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The Sun-Eit002G_b.jpgOur "restless" Sun... (7)58 visitenessun commento
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The Sun-EIT99promcloseG.jpgOur "restless" Sun...and Us!58 visitenessun commento
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The Sun-Suncombo1G.jpgOur "restless" Sun... (10)58 visitenessun commento
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IC-1805~0.jpgIC 1805 (alias "The Heart Nebula")58 visite"...You have pain now; but I will see you again, and your hearts will rejoice, and no one will take your joy from you..."
- John 16:22
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S-PIA08816.jpgCape Verde and Cabo Frio (2)58 visiteThis image from the High Resolution Imaging Science Experiment on NASA's Mars Reconnaissance Orbiter shows the Mars Exploration Rover Opportunity near the rim of "Victoria crater." Victoria is an impact crater about 800 meters (half a mile) in diameter at Meridiani Planum near the equator of Mars. Opportunity has been operating on Mars since January, 2004. Five days before this image was taken, Opportunity arrived at the rim of Victoria crater, after a drive of more than 9 kilometers (over 5 miles). It then drove to the position where it is seen in this image.
Shown in the image are "Duck Bay," the eroded segment of the crater rim where Opportunity first arrived at the crater; "Cabo Frio," a sharp promontory to the south of Duck Bay; and "Cape Verde," another promontory to the north. When viewed at the highest resolution, this image shows the rover itself, wheel tracks in the soil behind it, and the rover's shadow, including the shadow of the camera mast. Since this image was taken, Opportunity has moved to the very tip of Cape Verde to perform more imaging of the interior of the crater.
This view is a portion of an image taken by the High Resolution Imaging Science Experiment (HiRISE) camera onboard the Mars Reconnaissance Orbiter spacecraft on Oct. 3, 2006. The complete image is centered at minus7.8 degrees latitude, 279.5 degrees East longitude. The range to the target site was 297 kilometers (185.6 miles). At this distance the image scale is 29.7 centimeters (12 inches) per pixel (with 1 x 1 binning) so objects about 89 centimeters (35 inches) across are resolved. The image shown here has been map-projected to 25 centimeters (10 inches) per pixel and north is up. The image was taken at a local Mars time of 3:30 PM and the scene is illuminated from the west with a solar incidence angle of 59.7 degrees, thus the sun was about 30.3 degrees above the horizon. At a solar longitude of 113.6 degrees, the season on Mars is northern summer.
Images from the High Resolution Imaging Science Experiment and additional information about the Mars Reconnaissance Orbiter are available online at: http://www.nasa.gov/mro or http://HiRISE.lpl.arizona.edu.
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T-TRA_000828_1805_RED.jpgYardangs in Medusa Fosse58 visiteThis image covers a portion of an outcrop of the Medusae Fossae Formation, a series of light-toned terrains in the Martian mid-latitudes. The Medusae Fossae has been and remains one of the most enigmatic features on Mars. The unit is characterized by wind-sculpted landforms, most notably eroded ridges known as yardangs. The composition of the Medusae Fossae is not known, but candidates include indurated (hardened) volcanic ash or remnants of dust-ice mixtures that formed in a different Martian climate. This HiRISE image reveals new details of the Medusae Fossae.
Three prominent yardangs are seen, at upper right, lower center right, and partially at lower right. They are aligned with their long axes pointing NW-SE, with tapered ends on the NW, consistent with erosion from a southeasterly wind. One or more hard rocky layers within the yardangs are visible, with the layers commonly segregated into discreet boulders. Isolated rocks are seen on the slopes and at the base of the yardangs, indicating that some formed from breakup of the layers. The rocks may be similar in composition to the softer, non-rocky parts of the yardangs, but simply more indurated. Alternatively, they may be compositionally distinct, challenging current hypotheses for the origin of the Medusae Fossae.
Light-toned ridges at center left have a gross morphology similar to that of barchanoid dunes, formed from wind-blown sand. If these are dunes or ripples, their orientation is consistent with the presumed wind direction that carved the yardangs. However, zooming in to full resolution reveals flat tops, grooves, and smaller, darker ripple forms to the northwest of the ridges. Therefore if these are dunes, they seem indurated.
