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The_Rings-PIA08827.jpgMimas and the Rings56 visiteCaption NASA:"A recently discovered diffuse ringlet shines brightly in the Cassini Division as Mimas cruises past at bottom. Most of the main Rings are comprised of particles ranging from marble-size to house-size. In contrast, the brightness of this ringlet (seen right of center) when viewed at a high phase angle (the Sun-Saturn-Spacecraft angle) indicates it contains a large quantity of microscopic particles, which were likely generated by the disruption of a larger body. Such an event was probably recent, since this ringlet was not observed by the Voyager spacecraft in 1980 and 1981.
This view looks toward the lit side of the Rings from about 1° below the Ring-Plane. Mimas, which is in the foreground between Cassini and the Rings, is 397 Km (about 247 miles) wide. See PIA08330 and PIA08331 for other views of the new ringlet.
The image was taken in visible light with the Cassini spacecraft wide-angle camera on Nov. 18, 2006 and from a phase angle of 140°. Cassini was then at a distance of about 1,2 MKM (about 800.000 miles) from Saturn. Image scale is roughly 7 Km per pixel".MareKromium
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LH-95.jpgLH-95 Star Forming Region56 visite"...How beautiful upon the mountains are the feet of the Messenger who announces Peace..."
- Isaiah, 52:7MareKromium
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Enceladus-PIA09037.jpgActive Enceladus56 visiteOn Nov. 9, 2006, Cassini's Composite Infrared Spectrometer captured its first view of the Infrared Heat Radiation emanating from the "Tiger Stripe" fractures at the South Pole of Saturn's moon Enceladus (right) since the discovery of the hot spot 16 months earlier (left). The original discovery was made just before a close flyby of Enceladus on July 14, 2006, and coincided with the discovery of plumes of water-rich gas and ice particles jetting out of the Tiger Stripes. However, the spacecraft's orbit did not provide any good views of the South Pole for follow-up observations until November 2006.
The new observations were made from a range of 110.000 Km (68.350 miles), slightly more distant than the 80.000-Km range (49.700 miles) of the original observations.
Comparison of the two images shows that the South Polar Region continues to be active, and the distribution of temperatures there has changed little in 16 months.
The distribution of Heat Radiation suggests that most or all of the South Polar heat comes from the Tiger Stripes themselves, though the individual stripes are not resolved at the approximate 30-Km (19-mile) spatial resolution of these images.
The images show the intensity of Heat Radiation in the 10- to 16-micron wavelength range, translated into temperature and displayed in false color.
Peak South Polar temperature on both dates reached about 85 Kelvin (- 306 degr. Fahrenheit), averaged over the 30-Km (19-mile) spatial resolution of the data. However, the variation in brightness with wavelength, which is also measured by the Composite Infrared Spectrometer, reveals that the warm region includes small areas, possibly zones a few 100 mt (320 feet) wide along the length of the Tiger Stripes, that are at higher temperatures, reaching at least 130 Kelvin (- 225 degr. Fahrenheit) and perhaps much warmer still.
While the South Polar Tiger Stripes are almost certainly heated by energy from the moon's interior, daytime regions at low latitudes are warmed by sunlight to temperatures in the high 70s Kelvin (about - 320 degrees Fahrenheit).
The white numbers on the images show West Longitudes on Enceladus, which is 500 Km (310 miles) in diameter.
The dashed line shows the Terminator, the boundary between day and night.
The blotchy appearance of the cooler regions away from the South Pole, and of the sky beyond the globe of Enceladus, is an artifact resulting from the fact that apart from the Polar Hot Spot, the Composite Infrared Spectrometer can barely detect the very faint Heat Radiation from this very cold moon.MareKromium
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Dione-PIA08839.jpgThe "fractured face" of Dione56 visiteCaption NASA:"The fractured terrain so distinctive to Dione curves away toward the South in this view, which looks down at the moon's Northern Hemisphere.
Lit terrain in this view is on the Saturn-Facing Hemisphere of Dione.
The image was taken in visible light with the Cassini spacecraft narrow-angle camera on Nov. 22, 2006 at a distance of approx. 943.000 Km (about 586.000 miles) from Dione and at a Sun-Dione-spacecraft, or phase, angle of 109°.
Image scale is roughly 6 Km (a little less than 4 miles) per pixel".MareKromium
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Titan-PIA08351.jpgClose "Friends"...56 visiteCaption NASA originale:"Cassini peers around the hazy limb of Titan to spy the sunlit South Pole of Saturn in the distance beyond.
