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Saturn's Atmosphere - New Discoveries


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#16    Waspie_Dwarf

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Posted 09 November 2006 - 09:43 PM

IPB Image\

Looking Saturn in the Eye
November 9, 2006

+ View Movie

Cassini stares deep into the swirling hurricane-like vortex at Saturn's south pole, where the vertical structure of the clouds is highlighted by shadows. Such a storm, with a well-developed eye ringed by towering clouds, is a phenomenon never before seen on another planet.

This 14-frame movie shows a swirling cloud mass centered on the south pole, around which winds blow at 550 kilometers (350 miles) per hour. The frames have been aligned to make the planet appear stationary, while the sun appears to revolve about the pole in a counterclockwise direction. The clouds inside the dark, inner circle are lower than the surrounding clouds, which cast a shadow that follows the sun.

At the beginning of the movie, the sun illuminates directly from the top, and by the end it illuminates from the left. The width of the shadow and the height of the sun above the local horizon yield a crude estimate of the height of the surrounding clouds relative to the clouds in the center. The shadow-casting clouds tower 30 to 75 kilometers (20 to 45 miles) above those in the center. This is two to five times greater than the tallest terrestrial thunderstorms and two to five times the height of clouds surrounding the eye of a terrestrial hurricane. Such a height difference arises because Saturn's hydrogen-helium atmosphere is less dense at comparable pressures than Earth's atmosphere, and is therefore more distended in the vertical dimension.

The south polar storm, which displays two spiral arms of clouds extending from the central ring and spans the dark area inside a thick, brighter ring of clouds, is approximately 8,000 kilometers (5,000 miles) across, which is considerably larger than a terrestrial hurricane.

Eye-wall clouds are a distinguishing feature of hurricanes on Earth. They form where moist air flows inward across the ocean's surface, rising vertically and releasing a load of precipitation around an interior circular region of descending air, which is the eye itself.

Though it is uncertain whether moist convection is driving this storm, as is the case with Earthly hurricanes, the dark 'eye' at the pole, the eye-wall clouds and the spiral arms together indicate a hurricane-like system. The distinctive eye-wall clouds especially have not been seen on any planet beyond Earth. Even Jupiter's Great Red Spot, much larger than Saturn's polar storm, has no eye, no eye-wall, and is relatively calm at the center.

This giant Saturnian storm is apparently different from hurricanes on Earth because it is locked to the pole, does not drift around like terrestrial hurricanes and because it does not form over liquid water oceans.

The images were acquired over a period of three hours on Oct. 11, 2006, when Cassini was approximately 340,000 kilometers (210,000 miles) from Saturn. Image scale is about 17 kilometers (11 miles) per pixel. The images were taken with the wide-angle camera using a spectral filter sensitive to wavelengths of infrared light centered at 752 nanometers. All frames have been contrast enhanced using digital image processing techniques. The unprocessed images show an oblique view toward the pole, and have been reprojected to show the planet from a perspective directly over the south pole.

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 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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#17    Waspie_Dwarf

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Posted 28 March 2007 - 02:09 AM

Cassini Images Bizarre Hexagon on Saturn

March 27, 2007
(Source: Jet Propulsion Laboratory)

Pasadena, Calif. -- An odd, six-sided, honeycomb-shaped feature circling the entire north pole of Saturn has captured the interest of scientists with NASA's Cassini mission.

NASA's Voyager 1 and 2 spacecraft imaged the feature over two decades ago. The fact that it has appeared in Cassini images indicates that it is a long-lived feature. A second hexagon, significantly darker than the brighter historical feature, is also visible in the Cassini pictures. The spacecraft's visual and infrared mapping spectrometer is the first instrument to capture the entire hexagon feature in one image.

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Saturn's Active North Pole

"This is a very strange feature, lying in a precise geometric fashion with six nearly equally straight sides," said Kevin Baines, atmospheric expert and member of Cassini's visual and infrared mapping spectrometer team at NASA's Jet Propulsion Laboratory, Pasadena, Calif. "We've never seen anything like this on any other planet. Indeed, Saturn's thick atmosphere where circularly-shaped waves and convective cells dominate is perhaps the last place you'd expect to see such a six-sided geometric figure, yet there it is."

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Saturn's North Pole Hexagon and Aurora

The hexagon is similar to Earth's polar vortex, which has winds blowing in a circular pattern around the polar region. On Saturn, the vortex has a hexagonal rather than circular shape. The hexagon is nearly 25,000 kilometers (15,000 miles) across. Nearly four Earths could fit inside it.

The new images taken in thermal-infrared light show the hexagon extends much deeper down into the atmosphere than previously expected, some 100 kilometers (60 miles) below the cloud tops. A system of clouds lies within the hexagon. The clouds appear to be whipping around the hexagon like cars on a racetrack.