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T-TRA_000836_1740_RED_CandorChasma_01.jpgCandor Chasma58 visiteCandor Chasma is one of several large troughs that make up Valles Marineris, the largest canyon system in the Solar System. Much of Candor Chasma is filled with layered deposits, like those shown in this HiRISE sub-image. Layers only 1-2 meters thick can be resolved by HiRISE and provide details on the processes that emplaced and modified these sediments. The layered deposits could be volcanic, lacustrine, or eolian sediments that filled in some portions of the trough of Valles Marineris. The variations in brightness of the layers could represent compositional differences in the layers or the thickness of overlying debris, such as sand or dust. This area was targeted because minerals rich in sulfur were detected here by the OMEGA instrument on Mars Express. By using HiRISE images to look at specific geologic units that correspond to these locations of sulfate, it may be possible to determine the origin of the sediments, particularly those that contain the sulfates. The paucity of impact craters on the layered deposits suggests either a young age for the sediments or erosion has removed much of the upper layers to reveal a fresher-looking surface. Dark dunes and ripples indicate that wind has been, and still may be, moving debris across the sedimentary deposits.
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T-TRA_000862_1710_RED_CandorChasma_01.jpgCandor Chasma58 visiteThis HiRISE sub-image shows the steep slopes along wallrock in the eastern edge of West Candor Chasma. In general, the rocks in the upper part of the canyons are interpreted to be lava flows that cover the plains surrounding Valles Marineris, whereas the deeper material along the walls could be either more lava flows or megaregolith that resulted from numerous impact craters that disrupted the Martian surface during the first billion years after formation of the planet. Resistant material is visible in portions of the sub-image and HiRISE is able to resolve 1-2 meter size boulders shedding out of these resistant wallrock units. The bright and dark lineations seen in the right of the sub-image follow the slope of the wallrock (downslope is towards the top of the sub-image) and likely represent bright dust and dark sand that are sliding downslope. The large number of small impact craters visible along the slopes indicates that there isn't a large amount of material moving downslope recently because these craters would have been destroyed or buried.
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Craters-Holden_Crater-TRA_000861_1530_RED_Holden_Delta_00.jpgThe beautiful Holden Crater58 visiteThis HiRISE image covers a portion of the floor of Holden Crater situated in southwest Margaritifer Terra. Holden crater has likely experienced extensive modification by running water, which is supported by observations of drainage and deposition into the crater from a large channel breaching Holden's rim and the alluvial fans that built out along the floor of the crater. The HiRISE sub-image shows relatively bright finely layered deposits that are capped by relatively darker materials. Unlike previous images, the HiRISE image shows that the thickness of some of the individual layers are on the order of a meter or even less in thickness and are laterally uniform and continuous over the extent of the imaged outcrop. Some of the layers in the outcrop display an orthogonal pattern or what may be fractures or joints. The "layer-cake" appearance of these layers suggests that they may have been deposited into a lake that once occupied the crater floor and have seen little in the way of deformation since that time. By contrast, the darker materials overlying the layers are younger and may have been sediments deposited off the nearby alluvial fans. Alternatively, they may represent wind-blown deposits lain down during a later much drier period similar to the conditions that currently exist at the surface today. In some locations, the darker materials have been stripped and expose the lighter finely layered sediments underneath, thereby implying the finely layered materials extend much farther than what is visible along the large outcrop.
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M-016-99.jpgM 16 - The "Eagle Nebula"58 visite"...Omnia Mors poscit. Lex est, non poena, perire..."
(Seneca)
"...La Morte chiama a sè ogni cosa, ed il morire non è una pena, ma una Legge..."
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M-042-93.jpgM 42 - The "Great Orion Nebula"58 visite"...Bibamus et gaudeamus dum juvenes sumus; nam cito tarda senectus venit: post eam, Mors et post Mortem, nihil...
(detto dei Goliardi - Medio Evo)
"...Beviamo e divertiamoci, sinchè siamo giovani, poichè rapida sopraggiunge la vecchiaia e, dopo di essa, la Morte. E dopo la Morte, il nulla..."
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Titan-Lakes-Unnamed_North_Polar_Lakes-02-PIA01942.jpgTitanian Northern Lakes (3)58 visiteCaption NASA originale:"Using its radar system, the Cassini spacecraft has imaged new lakes on Titan.
The large dark patch seen on this image, at high latitudes surrounding Titan's North Pole, is most likely a hydrocarbon lake. Several dark channels can be seen; the longest one at the left meanders over almost 100 Km (about 62 miles), and appears to drain into the lake. Some dark channels are remarkably straight, suggesting possible faulting in the subsurface. The bright landforms jutting into the lake indicate that old, eroded landforms may have flooded.
This radar image was acquired by the Cassini radar instrument in synthetic aperture mode on Oct. 9, 2006. The image is centered near 73° North Latitude and 343° West Longitude; it measures about 300 by 140 Km (such as about 190 by 90 miles). Smallest details in this image are about 500 mt (approx. 1.640 feet) across".
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