The thick, smog-like atmosphere of frigid Titan is a major source of interest for the Cassini mission. The moon is 5.150 Km (about 3.200 miles) across.
Images taken using red, green and blue spectral filters were combined to create this natural-color view. The image was taken with the Cassini spacecraft narrow-angle camera on Dec. 26, 2005, at a distance of approx. 26.000 Km (about 16.000 miles) from Titan. Image scale is roughly 1 Km (4.643 feet) per pixel".
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Helene-PIA08335-00.jpgHelene (HR and False Colors)56 visiteCaption NASA:"Cassini came close to Saturn's small moon Helene on Feb. 25, 2006, acquiring this High-Resolution (HR) view. This object seems to be buried in its own crater debris, like another Saturnian moon, Telesto.
Helene (32 Km, or 20 miles across) orbits 60° ahead of Dione in the larger moon's orbit, making it a "trojan" moon of Dione. Trojan moons are named for the Trojan group of asteroids that orbit 60° ahead of and behind Jupiter as it circles the Sun.
This image was taken in visible light with the Cassini spacecraft narrow-angle camera at a distance of approx. 68.000 Km (42.000 miles) from Helene and at a Sun-Helene-spacecraft, or phase, angle of 99°. Image scale is roughly 406 mt (1.334 feet) per pixel".
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Titan-Regions-Fensal_and_Aztlan_Region-PIA08352.jpgFensal and Aztlan Region56 visiteAs Cassini continues its reconnoitering flybys of Titan, the imaging science team continues to improve its ability to tease out surface details hidden in the unprocessed images. This mosaic provides the best view yet obtained by Cassini's cameras, showing terrain on the moon's sub-Saturn Hemisphere -- the side of the moon that always faces toward Saturn. This mosaic has better resolution, both in pixel scale and from improved signal-to-noise, compared to previous views of the area.
"Signal-to-noise" is a term scientists use to refer to the amount of meaningful or useful information (signal) in their data versus the amount of background noise. A higher signal-to-noise ratio yields sharper, clearer views of Titan's surface.
The view is centered on terrain in the Fensal-Aztlan region on Titan, at 0,03° South Lat. and 22,18° West Long. The mosaic covers an area 3.500 Km (2.180 miles) North to South and 3.600 Km (2.240 miles) West to East. North is up.
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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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OPP-SOL1043-1N220787889EDN7800P1585L0M1.jpgBright Sun, Dark Sky... - Sol 104356 visiteSe l'atmosfera di Marte è realmente sottile come dice la NASA, allora, già a "mezzo cielo" - e cioè intorno ai 45° dall'orizzonte - il cielo di Marte dovrebbe diventare scuro, molto scuro, così come appare in questa immagine elaborata da noi, su frame NASA-Opportunity, e così come appare anche sulla Terra, in montagna, ad altezze superiori ai 5000 metri.
L'unica differenza è che, sulla Terra, la dominante - anche in caso di cielo molto scuro, è l'azzurro; su Marte, è l'arancio.
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The_Rings-N00073991.jpgSomething's in the Rings...56 visitenessun commento
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Saturn-PIA08340.jpgShadowlands56 visiteL'espressione "Shadowland/s" l'avevamo inventata un paio d'anni fa, per commentare le immagini che mostravano il profilo di rilievi elevati i quali si trovavano, al momento di effettuazione della ripresa, sul cosiddetto "Terminatore" (ossìa la linea che divide il giorno dalla notte).
E' non solo curioso ma anche, ed almeno dal nostro punto di vista, fonte di piacere il fatto di vedere che la NASA - chissà, forse anche ispirata da qualcuno dei "titoli" che diamo alle immagini... - abbia adottato questa medesima espressione per descrivere il regno di ombre che sembra caratterizzare, nel frame in oggetto, il Gigante Anellato più famoso del Sistema Solare: Saturno.
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OPP-SOL108-1NN108EFF23CYL00P1981L000M1-B110R1-00.jpgEarly morning on Mars (after a sand storm)56 visiteInterpretazione di fantasia sul come dovrebbe apparire Marte (Regione di Meridiani Planum, prossimità del Cratere Endurance) nelle prime luci dell'alba e subito dopo la fine di una tempesta di polveri.MareKromium
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