| Piú viste - Saturn: the "Ringed Beauty" and His Moons |
Enceladus-PIA10483.jpgThe Leading Hemisphere of Enceladus56 visiteCaption NASA:"During a distant flyby encounter with Enceladus, Cassini imaged the moon's wrinkled Leading Hemisphere.
At the scale visible here, this region of the surface is generally devoid of impact craters, suggesting that the terrain has been modified and renewed during the moon's history.
To the North lies a heavily cratered and presumably older Region. The sinuous boundary of the geologically active South Polar Region is seen at bottom. North on Enceladus is toward the top of the image.
The image was taken in visible green light with the Cassini Spacecraft narrow-angle camera on Sept. 30, 2007. The view was acquired at a distance of approx. 108.000 Km (such as about 67.000 miles) from Enceladus and at a Sun-Enceladus-Spacecraft, or phase, angle of 75°.
Image scale is 644 meters (2111 feet) per pixel".MareKromium
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Saturn-SP-PIA11104.jpgSouthern Turbulence (False Colors; credits: Lunexit)56 visiteCaption NASA:"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 PIA11103 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 PIA09859) 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° below the Ring-Plane. 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 approx. 392.000 Km (243.000 miles) from Saturn and at a Sun-Saturn-Spacecraft, or Phase, Angle of 60°.
Image scale is roughly 2 Km (a little more than 1 mile) per pixel".MareKromium
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Dione-PIA10496.jpgThe Bright Canyons of Dione56 visiteCaption NASA:"Dione's defining feature, the fractures on its Trailing Side, shine brilliantly in this Cassini Spacecraft view.
The view was acquired from a position 33° South of the moon's Equator. Lit terrain seen here is on the Trailing Side of Dione (approx. 1123 Km, or about 698 miles across). North is up and rotated 8° to the right.
The image was taken in visible light with the Cassini spacecraft narrow-angle camera on Sept. 11, 2008. The view was obtained at a distance of approximately 833,000 kilometers (517,000 miles) from Dione and at a Phase Angle of 67°. Image scale is about 5 Km (a little more than 3 miles) per pixel.
The image was taken with the Cassini Spacecraft wide-angle camera on Aug. 26, 2008 using a spectral filter sensitive to wavelengths of infrared light centered at 752 nanometers.
The view was acquired at a distance of approx. 397.000 Km (about 246.000 miles) from Saturn.
Image scale is roughly 20 Km (about 13 miles) per pixel".MareKromium
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Saturn-SouthPole_cassini_big.jpgBeneath the South Pole of Saturn56 visiteCaption NASA:"What clouds lurk beneath Saturn's unusual South Pole?
To help find out, the robotic Cassini Spacecraft currently orbiting Saturn imaged the nether region of the gigantic ringed orb in infrared light.
There thick clouds appear dark as they mask much of the Infrared Light emitted from warmer regions below, while relatively thin clouds appear much lighter. Bands of clouds circle Saturn at several latitudes, while dark ovals indicate many dark swirling storm systems. Surprisingly, a haze of upper level clouds visible towards Saturn's Equator disappears near the Pole, including over Saturn's strange Polar Vortex.
Cassini entered orbit around Saturn in 2004, and recorded the above image last year (2007)". MareKromium
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Dione-PIA10500.jpgCross-Worlds: the Answer!56 visiteRicordate la sequenza (intitolata, appunto, Cross-Worlds) che pubblicammo qualche settimana fa (era il 14 Settembre 2008, per l'esattezza) e che ci mostrava (ovviamente nell'ottica di CASSINI) Dione mentre eclissava un'altra Luna non identificata?
Noi ipotizzammo che si potesse trattare di Mimas o di Encelado. La NASA, oggi, tramite il suo Planetary Photojournal, ci ha risposto: si trattava di Encelado.
Un grazie alla NASA (che, quando vuole, sa anche rispondere) ed un 6+ a noi perchè, anche se non siamo riusciti ad identificare con sicurezza assoluta la seconda luna "misteriosa" in transito, siamo stati comunque abbastanza bravi dal ridurre la rosa dei "candidati" a due soli Corpi Celesti.
