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| Ultimi arrivi - Titan: The "Foggy" Moon |
Titan-PIA12817-PCF-LXTT.jpgTitanian "Arrow-shaped Storm" (Natural Colors; credits for the additional process. and color.: Dr Paolo C. Fienga - Lunexit Team)195 visiteCaption NASA:"A huge arrow-shaped Storm blows across the Equatorial Regions of Titan in this image from NASA's Cassini Spacecraft, chronicling the Seasonal Weather Changes on Saturn's largest moon.
This Storm created large effects in the form of dark -- likely wet -- areas on the Surface of Titan, as better visible in later images. After this Storm dissipated, Cassini observed significant changes on Titan's Surface at the Southern Boundary of the Dunefield named Belet.
Those changes covered an area of approx. 500.000 square Km (310.500 square miles), or roughly the combined area of Arizona and Utah in the United States.
The part of the Storm that is visible here measures approx. 1200 Km (745,2 miles) in length East-to-West. The wings of the Storm that trail off to the North/West and South/West from the Easternmost point of the storm are each approx. 1500 Km (931,5 miles) long.
Titan's weather has been changing since the August 2009 Equinox, when the Sun lays directly over the Equators of Saturn and its moons, and Storms at low Latitudes are now more common.
This image is a mosaic of two Cassini images. Most of this view is from an image of the storm captured on Sept. 27, 2010. However, because that image's framing cut off the South Polar Region of the Planet, a second image of Titan, taken on July 9, 2010, was used to fill in that portion of the celestial body. This second image was re-projected to the same Viewing Geometry as the first.
Lit Terrain seen here is in the area between the Trailing Hemisphere, which is the side of Titan that faces backward in its orbit around Saturn, and the side of Titan that always faces away from Saturn. North on Titan is up.
The images were taken with the Cassini Spacecraft narrow-angle camera using a spectral filter of Near-InfraRed Light centered at 938 nanometers. The view was acquired at a distance of approx. 1,3 MKM (807.300 miles) from Titan and at a sun-Titan-Spacecraft, or Phase, Angle of 44°.
Image scale is roghly 8 Km (4,968 miles) per pixel".MareKromiumMar 22, 2011
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Titan-Clouds-Rain_Clouds-PIA12818-00.jpgTitanian "Deluge"106 visitenessun commentoMareKromiumMar 22, 2011
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Titan-Clouds-Rain_Clouds-PIA12818-01.jpgTitanian "Deluge"138 visiteCaption NASA:"This series of images from NASA's Cassini Spacecraft shows changes on the Surface of Saturn's moon Titan, as the transition to Northern Spring brings Methane Rains to the moon's Equatorial Latitudes. Some of the most significant changes appear within a period of only a couple of weeks.
The brightest objects seen in these images are Methane Clouds in the Troposphere, such as the lowest part of the Atmosphere, which are most visible on the left of panel B, the lower half of panel C, and the right of panel D.
Surface features appear in shades of gray.
These images show changes (outlined area) along the Southern Boundary of a Dunefield near the Equator named Belet. Dark Belet occupies most of the top of these images (Belet looks dark because it is made from different materials than neighboring areas).
Titan's Equatorial Latitudes are mostly arid. However, scientists interpret the changes seen in these images to be evidence of Methane Rain wetting the Surface. Scientists have monitored the brightness of Titan's Surface, including this area, for years and have ruled out other possible causes of the changes. In these images, some of the dark areas grow larger and then recede within weeks. The maximum extent of the changes is shown with a blue outline.
Years ago, images from the European Space Agency's Huygens probe and the Cassini radar instrument revealed Dry Channels near the Equator. The new observations suggest the climate here is similar to that in the South-Western part of the United States, where infrequent Rain carves washes and riverbeds.
Titan's weather has been changing with the Seasons, and Storms now are more common at low Latitudes, such as those observed here. An arrow-shaped Storm cloud several hundred kilometers across was observed on Sept. 27, 2010.
The first image in this montage, panel A on the left, was taken early in the Cassini Mission on Oct. 22, 2007, and shows how this Region had appeared before the Storms.
The second image, panel B, was taken on Sept. 27, 2010. The huge arrow-shaped Cloud is just out-of-frame to the left in panel B.