"It's amazing to see such striking differences on opposite ends of Saturn's poles," said Bob Brown, team leader of the Cassini visual and infrared mapping spectrometer, University of Arizona, Tucson. "At the south pole we have what appears to be a hurricane with a giant eye, and at the north pole of Saturn we have this geometric feature, which is completely different."

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Saturn's Strange Hexagon

The Saturn north pole hexagon has not been visible to Cassini's visual cameras, because it's winter in that area, so the hexagon is under the cover of the long polar night, which lasts about 15 years. The infrared mapping spectrometer can image Saturn in both daytime and nighttime conditions and see deep inside. It imaged the feature with thermal wavelengths near 5 microns (seven times the wavelength visible to the human eye) during a 12-day period beginning on Oct. 30, 2006. As winter wanes over the next two years, the feature may become visible to the visual cameras.

Based on the new images and more information on the depth of the feature, scientists think it is not linked to Saturn's radio emissions or to auroral activity, as once contemplated, even though Saturn's northern aurora lies nearly overhead.

The hexagon appears to have remained fixed with Saturn's rotation rate and axis since first glimpsed by Voyager 26 years ago. The actual rotation rate of Saturn is still uncertain.

"Once we understand its dynamical nature, this long-lived, deep-seated polar hexagon may give us a clue to the true rotation rate of the deep atmosphere and perhaps the interior," added Baines.

The hexagon images and movie, including the north polar auroras are available at: http://www.nasa.gov/cassini
and http://saturn.jpl.nasa.gov and http://wwwvims.lpl.arizona.edu.

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 Science Mission Directorate, Washington. The Cassini orbiter was designed, developed and assembled at JPL. The Visual and Infrared Mapping Spectrometer team is based at the University of Arizona.

Contacts:
Carolina Martinez/Jane Platt 818-354-9382/818-354-0880
Jet Propulsion Laboratory, Pasadena, Calif.

NEWS RELEASE: 2007-034

Source: NASA/JPL - Cassini - News 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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#18    Waspie_Dwarf

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Posted 28 March 2007 - 02:15 AM

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Saturn's North Pole Hexagon and Aurora
March 27, 2007

This nighttime view of Saturn's north pole by the visual and infrared mapping spectrometer on NASA's Cassini orbiter reveals a dynamic, active planet at least 75 kilometers (47 miles) below the normal cloud tops seen in visible light. Clearly revealed is the bizarre six-sided hexagon feature present at the north pole.

This image is one of the first clear images of the north polar region ever acquired from a unique polar perspective. In this image, the blue color shows high-altitude emissions from atmospheric molecules excited by charged particles smashing into the atmosphere along Saturn's powerful magnetic field lines, producing the aurora at very high altitudes in Saturn's atmosphere. The red color indicates the amount of 5-micron wavelength radiation, or heat, generated in the depths of the warm interior of Saturn that escapes the planet. Clouds blocking this light are revealed as silhouettes against the background thermal glow of the planet.

This image is among the first to capture the entire hexagonal feature and north polar region in one shot. It is also one of the first polar views using Saturn's thermal glow at 5 microns (seven times the wavelength visible to the human eye) as the light source. This allows polar cloud features to be revealed during the persistent nighttime conditions under way during north polar winter.

The hexagonal feature was originally discovered by NASA's Voyager spacecraft in 1980, but those images and subsequent ground-based telescope images suffered from poor viewing perspectives, which placed the feature and the north pole at the extreme northern limb (edge) in those images.

The strong brightness of the hexagon feature indicates that it is primarily a clearing in the clouds, which extends deep into the atmosphere, at least down to the 3-bar (3-Earth atmospheres pressure) level, about 75 kilometers (47 miles) below the clouds and hazes seen in visible wavelengths. Thick clouds border both sides of the narrow feature, as indicated by the adjacent dark lanes paralleling the bright hexagon. This image and other images acquired over a 12-day period between Oct. 30 and Nov. 11, 2006, show that the feature is nearly stationary, and likely is an unusually strong pole-encircling planetary wave that extends deep into the atmosphere.

This image was acquired by the Cassini visual and infrared mapping spectrometer on Oct. 29, 2006, from an average distance of 905,000 kilometers (562,340 miles) above the clouds.

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, where this image was produced.

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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#19    Waspie_Dwarf

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Posted 28 March 2007 - 02:19 AM

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Saturn's Strange Hexagon
March 27, 2007

This nighttime view of Saturn's north pole by the visual and infrared mapping spectrometer onboard NASA's Cassini orbiter clearly shows a bizarre six-sided hexagon feature encircling the entire north pole. This is one of the first clear images taken of the north polar region ever acquired from a unique polar perspective.

In this image, the red color indicates the amount of 5-micron wavelength radiation, or heat, generated in the warm interior of Saturn that escapes the planet. Clouds near 3-bar (about 100 kilometers or 62 miles deeper than seen in visible wavelengths) block the light, revealing them in silhouette against the background thermal glow of Saturn. The bluish color shows sunlight striking the far limb (edge) of the planet, showing that the entire north pole is under the nighttime conditions characteristic of polar winter, as on Earth.

