| Piú viste - Titan: The "Foggy" Moon |
Titan-PIA07701~0.jpgThe atmosphere of Titan59 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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Titan-Rivers-Unnamed_Rivers_and_Channels-PIA08428-0.jpgThe rivers of Titan...59 visiteThis image from the Synthetic Aperture Radar instrument on the Cassini spacecraft shows the radar-bright western margin of Xanadu, one of the most prominent features on Titan.
In radar images, bright regions indicate a rough or scattering material, while a dark region might be smoother or more absorbing. This image was taken during a flyby of Titan on April 30, 2006.
Narrow, sinuous, radar-bright channels, meandering like a maze, are seen on the right-hand-side of the image. These may be river networks that might have flowed onto the dark areas on the left of the image. Vast, dark areas covered by dunes are seen on the equatorial regions of Titan (see PIA03567) and have been referred to as Titan's "sand seas". Near the middle of the image is a radar-bright area that has a boundary with the dark sand seas. Because the radar illumination is coming from the top, this indicates that the bright region, Xanadu, is topographically higher than the sand seas.
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Titan-Lakes-Unnamed_North_Polar_Lakes-01-PIA08630-2.jpgTitanian Northern Lakes (2)59 visiteCaption NASA originale:"For all these reasons, scientists interpret the dark areas as lakes of liquid methane or ethane, making Titan the only body in the Solar System besides Earth known to possess lakes. Because such lakes may wax and wane over time, and winds may alter the roughness of their surfaces. Repeat coverage of these areas should test whether indeed these are bodies of liquid.
These two radar images were acquired by the Cassini radar instrument in synthetic aperture mode on July 21, 2006.
The image (1) is centered near 80° North Lat. and 92° West Long.; it measures about 380x120 Km.
The image (2) is centered near 78° North Lat. and 18° West Long.; it measures about 425x120 Km.
Smallest details in this image are about 500 mt (roughly 1640 feet) across".
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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".
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Titan-Craters-Unnamed_Crater-PIA09175.jpgFresh Crater on Titan?59 visiteCaption NASA:"This radar image of Titan shows a semi-circular feature that may be part of an impact crater. Very few impact craters have been seen on Titan so far, implying that the surface is young. Each new crater identified on Titan helps scientists to constrain the age of the surface.
Taken by Cassini's radar mapper on Jan. 13, 2007, during a flyby of Titan, the image swath revealed what appeared to be the northernmost half of an impact crater. This crater is roughly 180 Km (about 110 miles) wide. Only three impact craters have been identified on Titan and several others, like this one, are likely to also have been caused by impact. The bright material is interpreted to be part of the crater's ejecta blanket, and is likely topographically higher than the surrounding plains. The inner part of the crater is dark, and may represent smooth deposits that have covered the inside of the crater.
This image was taken in synthetic aperture mode and has a resolution of approx. 350 mt (1150 feet). North is toward the top left corner of the image, which is approx. 240 Km (about 150 miles) wide by 140 Km (90 miles) high. The image is centered at about 26,5° North and 9° West".
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Titan-Seas-PIA09211.jpgJust like California...59 visiteOn May 12, 2007, Cassini completed its 31st Fly-By of Saturn's moon Titan, which the team calls T30. The radar instrument obtained this image showing the coastline and numerous island groups of a portion of a large sea, consistent with the larger sea seen by the Cassini imaging instrument.
Like other bodies of liquid seen on Titan, this feature reveals channels, islands, bays, and other features typical of terrestrial coastlines and the liquid, most likely a combination of methane and ethane, appears very dark to the radar instrument. What is striking about this portion of the sea compared to other liquid bodies on Titan is the relative absence of brighter regions within it, suggesting that the depth of the liquid here exceeds tens of meters.
Of particular note is the presence of isolated islands, which follow the same direction as the peninsula to their lower right, suggesting that they may be part of a mountain ridgeline that has been flooded. This is analogous to, for example, Catalina Island off the coast of Southern California.
MareKromium
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Titan-Regions-Shangri_La_Region-PIA08971.jpgShangri-la and other Equatorial Regions of Titan59 visiteCaption NASA:"This view of Titan's surface highlights NorthWestern Shangri-la - a large, Equatorial Dark Region revealed by radar observations to be covered in longitudinal dune fields. The bright, circular feature right of center is a potential impact crater - few of which have been spotted on Titan thus far.
North on Titan is up and rotated about 15° to the right. This view was created by combining multiple images taken using a combination of spectral filters sensitive to wavelengths of infrared light centered at 938 and 619 nanometers.
The images were taken with the Cassini spacecraft narrow-angle camera on May 13, 2007 at a distance of approx. 125.000 Km (about 77.000 miles) from Titan. Image scale is roughly 1 Km (0,6 miles) per pixel. Due to scattering of light by Titan's hazy atmosphere, the sizes of surface features that can be resolved are a few times larger than the actual pixel scale".MareKromium
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Titan-N00121492.jpgTitan (natural colors; credits: Lunexit)59 visitenessun commentoMareKromium
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Titan-W00049900.jpgLost in the Space of Saturn... (natural colors; credits: Lunexit)59 visiteTitano: il disco, appena percettibile, splende di un leggero color giallo. Siamo a circa 1,8 MKM dalla "Luna Nebbiosa".MareKromium
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Titan-Shoreline_and_Drainage_Channels-01.jpgShoreline and Drainage Channels' Network on Titan (possible True Colors; credits: Lunar Explorer Italia)59 visitenessun commentoMareKromium
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Titan-Surface-38.gifOn the way down... - Sol 1 (GIF-Movie; credits: Dr G. Barca)59 visiteLe Condizioni di Illuminazione
Innanzitutto, ed a dispetto di quanto mostrato dalle immagini ESA-Huygens (e da tante altre “visioni artistiche” di Titano made by NASA, la nostra prima considerazione attiene le condizioni medie di illuminazione di questo mondo.
Le fotografie ESA (ottenute sia durante la discesa, sia dalla superficie di Titano), al pari delle interpretazioni artistiche NASA, ci danno l’impressione di un mondo, ancora una volta, alquanto luminoso…
MareKromium
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Titan-Clouds-Noctilucent_Clouds-GIFMovie-N00023501-N00023599.gifNoctilucent Clouds over Titan (GIF-Movie; credits: Dr G. Barca)59 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"...
MareKromium
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