| Piú viste - Titan: The "Foggy" Moon |
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".MareKromium
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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".MareKromium
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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".
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Titan-Regions-Xanadu_Region-PIA06107.jpgXanadu Region56 visiteThis image taken on Oct. 24, 2004, reveals Titan's bright "continent-sized" terrain known as Xanadu. It was acquired with the narrow angle camera on Cassini's imaging science subsystem through a spectral filter centered at 938 nnmts, a wavelength region at which Titan's surface can be most easily detected. The surface is seen at a higher contrast than in previously released imaging science subsystem images due to a lower phase angle (Sun-Titan-Cassini angle), which minimizes scattering by the haze.
The image shows details about 10 times smaller than those seen from Earth. Surface materials with different brightness properties (or albedos) rather than topographic shading are highlighted. The image has been calibrated and slightly enhanced for contrast. It will be further processed to reduce atmospheric blurring and to optimize mapping of surface features. The origin and geography of Xanadu remain mysteries at this range. Bright features near the South Pole (bottom) are clouds.
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Titan-Dunes-PIA09111.jpgTitanian Dunes56 visiteCaption NASA:"This pair of images, taken by the Cassini spacecraft radar mapper on two different Titan passes on Dec. 11, 2006 (T21 left) and Oct. 29, 2005 (T8 right), represent two different views of a field of dunes located near 9,4° South Latitude by 290° West Longitude.
The images were taken in synthetic aperture mode and have a resolution of approximately 500 mt(1.640 feet). North is toward the top of both images and each image is approx. 400 Km (250 miles) long by 275 Km (about 170 miles) wide.
The images are different only because the radar instrument illuminated the dunes from different directions. Acting somewhat like a flash camera, the radar sends out microwave pulses and makes an image from the pulses after they are reflected back. Imagine that both the camera and the flash come from the left in the left image and from the top in the right image.
Most obvious differences are seen in the large bright feature at the center of both images. At left, its left edge is brighter, emphasizing the more steep slopes there. Farther left, the dunes are more clearly defined in the right image as their faces are caught by the illumination. However, since the dunes are visible in both images, it is likely that the materials making up the dark and light stripes are also somehow different. More detailed studies of how materials on Titan reflect and scatter at different angles are giving us clues about what different materials might be present in this cold and distant world".
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Titan-North_Polar_Regions-PIA09171.jpgStrong turbulence over Titan's North Pole56 visiteCaption NASA:"Cassini's VIMS (Visual and Infrared Mapping Spectrometer) has imaged a huge cloud system covering the North Pole of Titan.
This composite image shows the cloud, imaged at a distance of 90.000 Km (about 54.000 miles) during a Dec. 29, 2006, flyby designed to observe the limb of the moon. Cassini's VIMS scanned the limb, revealing this spectacular cloud system.
It covers the North Pole down to a Latitude of 62° North and at all observed Longitudes.
Such a cloud cover was expected, according to the atmospheric circulation models of Titan, but it had never been observed before with such details. The condensates may be the source of liquids that fill the lakes recently discovered by the radar instrument.
This image was color-coded, with blue, green and red at 2, 2,7 and 5 microns, respectively".
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Titan-Lakes-Unnamed_North_Polar_Lakes-07-PIA08363-1.jpgThe Great Lake of Titan (False Colors; elab. Lunexit)56 visiteCaption NASA:"This view of Titan taken on Feb. 25, 2007, reveals a giant lake-like feature in Titan's North Polar Region. It is approximately 1100 Km (about 680 miles) long and has a surface area slightly smaller than that of Earth's largest lake, the Caspian Sea".
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Titan-Huygens_Landing_Site-04-IMG002629-br500.jpgDrainage, flow and erosion on the Huygens landing site56 visiteClose - by are stubby canyons with only a few branches. They have probably been formed by ‘spring sapping’, whereby methane flows through the subsurface before emerging as a spring near the base of a hill. The spring erodes the hillside, causing it to collapse and form a cliff face.
The third area is the flat dark plain. This is mostly water ice mixed with tholin grit. “Titan’s river channels, canyons, and flood plains rival the variety seen on Earth,” says Soderblom. The dark plains show markings that suggest the region occasionally experiences flash flooding, but not from the highland drainage channels. Instead large quantities of liquid methane appear to flow from east to west.
Planetary scientists can now begin to piece together the sequence of events that led to the formation of this exotic landscape. “Huygens and Cassini have taken giant steps forward in our understanding of Titan,” says Soderblom.
MareKromium
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Titan-Huygens_Landing_Site-05-LS27_PSS_LSoderblom_DISR_Topo20070323.jpgTectonic and fluid-flow patterns on Titan (HR)56 visiteThis image of Titan’s surface, obtained by Huygens’ DISR imager, shows patterns of tectonic and fluid-flow activity.
The tectonic patterns are indicated by blue lines; the drainage divide is indicated by the red line; flow directions are indicated by the green arrows.
The Huygens Landing Site is marked by a white cross.
MareKromium
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Titan-Huygens_Landing_Site-00-LS27_PSS_LSoderblom_DISR_Topo20070323.jpgHuygens Probe Landing Site (perspective)56 visiteThis West-looking perspective of the Huygens Landing Site shows the Huygens descent trajectory in blue (the blue vertical lines indicate the ground track location). The base map (16 metres per pixel) is a mosaic obtained by the Descent Imager and Spectral Radiometer (DISR) on board Huygens.MareKromium
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Titan-N00084850.jpgInterpreting Titan (5)56 visitenessun commentoMareKromium
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Titan-N00084842.jpgInterpreting Titan (4)56 visitenessun commentoMareKromium
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