| Ultimi arrivi - Titan: The "Foggy" Moon |
Titan-PIA06107-00.jpgThe "True Colors" of Titan, according to Lunexit60 visiteLa NASA, allorchè si tratta di colorizzare Titano, oscilla fra il giallo/arancio (come ben si vede nei frames Voyager), il giallo "canarino", con bordi bluastri (si vedano i primi frames Cassini, tipo PIA06089) ed una colorazione ambigua che potremmo definire giallo/salmonato, con bordi verde chiaro (ultimi frames Cassini, tipo PIA08351). Ma la NASA ha le idee chiare in tema di colori? Diremmo proprio di no, ed a nulla valgono le precisazioni che vengono fatte allorchè la NASA stessa precisa le diverse lunghezze d'onda impiegate per le colorizzazioni (jargon&tecnochiacchiere, nulla di più).
E allora?
E allora subentra - ancora una volta - il buon senso e l'osservazione telescopica (sia da Terra, sia HST). Risultato: Titano è (globalmente) color giallo-pallido, con toni più chiari ed accesi nelle sue Regioni Nord Polari e più sbiaditi in quelle Equatoriali.
Ed i bordi blu e verdi? Ed i bianchi accesi? E gli arancioni? Beh, se la NASA "li vede", vuol dire che ci saranno; ma noi non li "vediamo", neppure filtrando banda-per-banda i loro stessi color-frames e quindi...Questo è Titano, secondo noi, in "colori naturali" (ossìa come li vedremmo se ci trovassimo nei suoi pressi).Dic 30, 2006
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Titan-Surface-Unexplained_Surface_Features-PIA06111.jpgUnexplainable Surface Features56 visiteCaption NASA:"This image acquired at a range of 344.000 Km (about 213.700 miles) shows details at Titan's surface never seen before. The image shows only surface brightness no topographic shading. The finest features are less than 10 Km (a little more than 6 miles) across. In other areas the surface boundaries are less distinct perhaps due to different geologic process or atmospheric effects. There are some linear features that could be impact craters but the fact that many features are linear suggests that other geologic processes are shaping the surface".Dic 30, 2006
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Titan-Clouds-White_Clouds-PIA06112.jpgWhite Clouds60 visiteCaption NASA:"Shown here is a blowup of a region of Titan imaged on July 2, 2004. This image was taken at a distance of 339.000 Km (about 210.600 miles) and shows brightness variations on the surface of Titan and a bright field of clouds near the South Pole. The field of clouds is 450 Km (about 280 miles) across and is the about the size of Arizona. Features as small as 10 Km (a little more than 6 miles) can be discerned". Dic 30, 2006
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Titan-Regions-Fensal_and_Aztlan_Region-PIA08352.jpgFensal and Aztlan Region55 visiteAs Cassini continues its reconnoitering flybys of Titan, the imaging science team continues to improve its ability to tease out surface details hidden in the unprocessed images. This mosaic provides the best view yet obtained by Cassini's cameras, showing terrain on the moon's sub-Saturn Hemisphere -- the side of the moon that always faces toward Saturn. This mosaic has better resolution, both in pixel scale and from improved signal-to-noise, compared to previous views of the area.
"Signal-to-noise" is a term scientists use to refer to the amount of meaningful or useful information (signal) in their data versus the amount of background noise. A higher signal-to-noise ratio yields sharper, clearer views of Titan's surface.
The view is centered on terrain in the Fensal-Aztlan region on Titan, at 0,03° South Lat. and 22,18° West Long. The mosaic covers an area 3.500 Km (2.180 miles) North to South and 3.600 Km (2.240 miles) West to East. North is up. Dic 30, 2006
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Titan-PIA08351.jpgClose "Friends"...54 visiteCaption NASA originale:"Cassini peers around the hazy limb of Titan to spy the sunlit South Pole of Saturn in the distance beyond.
The thick, smog-like atmosphere of frigid Titan is a major source of interest for the Cassini mission. The moon is 5.150 Km (about 3.200 miles) across.
Images taken using red, green and blue spectral filters were combined to create this natural-color view. The image was taken with the Cassini spacecraft narrow-angle camera on Dec. 26, 2005, at a distance of approx. 26.000 Km (about 16.000 miles) from Titan. Image scale is roughly 1 Km (4.643 feet) per pixel".Dic 30, 2006
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Titan-PIA09032.jpgTitanian "Sierras"55 visiteCaption NASA originale"This composite image shows a massive mountain range running just south of Titan's Equator. Near the center of the image, the mountain range runs from South-East to North-West. It is about 150 Km long (approx. 93 miles) and 30 Km (about 19 miles) wide and approx. 1,5 Km (nearly a mile) high.
This range and smaller ranges to the West and East of the main range, probably results from material welling up below as the crust of Titan is pulled apart by tectonic forces.
This image was obtained during an Oct. 25 flyby designed to obtain the highest resolution infrared views of Titan yet. Cassini's VIMS resolved surface features as small as 400 meters (1,300 feet).