This image is the first to capture the entire feature and north polar region in one shot, and is also the first polar view using Saturn's thermal glow at 5 microns (seven times the wavelength visible to the human eye) as the light source. This allows the pole to be revealed during the persistent nighttime conditions under way during winter. The hexagon feature was originally discovered by NASA's Voyager spacecraft in 1980, but those historic images and subsequent ground-based telescope images suffered from poor viewing perspectives, which placed the feature and the north pole at the extreme northern limb (edge) in those images.

In the new infrared images, the strong brightness of the hexagon feature indicates that it is primarily a clearing in the clouds, which extends deep into the atmosphere, at least some 75 kilometers (47 miles) underneath the typical upper hazes and clouds seen in the daytime imagery by Voyager. Thick clouds border both sides of the narrow feature, as indicated by the adjacent dark lanes paralleling the bright hexagon. This and other images acquired over a 12-day period between Oct. 30 and Nov. 11, 2006, show that the feature is nearly stationary, and likely is an unusually strong pole-encircling planetary wave that extends deep into the atmosphere.

This image was acquired with the Cassini visual and infrared mapping spectrometer on Oct. 30, 2006, from an average distance of 1.3 million kilometers (807,782 miles).

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, where this image was produced.

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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#20    Waspie_Dwarf

Waspie_Dwarf

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Posted 28 March 2007 - 02:21 AM

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Saturn's Active North Pole
March 27, 2007

A bizarre six-sided feature encircling the north pole of Saturn near 78 degrees north latitude has been spied by the visual and infrared mapping spectrometer on NASA's Cassini spacecraft. This image is one of the first clear images ever taken of the north polar region as seen from a unique polar perspective.

Originally discovered and last observed by a spacecraft during NASA's Voyager flybys of the early 1980's, the new views of this polar hexagon taken in late 2006 prove that this is an unusually long-lived feature on Saturn.

This image is the first to capture the entire feature and north polar region in one shot, and is also the first polar view using Saturn's thermal glow at 5 microns (seven times the wavelength visible to the human eye) as the light source. This allows the pole to be revealed during the nighttime conditions presently underway during north polar winter. Previous images from Voyager and from ground-based telescopes suffered from poor viewing perspectives, which placed the feature and the north pole at the extreme northern limb (edge) of the planet.

To see the deep atmosphere at night, the infrared instrument images the thermal glow radiating from Saturn¿s depths. Clouds at depths about 75 kilometers (47 miles) lower than the clouds seen at visible wavelengths block this light, appearing dark in silhouette. To show clouds as features that are bright or white rather than dark, the original image has been contrast reversed to produce the image shown here. The nested set of alternating white and dark hexagons indicates that the hexagonal complex extends deep into the atmosphere, at least down to the 3-Earth-atmosphere pressure level, some 75 kilometers (47 miles) underneath the clouds seen by Voyager. Multiple images acquired over a 12-day period between Oct. 30 and Nov. 11, 2006, show that the feature is nearly stationary, and likely is an unusually strong pole-encircling planetary wave that extends deep into the atmosphere.

This image was acquired on Oct. 29, 2006, from an average distance of 902,000 kilometers (560,400 miles) above the cloud tops of Saturn.

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, where this image was produced.

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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#21    Waspie_Dwarf

Waspie_Dwarf

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Posted 28 March 2007 - 02:27 AM

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GIF (no audio) (4.2 MB)     QuickTime (no audio) (4.2 MB)

Saturn's Strange Hexagon
    
This nighttime view of Saturn's north pole by the visual and infrared mapping spectrometer onboard NASA's Cassini orbiter clearly shows a bizarre six-sided hexagon feature encircling the entire north pole. This is one of the first clear images taken of the north polar region ever acquired from a unique polar perspective.

In this image, the red color indicates the amount of 5-micron wavelength radiation, or heat, generated in the warm interior of Saturn that escapes the planet. Clouds near 3-bar (about 100 kilometers or 62 miles deeper than seen in visible wavelengths) block the light, revealing them in silhouette against the background thermal glow of Saturn. The bluish color shows sunlight striking the far limb (edge) of the planet, showing that the entire north pole is under the nighttime conditions characteristic of polar winter, as on Earth.

This image is the first to capture the entire feature and north polar region in one shot, and is also the first polar view using Saturn's thermal glow at 5 microns (seven times the wavelength visible to the human eye) as the light source. This allows the pole to be revealed during the persistent nighttime conditions under way during winter. The hexagon feature was originally discovered by NASA's Voyager spacecraft in 1980, but those historic images and subsequent ground-based telescope images suffered from poor viewing perspectives, which placed the feature and the north pole at the extreme northern limb (edge) in those images.

