| Risultati della ricerca nelle immagini - "Venus" |
0-Venus.jpgVenus from Mariner 10170 visiteVenus Data and Statistics
Mass (kg) = 4.869e+24
Mass (Earth = 1) = 81476
Equatorial radius = 6.051,8 Km
Equatorial radius (Earth = 1) = 0,94886
Mean density (gm/cm^3) = 5,25
Mean distance from the Sun = 108.200.000 Km
Mean distance from the Sun (Earth = 1) = 0,7233
Rotational period (days) = 243,0187
Orbital period (days) = 224,701
Mean orbital velocity = 35,02 Km per second
Tilt of axis = 177,36°
Orbital inclination = 3,394°
Equatorial surface gravity (m/sec^2) = 8,87
Equatorial escape velocity = 10,36 Km per second
Magnitude (Vo) = - 4,4
Mean surface temperature = + 482°C
Atmospheric pressure (bars) = 92
Atmospheric composition: Carbon dioxide 96%, Nitrogen 3% and trace amounts of: Sulfur dioxide, water vapor, carbon monoxide, argon, helium, neon, hydrogen chloride and hydrogen fluoride.
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1-Venus_Galileo_Visible.jpgVenus136 visiteUna magnifica ricostruzione di Venere - ad opera dello "Space Artist" Don P. Mitchell - nei colori in cui un umano che fosse nello spazio la vedrebbe.
Queste le annotazioni originali dell'Artista:
Full spectral data is rarely available, and instead we must use views through color filters. Above, the Galileo probe captured Venus through a clear filter (left) and through a 410 nm violet filter, which reveals the subtle yellow and white clouds. Unfortunately, many different color images could result in the same two clear and violet signals above. Even when so-called red, green and blue filters are used, the problem is just as difficult, because the filters are not really the right red, green and blue to just plug into the channels of a color display. Theoretically, information from the two images above and from the Cassini spectrum could be combined using Bayesian decision theory, to compute the most probable color image. If colors are estimated correctly, there is a final issue of tone mapping. How bright does the image appear to the eye in a given context. The image above is the best color image of Venus I've found, showing the planet as it would likely appear to a human observer in space. It was made by Turkish astronomer A. Tayfun Oner, using the two color channels from the Galileo camera, and a third interpolated channel.
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2-Rising_Venus.jpgThe Phases of Venus (1)101 visiteThe images above, by the talented amateur astronomer Damian Peach, show the appearance of Venus through a high-quality telescope, at various points in its orbit. When Venus is close, its diameter is almost visible to the naked eye (one minute of arc), but it is then lit from behind.
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6-Venus.jpgVenus from Galileo140 visiteCaption NASA originale:"This colorized picture of Venus was taken February 14, 1990, from a distance of almost 1,7 MMs, about 6 days after Galileo's closest approach to the planet. It has been colorized to a bluish hue to emphasize subtle contrasts in the cloud markings and to indicate that it was taken through a violet filter. Features in the sulfuric acid clouds near the top of the planet's atmosphere are most prominent in violet and ultraviolet light".
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7-Venus_orbit31V3_fc_H.jpgThe Bright&Blue Northern Hemisphere of Venus59 visitenessun commento
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8-Venus.jpgVenus from 2.700.000 Km (Galileo Probe)170 visiteUna meravigliosa visione di Venere, davvero simile alla Terra vista dalla Luna, mentre la fitta coltre di nuvole che la ricopre riflette i raggi del Sole. Come avevamo detto in sede di commento alle prime foto, Venere suggerisce un'idea di "tranquillità e benessere".
Un Mondo bianco e azzurro apparentemente simile al nostro ma, come avete visto insieme a noi, in realtà violento ed assolutamente inospitale.
Un Mondo comunque bellissimo da guardare, ammirare e studiare, ma ... Restando lontan!
...Molto lontani...
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8-Venus_from_Venus_Express-VIRTIS_COB05_vis_397_b.jpgVenus, from Venus Express (natural colors)78 visiteCaption ESA originale:"Views of the Southern Hemisphere of Venus in visible and ultraviolet light show interesting atmospheric stripe-like structures.
