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Saturn-the Encke Gap-PIA06534_modest.jpgThe "Encke Gap" of Saturn's Rings59 visiteCaption NASA originale:"An intriguing knotted ringlet within the Encke Gap is the main attraction in this Cassini image. The Encke Gap is a small division near the outer edge of Saturn's rings that is about 300 Km wide. The tiny moon Pan (20 Km across) orbits within the gap and maintains it.
Many waves produced by orbiting moons are also visible.
The image was taken in visible light with the Cassini spacecraft narrow angle camera on Oct. 29, 2004, at a distance of about 807,000 Km from Saturn. The image scale is 4,5 Km per pixel".
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Japetus-PIA06145_modest.jpgSharp views of Japetus59 visiteIn sequenza, alcune delle migliori immagini di Giapeto ottenute da Cassini e superiori, per qualità e dettaglio, a quelle ottenute dalla Sonda Voyager 2 qualche anno fa. Le immagini a colori visibili sulla Sn dell'Osservatore ed al centro sono state ottenute usando (e combinando) i filtri per l'ultravioletto (a 338 Nnmts), il verde (a 568 Nnmts) e l'infrarosso (a 930 Nnmts); l'immagine a Dx è stata ottenuta riprendendo nel cosiddetto "spettro visibile". Le immagini sono state riprese da una distanza oscillante fra gli 1,1 e gli 1,3 MKMs; Giapeto si caratterizza sia per il gigantesco cratere da impatto visibile nell'emisfero sud (400 Km di diametro), sia per alcune notevoli differenze di albedo fra diverse zone della sua superficie (il che ci fa supporre che esistano aree ricoperte, probabilmente, da vasti depositi di polveri - che sono causa di una bassa riflessione della luce ergo di una bassa albedo - ed altre aree che, forse, sono costituite da rocce o addirittura da depositi di ghiaccio).
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OPP-SOL317-1N156329337EFF3940P0705L0M1.jpgOut of Endurance Crater: the "orange" desert, again!59 visiteVeduta di Meridiani Planum, ovvero il "deserto arancione" (ma sarà poi davvero arancione?!?) che circonda il Cratere Endurance. Alla NASA dicono che il primo obbiettivo di Opportunity sarà lo Scudo Termico e poi...Avanti in direzione Sud, senza una mèta in particolare. Ora il Rover è fermo ed ha aperto i suoi pannelli per ricaricarsi; nei prossimi Soles, vedremo che cosa Marte ha in serbo per noi...
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Titan-Clouds-PIA06158.jpgTitanian Clouds (October 2004 fly-by)59 visiteCaption NASA originale:"Cutting through the middle of the image is a sharp boundary between the bright region known as Xanadu Regio on the right and dark terrain to the left. Several smaller bright features, between 30 and 200 Km across are seen within the dark terrain. These intriguing features are a focus of further research and observations for Cassini scientists. One clue to their origin and history is the presence of bright "trails" within the dark material on the eastern sides of the bright spots. A mottled texture is seen within Xanadu, including dark, crisscrossing lines, suggestive of tectonic activity. No definitive craters have been found in these images, though several bright rings or circular features are seen in the dark terrain. However, without topographic shading, their identification as impact structures can not be confirmed. The images in this mosaic have been processed to enhance surface features and sharpen boundaries".
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Dione-PIA06542_modest.jpgA line of craters on Dione and a crater with "something" inside...59 visiteAl di là della oggettiva bellezza e della grande suggestione che suscita questa immagine, la domanda (scherzosa, naturalmente) sorge in noi spontanea: ma dentro il "cratere maggiore" (proprio in centro, a ridosso del terminatore), che cosa c'è?!?
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EROS-PIA02906_modest.jpgHorizon view59 visiteThis image of Eros, taken from the NEAR Shoemaker spacecraft on May 2, 2000, from an orbital altitude of 52 kilometers (32 miles), shows a view toward Eros' horizon. The section shown is about 1.8 kilometers (1.1 miles) across. This particular view provides a snapshot of three of the most common types of features seen on the asteroid: craters whose rims have been rounded by erosion due to smaller impacts and blanketing by the impact debris, or regolith (impact debris); variations in the brightness of material on the walls of the craters; and a scattering of boulders ranging in size from nearly 100 meters (328 feet) down to about 8 meters (26 feet).