In the new infrared images, the strong brightness of the hexagon feature indicates that it is primarily a clearing in the clouds, which extends deep into the atmosphere, at least some 75 kilometers (47 miles) underneath the typical upper hazes and clouds seen in the daytime imagery by Voyager. Thick clouds border both sides of the narrow feature, as indicated by the adjacent dark lanes paralleling the bright hexagon. This and other images acquired over a 12-day period between Oct. 30 and Nov. 11, 2006, show that the feature is nearly stationary, and likely is an unusually strong pole-encircling planetary wave that extends deep into the atmosphere.

This image was acquired with the Cassini visual and infrared mapping spectrometer on Oct. 30, 2006, from an average distance of 1.3 million kilometers (807,782 miles).

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, where this image was produced.  

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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#22    Waspie_Dwarf

Waspie_Dwarf

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Posted 08 May 2007 - 04:02 PM

Cassini Finds that Storms Power Saturn's Jet Streams

New Cassini research suggests eddies, or giant rotating storms, are the "engine" powering Saturn's jet stream winds.

"The new information about how Saturn's jet streams are powered is exactly the opposite of what we thought prior to Cassini," said Anthony Del Genio of NASA's Goddard Institute for Space Studies, New York, N.Y. Del Genio is a Cassini imaging team member and lead author of a paper describing this research in press in the journal Icarus.

linked-image
Image above: The image shows small-scale, sheared-out cloud features
associated with turbulent eddies in the vicinity of one of Saturn's eastward
flowing jet streams, or "jets."
Image credit: NASA/JPL/Space Science Institute


Jet streams are motions in an atmosphere that carry clouds rapidly eastward or westward. The eddies get fed into the jet streams, in much the same way that rotating gears can power a conveyor belt.

"While we thought the conveyor belt--in this case, the jet streams--powered the rotating eddies, we now think the opposite: the rotating eddies power the jet streams," said Del Genio.

"Intuition would say that the eddies take energy out of the jets, because of the friction and tugging of the storms. Instead, what we find is that they are pumping energy into the jets," said Andrew Ingersoll, a Cassini imaging team member with the California Institute of Technology, Pasadena, Calif. Ingersoll says that while this process has been known to occur on Earth, it was only recently shown to operate on Jupiter and is a new idea for Saturn, where data from the earlier Voyager missions had failed to detect the eddy-jet interactions.

The Cassini team analyzed, for the first time, how storms and eddies interact with Saturn's jet streams. By tracking the movements of these cloud features in successive images separated by about 10 hours (about one Saturn rotation), Cassini scientists have confirmed that the eddies on either side of the jet give up their energy and momentum, which helps keep the winds in the jet blowing.

"We knew the eddies were powering the jets because they were pointing in the same direction and carrying momentum in that direction. If the eddies had been tapering the other way, we would have concluded the opposite," added Ingersoll.

The analysis of Cassini images covering most of Saturn's southern hemisphere suggests that similar processes are occurring all over the planet. This explains why Saturn's alternating pattern of eastward and westward jets has remained constant over most of the planet during the many decades that scientists have been able to observe it. The same process was also recently found to occur on Jupiter, in data obtained when Cassini flew by that planet on its way to Saturn. The process is a well known feature on Earth in the two jet streams that circle the globe in the northern and southern hemisphere.

The findings suggest that traditional ideas about the banded clouds of Jupiter and Saturn need to be revised.

"We used to assume that the bright cloud bands are regions where air rises and the dark bands are where air sinks. But if the eddies power the jets in the way we observe, the opposite must be true," said Del Genio. "And indeed, we find thunderstorms only in the dark bands on both planets, which has to mean that the air is rising there."

An image from the study, showing cloud features near one of Saturn's jet streams, is available at http://www.nasa.gov/cassini
, http://saturn.jpl.nasa.gov and http://ciclops.org . The paper is available at http://www.sciencedirect.com.

The Cassini-Huygens mission is a cooperative project of NASA, the European Space Agency and the Italian Space Agency. NASA's Jet Propulsion Laboratory, a division of Caltech, manages the Cassini-Huygens mission for NASA's Science Mission Directorate, Washington. The Cassini orbiter and its two onboard cameras were designed, developed and assembled at JPL. The imaging team is based at the Space Science Institute.


Media contact: Carolina Martinez 818-354-9382
Jet Propulsion Laboratory, Pasadena, Calif.

Preston Dyches 720-974-5859
Cassini Imaging Central Laboratory for Operations
Space Science Institute, Boulder, Colo.

2007-053


Source: NASA - Cassini - News

Edited by Waspie_Dwarf, 08 May 2007 - 06:00 PM.

"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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#23    Waspie_Dwarf

Waspie_Dwarf

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Posted 08 May 2007 - 04:04 PM

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Powering Saturn's Jets (with labels)
May 8, 2007

Using images like the one presented here, Cassini imaging scientists have made a major finding about the mechanism powering the general circulation of Saturn.

The image shows small-scale, sheared-out cloud features associated with turbulent eddies in the vicinity of one of Saturn's eastward flowing jet streams, or "jets."

