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| Piú viste - Saturn: the "Ringed Beauty" and His Moons |
Prometheus-PIA10593.jpgStreamer Channel (Natural Colors; credits: Lunar Explorer Italia)67 visiteCaption NASA:"Half an hour after Prometheus tore into this region of Saturn's F -Ring, the Cassini Spacecraft snapped this image just as the moon was creating a new Streamer in the Ring. The dark pattern shaped like an upside down check mark in the lower left of the image is Prometheus and its shadow.
The potato shaped moon can just be seen coming back out of the Ring. The moon's handiwork also is apparent in 2 previous Streamer-Channel formations on the right of the image. The darkest Streamer-Channel stretching from the top right to the center of the image shows Prometheus' previous apoapse passage about 15 hours earlier. A fainter, even earlier channel extends to the edge of the image.
Prometheus (about 86 Km, or approx. 53 miles across) dips into the inner edge of the F-Ring when it reaches apoapse, the moon's farthest orbital point from Saturn. At apoapse, the moon's gravity pulls particles of the ring outward into a streamer.
As Prometheus moves onward toward periapse — its orbit's closest point to the Planet — the Streamer gets longer. Then, as Prometheus moves back toward apoapse, the Streamer breaks apart which results in a dark channel.
This Streamer-Channel cycle repeats once every orbit with the Streamer-Channel features being streamers during Prometheus periapse and channels during Prometheus apoapse. The F-Ring is overexposed in this image which has been brightened to reveal the moon.
This view looks toward the unilluminated side of the Rings from about 18° above the Ring-Plane. The image was taken in Visible Light with the Cassini Spacecraft narrow-angle camera on Jan. 14, 2009.
The view was obtained at a distance of approx. 555.000 Km (345.000 miles) from Saturn and at a Sun-Saturn-Spacecraft, or Phase, Angle of 145°.
Image scale is roughly 3 Km (a little less than 2 miles) per pixel".MareKromium
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Saturn-PIA11473.jpgThe Northern Region of Saturn (Natural Colors; credits: NASA/JPL/Space Science Institute)67 visiteCaption NASA:"Saturn's Northern Hemisphere is seen here against its nested Rings.
This view from the Cassini Spacecraft looks toward the unilluminated side of the Rings from about 30° above the Ring-Plane. The rings have been brightened relative to the Planet to enhance visibility.
Images taken using red, green and blue spectral filters were combined to create this Natural Color view.
The images were acquired with the Cassini Spacecraft wide-angle camera on Feb. 24, 2009 at a distance of approx. 866.000 Km (about 538.000 miles) from Saturn.
Image scale is roughly 38 Km (about 24 miles) per pixel".MareKromium
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Saturn-PIA11493.jpgBetween Day and Night... (Natural Colors; credits: NASA/JPL/Space Science Institute)67 visiteCaption NASA:"Rays of light from the Sun have taken many different paths to compose this glorious image of Saturn and its Rings.
This view looks toward the unilluminated (North) side of the Rings and, at the top of the image, the night side of Saturn. Sunlight has been reflected off the illuminated side of the Rings to light the Planet's Southern Hemisphere, seen here as a bright band of yellow-orange.
The Northern Hemisphere, in the top left corner of the image, is dimly lit by light diffusely scattered through the rings. The Planet's shadow cuts across the Rings, but light reflected off the Southern Hemisphere backlights parts of the C-Ring, making them visible in silhouette. Bright points of light in the image are stars occulted by the Rings.
This view looks toward the unilluminated side of the Rings from about 41° above the Ring-Plane. Images taken using red, green and blue spectral filters were combined to create this Natural Color view. The images were acquired with the Cassini Spacecraft wide-angle camera on March 20, 2009 at a distance of approx. 892.000 Km (such as about 554.000 miles) from Saturn.
Image scale is roughly 50 Km (about 31 miles) per pixel".MareKromium
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Japetus-EB.gifJapetus, like a "True Star"! (GIF-Movie; credits: Elisabetta Bonora - Lunexit Team)67 visitenessun commentoMareKromium
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Helene-EB.jpgIn front of the Giant... (Natural Colors; credits: Elisabetta Bonora - Lunexit Team)67 visitenessun commentoMareKromium
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Saturn-PIA12825.jpgSaturnian Storm (False Colors; credits: NASA/JPL-Caltech/Space Science Institute)67 visiteCaption NASA:"These false-color images from NASA's Cassini Spacecraft chronicle a day in the life of a huge storm that developed from a small spot that appeared 12 weeks earlier in Saturn's Northern Mid-Latitudes.
