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Saturn: the "Ringed Beauty" and His Moons
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Saturn-PIA11649.jpgOut of the Darkness...56 visiteCaption NASA:"Dramatic differences between dark and light embellish this Cassini Spacecraft image of Saturn, its rings and its moons Dione and Enceladus.
Saturn's Northern and Southern Latitudes appear dark in this image because of the camera filter used. This view uses a spectral filter sensitive to absorption of certain wavelengths of light by Methane in Saturn's Atmosphere. The cloud tops in the Northern and Southern Latitudes are at a slightly greater depth than in the Equatorial Region, and are underneath a layer of Methane. This means that light travels along a longer path compared to the Equatorial Region as it enters the Atmosphere, reflects off the cloud tops, and returns through the Upper Atmosphere to enter the camera.
The light at Near-InfraRed wavelengths thus passes through more light-absorbing Methane at the Northern and Southern Latitudes than at the Equator, and so these Latitudes appear darker.
Dione (approx 1123 Km, or about 698 miles across) can be seen on the left of the image. Enceladus (approx. 504 Km, or about 313 miles across) is visible on the right.
This view looks toward the Northern, sunlit side of the Rings from just above the Ring-Plane.
The image was taken with the Cassini Spacecraft wide-angle camera on Oct. 21, 2009 using a spectral filter sensitive to wavelengths of Near-InfraRed Light centered at 890 nanometers. The view was obtained at a distance of approx. 2,5 MKM (such as about 1,6 MMs) from Saturn and at a Sun-Saturn-Spacecraft, or Phase, Angle of 104°.
Image scale is roughly 143 KM (such as about 89 miles) per pixel".MareKromium
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Saturn-PIA11667.jpgThe Lord of the Rings (Natural Colors; credits: NASA/JPL/Space Science Institute)56 visiteCaption NASA:"Of the countless Equinoxes Saturn has seen since the birth of the Solar System, this one, captured here in a mosaic of light and dark, is the first witnessed up close by an emissary from Earth … none other than our faithful robotic explorer, Cassini.
Seen from our planet, the view of Saturn’s Rings during Equinox is extremely foreshortened and limited. But in orbit around Saturn, Cassini had no such problems. From 20° above the Ring-Plane, Cassini’s wide angle camera shot 75 exposures in succession for this mosaic showing Saturn, its Rings, and a few of its moons a day and a half after exact Saturn Equinox, when the Sun’s disk was exactly overhead at the Planet’s Equator.
The novel illumination geometry that accompanies equinox lowers the Sun’s angle to the Ring-Plane, significantly darkens the Rings and causes out-of-plane structures to look anomalously bright and to cast shadows across the Rings themselves.
These scenes are possible only during the few months before and after Saturn’s Equinox which occurs only once in about 15 Earth years.
Before and after Equinox, Cassini’s cameras have spotted not only the predictable shadows of some of Saturn’s moons (see also PIA11657), but also the shadows of newly revealed vertical structures in the Rings (see, for example, PIA11665).
Also at Equinox, the shadows of the Planet’s expansive Rings are compressed into a single, narrow band cast onto the Planet as seen in this mosaic. (For an earlier view of the Rings’ wide shadows draped high on the Northern Hemisphere, see PIA09793)
The images comprising the mosaic, taken over about eight hours, were extensively processed before being joined together. First, each was re-projected into the same viewing geometry and then digitally processed to make the image “joints” seamless and to remove lens flares, radially extended bright artifacts resulting from light being scattered within the camera optics.
At this time so close to Equinox, illumination of the Rings by sunlight reflected off the planet vastly dominates any meager sunlight falling on the Rings. Hence, the half of the Rings on the left illuminated by planetshine is, before processing, much brighter than the half of the Rings on the right. On the right, it is only the vertically extended parts of the Rings that catch any substantial sunlight.
With no enhancement, the Rings would be essentially invisible in this mosaic. To improve their visibility, the dark (right) half of the Rings has been brightened relative to the brighter (left) half by a factor of three, and then the whole Ring System has been brightened by a factor of 20 relative to the Planet. So the dark half of the rings is 60 times brighter, and the bright half 20 times brighter, than they would have appeared if the entire System, Planet included, could have been captured in a single image.
