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Saturn's Atmosphere - New Discoveries


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#31    Waspie_Dwarf

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Posted 08 May 2008 - 01:29 PM

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Saturn's Infrared Temperature Snapshot
May 7, 2008

Scientists have discovered a wave pattern, or oscillation, in Saturn's atmosphere only visible from Earth every 15 years. The pattern ripples back and forth like a wave within Saturn's upper atmosphere. In this region, temperatures switch from one altitude to the next in a candy cane-like, striped, hot-cold pattern.

The temperature "snapshot" shown in these two images captures two different phases of this wave oscillation: the temperature at Saturn's equator switches from hot to cold, and temperatures on either side of the equator switch from cold to hot every Saturn half-year.

The image on the left was taken in 1997 and shows the temperature at the equator is colder than the temperature at 13 degrees south latitude. Conversely, the image on the right taken in 2006 shows the temperature at the equator is warmer.

These images were taken with NASA's Infrared Telescope Facility in Mauna Kea, Hawaii.

Credit: NASA/JPL

Source: NASA/JPL - Cassini

"Space is big. Really big. You just won't believe how vastly, hugely, mind-boggingly big it is. I mean, you may think it's a long way down the street to the chemist, but that's just peanuts to space." - The Hitch-Hikers Guide to the Galaxy - Douglas Adams 1952 - 2001

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#32    Waspie_Dwarf

Waspie_Dwarf

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Posted 14 October 2008 - 10:06 PM

Giant Cyclones at Saturn's Poles Create a Swirl of Mystery

October 13, 20088
(Source: Jet Propulsion Laboratory)
New images from NASAís Cassini spacecraft reveal a giant cyclone at Saturnís north pole, and show that a similarly monstrous cyclone churning at Saturnís south pole is powered by Earth-like storm patterns.

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Infrared Images of Saturnís Poles
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The new-found cyclone at Saturnís north pole is only visible in the near-infrared wavelengths because the north pole is in winter, thus in darkness to visible-light cameras. At these wavelengths, about seven times greater than light seen by the human eye, the clouds deep inside Saturnís atmosphere are seen in silhouette against the background glow of Saturnís internal heat.

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Saturn's South Polar Region Revealed

The entire north pole of Saturn is now mapped in detail in infrared, with features as small as 120 kilometers (75 miles) visible in the images. Time-lapse movies of the clouds circling the north pole show the whirlpool-like cyclone there is rotating at 530 kilometers per hour (325 miles per hour), more than twice as fast as the highest winds measured in cyclonic features on Earth. This cyclone is surrounded by an odd, honeycombed-shaped hexagon, which itself does not seem to move while the clouds within it whip around at high speeds, also greater than 500 kilometers per hour (300 miles per hour). Oddly, neither the fast-moving clouds inside the hexagon nor this new cyclone seem to disrupt the six-sided hexagon.

New Cassini imagery of Saturnís south pole shows complementary aspects of the region through the eyes of two different instruments. Near-infrared images from the visual and infrared mapping spectrometer instrument show the whole region is pockmarked with storms, while the imaging cameras show close-up details.

The new views are available online at: http://www.nasa.gov/cassini and http://saturn.jpl.nasa.gov.

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Convection in Saturn's Southern Vortex

Unlike Earth-bound hurricanes, powered by the oceanís heat and water, Saturn's cyclones have no body of water at their bases, yet the eye-walls of Saturnís and Earthís storms look strikingly similar. Saturn's hurricanes are locked to the planet's poles, whereas terrestrial hurricanes drift across the ocean.

"These are truly massive cyclones, hundreds of times stronger than the most giant hurricanes on Earth," said Kevin Baines, Cassini scientist on the visual and infrared mapping spectrometer at NASA's Jet Propulsion Laboratory, Pasadena, Calif. "Dozens of puffy, convectively formed cumulus clouds swirl around both poles, betraying the presence of giant thunderstorms lurking beneath. Thunderstorms are the likely engine for these giant weather systems," said Baines.

Just as condensing water in clouds on Earth powers hurricane vortices, the heat released from the condensing water in Saturnian thunderstorms deep down in the atmosphere may be the primary power source energizing the vortex.

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The Yet Yawning Gulf

In the south, the new infrared images of the pole, under the daylight conditions of southern summer, show the entire region is marked by hundreds of dark cloud spots. The clouds, like those at the north pole, are likely a manifestation of convective, thunderstorm-like processes extending some 100 kilometers (62 miles) below the clouds. They are likely composed of ammonium hydrosulfide with possibly a mixture of materials dredged up from the depths. By contrast, most of the hazes and clouds seen on Saturn are thought to be composed of ammonia, which condenses at high, visible altitudes.