The arrow-shaped cloud was quickly followed by extensive changes on the Surface that can be seen in panel C, an image captured on Oct. 14, 2010. These changes cover an area of approx. 500.000 square Km (310.500 square miles), roughly the combined area of Arizona and Utah in the United States.
The wet Terrain can still be seen about a month after the storm in panel D, which was taken on Oct. 29, 2010.
But by Jan. 15, 2011, which was the date of panel E, the area mostly appears dry and bright, with a much smaller area still dark (such as wet).
These images were re-projected, and the view in each is centered on Terrain at 19° South Latitude and 251° West Longitude.
Images in panels A, B, D, and E were taken with the Cassini Spacecraft narrow-angle camera using a spectral filter sensitive to wavelengths of Near-InfraRed Light centered at 938 nanometers.
The image in panel C was taken with the Cassini wide-angle camera using the same filter. The views were obtained at a range of distances from approx. 211.000 Km (131.031 miles) to about 1,85 MKM (such as 1.148.850 miles) from Titan.
Scale is about 7 Km (4,3469 miles) per pixel in these re-projected images".MareKromiumMar 22, 2011
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Titan-Clouds-Rain_Clouds-PIA12819.jpgThe "Rain Season" on Titan161 visiteCaption NASA:"Images from NASA's Cassini Spacecraft show changes caused by Methane Rain in the bright Adiri Region near the Equator of Saturn's largest moon, Titan.
Although no Clouds are present in these images, the changes wrought by recent Methane Rainstorms are visible. These images show areas of brightened Terrain within the already bright Region known as Adiri. Adiri's Terrain appears near the center of these frames.
The dark, low-lying Dunefield known as Belet extends West from the left of these frames. Terrain South of Belet was soaked by Methane Rains in late 2010 (Adiri and Belet have different brightnesses because they - most likely - have different compositions).
The first image, panel A on the left, was taken on May 13, 2007, and shows what this area looked like earlier in the Cassini Mission.
Panels B and C were both captured on Jan. 15, 2011, 15 hours apart. New bright areas (within the white outlines of panels B and C) are thought to be on or near the Surface of the Planet.
These bright objects are not high altitude Clouds because they do not drift during the 15 hours between when panel B and panel C were taken.
Scientists are still analyzing the findings, but these brightened spots could be low-lying Fog or Clouds in areas with higher amounts of moisture on the Surface.
They could also possibly be Terrain that has been washed clean by Methane Rains (the bright spots did not become brighter in the 15 hours between panels B and C. They appear brighter only because of a change in the so-called "Viewing Geometry").
Titan's weather has been changing with the Seasons, and Storms now are more common at low Latitudes such as those observed here.
These images were re-projected, and the view in each is centered on terrain at 7° South Latitude and 215° West Longitude.
These images were taken with the Cassini Spacecraft narrow-angle camera using a spectral filter sensitive to wavelengths of Near-InfraRed Light centered at 938 nanometers. The views were obtained at a range of distances from approx. 150.000 Km (93.150 miles) to approx. 997.000 Km (619.137 miles) from Titan.
Scale is about 7 Km (4,3469 miles) per pixel in these re-projected images".MareKromiumMar 22, 2011
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Titan-W00039678.jpgCrescent Titan (Enhanced Natural Colors; credits: Dr Paolo C. Fienga - Lunexit Team)246 visitenessun commentoMareKromiumMar 06, 2011
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Titan-W00039722.jpgThrough the Fogs... (Absolute Natural Colors; credits for the additional process. and color.: Dr Paolo C. Fienga - Lunexit Team)95 visitenessun commentoMareKromiumFeb 09, 2011
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Titan_and_Tethys-PIA12745.jpgBrothers in the Night84 visiteCaption NASA:"The Cassini Spacecraft watches a pair of Saturn's moons, showing the hazy orb of giant Titan beyond smaller Tethys.
In the foreground of the image, Ithaca Chasma can be seen running roughly North-South for more than 1000 Km (about 620 miles) on Tethys. Titan's detached, high-altitude Haze Layer and North Polar "Hood" are also visible here.
This view looks toward the Saturn-facing sides of Titan and Tethys.
