| Piú viste - Titan: The "Foggy" Moon |
Titan-W00003639.jpgClouds around Titan55 visiteImmagine di Titano ripresa da circa 29.000 Km. Oltre alle nuvole (sempre bianche e vaporose) non si riesce a distinguere alcun dettaglio della superficie di questa luna.
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Titan-Shoreline_and_Drainage_Channels-04.jpgShoreline and Drainage Channels (Mosaic)55 visiteCaption ESA originale:"This composite was produced from images returned yesterday, 14 January 2005, by ESA's Huygens probe during its successful descent to land on Titan. It shows a full 360-degree view around Huygens. The left-hand side, behind Huygens, shows a boundary between light and dark areas. The white streaks seen near this boundary could be ground 'fog' of methane or ethane vapour, as they were not immediately visible from higher altitudes. As the probe descended, it drifted over a plateau (centre of image) and was heading towards its landing site in a dark area (right). This dark area is possibly a drainage channel which might still contain liquid material. From the drift of the probe, the wind speed has been estimated at around 6-7 mt per second. These images were taken from an altitude of about 8 Km with a resolution of about 20 mt per pixel".
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Titan-PIA06220.jpgA New Continent on Titan (from 130.000 up to 146.000 Km)55 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".
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Titan-PIA07878-Titan_sOddSpot.jpgThe "Odd-Spot" on Titan (detail mgnf)55 visiteLa 'Nuvola Permanente': una nuova ed incredibile scoperta su Titano che apre nuovi orizzonti ai panorami di pseudo-certezze che la maggior parte dei Ricercatori si stavano costruendo relativamente a questa "Terra in fieri" (una bella definizione per Titano, nata dopo che sono stati visionati i frames relativi ai primi passaggi ravvicinati della Sonda Cassini e dopo il landing dell'Huygens Probe).
Alla NASA hanno già fatto delle ipotesi; qualcuna plausibile - un uragano permanente - e qualche altra, diciamo così... , un pò "forzata" - tipo la vetta luminosa di una mega-montagna.
E se fosse un 'pennacchio' di fumo, ceneri e polveri - spesso e denso - proveniente da un vulcano attivo (il 'cuore caldo' del Pianeta...)?
E' così improponibile pensare ad un vulcano e, quindi, ad un Pianeta geologicamente attivo?!?
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Titan-Volcano-02.jpgThe Titanian Volcano (3)55 visiteCaption NASA originale:"From infrared images that show variations in brightness and texture, a geological map of a 'possible Titanian volcano', has been obtained using Cassini's VIMS. This geologic map shows that the circular feature has what appear to be several series of flows, as shown by the black lines. The flows represent episodes of activity on the volcano. A dark central pit, called a caldera, is similar to vents (----> aperture da sfogo; crepacci che fungono da sfogo) that appear above reservoirs of molten material on Earth's volcanoes. The colors on the map represent the brightness of features. Yellow and light green represent bright patches. Blue represents dark patches. Red represents mottled (----> screziato, a chiazze) material. The yellow area is where the volcano lies".
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Titan-PIA07729.jpgTitan, from about 213.000 Km (natural colors)55 visiteAs Cassini approached Titan on Aug. 21, 2005, it captured this natural color view of the moon's orange (nota: veramente, a parte i nostri occhi - che, come tutti sanno, possono sbagliare -, il software che utilizziamo per valutare la densità cromatica dei frames NASA che pubblichiamo e che ci permette altresì di identificare i 'colori maggiori' che sono presenti in essi ci dice che il colore dominante è il "giallo"...), global smog. Titan's hazy atmosphere was frustrating to NASA Voyager scientists during the first tantalizing Titan flybys 25 years ago, but now Titan's surface is being revealed by Cassini with startling clarity (...).
Images taken with the wide-angle camera using red, green and blue spectral filters were combined to create this color view. The images were acquired at a distance of approximately 213.000 Km from Titan and at a Sun-Titan-spacecraft, or phase, angle of 55°. Resolution in the image is about 13 Km per pixel.
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Titan-Shoreline-PIA03563_modest.jpgShoreline on Titan?55 visiteCaption originale:"This SAR (Synthetic Aperture Radar) image of the surface of Saturn's moon Titan, was obtained by the Cassini spacecraft on Sept. 7, 2005. The bright, rough Region on the left side of the image seems to be topographically "high terrain" that is cut by "channels" and "bays".
