches the orbit of the Moon. Once in this orbit, the trajectories are adjusted so they can receive gravity-assists from the Moon. The gravity assist will send them both into heliocentric orbits, one spacecraft ahead of the Earth and the other behind the Earth. This trajectory was generated using a spacecraft ephemeris generated shortly after launch. |
| Completed |
2007-02-05 |
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STEREO's Routes to Solar Orb
…
| Title |
STEREO's Routes to Solar Orbits |
| Abstract |
The two STEREO spacecraft, A (red path) and B (yellow path), are launched from the Earth into a highly eccentric orbit with an apogee that reaches the orbit of the Moon. Once in this orbit, the trajectories are adjusted so they can receive gravity-assists from the Moon. The gravity assist will send them both into heliocentric orbits, one spacecraft ahead of the Earth and the other behind the Earth. This trajectory was generated using a spacecraft ephemeris generated shortly after launch. |
| Completed |
2007-02-05 |
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STEREO's Routes to Solar Orb
…
| Title |
STEREO's Routes to Solar Orbits |
| Abstract |
The two STEREO spacecraft, A (red path) and B (yellow path), are launched from the Earth into a highly eccentric orbit with an apogee that reaches the orbit of the Moon. Once in this orbit, the trajectories are adjusted so they can receive gravity-assists from the Moon. The gravity assist will send them both into heliocentric orbits, one spacecraft ahead of the Earth and the other behind the Earth. This trajectory was generated using a spacecraft ephemeris generated shortly after launch. |
| Completed |
2007-02-05 |
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STEREO's Routes to Solar Orb
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| Title |
STEREO's Routes to Solar Orbits |
| Abstract |
The two STEREO spacecraft, A (red path) and B (yellow path), are launched from the Earth into a highly eccentric orbit with an apogee that reaches the orbit of the Moon. Once in this orbit, the trajectories are adjusted so they can receive gravity-assists from the Moon. The gravity assist will send them both into heliocentric orbits, one spacecraft ahead of the Earth and the other behind the Earth. This trajectory was generated using a spacecraft ephemeris generated shortly after launch. |
| Completed |
2007-02-05 |
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STEREO's Routes to Solar Orb
…
| Title |
STEREO's Routes to Solar Orbits |
| Abstract |
The two STEREO spacecraft, A (red path) and B (yellow path), are launched from the Earth into a highly eccentric orbit with an apogee that reaches the orbit of the Moon. Once in this orbit, the trajectories are adjusted so they can receive gravity-assists from the Moon. The gravity assist will send them both into heliocentric orbits, one spacecraft ahead of the Earth and the other behind the Earth. This trajectory was generated using a spacecraft ephemeris generated shortly after launch. |
| Completed |
2007-02-05 |
|
STEREO's Routes to Solar Orb
…
| Title |
STEREO's Routes to Solar Orbits |
| Abstract |
The two STEREO spacecraft, A (red path) and B (yellow path), are launched from the Earth into a highly eccentric orbit with an apogee that reaches the orbit of the Moon. Once in this orbit, the trajectories are adjusted so they can receive gravity-assists from the Moon. The gravity assist will send them both into heliocentric orbits, one spacecraft ahead of the Earth and the other behind the Earth. This trajectory was generated using a spacecraft ephemeris generated shortly after launch. |
| Completed |
2007-02-05 |
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STEREO's Routes to Solar Orb
…
| Title |
STEREO's Routes to Solar Orbits |
| Abstract |
The two STEREO spacecraft, A (red path) and B (yellow path), are launched from the Earth into a highly eccentric orbit with an apogee that reaches the orbit of the Moon. Once in this orbit, the trajectories are adjusted so they can receive gravity-assists from the Moon. The gravity assist will send them both into heliocentric orbits, one spacecraft ahead of the Earth and the other behind the Earth. This trajectory was generated using a spacecraft ephemeris generated shortly after launch. |
| Completed |
2007-02-05 |
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STEREO's Routes to Solar Orb
…
| Title |
STEREO's Routes to Solar Orbits |
| Abstract |
The two STEREO spacecraft, A (red path) and B (yellow path), are launched from the Earth into a highly eccentric orbit with an apogee that reaches the orbit of the Moon. Once in this orbit, the trajectories are adjusted so they can receive gravity-assists from the Moon. The gravity assist will send them both into heliocentric orbits, one spacecraft ahead of the Earth and the other behind the Earth. This trajectory was generated using a spacecraft ephemeris generated shortly after launch. |
| Completed |
2007-02-05 |
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STEREO's Routes to Solar Orb
…
| Title |
STEREO's Routes to Solar Orbits |
| Abstract |
The two STEREO spacecraft, A (red path) and B (yellow path), are launched from the Earth into a highly eccentric orbit with an apogee that reaches the orbit of the Moon. Once in this orbit, the trajectories are adjusted so they can receive gravity-assists from the Moon. The gravity assist will send them both into heliocentric orbits, one spacecraft ahead of the Earth and the other behind the Earth. This trajectory was generated using a spacecraft ephemeris generated shortly after launch. |
| Completed |
2007-02-05 |
|
STEREO's Routes to Solar Orb
…
| Title |
STEREO's Routes to Solar Orbits |
| Abstract |
The two STEREO spacecraft, A (red path) and B (yellow path), are launched from the Earth into a highly eccentric orbit with an apogee that reaches the orbit of the Moon. Once in this orbit, the trajectories are adjusted so they can receive gravity-assists from the Moon. The gravity assist will send them both into heliocentric orbits, one spacecraft ahead of the Earth and the other behind the Earth. This trajectory was generated using a spacecraft ephemeris generated shortly after launch. |
| Completed |
2007-02-05 |
|
STEREO's Routes to Solar Orb
…
| Title |
STEREO's Routes to Solar Orbits |
| Abstract |