The jet itself, located at 27.5 degrees south latitude, is indicated by the large horizontal arrow. Winds in this jet have blown continuously at speeds close to 320 kilometers per hour (200 miles per hour) for as long as scientists have observed Saturn.

By tracking the movements of these cloud features in successive images separated by about 10 hours (about one Saturn rotation), Cassini scientists have confirmed that the eddies on either side of the jet give up their energy and momentum to help keep the winds in the jet blowing.

The tilted arrows indicate the direction in which the eddies move the energy and momentum that power the jet. The winds that accomplish this are so strong that they combine to stretch out the eddies into bright, tilted streaks that are visible here, parallel to the arrows.

The analysis of Cassini images covering most of Saturn's southern hemisphere suggests that similar processes occurring all over Saturn explain the remarkable decades-long stability of its alternating pattern of eastward and westward jets. The same process also occurs on Jupiter, and on Earth in the storm track along the east coast of the United States.

Prior to this discovery, it was thought that the jets on Saturn and Jupiter were powered by an entirely different process, analogous to the tropical circulation on Earth. But now it appears that a comparison to the atmospheric motions in the Earth's mid-latitudes is more appropriate.

The eddies seen in this image also create circulation patterns of upward and downward motion (in altitude) at different latitudes that help explain the general banded structure of global cloud patterns on the Jovian planets.

The image was taken using a spectral filter sensitive to wavelengths of infrared light centered at 750 nanometers. The view was acquired with the Cassini spacecraft narrow-angle camera on Feb. 5, 2005, at a distance of approximately 3.4 million kilometers (2.1 million miles) from Saturn. Image scale is 20 kilometers (12 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

Edited by Waspie_Dwarf, 08 May 2007 - 05:50 PM.

"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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#24    Waspie_Dwarf

Waspie_Dwarf

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Posted 08 May 2007 - 05:48 PM

linked-image

Powering Saturn's Jets (without labels)
May 8, 2007

Using images like the one presented here, Cassini imaging scientists have made a major finding about the mechanism powering the general circulation of Saturn.

The image shows small-scale, sheared-out cloud features associated with turbulent eddies in the vicinity of one of Saturn's eastward flowing jet streams, or "jets."

The jet itself, located at 27.5 degrees south latitude, is indicated by the large horizontal arrow. Winds in this jet have blown continuously at speeds close to 320 kilometers per hour (200 miles per hour) for as long as scientists have observed Saturn.

By tracking the movements of these cloud features in successive images separated by about 10 hours (about one Saturn rotation), Cassini scientists have confirmed that the eddies on either side of the jet give up their energy and momentum to help keep the winds in the jet blowing.

The tilted arrows indicate the direction in which the eddies move the energy and momentum that power the jet. The winds that accomplish this are so strong that they combine to stretch out the eddies into bright, tilted streaks that are visible here, parallel to the arrows.

The analysis of Cassini images covering most of Saturn's southern hemisphere suggests that similar processes occurring all over Saturn explain the remarkable decades-long stability of its alternating pattern of eastward and westward jets. The same process also occurs on Jupiter, and on Earth in the storm track along the east coast of the United States.

Prior to this discovery, it was thought that the jets on Saturn and Jupiter were powered by an entirely different process, analogous to the tropical circulation on Earth. But now it appears that a comparison to the atmospheric motions in the Earth's mid-latitudes is more appropriate.

The eddies seen in this image also create circulation patterns of upward and downward motion (in altitude) at different latitudes that help explain the general banded structure of global cloud patterns on the Jovian planets.

A labeled version of the image is presented here as well.

The image was taken using a spectral filter sensitive to wavelengths of infrared light centered at 750 nanometers. The view was acquired with the Cassini spacecraft narrow-angle camera on Feb. 5, 2005, at a distance of approximately 3.4 million kilometers (2.1 million miles) from Saturn. Image scale is 20 kilometers (12 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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#25    Waspie_Dwarf

Waspie_Dwarf

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Posted 05 January 2008 - 11:09 AM

Hot Cyclones Churn at Both Ends of Saturn

January 3, 2008
(Source: Jet Propulsion Laboratory)

Despite more than a decade of winter darkness, Saturn's north pole is home to an unexpected hot spot remarkably similar to one at the planet's sunny south pole. The source of its heat is a mystery. Now, the first detailed views of the gas giant's high latitudes from the Cassini spacecraft reveal a matched set of hot cyclonic vortices, one at each pole.

linked-image
This image shows newly discovered "hot spot"
on Saturn's north pole and the mysterious
hexagon that encircles the pole. The "hot spot"
appears to be related to Saturn's dynamic
weather systems, rather than to seasonal
changes in the amount of sunlight at the pole.

Credit:NASA/JPL/GSFC/Oxford University


While scientists already knew about the hot spot at Saturn's south pole from previous observations by the W. M. Keck Observatory in Hawaii, the north pole vortex was a surprise. The researchers report their findings in the Jan. 4 issue of Science.