Spotted for the first time by Mariner 10 in the 1970s, they may be due to the presence of dust and aerosols in the atmosphere, but their true nature is still unexplained. "Venus Express has the tools to investigate these structures in detail. Studies have already begun to dig into the properties of the complex wind fields on Venus, to understand the atmospheric dynamics on local and global scales".
Venus Express also made use for the first time ever from orbit of the so-called 'infrared windows' present in the atmosphere of Venus – if observed at certain wavelengths, it is possible to detect thermal radiation leaking from the deepest atmospheric layers, revealing what lies beneath the dense cloud curtain situated at about 60 Km altitude".
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9-Venus.gifApproaching Venus (GIF anim.)54 visiteOn 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.
Infrared images taken by the Ultraviolet/Visible/Near-Infrared spectrometer (VIRTIS) on board the spacecraft not only provided the first clear view of the vortex, but also gave a much closer insight into it when Venus Express flew over the South Pole at the end of May this year (2006). MareKromium
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9-Venus.jpgVenus from 2.700.000 Km (Galileo Probe)212 visiteLa competizione USA/URSS, finchè l'URSS è esistita, ha dato grandi risultati in termini di inventiva, volontà, capacità di fronteggiare le difficoltà e superare gli ostacoli (il Programma Apollo ne è la prova lampante!) ma poi...Dissoltasi l'Unione Sovietica e svanita la 'corsa' verso le Stelle, si è incominciato a guardare il 'portafogli' e, dato che le missioni spaziali "costano care", la NASA (o dovremmo dire "Il Congresso"?!?) ha ritenuto più saggio, sicuro ed economico limitarsi ad inviare sonde programmate per entrare in orbita attorno a Venere e poi scattare foto a raggi X della superficie, così da superare l'ostacolo costituito dalla coltre perenne di nubi che sovrasta il Pianeta, SENZA dover ricorrere al landing ed alla successiva, rapida ed inevitabile perdita della navicella.
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A-Venus.gifThe Phases of Venus (2) - GIF107 visiteCaption originale:"Venus goes through phases. Just like our Moon, Venus can appear as full as a disk or as a thin as a crescent. Venus, frequently the brightest object in the post-Sunset or pre-Sunrise Sky, appears so small, however, that it usually requires binoculars or a small telescope to clearly see its current phase. The above time-lapse sequence, however, was taken over the course of many months and shows not only how Venus changes phase but how it's apparent angular size also changes. In the middle negative image, Venus is in a new phase, the same phase that occurred during its rare partial eclipse of the Sun in 2004".
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Aeolian_Features-Windstreaks.jpgMagellan Probe: radio image of Windstreaks128 visiteUn'immagine decisamente chiara e relativa a quel fenomeno che viene chiamato 'wind streaking' e che ci indica, fra l'altro, la direzione usuale dei venti e la capacità di resistenza che i rilievi oppongono ad essi.
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Channels-Unnamed_Outflow_Channel-PIA00483.jpgOutflow Channel in South Nawka Vallis (possible Natural Colors; credits: Dr Paolo C. Fienga - Lunexit Team)54 visiteThis SAR image from the Southern portion of Navka (24,4-25,3° South Latitude and 338,5-340,5° East Longitude) is a mosaic of twelve Magellan orbits that covers approx. 180 Km (about 108 miles) in width and approx. 78 Km (about 47 miles) in length.
In the center of this image are two bright Deposits running North to South.
These Deposits outline an Outflow Channel that flowed from an about 60-Km diameter Crater that is to the South of the Channel itself. Inside the Outflow Channel and outlined by some so-called 'Bathtub Ring' Deposits are small Cones, most likely of volcanic origin.
At the end of the Outflow Channel, where one would expect the smallest particles to be deposited, are specular features which may represent Sand Dunes.
Seasat and space shuttle radar images of sand dunes on Earth also show specular reflections from smooth dune faces that are near-normal to the radar beam.
Other evidence for aeolian activity are the dark and bright Windstreaks running East to West and that formed behind the Cones. Notice how the wind changes direction from a South/East-North/West flow at the right of the image to an East-West flow at the eastern edge of the Outflow Channel.MareKromium
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