The moon Janus (about 179 Km, or approx. 111 miles across) is on the lower left of this image. Epimetheus about (113 Km, or approx. 70 miles across) appears near the middle bottom. Pandora (about 81 Km, or approx. 50 miles across) orbits outside the Rings on the right of the image. The small moon Atlas (about 30 Km, or approx. 19 miles across) orbits inside the thin F-Ring on the right of the image.
The brightnesses of all the moons, relative to the Planet, have been enhanced between 30 and 60 times to make them more easily visible. Other bright specks are background stars. Spokes -- ghostly radial markings on the B ring -- are visible on the right of the image.
This view looks toward the northern side of the Rings from about 20° above the Ring-Plane.
The images were taken on Aug. 12, 2009, beginning about 1,25 days after exact equinox, using the red, green and blue spectral filters of the wide angle camera and were combined to create this Natural Colors view.
The images were obtained at a distance of approx. 847.000 Km (about 526.000 miles) from Saturn and at a Sun-Saturn-Spacecraft, or Phase, Angle of 74°.
Image scale is roughly 50 Km (about 31 miles) per pixel".
Nota Lunexit: una interpretazione in Colori Naturali davvero stupenda, per qualità, definizione e realismo. Una prova evidente che i lavori "brutti" (e cioè il 99% dei prodotti fotografici a colori riguardanti Marte) la NASA non li fa perchè "non è capace" (ovviamente), ma solo perchè "non vuole farli com sa fare".
Il motivo? Beh, certo non è "pigrizia" (anche se non si può mai dire)...MareKromium
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Saturn-PIA11832.jpgSaturnian Aurora55 visiteCaption NASA:"Glowing like a neon lasso, Saturn’s Aurora is seen spinning above Saturn’s North Pole over the course of most of a Saturn day in this image taken by the ultraviolet imaging spectrograph on NASA’s Cassini Spacecraft.
Saturn’s auroral lights are the result of a rain of electrically charged particles from the magnetic bubble, called the Magnetosphere, that surrounds the Planet.
When the particles strike gaseous Hydrogen in Saturn’s Atmosphere, the Hydrogen becomes excited and glows, creating Aurorae. Neon signs work in a similar way: electricity is used to excite a gas, usually Neon or Argon, in a tube.
Changes that occur in Saturn’s Magnetosphere can cause fluctuations in the Aurora. Undulations in the Aurora may be caused by waves moving along magnetic field lines.
A surge in auroral brightness is the result of a sudden injection of particles into the Magnetosphere. These charged particles come from a variety of sources, including the Sun, Saturn’s Rings, and the water ice plume of Saturn’s moon Enceladus.
This image was taken on May, 25th, 2007.
Saturn's Aurorae were discovered by NASA’s Pioneer 11 Spacecraft in 1979 and observed in the Saturn flybys by the NASA Voyager 1 and 2 Spacecrafts in the early '80s. NASA’s Hubble Space Telescope first obtained images of an Aurora in 1994. From Cassini’s always-changing orbit around Saturn, fresh observations in UltraViolet and InfraRed wavelengths are being combined with other data to help characterize similarities and differences among the Aurorae of Saturn, Jupiter and Earth". MareKromium
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Saturn-PIA12318.jpgCosmic Vision (Natural Colors; credits: NASA/JPL/Space Science Institute)56 visiteCaption NASA:"Looking cool and serene, Saturn shares its soft glow with Cassini. This view of Saturn, its Rings and the moon Tethys represents "Target 1" in the fall 2009 edition of the Cassini Scientist for a Day contest.
(See http://saturn.jpl.nasa.gov/education/scientistforaday8thedition/.) The contest is designed to give students a taste of life as a scientist by challenging them to write an essay describing the value of one target choice among three for Cassini to image.
A bonus feature in the image is the presence of bright Spokes on and just above the ansa, or curved edge of the darkened Ring-Plane. The Spokes are made visible here by sunlight scattering through the dust-sized icy particles and toward Cassini's cameras.
Images taken using red, blue and green spectral filters were combined to create this color view.
The images were acquired with the Cassini wide-angle camera on Oct. 11, 2009 at a distance of approx. 1,7 MKM (a little more than 1 MMs) from Saturn".