"We had speculated that the south pole hot spot was connected to the southern, sunlit conditions," said Glenn Orton, a senior research scientist at NASA's Jet Propulsion Laboratory, Pasadena, Calif., and co-investigator on Cassini's composite infrared spectrometer. "Since the north pole has been deprived of sunlight since the arrival of winter in 1995, we didn't expect to find a similar feature there."

The infrared data show that the shadowed north pole vortex shares much the same structure and temperature as the one at the sunny south pole. The cores of both show a depletion of phospine gas, an imbalance probably caused by air moving downward into the lowest part of Saturn's atmosphere, the troposphere. Both polar vortices appear to be long-lasting and intrinsic parts of Saturn and are not related to the amount of sunlight received by one pole or the other.

"The hot spots are the result of air moving polewards, being compressed and heated up as it descends over the poles into the depths of Saturn," said Leigh Fletcher, a planetary scientist from the University of Oxford, England, and the lead author of the Science paper. "The driving forces behind the motion, and indeed the global motion of Saturn's atmosphere, still need to be understood."

Though similar, the two polar regions differ in one striking way. At the north pole, the newly discovered vortex is framed by the distinctive, long-lived and still unexplained polar hexagon. This mysterious feature encompassing the entire north pole was first spotted in the 1980s by NASA's Voyager 1 and 2 spacecraft. Cassini's infrared cameras also detected the hexagon in deep atmospheric clouds early in 2007.

In their paper, Fletcher and his colleagues report that the bright, warm hexagon is much higher than previous studies had shown. "It extends right to the top of the troposphere," says Fletcher. "It is associated with downward motion in the troposphere, though the cause of the hexagonal structure requires further study."

Winter lasts about 15 years on Saturn. Researchers anticipate that when the seasons change in the coming years and Saturn's north pole is once again in sunlight, they will be able to see a swirling vortex with high eye walls and dark central clouds like the one now visible at the south pole. "But Saturn may surprise us again," says Fletcher.

"The fact that Neptune shows a similar south polar hot spot whets our appetite for the strange dynamics of the poles of the other gas giants," Fletcher says.

More information about Jupiter's poles will come from NASA's Juno mission, currently scheduled for launch in 2011 and arrival in 2016.

Fletcher¿s research was funded by the United Kingdom's Science and Technology Facilities Council.

The Cassini-Huygens mission is a cooperative project of NASA, the European Space Agency and the Italian Space Agency. JPL, a division of the California Institute of Technology in Pasadena, manages the Cassini-Huygens mission for NASA's Science Mission Directorate, Washington. The Cassini orbiter was designed, developed and assembled at JPL. The science team for Cassini's composite infrared spectrometer team is based at NASA's Goddard Space Flight Center, Greenbelt, Md.

Contacts:
Rosemary Sullivant/Carolina Martinez 818-354-5011
Jet Propulsion Laboratory, Pasadena, Calif.


NEWS RELEASE: 2008-001

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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#26    Waspie_Dwarf

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Posted 05 January 2008 - 11:14 AM

linked-image

Saturn's North Pole Hot Spot and Hexagon
January 3, 2008

This image shows the unexpected "hot spot" at Saturn's north pole. Scientists were surprised to find that the north pole, despite being in winter darkness for more than a decade, is home to a hot, cyclonic vortex very similar to that found on Saturn's much sunnier south pole.
Created with data from the Cassini spacecraft's composite infrared spectrometer, this image, centered on the north pole, shows temperatures in Saturn's northern hemisphere near its 100-millibar tropopause, the top of its convective layer.

The false color denotes temperatures from 72 to 84 Kelvin (about 330 to 310 degrees below zero Fahrenheit). Latitudes are displayed from 30 degrees N at the edges to the north pole in the center. The hot pole is clear at the center of the projection. The distinctive polar hexagon is also evident in the initial warm "ring" around the pole between 75 and 80 degrees North latitude.

Although there is a similar hot pole in the southern hemisphere, there is no hexagon and the atmosphere is otherwise much warmer than in the north, having been heated during Saturn's southern summer for over a decade
.

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 _http://saturn.jpl.nasa.gov/home/index.cfm. The composite infrared spectrometer team homepage is _http://cirs.gsfc.nasa.gov/.


Credit: NASA/JPL/GSFC/Oxford University

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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#27    Waspie_Dwarf

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Posted 05 May 2008 - 03:49 PM

NASA Spacecraft Tracks Raging Saturn Storm

April 29, 2008
(Source: NASA/JPL/Space Science Institute)

PASADENA, Calif. – As a powerful electrical storm rages on Saturn with lightning bolts 10,000 times more powerful than those found on Earth, the Cassini spacecraft continues its five-month watch over the dramatic events.

Scientists with NASA's Cassini-Huygens mission have been tracking the visibly bright, lightning-generating storm--the longest continually observed electrical storm ever monitored by Cassini.

linked-image
Cassini detected this particular tempest after
nearly two years during which Saturn did not
appear to produce any large electrical storms
of this kind.