The two STEREO spacecraft, A (red path) and B (yellow path), are launched from the Earth into a highly eccentric orbit with an apogee that reaches the orbit of the Moon. Once in this orbit, the trajectories are adjusted so they can receive gravity-assists from the Moon. The gravity assist will send them both into heliocentric orbits, one spacecraft ahead of the Earth and the other behind the Earth. This trajectory was generated using a spacecraft ephemeris generated shortly after launch. |
| Completed |
2007-02-05 |
|
STEREO's Routes to Solar Orb
…
| Title |
STEREO's Routes to Solar Orbits |
| Abstract |
The two STEREO spacecraft, A (red path) and B (yellow path), are launched from the Earth into a highly eccentric orbit with an apogee that reaches the orbit of the Moon. Once in this orbit, the trajectories are adjusted so they can receive gravity-assists from the Moon. The gravity assist will send them both into heliocentric orbits, one spacecraft ahead of the Earth and the other behind the Earth. This trajectory was generated using a spacecraft ephemeris generated shortly after launch. |
| Completed |
2007-02-05 |
|
STEREO's Routes to Solar Orb
…
| Title |
STEREO's Routes to Solar Orbits |
| Abstract |
The two STEREO spacecraft, A (red path) and B (yellow path), are launched from the Earth into a highly eccentric orbit with an apogee that reaches the orbit of the Moon. Once in this orbit, the trajectories are adjusted so they can receive gravity-assists from the Moon. The gravity assist will send them both into heliocentric orbits, one spacecraft ahead of the Earth and the other behind the Earth. This trajectory was generated using a spacecraft ephemeris generated shortly after launch. |
| Completed |
2007-02-05 |
|
STEREO's Routes to Solar Orb
…
| Title |
STEREO's Routes to Solar Orbits |
| Abstract |
The two STEREO spacecraft, A (red path) and B (yellow path), are launched from the Earth into a highly eccentric orbit with an apogee that reaches the orbit of the Moon. Once in this orbit, the trajectories are adjusted so they can receive gravity-assists from the Moon. The gravity assist will send them both into heliocentric orbits, one spacecraft ahead of the Earth and the other behind the Earth. This trajectory was generated using a spacecraft ephemeris generated shortly after launch. |
| Completed |
2007-02-05 |
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Solar Eclipse over Africa
| Title |
Solar Eclipse over Africa |
| Description |
Eastern Africa was cloaked in darkness when the Moderate Resolution Imaging Spectroradiometer (MODIS [ http://modis.gsfc.nasa.gov ]) on NASA's Aqua [ http://aqua.nasa.gov/ ] satellite caught this image on October 3, 2005. The inky blackness that covers much of Ethiopia, Kenya, Uganda, and parts of Sudan and the Democratic Republic of the Congo in this image was caused when the Moon crossed in front of the Sun in an annular solar eclipse. During such an eclipse, the Sun is visible as a fiery circle around the black disk of the moon. In the dimness beneath the Moon's shadow, very little light remained for MODIS to capture this image. Under normal conditions [ http://rapidfire.sci.gsfc.nasa.gov/subsets/?NAfrica_3_07/2005276 ], the land in the lower half of the image is a lush green, with patches of tan where the land is bare. Here, the tan areas have a red tint in the low light, while the green is completely black. Red dots show where fires were burning in vegetated areas. In the top half of the image, the orange of the Sahara desert is shown in darker tones than normal [ http://rapidfire.sci.gsfc.nasa.gov/subsets/?NAfrica_2_07/2005276 ]. Only in the upper right corner of the image, where full daylight has returned, does the desert look normal. Gradations of darkness within the shadowed area can be seen in the clouds. Bright white clouds reflect light well, so they are easily visible, even in the shadow. Since some light reached the Earth, the clouds remain bright along the outer edges of the shadowed region. As the eclipse progressed, the moon's shadow traveled southeast across the globe. When this image was taken, the deepest shadow lay over Kenya in the lower right corner of the image. Here the clouds are darker, an indication that there was less light to reflect back to the satellite. If this had been a total solar eclipse, the shadow cast by the moon would have been complete. The difference between a total solar eclipse and an annular eclipse is caused by the Moon's orbit around the Earth. The Moon's orbit is not circular, it is elliptical, like a squashed circle with the Earth at its center. This means that the Moon is not always the same distance from the Earth. When it is close to the Earth, the Moon appears larger than when it is far away. During a total solar eclipse, the Moon is closer to the Earth and so is able to block out the Sun entirely. An annular eclipse occurs when the Moon is farther from the Earth, and so the Moon's disk is not large enough to cover the Sun. The large image provided above has a resolution of 500 meters per pixel. It is available in additional resolutions from the MODIS Rapid Response Team. Tiny blue flecks in the large image are defects in the data. NASA image courtesy the MODIS Rapid Response Team [ http://rapidfire.sci.gsfc.nasa.gov ] at NASA GSFC. |
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Total Solar Eclipse over Afr
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| Title |
Total Solar Eclipse over Africa and the Mediterranean |
| Description |
At 10:40 UTC (Coordinated Universal Time), NASA's Aqua [ http://aqua.nasa.gov ] satellite flew over the eastern Mediterranean as the shadow of the Moon traveled across Libya and the Mediterranean. As Aqua passed over, the Moderate Resolution Imaging Spectroradiometer (MODIS) [ http://modis.gsfc.nasa.gov ] captured the top image in this pair. The deep shadow cast by the Moon as it passed in front of the Sun is clearly visible on the Earth, in stark contrast to the daylight view of the same area captured just an hour earlier by the MODIS on the Terra [ http://terra.nasa.gov ] satellite. During the eclipse, clouds and snow were still visible, but the land surface below was lost in darkness. NASA images created by Jesse Allen, Earth Observatory, using data obtained courtesy of the MODIS Rapid Response team. |
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Total Solar Eclipse over Afr
