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Post Info TOPIC: Saturn's upper atmosphere


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This close-up view of Saturn's atmosphere shows a circular vortex surrounded by numerous attendant bright clouds.

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Credit: NASA/JPL/Space Science Institute

The image was taken in visible light with the Cassini spacecraft narrow-angle camera on Jan. 3, 2007 at a distance of approximately 1.3 million kilometres from Saturn. Image scale is 15 kilometres per pixel.

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Two bright vortices roll across the cloud-lined face of Saturn, where winds howl at high speeds never experienced on Earth.
This view was acquired at about the same time as Cloud Lanes but the planet appears darker here. This is because the spectral filter used to acquire this image looks at a part of the spectrum where methane absorption in Saturn's atmosphere is stronger. Thus, photons do not penetrate as deep into the Saturn atmosphere as they do at the wavelengths observed in Cloud Lanes. Since more photons are absorbed here, the planet looks darker.

SAT08866
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Credit: NASA/JPL/Space Science Institute

The icy particles composing the rings do not contain methane, and therefore appear bright relative to Saturn.
The image was taken using a spectral filter sensitive to wavelengths of infrared light centred at 862 nanometers. The view was obtained using the Cassini spacecraft wide-angle camera on Dec. 13, 2006 at a distance of approximately 775,000 kilometres from Saturn. Image scale is 43 kilometres per pixel.

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From its unique perspective high above the planet, the Cassini spacecraft looks down upon Saturn's murky northern hemisphere. The bluish hues seen in some Cassini views of Saturn's north are notably absent in this viewing geometry.
The dark side of Saturn's extensive rings is just visible in the top half of the image.

PIA08822b
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Credit: NASA/JPL/Space Science Institute

The view looks toward the unlit side of the rings from about 44 degrees above the ringplane.
Images taken using red, green and blue spectral filters were combined to create this natural colour view. The images were taken with the Cassini spacecraft wide-angle camera on Oct. 30, 2006 at a distance of approximately 1.4 million kilometres from Saturn and at a Sun-Saturn-spacecraft, or phase, angle of 150 degrees. Image scale is 78 kilometres per pixel.

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This spectacular image of Saturn's clouds looks obliquely across the high northern latitudes. The Sun is low on the horizon here, making the vertical extent of the clouds easier to see. Cloud bands surrounding the vortex at lower left rise above their surroundings, casting shadows toward the bottom of the image.
Some motion blur is apparent in this view.

Saturn301006
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Credit: NASA/JPL/Space Science Institute

The image was taken with the Cassini spacecraft narrow-angle camera using a spectral filter sensitive to wavelengths of infrared light centred at 938 nanometers on Oct. 30, 2006. Cassini was then at a distance of approximately 1.2 million kilometres from Saturn and at a Sun-Saturn-spacecraft, or phase, angle of 142 degrees. Image scale is 7 kilometres per pixel.

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The Cassini data presented in this view appear to confirm a region of warm atmospheric descent into the eye of a hurricane-like storm locked to Saturn's south pole. The view shows temperature data from the Cassini spacecraft composite infrared spectrometer overlaid onto an image from the imaging science subsystem wide-angle camera.

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The composite infrared spectrometer data refer to a depth in Saturn's upper stratosphere where the pressure is 0.5 millibars (324 kilometres above the 1-bar level), a region higher than that imaged by the imaging camera and visual and infrared spectrometer during the same observation period. The composite infrared spectrometer data show a very small hot spot over the pole, similar in size to the "eye" of the storm seen in the imaging science subsystem images.

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NASA says its Cassini spacecraft has found a hurricane-like storm at Saturn's South Pole, nearly 5,000 miles across -- or two-thirds Earth's diameter.

These images of Saturn's south pole, taken by two different instruments on Cassini, show the hurricane-like storm swirling there and features in the clouds at various depths surrounding the pole. Different wavelengths reveal the height of the clouds, which span tens of kilometres in altitude.

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The four monochrome images displayed here were acquired by the imaging science subsystem; the blue and red images in the bottom row were taken by the visual and infrared mapping spectrometer. The images are arranged in order of increasing wavelength in nanometers as follows: (top row) 460 nm, 752 nm, 728 nm; (bottom row) 890 nm, 2,800 nm, 5,000 nm.
At the centre of the cauldron of storms spinning around the south pole is the south pole itself, which literally appears to be the eye of this vast polar storm system. As in a hurricane on Earth, the south polar "eye" is relatively clear of clouds and is surrounded by a wall of towering clouds that cast shadows into the centre. However, while morphologically similar, it is not clear if this vortex operates in the same fashion as a terrestrial hurricane. In most of the images, the centre of the polar storm is quite dark, indicating an unusually cloud-free atmosphere in the upper skies, which are otherwise typically inhabited by bright ammonia clouds. This polar hole in the ammonia cloud layer represents the eye of the hurricane-like storm. Unusually dark clouds likely exist at the bottom of this deep hole, enhancing the murkiness there.

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This image of Saturns cloudtops was taken by the Cassini spacecraft on October 30, 2006, when it was approximately 1,147,785 kilometres away.

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Credit NASA

The image was taken using the CL1 and CB3 filters.

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In this image, Saturn's fascinating meteorology manifests itself in a "string of pearls" formation, spanning over 60,000 kilometres.

Saturn
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Credit NASA

Seen in new images acquired by Cassini's visual and infrared mapping spectrometer and lit from below by Saturn's internal thermal glow, the bright "pearls" are actually clearings in Saturn's deep cloud system. More than two dozen occur at 40 degrees north latitude. Each clearing follows another at a regular spacing of some 3.5 degrees in longitude.
This is the first time such a regular and extensive train of cloud-clearings has been observed. The regularity indicates that they may be a manifestation of a large planetary wave. Scientists plan to take more observations of this phenomenon over the next few years to try to understand Saturn's deep circulation systems and meteorology. This image was taken on April 27, 2006.

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Saturn's dark vortices
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With no solid land to obstruct their progress, dark vortices often roll through Saturn's atmosphere for months or years, before merging with other vortices. On Earth, the continents usually halt the progress of large storms, like hurricanes.

dark vortices
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Credit NASA

Vortices like these are part of the general circulation pattern of east-west flowing cloud bands, called jets, on Saturn.
The image was taken using a spectral filter sensitive to wavelengths of infrared light centred at 939 nanometers. The image was obtained with the Cassini spacecraft wide-angle camera on Aug. 16, 2006 at a distance of approximately 259,000 kilometres from Saturn. Image scale is 12 kilometres per pixel.

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This false-colour image of Saturn shows ring shadows running across the upper portion of the planet, and sunlight illuminating the lower portion of the planet.


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Credit NASA

The upper area, in the ring shadow, would be black in visible light but glows red in infrared because Saturn is warm inside. This light shines out through the clouds, giving scientists a look at some of Saturn's interesting atmospheric structure.
This image was taken on June 30, 2006, with Cassini's visual and infrared mapping spectrometer. It was constructed from images taken at wavelengths of 0.91 microns shown in blue, 2.25 microns shown in green, and at 5.01 microns shown in red. The distance from Cassini to Saturn's centre in this image is 335,000 kilometres.

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