Insomma...Non male!MareKromium
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Enceladus-PIA11120.jpgEnceladus Oct. 9, 2008 Flyby56 visiteCaption NASA:"This image was taken with the Cassini Spacecraft narrow-angle camera on Oct. 9, 2008, from a distance of approx. 26.000 Km (16,000 miles) from Enceladus. Image scale is 312 meters (1024 feet) per pixel".MareKromium
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Enceladus-PIA11119.jpgEnceladus Oct. 9, 2008 Flyby56 visiteCaption NASA:"This image was taken during Cassini's extremely close encounter with Enceladus on Oct. 9, 2008.
The image was taken with the Cassini Spacecraft narrow-angle camera on Oct. 9, 2008, a distance of approx. 40.000 Km (such as about 25.000 miles) from Enceladus.
Image scale is approx. 477 meters (1566 feet) per pixel". MareKromium
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The_Rings-AtoG-PIA10505.jpgThe Rings (natural colors; credits: Lunexit)56 visitenessun commentoMareKromium
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Saturn-PIA10512.jpgLonely Shadow... (possible True Colors; credits: Lunexit)56 visiteCaption NASA:"The shadow of Tethys drifts across the face of Saturn. Nearby, shadows of the Planet's Rings form a darkened band above the Equator. This view looks toward Saturn from a vantage point 63° North of the Equator.
The image was taken in visible green light with the Cassini Spacecraft wide-angle camera on Oct. 1, 2008. The view was acquired at a distance of approx 615.000 Km (about 382000 miles) from Saturn.
Image scale is roughly 37 Km (approx. 23 miles) per pixel".MareKromium
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Saturn-PIA11396.jpgSouth Polar Aurora on Saturn56 visiteCaption NASA:"This image of the North Polar Regions of Saturn shows both the Aurora and underlying Atmosphere, seen at 2 different wavelengths of IR light as captured by NASA's Cassini spacecraft.
Energetic particles, crashing into the Upper Atmosphere cause the Aurora, shown in blue, to glow brightly at 4 microns (six times the wavelength visible to the human eye). The image shows both a bright ring, as seen from Earth, as well as an example of bright Auroral Emission within the Polar Cap that had been undetected until the advent of Cassini.
This Aurora, which defies past predictions of what was expected, has been observed to grow even brighter than is shown here. Silhouetted by the glow (cast here to the color red) of the hot interior of Saturn (clearly seen at a wavelength of 5 microns, or seven times the wavelength visible to the human eye) are the clouds and haze that underlie this Auroral Region. For a similar view of the Region beneath the Aurora see PIA09185.
This image is a composite captured with Cassini's Visual and Infrared Mapping Spectrometer. The aurora image was taken in the near-infrared on Nov. 10, 2006, from a distance of about 1 MKM (such as about 659.000 miles), with a phase angle of 157° and a sub-Spacecraft Planetocentric Latitude of 52° North.
The image of the clouds was obtained by Cassini on June 15, 2008, from a distance of approx. 602.000 Km (such as about 374.000 miles) and a sub-Spacecraft Planetocentric Latitude of 73° North".MareKromium
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Saturn-PIA10513.jpgThe South Pole of Saturn (natural colors; credits: Lunexit)56 visiteCaption NASA:"Long streamers of cloud encircle the South Polar Region of Saturn. Farther poleward, or toward lower left, faint, deeper atmospheric structures lurk beneath the haze.
This image was acquired from a vantage point 74° South of the Planet's equator.
The view was taken with the Cassini spacecraft wide-angle camera on Oct. 2, 2008 using a spectral filter sensitive to wavelengths of IR light centered at 728 nanometers. The view was obtained at a distance of approx. 369.000 Km (such as about 229.000 miles) from Saturn.
Image scale is roughly 19 Km (about 12 miles) per pixel".MareKromium
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Mimas-N00121934-3D-MF.jpgMimas and the Rings (Hi-Def-3D; credits and Copyright: Dr M. Faccin and Lunar Explorer Italia)56 visitenessun commentoMareKromium
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