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| Title |
Total Solar Eclipse over Africa and the Mediterranean |
| Description |
At 10:40 UTC (Coordinated Universal Time), NASA's Aqua [ http://aqua.nasa.gov ] satellite flew over the eastern Mediterranean as the shadow of the Moon traveled across Libya and the Mediterranean. As Aqua passed over, the Moderate Resolution Imaging Spectroradiometer (MODIS) [ http://modis.gsfc.nasa.gov ] captured the top image in this pair. The deep shadow cast by the Moon as it passed in front of the Sun is clearly visible on the Earth, in stark contrast to the daylight view of the same area captured just an hour earlier by the MODIS on the Terra [ http://terra.nasa.gov ] satellite. During the eclipse, clouds and snow were still visible, but the land surface below was lost in darkness. NASA images created by Jesse Allen, Earth Observatory, using data obtained courtesy of the MODIS Rapid Response team. |
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Total solar eclipse over Ant
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| 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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Earth, Moon, Hubble
| Title |
Earth, Moon, Hubble |
| Explanation |
The Space Shuttle Discovery Crew [ http://spaceflight.nasa.gov/shuttle/archives/sts-103/crew/ ] was fortunate enough to witness one of the brighter full moon's from orbit two weeks ago during their mission to fix the Hubble Space Telescope [ http://www.stsci.edu/hst/ ]. Pictured on the left [ http://spaceflight.nasa.gov/gallery/images/shuttle/sts-103/html/s103e5252.html ], the horizon of the Earth [ http://antwrp.gsfc.nasa.gov/apod/ap990619.html ] is visible below this full Moon [ http://antwrp.gsfc.nasa.gov/apod/ap991108.html ], which is below the edge of the Hubble Space Telescope [ http://antwrp.gsfc.nasa.gov/apod/ap970306.html ]. The full Moon on this day, last December 22 [ http://antwrp.gsfc.nasa.gov/apod/ap991222.html ], was a few percent brighter than average [ http://www.skypub.com/news/pr_991217brightmoon.html ] because it was full at nearly the same time it was at its closest to the Earth, which comes at a time when the Earth is relatively close to the Sun. The Shuttle Crew successfully showered [ http://spaceflight.nasa.gov/spacenews/reports/sts103/STS-103-13.html ] Hubble with needed holiday gifts, including six new gyroscopes [ http://hubble.gsfc.nasa.gov/sm3a_fact_sheets.html#gyroscopes ], a new computer [ http://hubble.gsfc.nasa.gov/sm3a_fact_sheets.html#advanced ], and new batteries [ http://www.howstuffworks.com/battery.htm ]. |
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Natural Saturn On The Cassin
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| Title |
Natural Saturn On The Cassini Cruise |
| Explanation |
What could you see approaching Saturn [ http://www.jpl.nasa.gov/cassini/Kids/stories/ ] aboard an interplanetary cruise [ http://www.jpl.nasa.gov:80/cassini/Mission/cruise.html ] ship? Your view would likely resemble this subtly shaded image [ http://oposite.stsci.edu/pubinfo/pr/1998/28/b.html ] of the gorgeous ringed gas giant. Processed by the Hubble Heritage project [ http://heritage.stsci.edu/ ], the picture intentionally avoids overemphasizing color contrasts and presents a natural looking Saturn [ http://heritage.stsci.edu/ public/Oct22/saturn/saturntable.html#caption ] with cloud bands, storms [ http://antwrp.gsfc.nasa.gov/apod/ap951018.html ], nearly edge-on rings [ http://antwrp.gsfc.nasa.gov/apod/ap981018.html ], and the small round shadow of the moon Enceladus near the center of the planet's disk. Of course, seats were not available on the only ship currently enroute [ http://www.jpl.nasa.gov/cassini/ ] - the Cassini spacecraft, launched in 1997 [ http://antwrp.gsfc.nasa.gov/apod/ap971016.html ] and scheduled to arrive at Saturn [ http://www.jpl.nasa.gov/cassini/today/ ] in the year 2004. After an extended cruise to a world 1,400 million kilometers from the Sun [ http://antwrp.gsfc.nasa.gov/apod/ap960727.html ], Cassini will tour the Saturnian system [ http://www.hawastsoc.org/solar/eng/saturn.htm ], conducting a remote, robotic exploration with software and instruments designed by [ http://www.jpl.nasa.gov/cassini/Partners/ ] denizens of planet Earth. But where is Cassini now [ http://www.jpl.nasa.gov/cassini/today/ ]? Still about 980 million kilometers from Saturn, last Sunday the spacecraft flew by asteroid 2685 Masursky [ http://www.jpl.nasa.gov/cassini/MoreInfo/ sigevents/sigevent000128.html ]. |
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Solar Eclipse and SOHO
| Title |
Solar Eclipse and SOHO |
| Explanation |
Neither rain, nor snow, nor dark of night can keep the space-based SOlar Heliospheric Observatory (SOHO) from watching the Sun [ http://antwrp.gsfc.nasa.gov/apod/ap051201.html ]. In fact, from its vantage point 1.5 million kilometers sunward of planet Earth, SOHO's cameras can always monitor [ http://sohowww.nascom.nasa.gov/data/latestimages.html ] the Sun's outer atmosphere, or corona. But only during a total solar eclipse [ http://www.kidseclipse.com/pages/a1b3c1d0.htm ] can earth-based observers see the lovely coronal [ http://antwrp.gsfc.nasa.gov/apod/ap021213.html ] streamers and structures - when the Moon briefly blocks the overwhelmingly bright solar surface. In this composite view, SOHO's [ http://sohowww.nascom.nasa.gov/hotshots/ 2006_03_29/ ] uninterrupted view of the solar corona above the solar photosphere (center) and corona far beyond the Sun's disk, are shown in orange hues. The middle, donut-shaped region is the corona [ http://www.phy6.org/Education/wcorona.html ] as recorded by the Williams College Eclipse Expedition to Kastelorizo [ http://antwrp.gsfc.nasa.gov/apod/ap060330.html ] Island, Greece, headed by Jay Pasachoff, during the March 29th total solar eclipse [ http://spaceweather.com/eclipses/ gallery_29mar06_page3.htm ]. Merging ground [ http://antwrp.gsfc.nasa.gov/apod/ap031208.html ] and space-based [ http://antwrp.gsfc.nasa.gov/apod/ap020516.html ] views allows astronomers to trace features in the corona that reach from just above the Sun's surface into the solar wind [ http://www.phy6.org/Education/wsolwind.html ]. |
|
A Lunar Eclipse Over Time
| Title |
A Lunar Eclipse Over Time |
| Explanation |