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Saturn-PIA06164-br500.jpgSaturn, Titan and Mimas in real colors59 visiteCaption NASA originale:"From its station nearly 1,2 BKMs (or 746 MMs) from Earth, the stalwart Cassini spacecraft sends holiday greetings to Earth with this lovely color portrait of Saturn and two of its moons. This color portrait serves as reminder of the Saturnian places we have already seen and the promise of future discovery at Titan when the European Space Agency's Huygens probe arrives at Titan on Jan. 14, 2005. A grayish, oval-shaped storm is visible in Saturn's southern hemisphere and is easily 475 Km across - the size of some hurricanes on Earth. Titan is visible near lower right with its thick, orange-colored atmosphere, and faint Mimas (398 Km across) appears just right of the rings' outer edge. Images taken in the red, green and blue filters with the Cassini spacecraft wide angle camera on Dec. 14, 2004, were combined to create this color view at a distance of approximately 719.000 Km from Saturn. The image scale is 43 Km (or 27 miles) per pixel".
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Japetus-N00026243.jpgJapetus (and the "Pentagon") from about 180.000 Km (3)59 visitenessun commento
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SOL351-2P157533938EFFA269P2587L7M1.jpgRocks...59 visiteL'apparenza, spesso, inganna.
Il titolo di una fotografia, infatti, deve riflettere, in pochissime parole (3 o 4, al massimo) il contenuto ed i temi che l'immagine mostra ed affronta, facendo capire al Lettore di che cosa si andrà a parlare e, se possibile, incuriosendolo anche un pò.
"Pietre", in questo caso, ci è parsa la soluzione migliore, ma quello che vediamo in questo frame non è solo un gruppo di rocce dalle forme strane e dalle dimensioni variabili. Osservate bene: tutte le pietre che vedete (specialmente quelle più grandi, che risultano più semplici da studiare), ad un'analisi (purtroppo solo) visuale, risultano molto simili a quelle che, sulla Terra, si trovano in prossimità dei fiumi. Sono pietre che recano addosso le tracce inconfondibili dell'incessante attività dell'acqua: una percepibile porosità ed i lineamenti smussati ed addolciti. Questo, almeno, è quello che vediamo noi...
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Japetus-temp.1-PIA07006_modest.jpgJapetus Temperature Variation Map59 visiteCaption NASA originale:"This plot shows how daytime temp.s at low latitudes on the Dark Material on Japetus vary with time of day from about 130 Kelvin (-226 F) at noon to about 70 Kelvin (-334 F) at sunset. The observations are compared to a "forecast" model (green line) which predicts temperatures based on an assumed value of a parameter called the "thermal inertia. Rock or solid ice has a high thermal inertia (approx. 2.000.000 as measured in the obscure units used for thermal inertia), meaning that it is good at storing heat and cools down or heats up relatively slowly. On Japetus, in contrast, temperatures drop precipitously in the afternoon as the Sun sinks towards the horizon and a very small value of the thermal inertia (30.000 units) is needed in the model to match the data. This means that Japetus's surface is extremely bad at storing heat and is thus extremely fluffy, probably due to the pulverizing effect of billions of years of meteorite impacts (...)".
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Japetus-PIA07002_modest.jpgJapetus' surface composition (organic material?!?)59 visiteCaption NASA originale:"The three colors used in the mosaic correspond to 1.01, 3.21, and 3.80 microns. The different colors represent vastly different surface compositions. The upper bright blue region is rich in water ice, while the lower, dark brown region is composed mainly of a substance rich in organic material. The yellow region consists of a mixture of ice and organics, suggesting a gradual change in composition on the surface. This pattern suggests Iapetus swept up the dark material, which may have come from debris created from meteoritic impacts onto the small, outer satellites of Saturn".
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Triton-PIA00317_modest.jpgTriton (False Colors; credits: NASA/JPL/USGS)59 visiteCaption NASA originale:"The color was synthesized by combining HR images taken through orange, violet and ultraviolet filters; these images were displayed as red, green and blue images and combined to create this color version. With a radius of 1.350 Km, about 22% smaller than Earth's Moon, Triton is by far the largest satellite of Neptune. It is 1 of only 3 objects in the Solar System known to have a nitrogen-dominated atmosphere (the others are Earth and Saturn's giant moon, Titan). Triton has the coldest surface known anywhere in the Solar System (38 K, about -391 degrees F); it is so cold that most of Triton's nitrogen is condensed as frost, making it the only satellite in the Solar System known to have a surface made mainly of nitrogen ice. The pinkish deposits constitute a vast south polar cap believed to contain methane ice, which would have reacted under sunlight to form pink or red compounds. The dark streaks overlying these pink ices are believed to be an icy and perhaps carbonaceous dust deposited from huge geyser-like plumes, some of which were found to be active during the Voyager 2 flyby. The bluish-green band visible in this image extends all the way around Triton near the equator; it may consist of relatively fresh nitrogen frost deposits. The greenish areas includes what is called the cantaloupe terrain, whose origin is unknown, and a set of "cryovolcanic" landscapes apparently produced by icy-cold liquids (now frozen) erupted from Triton's interior".
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