| Piú votate - Uranus and His Moons |
Miranda-PIA00140.jpgMiranda, from approx. 31.000 Km72 visiteCaption NASA originale:"This Voyager 2 image of Miranda was taken Jan 24, 1986, from a distance of about 31.000 Km (19.000 miles), shortly before the spacecraft's closest approach to the Uranian moon. The HR of 600 meters (2.000 feet) reveals a bewildering variety of fractures, grooves and craters, as well as features of different albedos (reflectancea). This clear-filter, narrow-angle view encompasses areas of older, heavily cratered terrain with a wide variety of forms. The grooves and troughs reach depths of a few Km (or miles) and expose materials of different albedos. The great variety of directions of fractures and troughs, and the different densities of impact craters on them, signify a long, complex geologic evolution of this satellite".
(10 voti)
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VG-Desdemona-V2.jpgDesdemona - Voyager 266 visitenessun commento
(10 voti)
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VF-Cressida, Ophoelia, Portia.jpgCressida, Ophoelia and Portia - Voyager 272 visiteUn piccolissimo commento (forse abbastanza scontato): noi non sappiamo chi, fisicamente, abbia dato i nomi a queste Lune Minori di Urano ma, certamente, si trattava di un appassionato lettore di Sir William Shakespeare.
Non credete?!?...
(10 voti)
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Miranda-V2-PIA01980_modest.jpgMiranda: a funny shaped Moon74 visiteIn questa seconda immagine di Miranda risulta ben visibile una vastissima depressione situata in prossimità del suo Polo Nord la quale potrebbe aver avuto origine a seguito di un impatto con un altro corpo celeste di notevoli dimensioni.
Una luna che ha "sofferto", dunque, e la cui storia risale - molto probabilmente - alle stesse origini del nostro Sistema Solare, quando gli impatti - specie nella sua "periferia" - avvenivano con una frequenza di gran lunga maggiore rispetto a quanto accade ai giorni nostri.
(10 voti)
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ZA-Uranus-IP-V2-PIA00346_modest.jpgFarewell Uranus... (1)56 visiteCaption NASA originale:"This image shows a crescent Uranus, a view that Earthlings never witnessed until Voyager 2 flew near and then beyond Uranus on January 24, 1986. The hazy blue-green atmosphere probably extends to a depth of around 5.400 miles, where it rests above what is believed to be an icy or liquid mixture (an 'ocean') of water, ammonia, methane and other volatiles, which in turn surrounds a rocky core, perhaps a little smaller than Earth".
(10 voti)
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UMBRIEL-vg2_p29502-A.jpgUmbriel's extremely unusual surface feature (HR - context image)63 visiteIl rilievo (che definire "fortemente anomalo" è riduttivo) che caratterizza il versante prossimo al Polo Nord di Umbriel è, almeno dalle immagini che sono in nostro possesso, del tutto inesplicabile.
Alcuni Ricercatori (anche nel Gruppo Lunar Explorer Italia) ipotizzano che si tratti di una montagna dalle dimensioni davvero incredibili (almeno in rapporto al corpo celeste a cui essa accede - immaginate come il Monte Everest apparirebbe dallo spazio se fosse alto 70 o più Km e largo 300, tanto per rendere l'idea...), mentre altri Studiosi ritengono che quello che si vede in questa immagine è solo il risultato di una deformazione del frame la quale potrebbe essere imputabile ad un vizio di trasmissione e/o di ricevimento ed elaborazione dati (il che equivarrebbe a dire che il rilievo in questione non esiste).
Altri ancora interpretano questo rilievo come una "plume" vulcanica (?) o una gigantesca formazione nuvolosa.
Purtroppo, il mistero non sarà risolto tanto facilmente...
(9 voti)
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AB-AB-vg2_2686312.gifThe limb of Uranus57 visiteOriginal caption:"Voyager 2 image of the limb of Uranus from about 694.000 Km. This narrow angle view is about 5.100 Km across and was taken 12 hours after closest approach. The image is centered at -10, 212 and North is up. (Voyager 2, FDS 26863.12)".
(9 voti)
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Miranda-PIA02218.jpgNot only Verona Rupes: more deep scarps on Miranda (HR)63 visiteCaption NASA originale:"View of Miranda showing light and dark banded scarps near the boundary of the banded ovoid and a deep graben that bounds the ovoid in this region".
(9 voti)
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Oberon-V2-PIA00034_modest.jpgOberon, from 660.000 Km - Voyager 256 visiteCaption NASA originale:"This Voyager 2 picture of Oberon is the best the spacecraft acquired of Uranus' outermost moon. The picture was taken shortly after 3:30 a.m. PST on Jan. 24, 1986, from a distance of 660.000 Km. The color was reconstructed from images taken through the narrow-angle camera's violet, clear and green filters. The picture shows features as small as 12 Km on the moon's surface. Clearly visible are several large impact craters in Oberon's icy surface surrounded by bright rays similar to those seen on Jupiter's moon Callisto. Quite prominent near the center of Oberon's disk is a large crater with a bright central peak and a floor partially covered with very dark material. This may be icy, carbon-rich material erupted onto the crater floor sometime after the crater formed. Another striking topographic feature is a large mountain (vedi il frame "Oberon's Peak"), about 6 km high, peeking out on the lower left limb".
(9 voti)
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VE-Caliban.jpgCaliban66 visiteUna "Luna Minore" di Urano, Calibano, persa fra le stelle ed individuabile solo grazie alla "cerchiatura" bianca inserita in questa (comunque molto bella) immagine.
(9 voti)
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UranusandAriel-Eclypse.jpgUranus and Ariel; Earth and Moon55 visiteCaption NASA originale"This illustrates the relative sizes of Uranus, Earth and Earth's Moon. The images are shown at the proper relative size, but not the correct relative distance from each other. Uranus is approx. 31.000 miles (about 50.000 Km) in diameter, or about 4 times the size of Earth. The Earth is approx. 7.900 miles (about 12.800 Km) in diameter, or about 4 times the diameter of the Moon (2.100 miles, such as about 3.500 Km)".
(8 voti)
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Uranus-HST-PIA01279.jpgUranus from Hubble Space Telescope57 visiteCaption NASA originale:"Uranus is sometimes called the sideways planet, because its rotation axis tipped more than 90° from the planet's orbit around the Sun. The year on Uranus lasts 84 Earth years, which creates extremely long seasons - winter in the Northern Hemisphere has lasted for nearly 20 years. Uranus has also been called bland and boring, because no clouds have been detectable in ground-based images of the planet. Even to the cameras of the Voyager spacecraft in 1986, Uranus presented a nearly uniform blank disk and discrete clouds were detectable only in the Southern Hemisphere. Voyager flew over the Planet's cloud tops near the dead of northern winter (when the northern hemisphere was completely shrouded in darkness).
Two images are shown here. The "aqua" image (on the left) is taken at 5,470 Angstroms, which is near the human eye's peak response to wavelength. Color has been added to the image to show what a person on a spacecraft near Uranus might see. Little structure is evident at this wavelength, though with image-processing techniques, a small cloud can be seen near the planet's northern limb (rightmost edge). The "red" image (on the right) is taken at 6,190 Angstroms, and is sensitive to absorption by methane molecules in the planet's atmosphere. The banded structure of Uranus is evident, and the small cloud near the northern limb is now visible".
(8 voti)
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