During last week's lunar eclipse [ http://sunearth.gsfc.nasa.gov/eclipse/SEextra/TLE2000Jan20.html ], our Moon [ http://www.seds.org/nineplanets/nineplanets/luna.html ] appeared to disappear. As the Earth moved between the Moon and the Sun, the Earth's shadow fell on the moon, making it quite dark [ http://antwrp.gsfc.nasa.gov/apod/ap970110.html ]. In the above photograph, the Earth's rotation caused the Moon and stars to appear as streaks [ http://antwrp.gsfc.nasa.gov/apod/ap980912.html ] during this four-hour exposure. In the foreground is the abbey of the Benedictive monastery of Sant Llorenc del Munt [ http://www.culturamatadepera.es/tpobl01a.htm ], a structure in Girona, Spain that has stood since the eleventh century. As the Earth's shadow engulfed the Moon [ http://sunearth.gsfc.nasa.gov/eclipse/LEcat/LEcatalog.html ], the Moon streak became less and less bright, practically disappearing during totality [ http://antwrp.gsfc.nasa.gov/apod/ap960926.html ]. At this time, the Moon, which normally shines by reflecting direct sunlight, shone only by sunlight refracted [ http://www.geom.umn.edu/education/calc-init/rainbow/refraction.html ] through the Earth's atmosphere [ http://csep10.phys.utk.edu/astr161/lect/earth/atmosphere.html ]. Later, clouds obscured the re-appearing Moon. |
|
Southwest Mercury
| Title |
Southwest Mercury |
| Explanation |
The planet Mercury resembles a moon. Mercury [ http://www.seds.org/nineplanets/nineplanets/mercury.html ]'s old surface is heavily cratered [ http://liftoff.msfc.nasa.gov/Academy/SPACE/SolarSystem/Meteors/Craters.html ] like many moons. Mercury [ http://www.solarviews.com/eng/mercury.htm ] is larger than most moons but smaller than Jupiter [ http://antwrp.gsfc.nasa.gov/apod/ap990806.html ]'s moon Ganymede [ http://antwrp.gsfc.nasa.gov/apod/ap990304.html ] and Saturn [ http://antwrp.gsfc.nasa.gov/apod/ap960717.html ]'s moon Titan [ http://antwrp.gsfc.nasa.gov/apod/ap990207.html ]. Mercury is much denser and more massive than any moon, though, because it is made mostly of iron. In fact, the Earth [ http://antwrp.gsfc.nasa.gov/apod/ap990131.html ] is the only planet more dense. A visitor to Mercury's surface [ http://antwrp.gsfc.nasa.gov/apod/ap960121.html ] would see some strange sights. Because Mercury [ http://www.oulu.fi/~spaceweb/textbook/mercury.html ] rotates exactly three times every two orbits around the Sun [ http://antwrp.gsfc.nasa.gov/apod/ap951004.html ], and because Mercury [ http://nssdc.gsfc.nasa.gov/photo_gallery/photogallery-mercury.html ]'s orbit is so elliptical, a visitor to Mercury [ http://antwrp.gsfc.nasa.gov/apod/ap990102.html ] might see the Sun [ http://antwrp.gsfc.nasa.gov/htmltest/gifcity/interv.html ] rise, stop in the sky, go back toward the rising horizon [ http://antwrp.gsfc.nasa.gov/apod/ap990619.html ], stop again, and then set quickly over the other horizon. From Earth [ http://antwrp.gsfc.nasa.gov/apod/ap980530.html ], Mercury's proximity to the Sun [ http://antwrp.gsfc.nasa.gov/apod/ap981212.html ] cause it to be visible only for a short time just after sunset or just before sunrise. |
|
A Total Solar Eclipse over T
…
| Title |
A Total Solar Eclipse over Turkey |
| Explanation |
Some views [ http://spaceweather.com/eclipses/gallery_29mar06.htm ] of last week's total eclipse [ http://en.wikipedia.org/wiki/Total_eclipse ] of the Sun were better than others. One spectacular view [ http://antwrp.gsfc.nasa.gov/apod/ap060331.html ] occurred over Adrasan (near Antalya [ http://en.wikipedia.org/wiki/Antalya ]), Turkey [ http://en.wikipedia.org/wiki/Turkey ] and was captured there by industrious astrophotographer Stefan Seip. The above digital mosaic [ http://www.photomeeting.de/astromeeting/sun/060329sofi_d1024.htm ] caught the Moon in several stages as it moved between the Earth and the Sun. During the center frame, a total solar eclipse [ http://www.mreclipse.com/Special/SEprimer.html ] was visible, the Moon completely blocked the Sun, the area became dark, and the magnificent corona [ http://antwrp.gsfc.nasa.gov/apod/ap010408.html ] of the Sun became visible. The foreground frame from the same location was taken during sunlight. The next total eclipse [ http://mreclipse.com/Special/SEnext.html ] of the Sun will occur in August 2008 and be visible from parts of North America [ http://www.cia.gov/cia/publications/factbook/reference_maps/north_america.html ], Europe [ http://antwrp.gsfc.nasa.gov/apod/ap030324.html ], and Asia [ http://en.wikipedia.org/wiki/Asia ]. |
|
Animation of Asteroids Passi
…
| Title |
Animation of Asteroids Passing Near Earth |
| Explanation |
How often does an asteroid whiz by the Earth? The above time-lapse animation [ http://cfa-www.harvard.edu/iau/Animations/Animations.html ] follows the orbit of the Earth around the Sun for two months in 2002 as numerous asteroids [ http://en.wikipedia.org/wiki/Asteroids ], also known as minor planets [ http://en.wikipedia.org/wiki/Minor_planet ], approach and pass by. Some asteroids appear out of nowhere [ http://antwrp.gsfc.nasa.gov/apod/ap041001.html ] as they are plotted only when they were discovered. Most asteroids plotted were discovered only [ http://antwrp.gsfc.nasa.gov/apod/ap040322.html ] during the previous year. Although none of the plotted objects came inside the orbit of our Moon, our Solar System is filled with objects [ http://antwrp.gsfc.nasa.gov/apod/ap050417.html ] as small as bits of sand, usually left by a comet, that appear as meteors as they streak into the Earth's atmosphere every day. The only objects displayed are those visible from Earth [ http://antwrp.gsfc.nasa.gov/apod/ap050102.html ] closer than 20 million kilometers, color coded by three-dimensional distance. In comparison, the Earth is a relatively small target having a radius of about 6,400 kilometers. One significant research area [ http://pan-starrs.ifa.hawaii.edu/public/asteroid-threat/asteroid_threat.html ] in modern astronomy involves trying to find the majority of asteroids that could pose a future collision threat [ http://neo.jpl.nasa.gov/risk/ ] with Earth. |
|
Crumbling Comet Schwassmann-
…
| Title |
Crumbling Comet Schwassmann-Wachmann 3 Approaches |
| Explanation |