Nota Lunexit: la dizione "Natural" l'abbiamo aggiunta noi, dato che la NASA - curiosamente - parla solo di "Color View" (insomma, adesso non fanno più nemmeno la fatica di dirci se si tratta di Natural, Approximate True, True e/o False Colors...bah!).MareKromium
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Saturn-PIA12513.jpgCrescent Saturn (Natural Colors; credits: NASA/JPL/Space Science Institute)55 visiteCaption NASA:"Saturn, stately and resplendent in this Natural Color view, dwarfs the icy moon Rhea.
Rhea orbits beyond the Rings on the right of the image. The moon Tethys is not shown here, but its shadow is visible on the Planet on the left of the image. This view looks toward the Northern, sunlit side of the Rings from just above the Ring-Plane.
Images taken using red, green and blue spectral filters were combined to create this Natural Color view. The images were obtained with the Cassini Spacecraft wide-angle camera on Nov. 4, 2009 at a distance of approx. 1,3 MKM (about 808.000 miles) from Saturn.
Image scale is roughly 72 Km (about 45 miles) per pixel".MareKromium
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Saturn-PIA12533.jpgEternal Vision (Natural Colors; credits: NASA/JPL/Space Science Institute)56 visiteCaption NASA:"A pastel crescent of Saturn is interrupted by the moon Mimas and the Rings in this color image.
Mimas (approx. 396 Km - or about 246 miles across) appears as a dark speck just above the Rings.
This view looks toward the Northern, sunlit side of the Rings, from just above the Ring-Plane.
Images taken using red, green and blue spectral filters were combined to create this Natural Color view. The images were obtained with the Cassini Spacecraft wide-angle camera on Oct. 27, 2009 at a distance of approx. 2,2 MKM (such as about 1,4 MMs) from Saturn.
Image scale is roughly 129 Km (approx. 80 miles) per pixel".MareKromium
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Saturn-PIA12721-PCF-LXTT.jpgThe "Oily Clouds" of Saturn (Natural Colors; credits for the additional process. and color.: Dr Paolo C. Fienga - Lunexit Team)94 visiteCaption NASA:"Clouds in Saturn's Upper Atmosphere create an intricate pattern reminiscent of whipped cream swirling in coffee. The view is centered on a region located about 15° South of the Planet's Equator. The image was taken with the Cassini Spacecraft narrow-angle camera on July 18, 2010 using a spectral filter sensitive to wavelengths of Near-InfraRed light centered at 727 nanometers.
The view was obtained at a distance of approx. 2,4 MKM (abput 1,5 MMs) from Saturn and at a Sun-Saturn-Spacecraft angle of 107°.
Image scale is roughly 14 Km (a little less than 9 miles) per pixel".MareKromium
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Saturn-PIA12824.jpgSaturnian Storm (Natural Colors; credits: NASA/JPL-Caltech/Space Science Institute)67 visiteCaption NASA:"The huge storm churning through the Atmosphere in Saturn's Northern Hemisphere overtakes itself as it encircles the Planet in this Natural Colors view from NASA's Cassini Spacecraft.
This picture, captured on Feb. 25, 2011, was taken about 12 weeks after the storm began, and the clouds by this time had formed a tail that wrapped around the Planet. Some of the clouds moved south and got caught up in a current that flows to the East (to the right) relative to the storm head. This tail, which appears as slightly blue clouds South and West (left) of the storm head, can be seen encountering the storm head in this view.
This storm is the largest, most intense storm observed on Saturn by NASA's Voyager or Cassini Spacecraft. It is still active today. As scientists have tracked this storm over several months, they have found it covers 500 times the area of the largest of the Southern Hemisphere storms observed earlier in the Cassini Mission (see PIA06197).
The shadow cast by Saturn's Rings has a strong seasonal effect, and it is possible that the switch to powerful storms now being located in the Northern Hemisphere is related to the change of seasons after the Planet's August 2009 Equinox.
Huge storms called Great White Spots have been observed in previous Saturnian years (each of which is about 30 Earth years), usually appearing in late Northern Summer. Saturn is now experiencing early Northern Spring, so this storm, if it is a Great White Spot, is happening earlier than usual. This storm is about as large as the largest of the Great White Spots, which also encircled the planet but had latitudinal sizes ranging up to approx. 20.000 Km (roughly 12.000 miles). The Voyager and Cassini Spacecrafts were not at Saturn for previous Great White Spot appearances.
