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Post Info TOPIC: Saturn's upper atmosphere
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Saturn's Rotation
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Title: Saturn's rotation period from its atmospheric planetary-wave configuration
Authors: P. L. Read, T. E. Dowling  &  G. Schubert

The rotation period of a gas giant's magnetic field (called the System III reference frame) is commonly used to infer its bulk rotation. Saturn's dipole magnetic field is not tilted relative to its rotation axis (unlike Jupiter, Uranus and Neptune), so the surrogate measure of its long-wavelength (kilometric) radiation is currently used to fix the System III rotation period. The period as measured now by the Cassini spacecraft is up to ~7 min longer than the value of 10 h 39 min 24 s measured 28 years ago by Voyager. Here we report a determination of Saturn's rotation period based on an analysis of potential vorticity. The resulting reference frame (which we call System IIIw) rotates with a period of 10 h 34 min 13 ± 20 s. This shifted reference frame is consistent with a pattern of alternating jets on Saturn that is more symmetrical between eastward and westward flow. This suggests that Saturn's winds are much more like those of Jupiter than hitherto believed.

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Blobrana


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RE: Saturn's upper atmosphere
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New images from NASA's Cassini spacecraft reveal a giant cyclone at Saturn's north pole, and show that a similarly monstrous cyclone churning at Saturn's south pole is powered by Earth-like storm patterns.
The new-found cyclone at Saturn's 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 Saturn's atmosphere are seen in silhouette against the background glow of Saturn's internal heat.
The entire north pole of Saturn is now mapped in detail in infrared, with features as small as 120 kilometres visible in the images. Time-lapse movies of the clouds circling the north pole show the whirlpool-like cyclone there is rotating at 530 kilometres 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 kilometres per hour. Oddly, neither the fast-moving clouds inside the hexagon nor this new cyclone seem to disrupt the six-sided hexagon.

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Blobrana


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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.

SaturnWave
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Credit: NASA/JPL/IRTF

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.

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Blobrana


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Two decades of scrutinising 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.

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An amateur astronomer from far western New South Wales is providing NASA with information about a storm on Saturn.
Trevor Barry from Broken Hill says he first noticed the storm in February, when he was photographing the planet on a webcam.
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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.

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Blobrana


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A false-colour movie of a whirling vortex at Saturn's south pole has been released. The storm may be driven by updrafts of warm, moist air just like hurricanes on Earth.
The vortex was discovered in images taken by the Cassini spacecraft when it flew over Saturn's south pole in October 2006. It is about 8000 kilometres across and rotates in the same direction as the planet's overall rotation, but about 550 kilometres per hour faster. A video pieced together from infrared images was released at the time, giving a black and white view of the whirling storm.
Scientists have now released false-colour images and a false-colour video of the storm, made from the 2006 infrared observations. The images are described in a paper in the journal Science, written by Ulyana Dyudina of Caltech in Pasadena, US, and her colleagues.
Saturn's whirling vortex


Saturn's whirling vortex (colour)



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Blobrana


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RE: Saturn's hot spot
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Saturns chilly north pole boasts a hot spot in the middle of its mysterious polar hexagon, according to new data from the Cassini spacecraft. The discovery could shed light on the atmospheric formations found on other planets such as Jupiter, Neptune and Mars.
Scientists already knew about the hot spot at Saturn's sunny south pole from previous observations but the north pole vortex came as a surprise. The researchers report their findings in this weeks Science.

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Blobrana


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RE: Saturn's upper atmosphere
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Both of Saturn's poles have surprising swirling hotspots that persist even through years of polar winter, a new study reveals.
The hotspots are localised areas in Saturn's gaseous atmosphere over its poles that are considerably warmer than the surrounding air they're actually about as warm as the atmosphere at Saturn's equator, said Leigh Fletcher of the University of Oxford.
The hotspot over the southern hemisphere was imaged by the Keck Observatories prior to arrival of the Cassini spacecraft, but the northern hemisphere has faced away from Earth for over a decade, so its hotspot was revealed only this year by Cassini.

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The image of Saturn's atmosphere was taken by the Cassini spacecraft on Sept. 17, 2007, using the space crafts narrow-angle camera and spectral filter sensitive to wavelengths of infrared light centred at 750 nanometers.
The view was obtained at a distance of approximately 3.5 million kilometres from Saturn.
Winds in this region of Saturn have been measured at greater than 360 kilometres per hour

sataAtmosOct_e1
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Credit: NASA/JPL/Space Science Institute

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