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Propeller-PIA11672-b.jpgGiant "Propeller" in the A-Ring (EDM)55 visiteIt has since become a growing realization resulting from Cassini’s exploration of Saturn that the objects forming Saturn’s Rings very likely span the full spectrum of sizes, from the smallest dust-sized ring particles to the ring-moons like Daphnis and 29-Km-wide (18-mile-wide) Pan - a significant advance in divining the origin of Saturn’s Rings.
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 cast long shadows across the Rings. (The Rings have been brightened in this image to enhance visibility)
These scenes are possible only during the few months before and after Saturn’s Equinox which occurs only once in about 15 Earth years.
This view looks toward the Northern Side of the Rings from about 20° above the Ring-Plane.
The image was taken in Visible Light with the Cassini Spacecraft narrow-angle camera on Aug. 13, 2009.
This view was acquired at a distance of approx. 1,2 MKM (about 746.000 miles) from Saturn and at a Sun-Saturn-Spacecraft, or Phase, Angle of 87°.
Image scale is roughly 7 Km (about 4,5 miles) per pixel.MareKromium
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OPP-SOL0235.jpgSharp Rocks - Sol 235 (credits: Dr M. Faccin)55 visitenessun commentoMareKromium
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OPP-SOL0206.jpgDeep Rover Tracks - Sol 206 (by Dr M. Faccin)55 visitenessun commentoMareKromium
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Saturn-PIA11667.jpgThe Lord of the Rings (Natural Colors; credits: NASA/JPL/Space Science Institute)55 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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PIA12200.jpgRadar Mapping of Icy Layers Under Mars' North Pole55 visiteThis composite graphic illustrates the use of the Shallow Radar instrument on NASA's Mars Reconnaissance Orbiter for mapping underground ice-rich layers of the North Polar Layered Deposits existing on the North Pole of Mars.
The picture on top of the image-composite, is a radargram from the instrument, showing a cross-section of Mars' North Polar Cap, based on time lags of radio-wave echoes returning from different layers.
The penetrating radar reveals icy layered deposits overlying a basal unit in some areas.
The vertical dimension in the cross section is exaggerated one-hundred-fold compared with the horizontal dimension. The vertical scale bar is one kilometer (3281 feet).
The horizontal scale bar is 100 Km (62 miles).
The Shallow Radar instrument was provided by the Italian Space Agency. Its operations are led by the University of Rome and its data are analyzed by a joint U.S.-Italian science team. NASA's Jet Propulsion Laboratory, a division of the California Institute of Technology in Pasadena, manages the Mars Reconnaissance Orbiter for the NASA Science Mission Directorate, Washington. Lockheed Martin Space Systems, Denver, is the prime contractor for the project and built the spacecraft. The High Resolution Imaging Science Experiment is operated by the University of Arizona, Tucson, and the instrument was built by Ball Aerospace & Technologies Corp., Boulder, Colo.
MareKromium
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SubsurfaceIce-PIA12220.jpgMaterial excavated by a "Fresh Impact" is identified as Water Ice (Natural Colors; credits: Lunexit)55 visiteThe bright material conspicuous in this image was excavated from below the Surface and deposited nearby by a 2008 impact that dug a crater about 8 meters (26 feet) in diameter.
The extent of the bright patch was large enough for the Compact Reconnaissance Imaging Spectrometer for Mars, an instrument on NASA's Mars Reconnaissance Orbiter, to obtain information confirming the material to be water ice.
This image, covering an area 50 meters (164 feet) across, was taken on Nov. 1, 2008, by the High Resolution Imaging Science Experiment on the same Orbiter. The time frame for the crater-forming impact to have occurred was bracketed by before-and-after images (not shown) taken by the Thermal Emission Imaging System camera aboard NASA's Mars Odyssey Orbiter on Jan. 26, 2008, and by the Context Camera on the Mars Reconnaissance Orbiter on Sept. 18, 2008.
This Crater is at 55,57° North Latitude and 150,62° East Longitude (Vastitas Borealis Region). MareKromium
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SubsurfaceIce-PIA12218.jpgSubsurface Ice (Natural Colors; credits: Lunexit)55 visiteThis 6-meter-wide (20-foot-wide) Impact Crater located in Mid-Latitude Northern Mars was created by an impact that occurred between Jan. 22, 2008, and Sept. 15, 2008, as bracketed by before-and-after images (not shown here).
The images shown here were taken by the High Resolution Imaging Science Experiment camera on NASA's Mars Reconnaissance Orbiter on Oct. 29, 2008, (left) and on Jan. 4, 2009. Each image is about 35 meters (115 feet) across.
The crater's depth is estimated to be 1,76 meters (5,8 feet).
The impact that dug the Crater excavated water ice from beneath the Surface. It is the bright material visible in this pair of images. A change in appearance from the earlier image to the later one resulted from some of the ice sublimating away during the Northern-Hemisphere Summer, leaving behind dust that had been intermixed with the ice. The thickening layer of dust on top obscured some of the remaining ice.
