| Ultimi arrivi - Titan: The "Foggy" Moon |
Titan-Atmosphere-PIA06224.jpgThe "Hig-Haze Layers" of Titan56 visiteCaption NASA originale:"Titan's "High Haze Layers" are amazing. Cassini captured this detailed view of the relatively faint haze in Titan's upper atmosphere as it receded from its close encounter on March 31, 2005. Similar examples of such complex structures in Titan's haze have been observed previously by Cassini. These observations will help reveal the processes responsible for forming the numerous layers that we see and how the structure and behavior of the layers change on daily and seasonal time scales.
The image was taken with the Cassini spacecraft narrow-angle camera using a filter sensitive to wavelengths of ultraviolet light centered at 338 nnmts and at a distance of 102.320 Km from Titan. Image scale is about 600 mt per pixel".Apr 09, 2005
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Titan-PIA06222_modest.jpgThe Eastern Region of Titan57 visite(...) Best view to date of the Region east of Xanadu Regio. This mosaic (...) reveals new detail of dark expanses and the surrounding brighter terrain. Some of the features seen here are reminiscent of those seen elsewhere on Titan, but the images also reveal new features. In the center of the image (fig. A) lies a bright area completely surrounded by darker material. The northern boundary of the bright "island" is relatively sharp and has a jagged profile, resembling the now-familiar boundary on the western side of XanadU. The profile of the southern boundary is similar. Streamers of bright material extend southeastward into the dark terrain. At the eastern end of the bright "island" lies a region with complex interconnected dark and bright regions (see fig. B). To the south, the bright terrain is cut by fairly straight dark lines. Their linearity and apparently angular intersections suggest a tectonic influence, similar to features in seen in the bright terrain west of Xanadu. Toward the northeastern edge of the dark material a dark, circular spot in the middle of a bright feature (see figure C) is an approximately 80-kilometer-wide (50-mile) crater identified in the February 2005 radar data (see PIA07368 for the radar image).Apr 09, 2005
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Titan_and_Saturn-PIA06225.jpgSaturn through the haze of Titan59 visiteCaption NASA originale:"Less than 20 minutes after Cassini's close approach to Titan on March 31, 2005, its cameras captured this view of Saturn through Titan's upper atmosphere. The northern part of Saturn's disk can be seen at the upper left; dark horizontal lines are shadows cast upon Saturn by its rings. Below this level, Titan's atmosphere is thick enough to obscure Saturn.
The diffuse bright regions of the image (below Saturn and at the right) are light being scattered by haze in the upper reaches of Titan's atmosphere.
This image is scientifically useful because it shows properties both of how Titan's haze transmits light (from the attenuation of light from Saturn) and of how the haze reflects light (from its brightness next to Saturn).
The image was taken in visible light with the Cassini spacecraft wide-angle camera at a distance of 7.980 Km (appx. 4.960 miles) from Titan, when Saturn was about 1,3 MKM (appx. 808.000 miles) away. Image scale is about 320 meters (1,050 feet) per pixel on Titan".Apr 09, 2005
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Titan-PIA06220.jpgA New Continent on Titan (from 130.000 up to 146.000 Km)56 visiteCaption NASA originale:"This view of Titan uncovers new territory not previously seen at this resolution by Cassini's cameras. The view is a composite of 4 nearly identical wide-angle camera images, all taken using a filter sensitive to wavelengths of infrared light centered at 939 nnmts. The individual images have been combined and contrast-enhanced in such a way as to sharpen surface features and enhance overall brightness variations. Some of the territory in this view was covered by observations made by the Cassini synthetic aperture radar in October 2004 and February 2005. At large scales, there are similarities between the views taken by the imaging science subsystem cameras and the radar results, but there also are differences. For example, the center of the floor of the approximately 80-kilometer-wide (50-mile) crater identified by the radar team in February (near the center in this image, see PIA07368 for the radar image) is relatively bright at 2.2 centimeters, the wavelength of the radar experiment, but dark in the near-infrared wavelengths used here by Cassini's optical cameras. This brightness difference is also apparent for some of the surrounding material and could indicate differences in surface composition or roughness".Apr 07, 2005
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Titan-Atmosphere-N00031071.jpgThe "Foggy" Limb of Titan57 visiteIl 4° fly-by di Titano si è compiuto e dalla Sonda Cassini, come al solito, ci arrivano una marea di frames completamente (o quasi) inesplicabili. Gli artifacts fotografici, come vedete in questo frame che abbiamo scelto fra tantissimi uguali, sono tanti (e la pulitura elettronica delle immagini avverrà solo in un futuro imprecisato); i rilievi della superficie di Titano - come ovvio - sono assolutamente impossibili da cogliere senza l'ausilio di attrezzature e tecniche all'avanguardia. Il risultato, purtroppo, è che noi non siamo in grado di dirVi nulla di "nuovo" su questa comunque affascinante Luna "Nebbiosa". La NASA, come sapete, esprime - di tanto in tanto - qualche commento a riguardo, ma il tutto si esaurisce (come per Marte) in grandi bolle di sapone: pillole di Scienza "usa & getta" che possono essere utili a dei Divulgatori (come noi, per esempio), ma che non servono quasi a nulla nel momento in cui si intendessero fare degli studi e delle ricerche un pò più profondi/e e dettagliati/e.