A crumbling comet will soon pass near the Earth. Comet 73P/Schwassmann-Wachmann 3 [ http://science.nasa.gov/headlines/y2006/24mar_73p.htm ] is brightening and may even be visible to the unaided eye [ http://webvision.med.utah.edu/anatomy.html ] when the fragmented comet [ http://antwrp.gsfc.nasa.gov/apod/ap040724.html ] zooms past Earth during the middle of next month. Still, the small comet poses no Earth hazard [ http://liftoff.msfc.nasa.gov/Academy/SPACE/SolarSystem/Meteors/ImpactHazard.html ], since it will pass the Earth at about 25 times the distance of the Moon. Exactly how bright Comet Schwassman-Wachmann 3 [ http://en.wikipedia.org/wiki/73P/Schwassmann-Wachmann ] will get is unknown. It is even possible, althought unlikely, that debris from the comet [ http://cometography.com/pcomets/073p.html ] will have spread out enough to cause a notable meteor shower [ http://antwrp.gsfc.nasa.gov/apod/ap031116.html ]. Pictured above [ http://www.eso.org/outreach/press-rel/pr-2006/phot-15-06.html ], Fragment B of Comet Schwassman-Wachmann 3 [ http://www.eso.org/outreach/press-rel/pr-2006/pr-15-06.html ] was photographed two nights ago by a 8.2-meter Very Large Telescope [ http://antwrp.gsfc.nasa.gov/apod/ap990309.html ] in Chile [ http://en.wikipedia.org/wiki/Chile ]. Visible [ http://antwrp.gsfc.nasa.gov/apod/ap060426.html http://www.space.com/spacewatch/060414_night_sky.html ] to the lower right of the large B fragment are many mini-comets that have broken off and now orbit the Sun separately. Each mini-comet itself sheds gas and dust and so appears to have its own hazy coma. The comet [ http://skyandtelescope.com/observing/objects/comets/article_1704_1.asp ] will pass closest to the Sun on June 7. |
|
Venus, Moon, and Neighbors
| Title |
Venus, Moon, and Neighbors |
| Explanation |
Rising before the Sun on February 2nd, astrophotographer [ http://pages.prodigy.net/pam.orman/JoeGallery.html ] Joe Orman anticipated [ http://pages.prodigy.net/pam.orman/JoeAlmanac2000.html ] this apparition of the bright morning star [ http://ispec.scibernet.com/station/morn_star.html ] Venus near a lovely crescent Moon above a neighbor's house in suburban Phoenix, Arizona, USA. Fortunately, the alignment of bright planets and the Moon is one of the most inspiring sights in the night sky [ http://www.skypub.com/sights/skyevents/0004skyevents.html ] and one that is often easy to enjoy and share without any special equipment. Take tonight [ http://spacescience.com/headlines/y2000/ast30mar_1m.htm ], for example. Those blessed with clear skies can simply step outside near sunset and view a young crescent Moon very near three bright planets in the west Jupiter [ http://galileo.jpl.nasa.gov/ ], Mars [ http://mars.jpl.nasa.gov/mgs/ ], and Saturn [ http://www.jpl.nasa.gov/cassini/ ]. Jupiter will be the unmistakable brightest star near the Moon with a reddish Mars just to Jupiter's north and pale yellow Saturn directly above. Of course, these sky shows [ http://drumright.ossm.edu/astronomy/conjunctions.html ] create an evocative picture [ http://antwrp.gsfc.nasa.gov/apod/ap000310.html ] but the planets and Moon just appear to be near each other -- they are actually only approximately lined up and lie in widely separated orbits. Unfortunately, next month's highly publicized alignment of planets [ http://www.griffithobs.org/SkyAlignments.html ] on May 5th will be lost from view in the Sun's glare but such planetary alignments [ http://www.skypub.com/news/special/whypanic.html ] occur repeatedly and pose no danger [ http://www.badastronomy.com/bad/misc/planets.html ] to planet Earth. |
|
Comet Schwassmann-Wachmann 3
…
| Title |
Comet Schwassmann-Wachmann 3 Passes the Earth |
| Explanation |
Rarely does a comet pass this close to Earth. Last week, dedicated astrofilmographers were able to take advantage of the close approach of crumbling 73P / Comet Schwassmann-Wachmann 3 [ http://en.wikipedia.org/wiki/Comet_73P ] to make time-lapse movies of the fast-moving comet. Large comet fragments passed about 25 times the Moon's distance from the Earth. The above time lapse movie of Fragment B [ http://antwrp.gsfc.nasa.gov/apod/ap060504.html ] of Comet Schwassmann-Wachmann 3 [ http://antwrp.gsfc.nasa.gov/apod/ap060511.html ] over Colorado [ http://en.wikipedia.org/wiki/Colorado ], USA [ http://www.cia.gov/cia/publications/factbook/geos/us.html ] was taken during a single night, May 16, with 83 consecutive 49-second exposures. Some observers report being able to perceive the slight motion of the comet with respect to the background stars using only their binoculars [ http://www.yesmag.bc.ca/Questions/binoculars.html ] and without resorting to the creation of fancy digital time-lapse movies. Fragment B of Comet Schwassmann-Wachmann 3 [ http://www.eso.org/outreach/press-rel/pr-2006/pr-15-06.html ] became just barely visible to the unaided eye two weeks ago but now is appearing to fade as the comet has moved past the Earth and nears the Sun. Many sky enthusiasts [ http://antwrp.gsfc.nasa.gov/apod/ap040808.html ] will be on the watch for a particularly active meteor shower tonight as the Earth made its closest approach to orbit of Comet Schwassmann-Wachmann 3 [ http://skyandtelescope.com/observing/objects/comets/article_1704_1.asp ] late yesterday. |
|
Planets In The Sun
| Title |
Planets In The Sun |
| Explanation |
Today [ http://science.nasa.gov/headlines/y2000/ast02may_1.htm ], all five naked-eye planets [ http://www.seds.org/nineplanets/nineplanets/ ] (Mercury, Venus, Mars, Jupiter, Saturn) plus the Moon and the Sun [ http://helios.gsfc.nasa.gov/ sun.html ] will at least approximately line-up. As viewed [ http://drumright.ossm.edu/astronomy/conjunctions.html ] from planet Earth, they will be clustered within about 26 degrees, the closest alignment for all these celestial bodies [ http://science.nasa.gov/headlines/y2000/ ast30mar_1m.htm#alignments ] since February 1962, when there was a solar eclipse [ http://antwrp.gsfc.nasa.gov/apod/ap990818.html ]! Such planetary alignments [ http://www.griffithobs.org/SkyAlignments.html ] are not dangerous, except of course that the Sun might hurt your eyes when you look at it [ http://antwrp.gsfc.nasa.gov/apod/ap981212.html ]. So it might be easier [ http://sohowww.nascom.nasa.gov/hotshots/ ] to appreciate today's solar system [ http://space.jpl.nasa.gov/ ] spectacle if |
|
Ultraviolet Earth from the M
…
| Title |
Ultraviolet Earth from the Moon |
| Explanation |