The boundary of the bright (rough) Region and the dark (smooth) Region appears to be a "shoreline". The patterns in the dark area indicate that it may once have been flooded, with the liquid having at least partially receded.
The image is 175 Km high and 330 Km wide (about 109 by 205 miles), and is located at 66 degrees south latitude, 356° West Longitude in the Southern Hemisphere of Titan".
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Titan-Channels-Unnamed_Channels-PIA03565.jpgTitan's rainfall?!?55 visiteIn contrast to the image "Canyonlands on Titan", this bright terrain is cut by channels that are variable in width; they form both radial and branching networks and such patterns are reminiscent of networks formed by rainfall on Earth.
At the bottom of the frame, the channels radiate from a possible source into a dark, smooth region that seems flatter and more plains-like. One interpretation is that the higher, rougher terrain has been cleansed of organic debris and eroded by methane rainfall. The removed material has then been deposited into the lower plains.
This Cassini SAR image of Titan was taken on Sept. 7, 2005, at a distance of 2000 Km from Titan. It is located near 48° South Latitude, 14° West Longitude and extends about 240 Km right to left.
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Titan-Dunes-PIA03568.jpgThe "Cat Scratches"55 visiteOriginal caption:"The geologic diversity of Titan's surface is well illustrated by this synthetic aperture radar image, obtained on Oct. 28, 2005, during the Cassini spacecraft's 9th Titan fly-by and 4th radar pass.
The bottom left and top right parts of the image show a series of parallel features resembling those discovered during the second radar pass. Called "cat scratches", these features may be dunes of water ice or hydrocarbon particles. The brighter area on the bottom right is thought to be rougher and possibly higher in elevation than the darker areas. Above the center of the image are dark, narrow winding channels carved by, and possibly still containing, liquids.
This image is about 300 by 250 Km and it is located 10° South Lat. and 292° West Long.".
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Titan-PIA07774.jpgCrescent Titan55 visiteWith its thick, distended atmosphere, Titan's orange globe shines softly, encircled by a thin halo of purple light-scattering haze. Images taken using blue, green and red spectral filters were used to create this enhanced-color view; the color images were combined with an ultraviolet view that makes the high-altitude, detached layer of haze visible.
The ultraviolet part of the composite image was given a purplish hue to match the bluish-purple color of the upper atmospheric haze seen in visible light.
Small particles that populate high hazes in Titan's atmosphere scatter short wavelengths more efficiently than longer visible or infrared wavelengths, so the best possible observations of the detached layer are made in ultraviolet light.
The images in this view were taken by the Cassini narrow-angle camera on May 5, 2005, at a distance of approx. 1,4 MKM (about 900.000 miles) from Titan and at a phase angle of 137°.
Image scale is 8 Km (5 miles) per pixel.
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Titan-Full_Disk-PIA02145-2.jpgTitan: Visual + IMS (2)55 visiteIn the December (2) mosaic, a North Polar hood that is bright at 5 microns is visible. Its composition is unknown.
The North Polar hood is barely seen in the October (1) and January (3) data.
Visible in the October and December images just South of the Equator is Tui Reggio, a Region nicknamed the "chevron". This Region is very bright at 5 microns and is among the brightest features on Titan at that wavelength.
Tui Reggio is thought to be a surface deposit, probably of volcanic origin, and may be water and/or carbon dioxide frozen from the vapor.
The December flyby data show that the western margins of Tui Reggio have a complex flow-like character consistent with eruptive phenomena.
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Titan-PIA07701~0.jpgThe atmosphere of Titan55 visiteThis view of Titan reveals structure in the moon's complex atmosphere. The geometry of the Cassini spacecraft's view of Titan during this flyby was similar to that of Voyager 1's pass in 1980.
The image was taken in visible violet light and shows the detached high haze layer that envelops Titan, with additional complexity to its structure in the far North. Some of this atmospheric structure is also visible in a color view (PIA07700) taken at about the same time..
The image was taken with the Cassini spacecraft wide-angle camera on Dec. 26, 2005, at a distance of approx. 194.000 Km (such as about 121.000 miles) from Titan and at a Sun-Titan-spacecraft, or phase, angle of 29°. The image scale is 11 Km (about 7 miles) per pixel.
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