| Piú votate - Titan: The "Foggy" Moon |
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?!?
(17 voti)
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Titan-Full_Disk-PIA06141_modest.jpgTitan (full disk, no haze) from 300.000 up to 650.000 Km59 visiteThe images that comprise the mosaic have been processed to reduce the effects of the atmosphere and to sharpen surface features. The mosaic has been trimmed to show only the illuminated surface and not the atmosphere above the edge of the moon. Pixel scales of the composite images vary from 2 to 4 Km per pixel. Surface features are best seen near the center of the disc, where the spacecraft is looking directly downwards; the contrast becomes progressively lower and surface features become fuzzier toward the outside, where the spacecraft is peering through haze, which washes out surface features. The brighter region on the right side and equatorial region is named Xanadu. Scientists are debating what processes may have created the bizarre surface brightness patterns seen here. The images hint at a young surface with no obvious craters. The exact nature of that activity, whether tectonic, wind-blown, fluvial, marine or volcanic is still unknown.
(25 voti)
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Titan-Dunes-PIA03567.jpgTitanian Dunes54 visiteOriginal caption:"Large areas of this Cassini synthetic aperture radar image of Titan are covered by long, dark ridges. They resemble the "cat scratches" seen in other places on Titan, but here they are longer and straighter. Spaced about 1 to 2 Km apart, they curve slightly around teardrop-shaped bright terrain, giving the impression of a Japanese garden of sand raked around boulders. The bright material appears to be high-standing rough material that the ridges bend around. This suggests that the ridges are dunes that winds have blown across the surface of Titan from left to right (roughly West to East).
This image was taken during the ninth Titan flyby on Oct. 28, 2005, (the fourth flyby for Cassini's synthetic aperture radar), at a distance of about 1300 Km (about 800 miles).
The image covers an area roughly 140 by 200 Km. It is located 13° South Lat. and 300° West Long.".
Nota: il vero mistero è 'dove' e 'come' la NASA abbia visto ed interpretato i rilievi in questione come possibili dune...
(22 voti)
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Titan-Huygens_Landing_Site-11-PIA07229_modest.jpgHuygens' descent map (3) 58 visiteThe octagons indicate anticipated fields of view of panoramic mosaics of images taken by Huygens' descent imager and spectral radiometer instrument as the probe reaches certain altitudes during its descent. This map shows the footprints for mosaics to be assembled from 36 individual images at each altitude, with the field of view cut off at 75° from straight down although the actual images will extend all the way to the hazy horizon. Each mosaic made this way will be about 1.300 by 1.300 pixels. The largest octagon (in red) is about 1.120 Km across and represents the field of view for the mosaic of images taken at an altitude of 150 Km. From that height, individual pixels in the center of the image will be about 150 mts across, though haze between the ground and the camera at that height will likely degrade the resolution in those images. The location of the anticipated landing site is based on modeling of Titan's winds, and the actual landing site will be different if the actual winds experienced by Huygens during descent differ from this model.
(12 voti)
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Titan-PIA06996_modest.jpgDoes Titan have a so-called "weather-pattern"?56 visiteIn the first image (left), obtained on the 1st Titan flyby, from a distance of 200.000 Km, Titan's skies are cloud-free, except for a patch of clouds observed over the South Pole near the bottom of the image. In contrast, the image on the right shows a recent view of this same area of Titan obtained 7 weeks later on the 2nd close Titan flyby, from a distance of 225.000 Km. This image clearly shows that several extensive patches of clouds have formed over temperate latitudes. The appearance of these clouds reveals the existence of weather. Tracking these features is currently underway by scientists, who hope to gain a better understanding of global circulation, regional weather patterns and localized meteorology in Titan's skies. The red color images the surface at a wavelength (2.01 micron) where the surface is relatively bright, making the surface appear reddish in these color images. The green color (2.83 micron) images the surface as well, but due to enhanced absorption of sunlight by the surface and lower atmosphere, the surface is relatively dark here compared to the red. The blue color (2.13 micron) is at a wavelength where sunlight cannot reach the surface at all due to strong absorption by the atmospheric gas methane. In contrast to the reddish surface, bright clouds at a relatively high altitude (here, about 30 kilometers (19 miles) above the ground) residing above most of the atmospheric absorption appear whitish in these representations, as they reflect sunlight effectively in all three near-infrared colors.
(12 voti)
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Titan-Regions-Ganesa_Macula_Region-PIA09176.jpgGanesa Macula65 visiteCaption NASA:"This radar image of Titan shows Ganesa Macula, interpreted as a cryovolcano (ice volcano), and its surroundings. Cryovolcanism is thought to have been an important process on Titan and may still be happening today.
This mosaic was made from images obtained by the Cassini radar mapper on two flybys. The lower part of the image was from the flyby on Oct. 26, 2005, while the upper part was from the Jan. 13, 2007, flyby.
Ganesa macula is the dark circular feature seen on the lower left of the mosaic.
Bright rounded features, interpreted as cryovolcanic flows, are seen towards the top and the right of the mosaic.
This image mosaic was taken in synthetic aperture mode. The resolution of the images is approx. 350 mt (1150 feet). North is toward the top. The image mosaic is about 570 Km (about 354 miles) wide and 390 Km (about 240 miles) high".
(14 voti)
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