| Piú viste - Venus |
Volcanoes-PIA00261.jpgVolcanoes in Guinevere Planitia (possible Natural Colors; credits: Dr Paolo C. Fienga - Lunexit Team)59 visiteThis image, with radar illumination from West to East, shows three unusual Volcanoes located in the Guinevere Planitia Lowland. At the center of the image is a large feature (approx. 50 Km or about31 miles in diameter) with an unusual shape; very round when viewed from above with steep slides and a flat top.
These Volcanoes are believed to be the result of relatively thick and sticky (viscous) Lava Flows that originated from a point source. Although a faint remnant of its original circular shape is preserved, the Northern Rim of this center Volcano has a steep Scarp.
The Scarp is probably the result of material that has slid away from the Volcano and subsequently has been covered by Lava Flows. This Volcano overlaps another feature to the South-West that is about 45 Km (approx. 28 miles) in diameter and disrupted by many fractures.
The South-Eastern Volcano (about 25 Km or approx. 15,5 miles in diameter) appears to be the highest of the three as its illuminated Western Edge has the brightest radar return. The scalloped Edges give this feature a bottlecap-like appearance. The highly scalloped Edges are probably the result of multiple material slides along the Volcano Margin.MareKromium
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Hestia_Rupes-PIA00469.jpgComplex Network of Narrow Fractures near Hestia Rupes Region (possible Natural Colors; credits: Dr Paolo C. Fienga - Lunexit Team)59 visiteThis is a Magellan radar image covering an about 105- Km (approx. 63-mile) by 45-Km (approx. 27-mile) Region near Hestia Rupes on the North-Western corner of Aphrodite Terra.
The complex network of narrow (such as <1 Km) Fractures in the center of the image extends for approx. 50 Km (about 31 miles). This network exhibits tributary-like branches similar to those observed in river systems on Earth. However, the angular intersections of the tributaries suggest tectonic control.
These features appear to be due to drainage of lava along preexisting fractures and subsequent collapse of the Surface. The underlying tectonic fabric can be observed in the North-East trending Ridges which predate the Plains.MareKromium
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Craters-Stephania_Crater-PIA00475.jpgStephania Crater (possible Natural Colors; credits: Dr Paolo C. Fienga - Lunexit Team)59 visiteCrater Stephania is located at 51,3° Norh Latitude and 333,3° East Longitude in Northern Sedna Planitia.
With a diameter of about 11 Km (6,8 miles), Stephania is one of the smaller Craters on Venus.
Because many small meteoroids disintegrate during their passage through the dense Venusian atmosphere, there is an absence of craters smaller than 3 Km (approx. 1,9 miles) in diameter, and even craters smaller than 25 Km (15,5 miles) are relatively scarce.
The apron of ejected material suggests that the impacting body made contact with the Surface from an oblique angle. Upon closer observation it is possible to delineate secondary craters, impact scars from blocks ejected from the primary crater.
A feature associated with this and many other Venusian Craters is a radar-dark halo.
Since dark radar return signifies a smooth surface, it has been hypothesized that an intense shock wave removed or pulverized previously rough surface material or that a blanket of fine material was deposited during or after the impact.MareKromium
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South_Polar_Vortex-00.jpgVenusian South Polar Vortex (1)58 visiteOriginal ESA caption:"On 20 April 2006, after its first 9-day, elongated orbit around Venus, ESA’s Venus Express started to get closer to the Planet, until it reached its final 24-hour long orbit on 7 May. During this time, and up to today, the spacecraft has been working relentlessly: the new data coming in are already providing first glimpses on planetary features never seen before.
If taking the first ever clear images of the double-eye vortex at Venus’ South Pole - imaged by Venus Express during its very first orbit - was already a first in the history of planetary exploration and a very pleasant surprise for the scientists, nobody could expect that the vortex had a structure even more complicated than possibly foreseen".
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Venusian_Clouds_tracking_infrared_2_b_H.jpgVenusian cloud structures - Night view (1)58 visiteOriginal ESA caption:"Tracking cloud motion and starting to characterise the wind speed is an exercise that the Venus Express scientists have already started. A spectacular night view of the mid to low atmospheric layers over low latitudes (between 20º and 90 º South) by VIRTIS, show clouds being clearly pushed by winds.
"We can now make a first qualitative assessment of the wind fields and circulation, which is comfortably matching with previous measurement from the Galileo mission over the North Pole", said Giuseppe Piccioni.
"We are now collecting more data from different atmospheric depths, to be able to provide the first precise numbers, possibly in the near future".
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Venusian_Atmosphere-ORB157_03_17_WB_H.jpgVenusian Turbulence: the Near-Equatorial Region58 visiteThis image of the Near-Equatorial Region of Venus was acquired on 24 September 2006 by the Ultraviolet, Visible and Near-Infrared Mapping Spectrometer (VIRTIS) on board ESA’s Venus Express, from a distance of about 37.000 Km from the Planet’s surface.
The image, taken on the night-side of Venus at a wavelength of 1,7 micron, provides a close-up view of a highly turbulent region, with irregular and warped clouds, which is common at these low latitudes. This is different from what happens at higher latitudes (pole-ward) where clouds are generally streaky and more regularly shaped.
The gray ‘bubble’ slightly below the centre of the image is located at about 27° Southern Latitude and 7° Western Longitude, and has a diameter of about 300 Km.
