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| Ultimi arrivi - Titan: The "Foggy" Moon |
Titan-PIA08943.jpgAn "Orthographic View" of Titan56 visiteCaption NASA:"Cassini acquired this view of Titan on April 13, 2007, following a flyby of the Mercury-sized moon. Titan's equatorial Dark Regions are visible in this view, along with faint, dark lineaments (linear features) in the otherwise bland-looking terrain of the North. Near the Terminator are the dark, lake-like features identified in Cassini flybys early in 2007.
To the east of the lake-like features is a bright patch of clouds that likely consist of a mixture of Methane and Ethane.
This view of Titan is an orthographic reprojection centered on 27,4° North Latitude. An orthographic view is most like the view seen by a distant observer looking through a telescope.
The view was obtained using a filter sensitive to near-infrared light centered at 939 nanometers, allowing for observations of Titan's Surface and Lower Atmosphere, added together. An image taken using a filter sensitive to visible light centered at 619 nanometers was then subtracted from the product, effectively removing the lower atmosphere contribution to the brightness values in the image, increasing image contrast and improving the visibility of surface features.
The Cassini spacecraft acquired this view with its narrow-angle camera at a distance of approx. 1,2 MKM (about 800.000 miles) from Titan. Image scale is roughly 7 Km (such as about 5 miles) per pixel".
MareKromiumMag 20, 2007
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Titan-Seas-Kraken_Mare-PIA08365.jpgTitanian Seas58 visiteCassini peers through the murky orange haze of Titan to spy what are believed to be bodies of liquid hydrocarbons, 2 of them as large as seas on Earth, near the moon's North Pole. This picture blends a near natural-color view and an infrared glimpse of Titan's surface obtained by the visual cameras, followed by a transition to imagery collected by the radar instrument aboard Cassini, for a dramatic reveal of the North Pole of Saturn's largest moon.
As the image zooms in on the North Pole, the most readily visible bodies are outlined in blue. The largest of these, on the left, is as big as the Caspian Sea on Earth; the next largest, on the right, is about the size of Lake Superior. When compared to the surface area of Titan however (which is six times smaller than Earth's), these bodies are equivalent in size to the Bay of Bengal and Timor Sea, respectively. Geographically speaking, they are more like seas. Mar 16, 2007
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Titan-Lakes-Unnamed_North_Polar_Lakes-07-PIA08363-1.jpgThe Great Lake of Titan (False Colors; elab. Lunexit)58 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". Mar 14, 2007
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Titan-Island-PIA09180.jpgTitanian Sea and Islands in it61 visiteCaption NASA:"This radar image, obtained by Cassini's radar instrument during a near-polar flyby on Feb. 22, 2007, shows a big island smack in the middle of one of the larger lakes imaged on Saturn's moon Titan. This image offers further evidence that the largest lakes are at the highest latitudes.
The island is about 90 Km (approx. 62 miles) by 150 Km (approx. 93 miles) across, about the size of Kodiak Island in Alaska or the Big Island of Hawaii.
The island may actually be a peninsula connected by a bridge to a larger stretch of land. As you go farther down the image, several very small lakes begin to appear, which may be controlled by local topography.
This image was taken in synthetic aperture mode at 700 mt (2300 feet) resolution. North is toward the left. The image is centered at about 79° North Lat. and 310° West Long".Feb 28, 2007
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Titan-Regions-Ganesa_Macula_Region-PIA09176.jpgGanesa Macula66 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".Feb 28, 2007
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Titan-Craters-Unnamed_Crater-PIA09175.jpgFresh Crater on Titan?60 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".Feb 28, 2007
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Titan-PIA08879.jpgTitan (true colors - elab. NASA)57 visiteCaption NASA:"Looking toward high Northern Latitudes on Titan, the Cassini spacecraft spies a banded pattern encircling the Pole.
This sort of feature is what scientists expect to see in the Stratosphere of Titan, where the Atmosphere is superrotating, or moving around the moon faster than the moon itself rotates.
Images taken using red, green and blue spectral filters were combined to create this natural color view. The images were taken by the Cassini spacecraft wide-angle camera on Jan. 28, 2007 at a distance of approx. 196.000 Km (about 122.000 miles) from Titan. Image scale is 12 Km (approx. 7 miles) per pixel".Feb 20, 2007
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Titan-PIA08868.jpgTitanian "Bands"56 visiteCaption NASA:"Titan bears a distinct East-West banded pattern in this Cassini spacecraft image taken in the ultraviolet.
The ultraviolet wavelength allows Cassini to see Titan's stratosphere, where superrotation -- in which the atmosphere moves around the moon faster than Titan rotates -- is strong. The recent appearance of this feature may be a harbinger of seasonal change on Titan.
The moon's halo -- its detached, high-altitude global haze layer -- is visible here as well, and is often its most prominent feature in such ultraviolet views. North on Titan is up and rotated 6° to the right in this image.
The view was obtained by the Cassini spacecraft narrow-angle camera using a spectral filter sensitive to wavelengths of polarized ultraviolet light.
The view was acquired on Dec. 25, 2006 at a distance of approx. 1,3 MKM (about 800.000 miles) from Titan and at a Sun-Titan-spacecraft, or phase, angle of 123°.
Image scale is roughly 8 Km per pixel".Feb 03, 2007
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Titan-North_Polar_Regions-PIA09171.jpgStrong turbulence over Titan's North Pole58 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".Feb 02, 2007
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Titan-Dunes-PIA09115.jpgTitanian Dunes57 visiteCaption NASA:"This radar image of Titan's well-known dunes is distinctive because it may show an age relationship between different classes of features on the surface of this frigid world.
Taken by Cassini's radar mapper on Jan. 13, 2007, during a flyby of Titan, three kinds of terrain can be seen. Throughout the image, the fine striping has been identified as dunes, possibly made from organic material and formed by wind activity. Dunes are a common landform on Titan.
The bright material at the lower right of the image is interpreted as being topographically higher than the dunes that go around it, and several circular features seen at the top center may be craters that are slowly being buried by the dunes. Since the dunes seem to lie over the craters, the dune activity probably occurred later in time.
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. 160 x 150 Km wide".MareKromiumGen 25, 2007
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Titan-Dunes-PIA09111.jpgTitanian Dunes57 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".Gen 12, 2007
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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.Dic 30, 2006
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