Here's a switch: the above picture is of the " Earth " taken from a " lunar " observatory! [ http://antwrp.gsfc.nasa.gov/apod/ap960608.html ] This false color picture [ http://images.jsc.nasa.gov/images/pao/AS16/10075878.htm ] shows how the Earth [ http://antwrp.gsfc.nasa.gov/apod/earth.html ] glows in ultraviolet [ http://antwrp.gsfc.nasa.gov/apod/lib/glossary.html#uv ] (UV) light. UV light is so blue humans can't see it. Very little UV light [ http://titan.srrb.noaa.gov/UV/ ] is transmitted through the Earth's atmosphere but what sunlight does make it through can cause a sunburn [ http://uhs.bsd.uchicago.edu/uhs/infoline/sunburn.htm ]. The Far UV Camera / Spectrograph [ http://cass.jsc.nasa.gov/pub/expmoon/Apollo16/A16_Experiments_UVC.html ] deployed and left on the Moon by the crew of Apollo 16 [ http://antwrp.gsfc.nasa.gov/apod/ap000319.html ] took the above picture. The part of the Earth facing the Sun [ http://antwrp.gsfc.nasa.gov/apod/sun.html ] reflects much UV light, but perhaps more interesting is the side facing away from the Sun. Here bands of UV emission [ http://imagine.gsfc.nasa.gov/docs/science/know_l2/emspectrum.html ] are also apparent. These bands [ http://antwrp.gsfc.nasa.gov/apod/ap970402.html ] are the result of aurorae [ http://antwrp.gsfc.nasa.gov/cgi-bin/apod/apod_ts?aurora ] and are caused by charged particles [ http://www-spof.gsfc.nasa.gov/Education/Intro.html ] expelled by the Sun. |
|
Eclipsed Moon Rising Over En
…
| Title |
Eclipsed Moon Rising Over England |
| Explanation |
Last Thursday, part of our Moon turned dark. The cause, this time, was not a partial lunar phase [ http://antwrp.gsfc.nasa.gov/apod/ap051113.html ] -- the Moon was full -- but rather that part of the Moon went into Earth's shadow. The resulting partial lunar eclipse [ http://antwrp.gsfc.nasa.gov/apod/ap041103.html ] was visible from the eastern Atlantic Ocean [ https://www.cia.gov/cia/publications/factbook/geos/zh.html ] through Europe [ http://antwrp.gsfc.nasa.gov/apod/ap051207.html ], Africa [ http://en.wikipedia.org/wiki/Africa ], and Asia [ http://en.wikipedia.org/wiki/Asia ] and into the western Pacific Ocean [ https://www.cia.gov/cia/publications/factbook/geos/zn.html ]. The darkest part of the lunar eclipse, when part of the Moon was completely shielded from sunlight [ http://antwrp.gsfc.nasa.gov/apod/ap060909.html ], lasted about 90 minutes. Pictured above, a partially eclipsed Moon is seen rising over an estate in Huddersfield [ http://en.wikipedia.org/wiki/Huddersfield_%28UK_Parliament_constituency%29 ], England [ http://en.wikipedia.org/wiki/British_Isles_%28terminology%29 ]. The above image was taken far away from the house in the foreground, as only this would allow it to appear as angularly small as the half-degree Moon [ http://antwrp.gsfc.nasa.gov/apod/ap031011.html ] far in the background. A setting twilight Sun lit the foreground. The next eclipse [ http://mreclipse.com/Special/LEnext.html ] of the Moon will occur in March 2007. |
|
Sirius, Sun, Moon, and South
…
| Title |
Sirius, Sun, Moon, and Southern Cross |
| Explanation |
From left to right are the enclosures of Yepun ("ye-poon", Sirius [ http://antwrp.gsfc.nasa.gov/apod/ap000611.html ]), Antu ("an-too", Sun [ http://antwrp.gsfc.nasa.gov/apod/ap000621.html ]), Kueyen ("qua-yen", Moon [ http://antwrp.gsfc.nasa.gov/apod/ap991222.html ]), and Melipal ("me-li-pal", Southern Cross [ http://antwrp.gsfc.nasa.gov/apod/ap000618.html ]), pictured here as night falls at Paranal Observatory [ http://www.eso.org/outreach/press-rel/pr-2000/ phot-15B-00.html ] in northern Chile. These are the four 8.2 meter wide telescope units of the European Southern Observatory's Very Large Telescope [ http://www.eso.org/outreach/press-rel/pr-2000/ phot-15-00.html ] (VLT). ESO astronomers and engineers plan to combine the light [ http://www.eso.org/projects/vlt/ ] of the individual units, achieving an equivalent aperture [ http://www.seds.org/billa/bigeyes.html ] of 16.4 meters which will, for a while [ http://nastol.astro.lu.se/~torben/50m/50m.html ], constitue the biggest [ http://www.sciam.com/specialissues/1299engineering/ 1299musserbox2.html ] telescope on planet Earth [ http://www.sciam.com/specialissues/1299engineering/ 1299musser.html ]. Of course, the individual telescopes also function independently. Antu, Kueyen, and Melipal have already achieved first light with Yepun expected to operate in 2001. The telescope names [ http://www.eso.org/outreach/info-events/ut1fl/names.html ] come from the Mapuche [ http://www.uchile.cl/cultura/mapa/ artesamapuche/ingles/index.htm ] language [ http://www-linguistics.stanford.edu/~arnold/mapuche/ mapudungun.html ]. They were unanimously chosen based on the winning "name-the-telescopes" essay by 17-year old Jorssy Albanez Castilla from Chuquicamata near the city of Calama. |
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Other Worlds and HD 38529
| Title |
Other Worlds and HD 38529 |
| Explanation |
After the latest round of discovery announcements [ http://www.iau.org/ga24press/ ], the list of known worlds of distant suns [ http://www.spaceart.org/lcook/extrasol.html ] has grown to 50 [ http://www.spaceref.com/news/viewnews.html?id=200 ]. While extrasolar planet [ http://exoplanets.org/ ] discoveries are [ http://obswww.unige.ch/~udry/planet/planet.html ] sure to continue, none - so far [ http://sim.jpl.nasa.gov/ ] - points clearly to another planetary system like our own [ http://antwrp.gsfc.nasa.gov/apod/ap991229.html ]. Take, for example, the newly discovered parent [ http://antwrp.gsfc.nasa.gov/apod/ap990611.html ] star HD38529 [ http://www.obspm.fr/encycl/HD38529.html ]. Shining in Earth's night sky at 6th magnitude, this sun-like star lies 137 light-years away in the constellation Orion [ http://aibn47.astro.uni-bonn.de/~gallery/constellations/orion/ main.html ]. Like most of the known extrasolar planets [ http://www.obspm.fr/encycl/encycl.html ], HD38529's planet was discovered by detecting the telltale Doppler wobble [ http://exoplanets.org/doppler.html ] in the parent star's spectrum. The data reveal that this planet orbits once every 14.3 days at an average of only 0.13 times the Earth-Sun distance and has a minimum of 0.77 Jupiter masses (about 240 Earth masses). There is even evidence [ http://www.iau.org/ga24press/pr000807_3.html#1 ] in the wobble data that HD38529, and other stars with one known planet have additional massive planets orbiting them. In this dramatic artist's vision, HD38529 and its newfound world are viewed from the moon of another massive ringed planet [ http://antwrp.gsfc.nasa.gov/apod/ap000330.html ] orbiting farther out. The ringed planet's moon is imagined to have a thin atmosphere and a surface covered with icy sheets and ridges similar to those found on Jupiter's moon Europa [ http://galileo.jpl.nasa.gov/moons/europa.html ]. |
