| Ultimi arrivi - Titan: The "Foggy" Moon |
Titan-Map-Wind_Patterns-PIA11801.jpgMapping Titan's Global Wind Patterns56 visiteScientists have used data from the Cassini Radar Mapper to map the Global Wind Pattern on Saturn's moon Titan using data collected over a four-year period, as depicted in this image.
The arrows indicate the direction in which sand is inferred to be transported along dunes observed in Titan radar data.
Underlying the arrows is a base map (PIA08399) from Cassini's Imaging Science Subsystem.
Many of the equatorial dark areas without arrows might have dunes but have not yet been imaged with radar. The dune orientations represent only the net effect of winds. It could be that sand transport only occurs on rare occasions, and winds from different directions can combine to yield the observed dune orientations.MareKromiumFeb 26, 2009
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Titan-Dunes-PIA11802.jpgAt the Edge of Titan's Dunes56 visiteThis is a portion of a Cassini Radar Mapper image obtained by the Cassini Spacecraft on its Dec. 21, 2008, flyby of Saturn's moon Titan.
The area shown covers the southern boundary of an equatorial band where longitudinal dunes (dunes that form along the wind direction) are pervasive.
Here the dunes are apparently created by winds locally coming from the West and North-West, and generally blowing toward the East. The dunes are interspersed with radar-bright features that are inferred to rise above the surrounding terrain.
In the lower part of the image there are no dunes at all, and the texture is more typical of featureless plains observed in many other areas of Titan that lack dunes.
In this Transition Zone, the sand-sized particles that make up the dunes might not be so plentiful. In this case, insufficient sand to replenish the dunes makes them gradually disappear.
To compare the nature of these dunes to those seen at the Northern Boundary of the dune fields observed in radar images obtained during the T3 flyby on Feb. 15, 2005 see PIA07009.
The image is centered near 19,2° South Lat. and 257,4° West Long.
It covers an area of about 220 Km (approx. 137 miles) by about 170 Km (approx. 106 miles). North is approximately toward the top of the image, the radar illumination is from the right, and the Solar Incidence Angle is about 25° (meaning that the Sun was 65° above the Local Horizon).
The vertical stripe across the image at its center is an artifact in this preliminary version.MareKromiumFeb 26, 2009
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Titan-Map-PIA11146.jpgUpdated Map of Titan57 visiteCaption NASA:"These updated maps of Saturn's moon Titan, consisting of data from the Cassini imaging science subsystem, include Cassini's August 2008 imaging of the moon's Northern Hemisphere.
Evidence from Cassini's imaging science subsystem, radar, and Visual and InfraRed Mapping Spectrometer instruments strongly suggests that dark areas near the Poles are lakes of liquid hydrocarbons (an analysis affirmed by images capturing those changes in the lakes thought to be brought on by rainfall).
Colored lines in the polar portions of these maps illustrate the boundaries between surface regions having different albedos — or differences in surface brightness — which Cassini scientists have interpreted as potential shorelines. Blue outlines indicate features that changed between observations made one year apart (see also PIA11147).
The top map is a simple cylindrical projection. Atmospheric effects complicate incorporation of data from high Northern Latitudes, which are shown separately in a polar view. The map at bottom left is a North Polar projection showing latitudes 55° to 90°. The bottom right map is a South Polar projection showing latitudes - 55° to - 90°.
The maps are compiled from images dating from April 2004 through August 2008, and their resolutions vary from a few meters to a few tens of kilometers per pixel. Brightness variations are due to differences in surface albedo rather than topographic shading".MareKromiumGen 30, 2009
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Titan-Lakes-South_Polar_Unnamed_Lakes-PIA11147.jpgChanges in the Titanian Lakes57 visiteCaption NASA:"These mosaics of the South Pole of Saturn's moon Titan, made from images taken almost one year apart, show changes in dark areas that may be lakes filled by seasonal rains of liquid hydrocarbons.
The images on the left (unlabeled at top and labeled at bottom) were acquired July 3, 2004. Those on the right were taken June 6, 2005. In the 2005 images, new dark areas are visible and have been circled.