Peccato...Apr 03, 2005
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Titan_and_Epimetheus-N00028722.jpgTitan and Epimetheus61 visitenessun commentoFeb 21, 2005
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Titan-Craters-Unnamed_Crater-PIA07368.jpgImpact Crater on Titan (radio-image)60 visiteCaption NASA originale:"This image shows a crater, approx. 60 Km in diameter, on the very eastern end of the radar image strip taken by the Cassini orbiter on its third close flyby of Titan on Feb. 15, 2005.
The appearance of the crater and the extremely bright (hence rough) blanket of material surrounding it is indicative of an origin by impact, in which a hypervelocity comet or asteroid, in this case, roughly 5-10 Km, in size, slammed into the surface of Titan. The bright surrounding blanket is debris, or ejecta, thrown out of the crater. The asymmetric appearance of this ejecta blanket could be an effect of "atmospheric winds" associated with the impact itself. Although clearly formed by impact, the feature lacks a central peak, suggesting that it has been eroded or otherwise modified after formation. Rainfall, wind erosion and softening of the solid material in which the crater formed are all possible processes that might have altered this impact feature".Feb 19, 2005
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Titan-PIA06183.jpgThe "yellow face" of Titan (natural colors)53 visiteCaption NASA originale:"There is a slight difference in brightness from Northern to Southern hemisphere of Titan, a seasonal effect that was noted in NASA's Voyager spacecraft images, and is also clearly visible in some of the infrared images from Cassini (see http://photojournal.jpl.nasa.gov/catalog/PIA06121).
The Northern polar region is largely in darkness at this time.
This image was taken with the Cassini spacecraft wide angle camera through using red, green and blue spectral filters were combined to create this natural color view. The image was acquired at a distance of approximately 229.000 Km from Titan and at a phase, angle of 20°. Resolution in the image is about 14 Km per pixel".Feb 18, 2005
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Titan-PIA06186.jpgTitan (almost) naked, from 2,5 MKM56 visiteCaption NASA originale:"Titan's surface and atmospheric features are shown here in this processed, visible-light image taken by Cassini. Cassini's visible-light spectral filter is sensitive to a broad range of light, from ultraviolet to near-infrared. Imaging scientists normally use a narrow-band filter centered at 938 nanometers to look at Titan's surface and cloud features. Most images of Titan taken between flybys are in visible light and are used to navigate the spacecraft. Views like these demonstrate that the surface, as well atmospheric features (such as the haze banding seen near the northern limb of Titan), can indeed be seen through this filter. Although the clear filter is not the best way to view the surface, this observation demonstrates that with sufficient processing, this filter can be used to keep track of cloud features during periods between flybys in order to provide a better understanding of the evolution of Titan's atmosphere as the moon nears spring in the northern hemisphere".Feb 18, 2005
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Titan-Atmosphere-PIA06182.jpgOver the Clouds of Titan57 visiteCaption NASA originale:"This image was taken during Cassini's 3rd close approach to Titan on Feb. 15, 2005.
The image was taken with the Cassini spacecraft narrow angle camera through a filter sensitive to wavelengths of polarized infrared light centered at 338 nanometers. The image was acquired at a distance of approximately 151.000 Km (approx. 94.000 miles) from Titan and at a phase angle of 20°.
Resolution in the image is about 900 meters (approx. 3.000 feet) per pixel".Feb 18, 2005
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Titan-Channels-Unnamed_Channels-Radar_Mapping-PIA07009.jpgChannels on Titan or just Windstreaks?58 visiteCaption NASA originale:"Running across the image (about 300 Km across) are a series of roughly parallel, mostly east-west dark linear features that join and separate, which are not seen in the previous radar images. They may be formed by the action of eastward-flowing winds, or geologic processes acting on the crust itself. In places they cut through adjacent terrain, while elsewhere the lineaments seem to be interrupted by brighter material, appearing again on the other side. Seams between radar segments are visible as horizontal, sawtooth-shaped lines. Bright material in radar images may be rough or sloped toward the radar (which is observing from the top in this frame). Also, some of what is seen may in fact be below the surface, revealed as the radio waves penetrate overlying, radar-transparent material".Feb 17, 2005
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Titan-Craters-Unnamed_Crater-Radar_Mapping-PIA07365-br500-01.jpgImpact Crater?58 visiteCaption NASA originale:"A huge annular feature with an outer diameter of approximately 440 kM (approx. 273 miles) appears in this image taken with Cassini's Titan radar mapper. It resembles a large crater or part of a ringed basin, either of which could be formed when a comet or asteroid tens of Kms in size slammed into Titan. This is the first impact feature identified in radar images of Titan. The surface of Titan appears to be very young compared to other Saturnian satellites. In Titan's case, debris raining down from the atmosphere or other geologic processes may mask or remove the craters. The pattern of brightness suggests that there is topography associated with this feature; for example, in the center of the image there appear to be mounds each about 25 Km across. Since they are dark on their lower edges that face away from the radar and bright on the opposite face, they must be elevated above the surrounding terrain". Feb 17, 2005
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