This storm is the largest and most intense observed on Saturn by NASA's Voyager or Cassini Spacecraft. The storm is still active. As seen in these and other Cassini images, the storm encircles the Planet - whose circumference at these latitudes is approx. 186.000 miles (about 300.000 Km).
From North to South, it covers a distance of about 9000 miles (approx. 15.000 Km), which is one-third of the way around the Earth. It encompasses an area of about 1,5 BSMs (Billion Square Miles - such as approx. 4 BSKM), or eight times the surface area of Earth. This storm is about 500 times the area of the biggest of the Southern Hemisphere storms observed by Cassini.
The highest clouds in the image are probably around 100 millibars pressure, or 60 miles (approx. 100 Km) above the regular undisturbed clouds. These false colors show clouds at different altitudes. Clouds that appear blue here are the highest and are semitransparent, or optically thin. Those that are yellow and white are optically thick clouds at high altitudes. Those shown green are intermediate clouds. Red and brown colors are clouds at low altitude unobscured by high clouds, and the deep blue color is a thin haze with no clouds below. The base of the clouds, where lightning is generated, is probably in the water cloud layer of Saturn's Atmosphere. The storm clouds are likely made out of Water Ice covered by crystallized Ammonia.
Taken about 11 hours -- or one Saturn day -- apart, the two mosaics in the lower half of this image product consist of 84 images each. The mosaic in the middle was taken earlier than the mosaic at the bottom. Both mosaics were captured on Feb. 26, 2011, and each of the two batches of images was taken over about 4,5 hours.
Two enlargements from the earlier, middle mosaic are shown at the top of this product. The white lines below the middle mosaic identify those parts of the mosaic that were enlarged for these close-up views. The enlargement on the top left shows the head of the storm, and that on the top right shows the turbulent middle of the storm. Cassini observations have shown the head of the storm drifting West at a rate of about 2,8° of Longitude each Earth day (28 meters per second, or 63 miles per hour). The central latitude of the storm is the site of a Westward jet, which means that the clouds to the North and South are drifting Westward more slowly or even drifting eastward. In contrast, clouds at Saturn's Equator drift Eastward at speeds up to 450 meters per second (about 1000 miles per hour).
Both of the long mosaics cover an area ranging from about 30° to 51° North Latitude. The views stretch from about 138° (on the left) to 347° West Longitude (on the right), passing through 360/0° West Longitude near the far right of the mosaics.
The images were taken with the Cassini Spacecraft narrow-angle camera using a combination of spectral filters sensitive to wavelengths of Near-InfraRed light. The images filtered at 889 nanometers are projected as blue. The images filtered at 727 nanometers are projected as green, and images filtered at 750 nanometers are projected as red.
The views were acquired at a distance of approx. 1,5 MMs (such as about 2,4 MKM) from Saturn and at a Sun-Saturn-Spacecraft Angle (i.e.: Phase Angle) of 62°. Both the top and bottom images are simple cylindrical map projections, defined such that a square pixel subtends equal intervals of Latitude and Longitude. At higher Latitudes, the pixel size in the North-South direction remains the same, but the pixel size in the East-West direction becomes smaller. The pixel size is set at the Equator, where the distances along the sides are equal. The images of the long mosaics have a pixel size of 33 miles (53,108 Km) at the Equator, and the two close-up views have a pixel size of 6 miles (9,656 Km) per pixel at the equator".MareKromium
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Saturn-North_Pole-PIA14945-PCF-LXTT-IPF.jpgNorth Polar Spring (Absolute Natural Colors; credits for the additional process. and color.: Dr Paolo C. Fienga/Lunar Explorer Italia/Italian Planetary Foundation)67 visiteThe North Pole of the Gas-Giant Planet Saturn, now illuminated by the fresh lights of the incoming Spring, is finally revealed in this image taken by the NASA - Cassini Spacecraft on November 27, 2012. As you know, the North Pole of Saturn has been hiding for a long time from the gaze of the Cassini's Imaging Cameras, and that circumstance was due to the fact that it was still Wintertime in (and therefore a deep darkness all over) the Northern Hemisphere of the Ringed Planet when the Spacecraft arrived in the Saturnian System in the AD 2004.