Saturn's electrical storms resemble terrestrial thunderstorms, but on a much larger scale. Storms on Saturn have diameters of several thousand kilometers (thousands of miles), and radio signals produced by their lightning are thousands of times more powerful than those produced by terrestrial thunderstorms.

Color images of the storm are available at: _http://saturn.jpl.nasa.gov and _http://www.nasa.gov/cassini and _http://ciclops.org .

Lightning flashes within the persistent storm produce radio waves called Saturn electrostatic discharges, which the radio and plasma wave science instrument first detected on Nov. 27, 2007. Cassini's imaging cameras monitored the position and appearance of the storm, first spotting it about a week later, on Dec. 6.

linked-image
The view at left approximate what the
human eye would see. The storm stands out
with greater clarity in the sharpened, enhanced
color view at right.


"The electrostatic radio outbursts have waxed and waned in intensity for five months now," said Georg Fischer, an associate with the radio and plasma wave science team at the University of Iowa, Iowa City. "We saw similar storms in 2004 and 2006 that each lasted for nearly a month, but this storm is longer-lived by far. And it appeared after nearly two years during which we did not detect any electrical storm activity from Saturn."

The new storm is located in Saturn's southern hemisphere--in a region nicknamed "Storm Alley" by mission scientists--where the previous lightning storms were observed by Cassini. "In order to see the storm, the imaging cameras have to be looking at the right place at the right time, and whenever our cameras see the storm, the radio outbursts are there," said Ulyana Dyudina, an associate of the Cassini imaging team at the California Institute of Technology in Pasadena, Calif.

Cassini's radio plasma wave instrument detects the storm every time it rotates into view, which happens every 10 hours and 40 minutes, the approximate length of a Saturn day. Every few seconds the storm gives off a radio pulse lasting for about a tenth of a second, which is typical of lightning bolts and other electrical discharges. These radio waves are detected even when the storm is over the horizon as viewed from Cassini, a result of the bending of radio waves by the planet's atmosphere.

Amateur astronomers have kept track of the storm over its five-month lifetime. "Since Cassini's camera cannot track the storm every day, the amateur data are invaluable," said Fischer. "I am in continuous contact with astronomers from around the world."

The long-lived storm will likely provide information on the processes powering Saturn's intense lightning activity. Cassini scientists will continue to monitor Storm Alley as the seasons change, bringing the onset of autumn to the planet's southern hemisphere.

The Cassini-Huygens mission is a cooperative project of NASA, the European Space Agency and the Italian Space Agency. JPL, a division of Caltech, manages the Cassini 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 team is based at the Space Science Institute, Boulder, Colo. The radio and plasma wave science team is based at the University of Iowa, Iowa City.

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

Preston Dyches 720-974-5859
Space Science Institute, Boulder, Colo.
media@ciclops.org

NEWS RELEASE: 2008-068

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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#28    Waspie_Dwarf

Waspie_Dwarf

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Posted 05 May 2008 - 03:53 PM

linked-image

Saturn's Long-lived Storm
April 29, 2008

It is no Great Red Spot, but these two side-by-side views show the longest-lived electrical storm yet observed on Saturn by NASA's Cassini spacecraft.

The views were acquired more than three months after the storm was first detected from its lightning-produced radio discharges on Nov. 27, 2007. See Hissing Storm (below) for an earlier color view of this storm. Cassini imaging scientists believe the storm to be a vertically extended disturbance that penetrates from Saturn's lower to upper troposphere.

The view at left was created by combining images taken using red, green and blue spectral filters, and shows Saturn in colors that approximate what the human eye would see. The storm stands out with greater clarity in the sharpened, enhanced color view at right. This view combines images taken in infrared, green and violet light at 939, 567 and 420 nanometers respectively and represents an expansion of the wavelength region of the electromagnetic spectrum visible to human eyes. This view looks toward the un-illuminated side of the rings from about 3 degrees above the ringplane. Janus (181 kilometers, or 113 miles across) appears as a dark speck just beneath the rings in both images.

These images were obtained with the Cassini spacecraft wide-angle camera on March 4, 2008, at a distance of approximately 1.3 million kilometers (800,000 miles) from Saturn. Image scale is 74 kilometers (46 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. The radio and plasma wave science team is based at the University of Iowa, Iowa City.

For more information about the Cassini-Huygens mission visit _http://saturn.jpl.nasa.gov. The Cassini imaging team homepage is at _http://ciclops.org. The radio and plasma wave science instrument team home page is at: _http://www-pw.physics.uiowa.edu/plasma-wave/cassini/home.html.

Credit: NASA/JPL/Space Science Institute

Source: NASA/JPL - Cassini

Edited by Waspie_Dwarf, 05 May 2008 - 03:58 PM.