The very bright features are clouds in the lower Atmosphere (the Troposphere). Titan's clouds behave similarly to those on Earth, changing rapidly on timescales of hours and appearing in different places from day to day. During the year that elapsed between these two observations, clouds were frequently observed at Titan's
South Pole by observers on Earth and by Cassini's imaging science subsystem (see also PIA06124).
It is likely that rain from a large storm created the new dark areas that were observed in June 2005. Some features, such as Ontario Lacus, show differences in brightness between the two observations that are the result of differences in illumination between the two observations. These mosaics use images taken in InfraRed Light at a wavelength of 938 nanometers.
The images have been oriented with the South Pole in the center (black cross) and the 0° Meridian toward the top.
Image resolutions are several kilometers per pixel".MareKromiumGen 30, 2009
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Titan-Regions-Senkyo_and_Aaru_Region-PIA10565.jpgSenkyo and Aaru Region84 visiteCaption NASA:"Named for other-worldly Paradises, the dark regions of Senkyo and Aaru comprise the center of this image of Saturn's moon Titan. The Egyptian fields of Aaru were Paradise for the god Osiris. This side of Titan, which always faces Saturn, is on the opposite side of the moon from Shangri-La and Adiri, the home to the Huygens probe.
The craft touched down on the border between the lowland dunes of Shangri-La and the higher terrains of Adiri. Like Senkyo and Aaru, these Regions' namesakes reflect heavenly aspirations. North is up in this image.
Senkyo is the Equatorial Region to the right of the center of the image. Aaru is above Senkyo.
The image was taken with the Cassini Spacecraft narrow-angle camera on Dec. 12, 2008 using a spectral filter sensitive to wavelengths of infrared light centered at 938 nanometers.The view was acquired at a distance of approx. 2,4 MKM (such as about 1,5 MMs) from Titan and at a Phase Angle of 35°.
Image scale is roughly 14 Km (about 9 miles) per pixel".MareKromiumGen 28, 2009
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Titan-PIA10546.jpgNorth Polar Haze (Saturated Natural Colors; credits for the additional process. and color.: Dr Paolo C. Fienga - Lunexit Team)55 visiteCaption NASA:"Titan's globally distributed detached haze layer and the moon's North Polar hood, both notable details of its thick atmosphere, are clearly seen in this image from the Cassini Spacecraft.
Titan is about 5150 Km (approx. 3200 miles) across, and therefore slightly larger than Mercury.
The image was taken with the Cassini Spacecraft narrow-angle camera using a combination of spectral filters sensitive to wavelengths of polarized ultraviolet light centered at 338 nanometers. The view was obtained at a distance of approx. 1,7 MKM (about 1,08 MMs) from Titan and at a Sun-Titan-Spacecraft, or Phase, Angle of 50°.
Image scale is roughly 10 Km (about 6 miles) per pixel".MareKromiumGen 01, 2009
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Titan-Clouds-Noctilucent_Clouds-GIFMovie-N00023501-N00023599.gifNoctilucent Clouds over Titan (GIF-Movie; credits: Dr G. Barca)57 visiteSu Titano è notte, ma come queste immagini (ottimamente montate a formare un GIF-Movie dal nostro Dr Gianluigi Barca) dimostrano piuttosto chiaramente, delle grandi e vaporose formazioni nuvolose passano attraverso gli occhi elettronici di Cassini e si rendono palesi.
Magia delle riprese IR?
No, perchè queste immagini sono state ottenute nello Spettro della Luce Visibile.
E allora, come spiegare la (ripetiamo: EVIDENTE) luminosità delle nuvole di Titano?
Beh, esistono almeno tre modi per provare a spiegare (sensatamente) questo intrigante ed affascinante fenomeno, ma la soluzione (puramente ed assolutamente teorica e speculativa, lo sappiamo) che ci piace privilegiare la potete trovare descritta nell'articolo "Oltre la Nebbia", pubblicato sul nostro Blog "True Planets"...