A Hurricane-like Storm circling Saturn's North Pole at about 89° North Latitude is also well visible inside the famous "Hexagon" Feature, which scientists think is a wandering Jet-Stream that whips around the North Pole of Saturn at a relatively constant mean speed of about 220 miles per hour (such as a little more than 354 Km per hour). Such a Jet-Stream it is folded into a six-sided shape because the Hexagon is a Stationary Wave that guides the path of the Gases existing inside the Jet itself. The Hexagon borders occur at about 77° North Latitude and the Feature is wider than two (flat) Earths. Last, but not least, a little section of the Rings of Saturn can also be seen in the upper right corner of the image.
This frame was acquired with the NASA - Cassini Spacecraft Wide-Angle Camera at a distance of approximately 260.000 miles (such as a little more than 418.000 Km) from the top of the Saturnian Clouds and at a Sun-Saturn-Cassini Spacecraft, or Phase, Angle of 96°. Image scale is roughly 18 miles (such as 28,968 Km) per pixel. For another image of the Hexagon and the Hurricane-like Storm that encircles the North Pole of Saturn, please refer to the APOD of December, 29, 2012.
This frame (which is a NASA - CASSINI Spacecraft Original Natural Color frame published on the NASA - Planetary Photojournal and identified by the serial n. PIA 14945) has been additionally processed, magnified, contrast enhanced and then re-colorized, according to an educated guess carried out by Dr Paolo C. Fienga (LXTT-IPF), in Absolute Natural Colors (such as the colors that a human eye would actually perceive if someone were onboard the NASA - Cassini Spacecraft and then looked outside, towards the North Pole of Satun), by using an original technique created - and, in time, dramatically improved - by the Lunar Explorer Italia Team. Different colors, as well as different shades of the same color, mean, among others, the existence of different Elements in the Upper Atmosphere of Satun, each having a different Albedo (---> Reflectivity) and Chemical Composition.MareKromium
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PHOEBE-PIA06072_modest.jpgPhoebe's Overview (1)66 visitenessun commento
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Atlas from appx. 23.685.000.jpgAtlas from approx. 23.685.000 Km66 visitenessun commento
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Japetus-PIA06521_modest.jpgThe "dark side" of Japetus66 visiteCaption NASA originale: "This image shows the dark, leading hemisphere of the mysterious moon Iapetus. The dark area is the Cassini region, named for Giovanni Cassini, who discovered the moon in 1672. The diameter of Iapetus is of approx. 1,436 Km (892 miles).
Cassini noted that he was able to see the moon on one side of its orbit around Saturn, but not on the other side. From this, he correctly deduced that one hemisphere must be dark while the other is much brighter".
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Enceladus-N00028182.jpgEnceladus: from VERY close! (2)66 visiteIn questa seconda immagine del Fly-by della Sonda Cassini su Encelado possiamo vedere, sul lato Sx del frame, a ridosso di un grande crepaccio che descrive un ampio arco di circonferenza (ed in apertissima contrapposizione rispetto al panorama che invece caratterizza il lato Dx dell'immagine: cioè un'area della superficie Enceladiana TOTALMENTE ricoperta da solchi, canali e crepacci), un vero e proprio "crater cluster", ossìa un "ammasso di crateri".
Questo 'crater cluster' costituisce la prova indelebile (o quasi...) di un'intensa e ravvicinata attività di bombardamento meteorico la quale ebbe ad interessare Encelado in epoche (molto probabilmente) assai remote.
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Japetus-A-W-Deathstar-16a.jpgThe "Pentagon" of Japetus66 visiteAl momento dell'impatto, la superficie di Giapeto (o della Luna, o di qualsiasi altro pianeta) si fonde, in ragione del calore viene sprigionato in quei momenti e la meteora, letteralmente, compie una sorta di 'splash-down' nel "corpo" del pianeta colpito (guardate cosa succede quando una goccia d'acqua cade nell'acqua...). La crosta fusa che viene proiettata verso l'alto a seguito dell'urto, viste le temperature del "deep space", solidifica in pochissimo tempo e così, quello che rimane dopo l'impatto, è una "colonna di roccia", tanto più alta quanto maggiore fu il quantitativo di crosta fusa che venne sollevato. Teoria credibile? Forse si e forse no, ma questo è l'approccio scientifico al problema! Continuiamo: guardate questo gigantesco rilievo montuoso posto a ridosso dell'equatore di Giapeto. Esso è fatto di colline, montagne, crateri e crepacci. Tutti rilievi naturali, eppure...Eppure non sembra che esso disegni un pentagono? E' anche questo un rilievo naturale e scientificamente spiegabile?
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