This composite image was taken at a distance of about 12.000 Km (7.200 miles) from Titan. This image was constructed from images taken at wavelengths of 1,3 microns shown in blue, 2 microns shown in green and 5 microns shown in red".MareKromiumDic 14, 2006
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Titan-Clouds-PIA09033.jpgClouds and Surface56 visiteCaption NASA originale:"This image set was taken at a distance of 15.000 Km (9.300 miles) from Titan and shows two views of an area riddled by mountain ranges that were probably produced by tectonic forces.
Near the bottom of the right image, a band of bright clouds is seen.
These clouds are probably produced when gaseous methane in Titan's atmosphere cools and condenses into methane fog as Titan's winds drive air over the mountains. It was once thought that these recurring clouds were produced by volcanic activity on Titan, but this image calls that idea into question.
These views were obtained during an Oct. 25 flyby designed to obtain the highest-resolution infrared views of Titan yet. Cassini's VIMS resolved surface features as small as 400 mt (1300 feet). The images were taken at wavelengths of 1,3 microns shown in blue, 2 microns shown in green and 5 microns shown in red".MareKromiumDic 14, 2006
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Titan-PIA09034.jpgCloudless Titan...56 visiteCaption NASA originale:"This image is a composite of several images taken during two separate Titan flybys on Oct. 9 (T19) and Oct. 25 (T20), 2006.
The large circular feature near the center of Titan's disk may be the remnant of a very old impact basin. The mountain ranges to the South-East of the circular feature and the long dark, linear feature to the North-West of the old impact scar may have resulted from tectonic activity on Titan caused by the energy released when the impact occurred.
The Oct. 9 images form the background globe for context and the most recent images from the Oct. 25 flyby are overlaid. The Oct. 9 images were taken at an average distance of about 30,000 Km (approx. 18.000 miles). The Oct. 25 images were taken at a distance of 12.000 Km (about 7.200 miles). The images were taken at wavelengths of 1,3 microns shown in blue, 2 microns shown in green and 5 microns shown in red".MareKromiumDic 14, 2006
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Titan-Clouds-PIA09036.jpgTitanian Clouds and Surface55 visiteCaption NASA originale:"This image composite contains a radar image taken during a February 2005 (T3) flyby, and overlaid are images from the Visual and Infrared Mapping Spectrometer (VIMS) taken on Sept. 7, 2006, (T17) and Oct. 25, 2006 (T20).
The thin strip is the infrared image taken on the inbound leg of the T20 flyby and crosses the radar image near an area with a small, crater-like feature. In the radar image a faint fan of material seems to originate at the crater and the portion of the infrared image that crosses the faint fan shows both a large brightness contrast and very sharp boundaries. The fan-like deposit has such sharp boundaries and strong contrast with its surroundings that it supports the idea that the deposit seen in the radar images is a flow of material erupted from the small crater. This may be the strongest evidence yet of cryovolcanism on Titan.
The infrared image was taken at a distance of about 1100 Km (680 miles) from the surface of Titan and resolves features as small as 400 mt (1300 feet)".MareKromiumDic 14, 2006
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Titan-Lakes-Unnamed_North_Polar_Lakes-04-PIA01943.jpgTitanian Northern Lakes (4)60 visiteCaption NASA originale:"In this image taken by the Cassini radar system, a previously unseen style of lakes is revealed. The lakes here assume complex shapes and are among the darkest seen so far on Titan.
The lake at the left is reminiscent both in form and scale of the flooded drainage system, Lake Powell in Utah and Arizona. However, the Titan lake has been filled with liquid methane and ethane rather than water. In the lake at right, older terrain may have been deeply cut by river valleys before it was flooded by the embaying lake.
This radar image was acquired Oct. 9, 2006, and is centered near 80° North Latitude and 357° West Longitude. It measures about 310 by 100 Km (such as about 190 by 62 miles). Smallest details in this image are about 500 mt (approx. 1.640 feet) across".Ott 13, 2006
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Titan-Lakes-Unnamed_North_Polar_Lakes-02-PIA01942.jpgTitanian Northern Lakes (3)58 visiteCaption NASA originale:"Using its radar system, the Cassini spacecraft has imaged new lakes on Titan.
The large dark patch seen on this image, at high latitudes surrounding Titan's North Pole, is most likely a hydrocarbon lake. Several dark channels can be seen; the longest one at the left meanders over almost 100 Km (about 62 miles), and appears to drain into the lake. Some dark channels are remarkably straight, suggesting possible faulting in the subsurface. The bright landforms jutting into the lake indicate that old, eroded landforms may have flooded.
This radar image was acquired by the Cassini radar instrument in synthetic aperture mode on Oct. 9, 2006. The image is centered near 73° North Latitude and 343° West Longitude; it measures about 300 by 140 Km (such as about 190 by 90 miles). Smallest details in this image are about 500 mt (approx. 1.640 feet) across".Ott 13, 2006
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Titan-N00067442.jpgShort "light-streak" in the space of Titan59 visiteCaption NASA:"N00067442.jpg was taken on October 10, 2006 and received on Earth on the same day. The camera was pointing toward Titan that, at the time, was approximately 168.568 Km away.
This image was taken using the CL1 and CB3 filters and it has not been validated or calibrated". Ott 13, 2006
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