MareKromiumDic 19, 2008
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Titan-Clouds-Cloud_System-GIFMovie-W00002371-W00002379.gifThe complex Titanian Cloud-System (GIF-Movie; credits: Dr G. Barca)56 visiteLe formazioni nuvolose di Titano? Semplicemente IMPONENTI!...MareKromiumDic 19, 2008
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Titan-Clouds-Night_Clouds-GIFMovie-W00002325-W00002338.gifNoctilucent Clouds over Titan (GIF-Movie; credits: Dr G. Barca)56 visiteDavvero molto interessanti le deboli Surface Features che si intravedono in questo breve - ma assai suggestivo - GIF-Movie realizzato dal Dr Barca. Sapreste individuarne almeno una?MareKromiumDic 19, 2008
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Titan-Clouds-Noctilucent_Clouds-GIFMovie-N00023443-N00023924.gifNoctilucent Clouds over Titan (GIF-Movie; credits: Dr G. Barca)56 visiteSu Titano è notte, ma come queste immagini (ottimamente montate a formare un GIF-Movie dal nostro Dr Gianluigi Barca) dimostrano piuttosto chiaramente, delle grandi e vaporose formazioni nuvolose passano attraverso gli occhi elettronici di Cassini e si rendono palesi.
Magia delle riprese IR?
No, perchè queste immagini sono state ottenute nello Spettro della Luce Visibile.
E allora, come spiegare la (ripetiamo: EVIDENTE) luminosità delle nuvole di Titano?
Beh, esistono almeno tre modi per provare a spiegare (sensatamente) questo intrigante ed affascinante fenomeno, ma la soluzione (puramente ed assolutamente teorica e speculativa, lo sappiamo) che ci piace privilegiare la potete trovare descritta nell'articolo "Oltre la Nebbia", pubblicato sul nostro Blog "True Planets"...MareKromiumDic 19, 2008
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Titan-Cryovolcanism_Map-PIA11701.jpgIR Map of Titan's Active (Cryovolcanic) Regions56 visiteThis infrared projection map of Titan was composed from images taken by NASA's Cassini Spacecraft, Visual and Infrared Mapping Spectrometer. The location of two regions that changed in brightness are labeled. These regions are hypothesized by some to be areas of cryovolcanic activity on Titan.
Rather than erupting molten rock, it is theorized that the cryovolcanoes of Titan would erupt volatiles such as Water, Ammonia and Methane. Scientists have suspected cryovolcanoes might be on Titan, and the Cassini mission has collected data on several previous passes of the moon that suggest their existence. Imagery of the moon has included a suspect haze hovering over flow-like surface formations, which are plausibly the result of icy volcanism.
Some Cassini scientists indicate that such volcanism could release Methane from the interior, which explains Titan's seemingly continuous supply of fresh Methane. Without replenishment, scientists say, Titan's original Atmospheric Methane should have been exhausted long ago.
This image is an overlay of all the high-resolution images from the first 45 flybys, up through last February 2007. The map was created using what 2,1 micron wavelength. Image scale is about 25 Km (approx. 16 miles) per pixel or 1,8 pixels per degree".MareKromiumDic 17, 2008
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Titan-Cryovolcanism_Map-PIA11702.jpgActive Cryovolcanism on Titan?56 visiteCaption NASA:"The Cassini Radar Mapper imaged Titan on Feb. 22, 2008 (as shown on the left) and April 30, 2006 (as shown on the right).
These radar images show the outlines of Regions "1" and "2" identified by Cassini's VIMS (such as the Visual and Infrared Mapping Spectrometer) and inferred to be variable (see VIMS flat map, PIA11701), and which have been hypothesized to be due to cryovolcanic activity. The lobate, flow-like features in Region 1 are consistent with this interpretation.
Region 1 is just north of the feature named Hotei Arcus and is centered on 28° South Lat. by 78° West Long.
The Region is about 400 Km (approx. 249 miles) across. Region 2 is on the western part of Xanadu and is centered on 7° South Lat. by 135° West Long. This region is about 900 Km (approx. 560 miles) across. In both cases, North is up, and features as small as 300-500 meters can be resolved".MareKromiumDic 17, 2008
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