"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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#29    Waspie_Dwarf

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Posted 05 May 2008 - 03:57 PM

linked-image

Hissing Storm
April 29, 2008

A bright, powerful, lightning-producing storm churns and coasts along the lane of Saturn's southern hemisphere nicknamed "Storm Alley" by scientists.

NASA's Cassini spacecraft detected this particular tempest after nearly two years during which Saturn did not appear to produce any large electrical storms of this kind. The storm appears as a bright, irregular splotch on the planet near lower right.

Lightning flashes within the persistent storm produce radio waves, called Saturn Electrostatic Discharges, which the Cassini radio and plasma wave science instrument first detected on Nov. 27, 2007. Cassini's imaging cameras then spotted the storm, taking the images used to create this color view about a week later on Dec. 6.

This electrical storm is similar in appearance and intensity to those previously monitored by Cassini. All of these powerful electrostatic producing storms appeared at about 35 degrees south latitude on Saturn. (See Storm at Night, Against the Current and The Dragon Storm for additional images of Saturn's electrical storms imaged by Cassini.)

This storm has now been continuously tracked by Cassini for several months, whereas previous storms observed by the spacecraft lasted for less than 30 days: See Saturn's Long-lived Storm (above) for images of the storm acquired three months after this view. The view looks toward the un-illuminated side of the rings from about 5 degrees above the ringplane. Tethys (1,071 kilometers, or 665 miles across) is seen here in the foreground, and casts its shadow onto the high northern latitudes.

Images taken using red, green and blue spectral filters were combined to create this natural color view. The images were acquired with the Cassini spacecraft wide-angle camera at a distance of approximately 1.7 million kilometers (1 million miles) from Saturn. Image scale is 97 kilometers (60 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. The radio and plasma wave science team is based at the University of Iowa, Iowa City.

For more information about the Cassini-Huygens mission visit _http://saturn.jpl.nasa.gov. The Cassini imaging team homepage is at _http://ciclops.org. The radio and plasma wave science instrument team home page is at: _http://www-pw.physics.uiowa.edu/plasma-wave/cassini/home.html.

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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#30    Waspie_Dwarf

Waspie_Dwarf

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Posted 08 May 2008 - 01:25 PM

Saturn Does the Wave In Upper Atmosphere

May 12, 2008

Two decades of scrutinizing Saturn are finally paying off, as scientists have discovered a wave pattern, or oscillation, in Saturn's atmosphere only visible from Earth every 15 years.

The discovery of the wave pattern is the result of a 22-year campaign observing Saturn from Earth (the longest study of temperature outside Earth ever recorded), and the Cassini spacecraft's observations of temperature changes in the giant planet's atmosphere over time.

linked-image
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. The image on the right, taken
in 2006, shows the temperature at the equator
is warmer.
Image credit: NASA/JPL.


The Cassini infrared results, which appear in the same issue of Nature as the data from the 22-year ground-based observing campaign, indicate that Saturn's wave pattern is similar to a pattern found in Earth's upper atmosphere. The earthly oscillation takes about two years. A similar pattern on Jupiter takes more than four Earth years. The new Saturn findings add a common link to the three planets.

Just as scientists have been studying climate changes in Earth's atmosphere for long periods of time, NASA scientists have been studying changes in Saturn's atmosphere. Glenn Orton of NASA's Jet Propulsion Laboratory in Pasadena, Calif., says patience is the key to studying changes over the course of a Saturnian year, the equivalent of about 30 Earth years.

"You could only make this discovery by observing Saturn over a long period of time," said Orton, lead author of the ground-based study. "It's like putting together 22 years worth of puzzle pieces, collected by a hugely rewarding collaboration of students and scientists from around the world on various telescopes."

The wave pattern is called an atmospheric oscillation. It ripples back and forth 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. These varying temperatures force the wind in the region to keep changing direction from east to west, jumping back and forth. As a result, the entire region oscillates like a wave.

Mike Flasar, co-author of the Cassini paper, and principal investigator for Cassini's Composite Infrared Spectrometer at NASA's Goddard Space Flight Center, Greenbelt, Md., said that Cassini helped define this oscillation in combination with the ground observation campaign.

"It's this great synergy of using ground-based data over time, and then getting up close and personal with the oscillation in Saturn's atmosphere through Cassini," said Flasar. "Without Cassini, we might never have seen the structure of the oscillation in detail."

Cassini scientists hope to find out why this phenomenon on Saturn changes with the seasons, and why the temperature switchover happens when the sun is directly over Saturn's equator.

More information on the Cassini-Huygens mission can be found at:: _http://saturn.jpl.nasa.gov and _http://www.nasa.gov/cassini.

The Cassini-Huygens mission is a cooperative project of NASA, the European Space Agency and the Italian Space Agency. JPL, a division of the California Institute of Technology in Pasadena, manages the Cassini 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.

Written by: Diya Chacko

For more information:

Diya Chacko: 818-393-5464
Carolina Martinez: 818-354-9382

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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