The Alpha Regio area is at the bottom left of the image. This area is characterised by a series of troughs, ridges, and faults that are oriented in many directions, with surface features that can be up to 4 Km high. It is not yet clear if atmospheric turbulences may be induced by the rough topography below the clouds.
The grey-scale of the image is such that black means more transparency, therefore less clouds, while white means more opacity, therefore more cloud concentration.MareKromium
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Venusian_Atmosphere-ORB157_multiple_H.jpgVenusian Turbulence: Image Mosaic of the (visible) Venusian Cloud System58 visiteThis image is a composite of four different views of the Venusian Cloud System.
The images were acquired on 24 September 2006 by the Ultraviolet, Visible and Near-Infrared Mapping Spectrometer (VIRTIS) on board ESA’s Venus Express, from distances of about 65.000 Km (top left), 60.000 Km (top right), 53.000 Km (bottom left), 37.000 Km (bottom right) from the Planet’s surface.
The images, showing a complex cloud system, were taken on the night-side of Venus (04:00 V.L.T.), at a wavelength of 1,7 micron that allows viewing the deep atmospheric layers.
The grey-scale of the images is such that black means more transparency, therefore less clouds, while white means more opacity, therefore more cloud concentration.MareKromium
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Venusian_Clouds-VI410_411_23_tot.gifVenusian Cloud Structure (GIF-movie)58 visiteCaption ESA:"This movie consists of a sequence of six images obtained by the VIRTIS imaging spectrometer on board ESA’s Venus Express on 5 and 6 June 2007, before and after NASA MESSENGER’s closest approach to the Planet. The image sequence, obtained by VIRTIS, provides a night-side view of the same region that Messenger flew over and imaged.
They were obtained at 1,7 micrometres, revealing atmospheric details down to an altitude of 50 Km from the surface".MareKromium
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Venusian_Atmosphere_and_the_Solar_Wind-Interaction.jpgInteraction between Venus and the Solar Wind58 visiteCaption ESA:"Mars, Earth and Venus are immersed in a flow of plasma, a ionised and highly variable gas originating from the Sun, called the Solar Wind. While Earth has a Planetary Magnetic Field, which can deviate its flow, Venus (and Mars) don’t.
Gases in the upper atmospheres of these Planets are ionised, and can thus interact with the Solar Wind. Venus is as large as Earth and it is difficult for its Atmosphere to escape due to the Planet’s Gravity. The Solar Wind is the best source of energy to accelerate the upper atmosphere’s charged particles, giving them enough energy to escape. This is why Venus loses its atmosphere due to interaction with the Solar Wind.
To understand this phenomenon, the key questions that the instruments studying plasma on Venus Express must answer are: what and how much of the Atmosphere is lost, and where is it lost? Right now, solar activity is at its minimum in the 11-year cycle, making the Solar Wind weaker than average.
The critical question now is how solar wind interacts with Venus when solar activity is low".MareKromium
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Venus-South_Pole-01.jpgThe South Pole of Venus (false colors; credits: ESA)58 visiteDa "NASA - Picture of the Day", del 26 Febbraio 2006:"Why did an acidic haze spread across Venus? The unusual clouds were discovered last July by ESA's robotic Venus Express Spacecraft currently orbiting Venus. The bright and smooth haze was found by Venus Express to be rich in Sulfuric Acid (H2SO4), created when an unknown process lifted Water Vapor and Sulphur Dioxide (SO2) from lower levels into Venus' upper Atmosphere.
There, sunlight broke these molecules apart and some of them recombined into the volatile Sulfuric Acid. Over the course of just a few days last July, the smooth acidic clouds spread from the South Pole of Venus across half the Planet.
The above false-color picture of Venus was taken last July 23rd (2007) in UV (Ultraviolet Light), and shows the unusual haze as relatively smooth regions across the image bottom. The cause of the dark streaks in the clouds is also not yet understood and is being researched".MareKromium
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Venus-South_Pole-00.jpgThe South Pole of Venus (False Colors; credits: ESA)58 visiteCaption ESA:"This is a false-colour image taken with the Venus Monitoring Camera (VMC) on board ESA’s Venus Express.
It shows the full view of the Southern Hemisphere from Equator (Dx) to the Pole.
The South Pole is surrounded by a dark oval feature. Moving to the right, away from the Pole and towards the Equator, we see streaky clouds, a bright mid-latitude band and mottled clouds in the convective Sub-Solar Region.
This image was taken in the ultraviolet at 365 nanometres on 23 July 2007 as Venus Express was about 35.000 Km from the Surface of the Planet".MareKromium
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Venusian_Surface-Venera_14-03.jpgVenus, from Venera 14 (Natural Colors; credits: Ted Stryk)58 visiteTed Stryk comments:"...Venera 14, which landed in a much rockier area, took a pretty good partial color pan (again, complete in black and white), but while the other pan was complete in both black and white and through color filters (althoug again the blue was almost useless), the color data in this set was horribly underexposed.
Here is the Venera 14 partial pan, my favorite of the set because of the cool rock right near the lander. It seems to be sitting on the rocky plain...it makes one wonder how it got there. I don't see anything else like it in the Venera pans, although given their limited coverage, it doesnt mean there aren't perhaps a few more rocks like it around. But still , it is lucky it was so close to the lander and in a color zone...".
Nota Lunexit: notate anche Voi una - secondo noi STRAORDINARIA - similitudine fra questa superficie e la superficie di Titano?...MareKromium
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