The image was taken in Visible Green Light with the Cassini Spacecraft narrow-angle camera on Oct. 18, 2010. The view was obtained at a distance of approx. 2,5 MKM (such as about 1,6 MMs) from Titan and at a Sun-Titan-Spacecraft, or Phase, Angle of 55°. The view was obtained at a distance of approx. 1,5 MKM(such as about 930.000 miles) from Tethys and at a Sun-Tethys-Spacecraft, or Phase, Angle of 55°".MareKromiumDic 22, 2010
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Titan-N00164130-32-EB-LXTT.jpgOn the Limb... (Superdefinition and True Colors; credits for the additional process. and color.: Elisabetta Bonora - Lunexit Team)81 visitenessun commentoMareKromiumOtt 16, 2010
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Titan-Clouds-N00163811-EB-PCF-LXTT.jpgExtremely bright Cloud-formations in Titan's Upper Atmosphere (Natural Colors; credits for the additional process. and color.: Elisabetta Bonora and Paolo C. Fienga - Lunexit Team)103 visitenessun commentoMareKromiumOtt 01, 2010
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Titan-Clouds-PIA13400-PCF-LXTT.jpgTitanian Clouds (Absolute Natural Colors; credits for the additional process. and color.: NASA/JPL/University of Arizona/University of Nantes/University of Paris Diderot and Dr Paolo C. Fienga - Lunexit Team)124 visitenessun commentoMareKromiumSet 24, 2010
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Titan-Clouds-PIA13400.jpgTitanian Clouds (False Colors; credits: NASA/JPL/University of Arizona/University of Nantes/University of Paris Diderot)92 visiteCaption NASA:"This pair of false-color images, made from data obtained by NASA's Cassini Spacecraft, shows clouds covering parts of Saturn's moon Titan in yellow. Based on the way Near-InfraRed channels of light were color-coded, cloud cover appears yellow, while Titan's hazy Atmosphere appears magenta. The images show cloud cover dissolving from Titan's North Polar Region between May 12, 2008 (left), and Dec. 12, 2009 (right). The clouds in the second image appear around 40° South Latitude, still active late after Titan's Equinox.
Cassini's first observations of clouds near this Latitude occurred during Summer in the Southern Hemisphere. Equinox, when the Sun shone directly over the Equator, occurred in August 2009. It brought a changing of the seasons, as Titan moved out of Southern Summer into Northern Spring.
For the past 6 years, Cassini has observed clouds clustered in three distinct Latitude Regions of Titan: large clouds at the North Pole, patchy cloud at the South Pole and a narrow belt around 40° South. Now scientists are seeing evidence of seasonal circulation turnover at Titan. Clouds at the South Pole disappeared just before Equinox and the clouds in the North are thinning out. This activity agrees with models that predict cloud activity reversing from one Hemisphere to another.
During Winter in the Northern Hemisphere, Northern Polar Clouds of Ethane formed in Titan's Troposphere, the lowest part of the Atmosphere, from a constant influx of Ethane and Aerosols from a higher part of the Atmosphere known as the Stratosphere.
In the Southern Hemisphere, atmospheric gases enriched with Methane welled up from the Surface to produce Mid and High-Latitude Clouds.
The data for the images was detected by Cassini's Visual and InfraRed Mapping Spectrometer in Near-IR wavelengths. Scientists focused on three wavelengths of IR radiation that were particularly good for observing cloud signatures and assigned them red, green and blue channels.
Emissions in the 2 micron wavelength of light, colored red, detect the Titan Surface.
Emissions in the 2,11 micron wavelength, colored green, detect the lowest part of the Titan Atmosphere, or Troposphere.
Emissions at the 2,21 micron wavelength, colored blue, detect the hazy Stratosphere, a higher part of the Atmosphere.
The clouds appear yellowish because they lit up the channels designated red and green, but not the blue channel".MareKromiumSet 24, 2010
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Titan-Clouds-Water_Ice_Clouds-MF-LXTT.jpgWater-ice Clouds' Complex on Titan (an Image-Mosaic by Dr Marco Faccin - Lunexit Team)96 visitenessun commentoMareKromiumSet 17, 2010
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