Complementary images of the south pole from Cassiniís imaging cameras, obtained in mid-July, are 10 times more detailed than any seen before. "What looked like puffy clouds in lower resolution images are turning out to be deep convective structures seen through the atmospheric haze," said Cassini imaging team member Tony DelGenio of NASAís Goddard Institute for Space Studies in New York. "One of them has punched through to a higher altitude and created its own little vortex."

The "eye" of the vortex is surrounded by an outer ring of high clouds. The new images also hint at an inner ring of clouds about half the diameter of the main ring, and so the actual clear "eye" region is smaller than it appears in earlier low-resolution images.

"Itís like seeing into the eye of a hurricane," said Andrew Ingersoll, a member of Cassini's imaging team at the California Institute of Technology, Pasadena. "Itís surprising. Convection is an important part of the planetís energy budget because the warm upwelling air carries heat from the interior. In a terrestrial hurricane, the convection occurs in the eyewall; the eye is a region of downwelling. Here convection seems to occur in the eye as well."

Further observations are planned to see how the features at both poles evolve as the seasons change from southern summer to fall in August 2009.

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 visual and infrared mapping spectrometer team is based at the University of Arizona. The imaging team is based at the Space Science Institute, Boulder, Colo.

Contacts:
Carolina Martinez 818-354-9382
Jet Propulsion Laboratory, Pasadena, Calif.
Carolina.Martinez@jpl.nasa.gov


NEWS RELEASE: 2008-192

Source: NASA/JPL - Cassini - Press Release

"Space is big. Really big. You just won't believe how vastly, hugely, mind-boggingly big it is. I mean, you may think it's a long way down the street to the chemist, but that's just peanuts to space." - The Hitch-Hikers Guide to the Galaxy - Douglas Adams 1952 - 2001

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#33    Waspie_Dwarf

Waspie_Dwarf

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Posted 14 October 2008 - 10:11 PM

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The Yet Yawning Gulf
October 13, 2008

Shadows reveal the topography of Saturn's south polar vortex. At high resolution, a new, inner ring of isolated, bright clouds is seen. These clouds are localized regions of convective upwelling, an important clue to understanding how heat energy is transported in Saturn's atmosphere.

See Convection in Saturn's Southern Vortex for a high-resolution Cassini view that looks more directly down onto the vortex, compared to this oblique perspective. Sunlight illuminates the scene from upper right, and the higher altitude rings of clouds surrounding the pole cast shadows toward lower left. North on Saturn is up.

The image was taken with the Cassini spacecraft narrow-angle camera on July 15, 2008, with a combination of spectral filters sensitive to wavelengths of polarized infrared light centered at 746 and 938 nanometers. The grainy quality of the image is due primarily to the low signal-to-noise ratio of images taken with the 938 nanometer spectral filter, which is near the upper limit of the wavelength range the camera can see. "Signal-to-noise" is a term scientists use to refer to the amount of meaningful or useful information (signal) in their data versus the amount of background noise. A higher signal-to-noise ratio yields sharper, clearer views of features in the atmosphere. The view was acquired from 24 degrees below the ringplane, at a distance of approximately 778,000 kilometers (483,000 miles) from Saturn. The sun-Saturn-spacecraft, or phase, angle is about 30 degrees. Image scale is 4 kilometers (3 miles) per pixel.

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 and its two onboard cameras were designed, developed and assembled at JPL. The imaging operations center is based at the Space Science Institute in Boulder, Colo.

For more information about the Cassini-Huygens mission visit http://saturn.jpl.nasa.gov. The Cassini imaging team homepage is at http://ciclops.org.

Credit: NASA/JPL/Space Science Institute

Source: NASA/JPL - Cassini

"Space is big. Really big. You just won't believe how vastly, hugely, mind-boggingly big it is. I mean, you may think it's a long way down the street to the chemist, but that's just peanuts to space." - The Hitch-Hikers Guide to the Galaxy - Douglas Adams 1952 - 2001

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#34    Waspie_Dwarf

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Posted 14 October 2008 - 10:14 PM

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Convection in Saturn's Southern Vortex
October 13, 2008

This detailed Cassini view of the monstrous vortex at Saturn's south pole provides valuable insight about the mechanisms that power the planet's atmosphere.

This view is 10 times more detailed than any previous image of the polar vortex. See The Yet Yawning Gulf for a more oblique, wide-angle view that provides context for this close-up.