The storm is a prodigious source of radio noise, which comes from lightning deep in the Planet's Atmosphere. The lightning is produced in the water clouds, where falling rain and hail generate electricity. The mystery is why Saturn stores energy for decades and releases it all at once. This behavior is unlike that at Jupiter and Earth, which have numerous storms going on at all times.
This view looks toward the sunlit side of the Rings from just 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 at a distance of approx. 1,4 MMs (such as about 2,2 MKM) from Saturn. Image scale is roughly 80 miles (128,7472 Km) per pixel".MareKromium
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Saturn-PIA12825.jpgSaturnian Storm (False Colors; credits: NASA/JPL-Caltech/Space Science Institute)66 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-PIA12826.jpgSaturnian Storm (Natural Colors; credits: NASA/JPL-Caltech/Space Science Institute)70 visitenessun commentoMareKromium
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Saturn-PIA14119.jpgLarge Ammonia Crystals in Saturn Storm (False Colors; credits: NASA/JPL-University of Arizona)66 visiteCaption NASA:"This false-color InfraRed image, obtained by NASA's Cassini Spacecraft, shows clouds of large Ammonia ice particles dredged up by a powerful storm in Saturn's Northern Hemisphere. Large updrafts dragged Ammonia gas upward more than 30 miles (approx. 50 Km) from below. The Ammonia then condensed into large crystals in the frigid Upper Atmosphere. This storm is the most violent ever observed at Saturn by an orbiting Spacecraft.
Cassini's Visual and InfraRed Mapping Spectrometer obtained these images on Feb. 24, 2011. Scientists colorized the image by assigning red to brightness detected from the 4.08-micron wavelength, green to brightness from the 0.90-micron wavelength, and blue to brightness from the 2.73-micron wavelength. Large particles (red) reflect Sunlight well at 4.08 microns. Particles at high altitude (green) reflect Sunlight well at 0.9 microns. Particles comprised of Ammonia -- especially large ones -- do not reflect 2.73-micron sunlight well, but instead absorb light at this wavelength.
The storm here shows up as yellow, demonstrating that it has a large signal in both red and green colors. This indicates the cloud has large particles and extends upward to relatively high altitude. In addition, the lack of blue in the feature indicates that the storm cloud has a substantial component of Ammonia Crystals. The head of the storm is particularly rich in such particles, as created by powerful updrafts of Ammonia gas from depth in the throes of Saturn's thunderstorm".MareKromium
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Saturn-PIA14656-PCF-LXTT-IPF.jpgThe restless Saturnian Atmosphere (Absolute Natural Colors; credits for the additional process. and color.: Dr Paolo C. Fienga/Lunar Explorer Italia/Italian Planetary Foundation)102 visiteThe always richly dynamic Atmosphere of Saturn rewards - once again - its observers by showing unique and fascinating (even though just temporary) Cloud Structures and Formations. Here, the NASA - Cassini Spacecraft used the Near-InfraRed filters on its Wide-Angle Camera to get a better look at some of Saturn's Cloud Patterns, which are continuously shaped (and re-shaped, restlessly) by the powerful Winds and Storms that keep blowing and forming, respectively, in the Upper Atmosphere of the ringed Gas-Giant Planet.
The view is centered at 30° North Latitude and 42° West Longitude; North is up and rotated 44° to the right. The image was taken with the NASA - Cassini Spacecraft Wide-Angle Camera on December 24, 2012, using a spectral filter sensitive to wavelengths of Near-InfraRed Light centered at 752 nanometers. The image was acquired at a distance of approximately 440.000 miles (such as about 708.000 Km) from the top of Saturn's Clouds and at a Sun-Saturn-CASSINI Spacecraft, or Phase, Angle of 14°. Image scale is roughly 26 miles (such as 41,84 Km) per pixel.
This picture (which is an Original NASA - Cassini Spacecraft b/w frame published on the NASA - Planetary Photojournal and identified by the n. PIA 14656) has been additionally processed and then 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 Gas-Giant Planet Saturn), 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 present in the Upper Atmosphere of Saturn, each having a different Albedo (---> Reflectivity) and Chemical Composition.
Note: it is possible (but we, as IPF, have no way to be one-hundred-percent sure of such a circumstance), that the actual luminosity of the Clouds and Hazes (as well as the luminosity of Saturn itself) seen in this frame would appear, to an average human eye, way lower than it has been shown (or, better yet: interpreted) here.MareKromium
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