|
Sharp Silhouette
| Title |
Sharp Silhouette |
| Explanation |
Though it's [ http://antwrp.gsfc.nasa.gov/apod/ap981212.html ] 93 million miles away, the Sun still hurts your eyes when you look at it. But bright sunlight (along with accurate planning and proper equipment!) resulted in this sharp silhouette [ http://www.astrophoto.fr/iss_atlantis_transit.html ] of spaceship and space station. The amazing telescopic view, recorded on September 17, captures shuttle orbiter Atlantis [ http://www.nasa.gov/centers/kennedy/shuttleoperations/ orbiters/atlantis-info.html ] and the International Space Station [ http://en.wikipedia.org/wiki/International_Space_Station ] in orbit over planet Earth. At a range of 550 kilometers from the observing site near Mamers, Normandy, France, Atlantis (left) has just undocked and moved about 200 meters away from the space station. Tomorrow, yet another [ http://antwrp.gsfc.nasa.gov/apod/ap050729.html ] satellite of planet Earth [ http://antwrp.gsfc.nasa.gov/apod/ap050430.html ] can be seen in silhouette - the Moon will eclipse the Sun. This last eclipse [ http://sunearth.gsfc.nasa.gov/eclipse/OH/ OH2006.html#2006Sep22A ] of 2006 will be seen as an annular [ http://antwrp.gsfc.nasa.gov/apod/ap051005.html ] solar eclipse along a track that crosses northern South America and the south Atlantic. |
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Earth from Saturn
| Title |
Earth from Saturn |
| Explanation |
What's that pale blue dot in this image taken from Saturn? Earth [ http://antwrp.gsfc.nasa.gov/apod/ap010204.html ]. The robotic Cassini spacecraft [ http://saturn.jpl.nasa.gov/spacecraft/index.cfm ] looked back toward its old home world earlier this month as it orbited Saturn [ http://en.wikipedia.org/wiki/Saturn_(planet) ]. Using Saturn itself to block the bright Sun [ http://antwrp.gsfc.nasa.gov/apod/ap030530.html ], Cassini imaged a faint dot on the right of the above photograph [ http://photojournal.jpl.nasa.gov/catalog/PIA08324 ]. That dot is expanded on the image inset, where a slight elongation in the direction of Earth's Moon [ http://antwrp.gsfc.nasa.gov/apod/ap030526.html ] is visible [ http://antwrp.gsfc.nasa.gov/apod/ap980904.html ]. Vast water oceans make Earth's reflection of sunlight somewhat blue [ http://www.sciam.com/askexpert_question.cfm?articleID=000CCDD2-DD07-1C71-9EB7809EC588F2D7 ]. Earth is home to over six billion humans [ http://desip.igc.org/populationmaps.html ] and over one octillion [ http://en.wikipedia.org/wiki/Octillion ] Prochlorococcus [ http://sciam.com/article.cfm?chanID=sa022&articleID=0005BE47-0078-1FA8-807883414B7F0000 ]. |
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In the Shadow of Saturn
| Title |
In the Shadow of Saturn |
| Explanation |
In the shadow of Saturn, unexpected wonders appear. The robotic Cassini spacecraft [ http://saturn.jpl.nasa.gov/spacecraft/index.cfm ] now orbiting Saturn [ http://antwrp.gsfc.nasa.gov/apod/saturn.html ] recently drifted in giant planet's shadow [ http://antwrp.gsfc.nasa.gov/apod/ap040926.html ] for about 12 hours and looked back toward the eclipsed Sun [ http://antwrp.gsfc.nasa.gov/apod/ap010408.html ]. Cassini saw a view unlike any other. First, the night side of Saturn [ http://antwrp.gsfc.nasa.gov/apod/ap060912.html ] is seen to be partly lit by light reflected from its own majestic ring system [ http://www.planetary.org/saturn/images_saturn_rings.html ]. Next, the rings themselves appear dark when silhouetted against Saturn, but quite bright when viewed away from Saturn and slightly scattering [ http://www.daviddarling.info/encyclopedia/F/forward_scattering.html ] sunlight, in the above exaggerated color image [ http://photojournal.jpl.nasa.gov/catalog/PIA08329 ]. Saturn's rings light up so much that new rings [ http://photojournal.jpl.nasa.gov/catalog/PIA08322 ] were discovered, although they are hard to see in the above image. Visible in spectacular detail, however, is Saturn's E ring [ http://www.planetary.org/explore/topics/saturn/rings.html ], the ring created by the newly discovered ice-fountains [ http://antwrp.gsfc.nasa.gov/apod/ap051205.html ] of the moon Enceladus [ http://antwrp.gsfc.nasa.gov/apod/ap050906.html ], and the outermost ring visible above. Far in the distance [ http://antwrp.gsfc.nasa.gov/apod/ap060927.html ], visible on the image left just above the bright main rings, is the almost ignorable pale blue dot [ http://en.wikipedia.org/wiki/Pale_Blue_Dot ] of Earth. |
|
A Perseid Aurora
| Title |
A Perseid Aurora |
| Explanation |
Just after the Moon set [ http://aa.usno.navy.mil/AA/data/docs/RS_OneYear.html ] but before the Sun rose [ http://antwrp.gsfc.nasa.gov/apod/ap991110.html ] in the early morning hours of August 12, meteors [ http://www.amsmeteors.org/showers.html ] pelted the Earth from the direction of the constellation Perseus [ http://www.seds.org/Maps/Stars_en/Fig/perseus.html ], while ions [ http://ParticleAdventure.org/ ] pelted the Earth from the Sun [ http://www.seds.org/nineplanets/nineplanets/sol.html ]. The meteors [ http://www.seds.org/nineplanets/nineplanets/meteorites.html ] were expected as sub-sand grains long left behind by Comet Swift-Tuttle [ http://antwrp.gsfc.nasa.gov/apod/ap960219.html ] annually create the Perseids Meteor Shower [ http://www.science.nasa.gov/newhome/headlines/ast09aug99_1.htm ]. The aurorae [ http://www.geo.mtu.edu/weather/aurora/ ] were unexpected, however, as electrons [ http://www.aip.org/history/electron/ ], protons [ http://hyperphysics.phy-astr.gsu.edu/hbase/particles/proton.html ], and heavier ions [ http://www-spof.gsfc.nasa.gov/Education/Ielect.html ] raced out from a large Coronal Mass Ejection [ http://science.nasa.gov/ssl/pad/solar/cmes.htm ] that had occurred [ http://antwrp.gsfc.nasa.gov/apod/ap000817.html ] just days before on the Sun. In the foreground is Hahn's Peak, an extinct volcano in Colorado [ http://www.state.co.us/ ], USA [ http://www.odci.gov/cia/publications/factbook/us.html ]. |