Previous images revealed an outer ring of high clouds surrounding a region previously thought to be mostly clear air interspersed with a few puffy clouds that circulate around the center. This new image shows that what looked like puffy clouds at lower resolution are actually vigorous convective storms that form yet another distinct, inner ring. In other words, they are deep convective structures seen through the atmospheric haze. One of the deeper structures (at the 10 o'clock position) has punched through to a higher altitude and created its own little vortex. The ring is similar to the eyewall of a terrestrial hurricane, but much larger. The clear air there is warm, like the eye of a terrestrial hurricane, but on Saturn it is locked to the pole, whereas a terrestrial hurricane drifts around.

Convective structures are small regions of intense upwelling air, but the clear air of the vortex eye indicates that this is generally an area of downwelling. Convection is an important part of the planet's energy budget because the warm upwelling air carries heat from the interior. In a terrestrial hurricane, the convection occurs in the eyewall. Here it seems to occur in the eye as well. The camera filter used for this image captures light at wavelengths where atmospheric gases like methane are fairly transparent, allowing for detailed views of deep cloud features. Other filters (see High Cloud, Low Cloud) use light that is strongly absorbed by methane gas; the light bounces off the high clouds, making them visible, but gets absorbed before it reaches the low clouds. Such "methane-band" images of the south polar vortex reveal that the convective clouds do not reach up to the base of the stratosphere, as convective clouds on Earth do. This view was acquired from 56 degrees below the ringplane. The image has been digitally reprojected to show the scene as it would appear to an observer positioned directly above the pole.

The image was taken with the Cassini spacecraft narrow-angle camera on July 14, 2008, using a combination of two spectral filters sensitive to wavelengths of polarized visible light centered at 617 and infrared light centered at 750 nanometers. The view was obtained at a distance of approximately 392,000 kilometers (243,000 miles) from Saturn and at a sun-Saturn-spacecraft, or phase, angle of 60 degrees. Image scale is 2 kilometers (1 mile) per pixel.

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 and its two onboard cameras were designed, developed and assembled at JPL. The imaging operations center is based at the Space Science Institute in Boulder, Colo.

For more information about the Cassini-Huygens mission visit http://saturn.jpl.nasa.gov. The Cassini imaging team homepage is at http://ciclops.org.

Credit: NASA/JPL/Space Science Institute

Source: NASA/JPL - Cassini

"Space is big. Really big. You just won't believe how vastly, hugely, mind-boggingly big it is. I mean, you may think it's a long way down the street to the chemist, but that's just peanuts to space." - The Hitch-Hikers Guide to the Galaxy - Douglas Adams 1952 - 2001

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#35    Waspie_Dwarf

Waspie_Dwarf

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Posted 14 October 2008 - 10:21 PM

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Saturn's South Polar Region Revealed
October 13, 2008

These two images of Saturn show the entire south polar region, not just the little area around the core of the hurricane-like vortex. Earth-like storm patterns seem to be powering this vortex.

These images were taken in the near-infrared on May 11, 2007, from a distance of 416,000 kilometers (258,500 miles), and with a phase angle of 36 degrees.

From this distance, the resolution is 208 kilometers (128 miles) per pixel. The upper image represents 5.04 microns, a near-infrared wavelength some seven times the reddest wavelength visible to the human eye. At this wavelength, the planet's own heat produces an internal glow against which clouds deep within Saturn are seen in silhouette. Thus, dark areas represent thick clouds while bright areas represent clearings in the clouds.

The lower image shows the polar region in false color, with red, green, and blue depicting the appearance of the pole in three different near-infrared colors. Here, red depicts the 5.04 micron image shown in the black and white image above. Green and blue show the polar region, as seen in reflected sunlight at 3.08 and 4.08 micron wavelengths. The aqua color produced by green and blue light together show bright hazes and clouds in the upper atmosphere away from the pole; the lack of an aqua color component over the pole reveals a surprising dearth of upper-level bright hazes and clouds at high latitudes poleward of 73 degrees latitude, perhaps indicative of a general downwelling, heating, and sublimation into gas vapor of aerosol particles there. This clearing of upper-level hazes and clouds then allows - at other wavelengths not depicted here - unusually clear sunlit views of the deep atmosphere of Saturn near the 1-bar level, much deeper than typically seen elsewhere on the planet.