This crater is at 45,05° North Latitude and 164,71° East Longitude.MareKromium
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The_Rings-PIA11587.jpgSpokes on the B-Ring55 visiteCaption NASA:"Saturn's B-Ring shows off bright Spokes in the middle of this image taken at high phase.
This image was captured at a Phase Angle of 119°. To learn more about these ghostly radial markings, see PIA10567 and PIA11144.
This view looks toward the northern, sunlit side of the Rings from about 10° above the Ring-Plane. The image was taken in Visible Light with the Cassini Spacecraft narrow-angle camera on Aug. 20, 2009. The view was acquired at a distance of approx. 2,3 MKM (such as about 1,4 MMs) from Saturn.
Image scale is roughly 13 Km (about 8 miles) per pixel".MareKromium
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The_Rings-PIA11674.jpgRocky-Rain on the Rings55 visiteCaption NASA:"The bright Streaks visible in these Cassini images taken during Saturn’s August 2009 Equinox are exciting evidence of a constant rain of interplanetary projectiles onto the Planet’s Rings.
Objects, each estimated to be one meter (3 feet) in size and traveling tens of kilometers per second (tens of thousands of miles per hour), likely smashed into the Rings and created elevated clouds of tiny particles that have been sheared out, or elongated and tilted, by orbital motion into bright streaks.
The image on the left shows an impact in the A-Ring. The Streak stretches from the right of the image to the middle, and it does not quite follow the arc of the Rings. The brightest part of that Streak is about 5000 Km (approx. 3100 miles) long (its azimuthal dimension) and about 200 Km (approx. 120 miles) wide (its radial extent, tip to tip) in this image.
The image on the right shows an impact into the C-Ring. This Streak is much smaller than the A-Ring Streak, and it appears on the right of the image. The brightest part of this Streak is approx. 200 Km (about 120 miles) long (its azimuthal dimension) and approx. 10 Km (about 6 miles) wide (its radial dimension, tip to tip) in this image.
By the brightness and dimensions of the Streaks, scientists estimate the impactor sizes at roughly one meter (3 feet), and the elapsed time since impact at one to two days. These Equinox data lend more confidence to a Cassini imaging observation made in 2005 of similar Streaks seen in the C-Ring (see PIA11675).
All together, these observations constitute the visual confirmation of a long-held belief that bits of interplanetary debris continually rain down on Saturn’s Rings and contribute to the Rings’ erosion and evolution.
Although the phase angle of these images is not the best for seeing clouds of small particles, these ejecta clouds are easily seen because very little sunlight is falling on the Rings during the exceedingly low Sun-angle condition prevalent during the four days surrounding exact Saturn Equinox.
Exact Equinox is when the sun is directly overhead at the Equator. A cloud of dust rising above the dark Ring-Plane is more directly catching the Sun’s rays, and is hence well lit and easily visible by contrast.
When the Ring background is at its usual brightness, impacts such as these are very difficult to detect.
The view of the A-Ring Streak on the left looks toward the northern side of the Rings from about 20° above the Ring-Plane. The image was taken in Visible Light with the Cassini Spacecraft narrow-angle camera on Aug. 13, 2009. The view was obtained at a distance of approx. 1,2 MKM (about 746.000 miles) from Saturn and at a Phase Angle of 87°.
Image scale is 7 kilometers (4 miles) per pixel.
The view of the C-Ring Streak on the right looks toward the southern side of the Rings from about 22° below the RingPlane. The image was taken in Visible Light with the Cassini Spacecraft narrow-angle camera on Aug. 11, 2009. The view was obtained at a distance of approx. 263.000 Km (about 164.000 miles) from Saturn and at a Phase Angle of 135°.
Image scale is roughly 1 Km (4007 feet) per pixel".MareKromium
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Craters-UnnamedCrater-Aonia_Terra-20091005a.jpgUnnamed Crater in Aonia Terra (False Colors; credits: Lunexit)55 visitenessun commentoMareKromium
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Titan-PIA11594.jpgNorthern Layers (UV + Natural Colors; credits: Lunexit)55 visiteCaption NASA:"This UltraViolet view of Titan shows the moon's North Polar "Hood" (---> cappuccio) and its detached, high-altitude haze layer. See also PIA08137 to learn more.
This view looks toward the Saturn-facing side of Titan.
North on Titan is up and rotated 2° to the left.
The image was taken with the Cassini Spacecraft narrow-angle camera on Aug. 13, 2009 using a spectral filter sensitive to wavelengths of UltraViolet Light centered at 338 nanometers. The view was acquired at a distance of approx. 2,2 MKM (about 1,4 MMs) from Titan and at a Sun-Titan-Spacecraft, or Phase, Angle of 61°.
Image scale is roughly 26 Km (about 16 miles) per pixel".MareKromium
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OPP-SOL2031-MF-LXT-ALLFILTERS-raw.jpgMetal v/s Metal - Sol 2031 (ALL Filters/RAW Natural Colors - credits: Dr M. Faccin)55 visitenessun commentoMareKromium
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