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Mercury's Transit: An Unusua
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| Title |
Mercury's Transit: An Unusual Spot on the Sun |
| Explanation |
What's that dot on the Sun? [ http://www.davidcortner.com/astro/mtransit/ ] If you look closely, it is almost perfectly round. The dot is the result of an unusual type of solar eclipse [ http://antwrp.gsfc.nasa.gov/apod/ap060404.html ] that occurred last week. Usually it is the Earth's Moon [ http://www.windows.ucar.edu/tour/link=/earth/ moons_and_rings.html ] that eclipses the Sun. Last week, for the first time in over three years, the planet Mercury [ http://en.wikipedia.org/wiki/Mercury_%28mythology%29 ] took a turn. Like the approach to New Moon before a solar eclipse [ http://antwrp.gsfc.nasa.gov/apod/ap040926.html ], the phase of Mercury became a continually thinner crescent [ http://antwrp.gsfc.nasa.gov/apod/ap061030.html ] as the planet progressed toward an alignment with the Sun. Eventually the phase of Mercury dropped [ http://antwrp.gsfc.nasa.gov/apod/ap040606.html ] to zero and the dark spot of Mercury crossed our parent star. The situation could technically be labeled a Mercurian annular eclipse [ http://www.mreclipse.com/Special/SEprimer.html ] with an extraordinarily large ring of fire [ http://antwrp.gsfc.nasa.gov/apod/ap020610.html ]. From above the cratered planes [ http://antwrp.gsfc.nasa.gov/apod/ap040912.html ] of the night side of Mercury, the Earth appeared in its fullest phase. Hours later, as Mercury continued in its orbit, a slight crescent phase appeared again. The next Mercurian solar eclipse [ http://en.wikipedia.org/wiki/ Transit_of_Mercury_from_Earth ] will occur in 2016. |
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Eclipse Moon Trail
| Title |
Eclipse Moon Trail |
| Explanation |
Tonight, Friday the 13th, October's big, bright, beautiful full Moon [ http://antwrp.gsfc.nasa.gov/apod/ap000113.html ] will be in the sky, rising as the sun sets. A time exposure of this evening's full Moon would show a brilliant circular arc or Moon trail tracing its celestial path. In fact, this single [ http://pages.prodigy.net/pam.orman/joemoon/ MoonPlanets_000120_2.html ], four hour long exposure from the evening of January 20 shows a full Moon trailing through hazy skies above [ http://pages.prodigy.net/pam.orman/ JoeGallery.html ] Phoenix, Arizona, USA. Of course, the picture also shows something you won't see tonight -- a total lunar eclipse [ http://www.mreclipse.com/Special/LEprimer.html ]. A lunar eclipse is caused when the full moon enters Earth's shadow [ http://image.gsfc.nasa.gov/poetry/ask/q2806.html ] and as the eclipsed Moon's light grows steadily fainter, the Moon trail becomes narrow and dim. The total eclipse phase, when the Moon passes completely within Earth's shadow [ http://space.jpl.nasa.gov/cgi-bin/wspace?tbody=3&vbody=103& month=1&day=21¢ury=20&decade=0&year=0&hour=04&minute=0& rfov=30&fovmul=-1&bfov=30 ], occurs near the middle of this Moon trail arc [ http://antwrp.gsfc.nasa.gov/apod/ap000905.html ]. But even during totality, the Moon trail is visible and noticeably red. Normally illuminated by sunlight which falls directly on its surface, during a total lunar eclipse the Moon is still illuminated [ http://antwrp.gsfc.nasa.gov/apod/ap991108.html ] by sunlight filtered and refracted through Earth's atmosphere. The refracted light lends the eclipsed Moon [ http://www.mreclipse.com/ ] a dim and reddish appearance. |
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The Ecliptic Plane
| Title |
The Ecliptic Plane |
| Explanation |
The Plane of the Ecliptic is well illustrated in this picture from the 1994 lunar prospecting Clementine spacecraft. Clementine's star tracker camera image reveals (from right to left) the Moon [ http://lunar.arc.nasa.gov/ ] lit by Earthshine, the Sun's corona [ http://antwrp.gsfc.nasa.gov/apod/ap960530.html ] rising over the Moon's dark limb, and the planets Saturn [ http://www.jpl.nasa.gov/cassini/ ], Mars [ http://mars.jpl.nasa.gov/ ], and Mercury [ http://sd-www.jhuapl.edu/MESSENGER/ ]. The ecliptic plane is defined as the imaginary plane containing the Earth's orbit around the Sun. In the course of a year, the Sun's apparent path [ http://www.astro.wisc.edu/~dolan/constellations/extra/Zodiac.html ] through the sky lies in this plane. The Solar System's [ http://space.jpl.nasa.gov/ ] planetary bodies all tend to lie near this plane, since they were formed from the Sun's spinning, flattened, proto-planetary disk [ http://antwrp.gsfc.nasa.gov/apod/ap990611.html ]. The snapshot above nicely captures a momentary line-up looking out along this fundamental plane of our Solar System [ http://antwrp.gsfc.nasa.gov/apod/ap990505.html ]. |
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Collinder 399: The Coat Hang
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| Title |
Collinder 399: The Coat Hanger |
| Explanation |
Is this coat hanger a star cluster or an asterism? This cosmic hang-up [ http://www.seds.org/messier/xtra/ngc/brocchi.html ] has been debated over much of last century, as astronomers wondered whether this binocular-visible object is really a physically associated open cluster [ http://antwrp.gsfc.nasa.gov/apod/open_clusters.html ] or a chance projection. Chance star projections are known as asterisms [ http://en.wikipedia.org/wiki/Asterism_%28astronomy%29 ], an example of which is the popular Big Dipper [ http://antwrp.gsfc.nasa.gov/apod/ap070108.html ]. Recent precise measurements from different vantage points [ http://instruct1.cit.cornell.edu/courses/astro101/java/parallax/parallax.html ] in the Earth's orbit around the Sun have recently uncovered discrepant angular shifts indicating that the Coat Hanger is better described as an asterism. Known more formally as Collinder 399 [ http://en.wikipedia.org/wiki/Brocchi's_Cluster ], this bright stellar grouping can be seen spanning more than a full moon [ http://antwrp.gsfc.nasa.gov/apod/ap040829.html ] toward the direction of the constellation of the Fox [ http://antwrp.gsfc.nasa.gov/apod/ap070112.html http://www.seds.org/Maps/Stars_en/Fig/vulpecula.html ] (Vulpecula). On the far right of the above image [ http://celestialwonders.com/Cr399_20061009.html ] is the open cluster of stars NGC 6802. |
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