Due to the lack of bright polar hazes, the pole itself shows up only in reddish hues in this color composite. These red hues depict the near-infrared warm glow of Saturnís interior heat diffusing upward through the clouds, thus revealing clouds at much deeper levels than what can be seen in reflected sunlight. Here, the brightest red coloring indicates clearings between low-lying clouds. These clearings extend downward from just below the haze layer down to about the 5-bar level some 125 kilometers (78 miles) below the upper-level hazes. The eye of the polar vortex is bright, showing that it is nearly cloud free. Dark spots throughout the region reveal the presence of thick convective clouds lurking in the depths of Saturn in the 2 to 5-bar region, about 50 to 125 kilometers (30-80 miles) underneath the hazes. At the edge of the polar region, where the greenish-blue tint of the upper hazes begins, a large ring of thick clouds can be seen in silhouette encircling the planet. Fine strands of streaky cloud material can be seen spiraling into this ring, indicating north/south motions in the planet's deep, dynamic atmosphere.

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 Visual and Infrared Mapping Spectrometer team is based at the University of Arizona.

For more information about the Cassini-Huygens mission visit http://saturn.jpl.na.../home/index.cfm. The visual and infrared mapping spectrometer team homepage is at http://wwwvims.lpl.arizona.edu.

Credit: NASA/JPL/University of Arizona

Source: NASA/JPL - Cassini

"Space is big. Really big. You just won't believe how vastly, hugely, mind-boggingly big it is. I mean, you may think it's a long way down the street to the chemist, but that's just peanuts to space." - The Hitch-Hikers Guide to the Galaxy - Douglas Adams 1952 - 2001

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#36    Waspie_Dwarf

Waspie_Dwarf

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    Oscar Wilde

Posted 14 October 2008 - 10:27 PM

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Infrared Images of Saturnís Poles -- Labeled
October 13, 2008

+ See unlabeled version

This is a side-by-side view of large cyclones at both poles of Saturn obtained by the visual and infrared mapping spectrometer onboard the Cassini spacecraft.

These high-spatial-resolution polar orthographic projections of the north (left) and south (right) polar regions show rings of clouds and hazes circling the poles, as observed in the near-infrared at a wavelength of 5 micron, some seven times the reddest wavelength observed by the human eye. The resolution is 200 kilometers (149 miles) per pixel.

The left image is the first detailed image of Saturnís entire north polar region ever obtained. The movie covers a six-hour period at close range, as close as 240,000 kilometers (149,000 miles) above the clouds from a nearly-overhead viewpoint. Winds reach over 150 meters per second (325 miles per hour) at 88.3 degrees south latitude, just outside the first bright ring nearest the pole. The pole itself is covered by a small cloud some 600 kilometers (about 375 miles) wide. The cyclone reaches out some 12,000 kilometers (7,500 miles) from the pole, bordered by the hexagon. This hexagon is populated by fast-moving clouds which also reach speeds of over 500 kilometers per hour (300 miles per hour).

The south pole image (right), acquired just a few hours after the north polar image also shows a polar cyclone, complete with a central eye clear of clouds. This cyclone extends out some 15,000 kilometers (9,000 miles) from the pole.

At both poles, the discrete, circular and oblong clouds dotting the image are likely convective upwelling originating deep inside the planet, which help to power the cyclones. These views show clouds throughout the atmosphere, down to as deep as 125 kilometers (78 miles) below the haze. Many of the features seen are thought to be deep-level clouds of ammonia-hydrosulfide, which form at these levels and rise to higher altitudes in convective updrafts.

Normally, Saturnís internal glow illuminates Saturnís deep clouds from below, thus rendering the clouds in silhouette against this background glow. In these images, the contrast has been reversed so as to make the clouds appear more like they would look if seen in reflected sunlight. The original images obtained by infrared spectrometer show the clouds as dark features against the internal glow. The grid shows planeticentric latitudes. In this polar orthographic projection, 0 degrees longitude is toward the top, 90 degrees west longitude to the right, etc, based on the longitude system established by Voyager.

These images were obtained on June 15, 2008 (left) and June 16, 2008 (right) from distances of 602,000 kilometers (374,000 miles) and 652,000 kilometers (405,000 miles) above the clouds, respectively, and a sub-spacecraft planetocentric latitude of 73 degrees north (left) and 48 degrees south (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 mission for NASA's Science Mission Directorate, Washington, D.C. The Cassini orbiter was designed, developed and assembled at JPL. The Visual and Infrared Mapping Spectrometer team is based at the University of Arizona.

For more information about the Cassini-Huygens mission visit http://saturn.jpl.na.../home/index.cfm. The visual and infrared mapping spectrometer team homepage is at http://wwwvims.lpl.arizona.edu.

Credit: NASA/JPL/University of Arizona

Source: NASA/JPL - Cassini

"Space is big. Really big. You just won't believe how vastly, hugely, mind-boggingly big it is. I mean, you may think it's a long way down the street to the chemist, but that's just peanuts to space." - The Hitch-Hikers Guide to the Galaxy - Douglas Adams 1952 - 2001

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