| Piú viste - Neptune and His Moons |
Triton-PIA00056_modest.jpgTriton's limb69 visiteCaption NASA originale:"Voyager 2 acquired this black and white image of Triton, Neptune's largest satellite, during the night of Aug. 24-25, 1989. Triton's limb cuts obliquely across the middle of the image. The field of view is about 1.000 Km (600 miles) across. Three irregular dark areas, surrounded by brighter material, dominate the image. Low-lying material with intermediate albedo occupies the central area, and fresh craters occur along the right margin. Sub-parallel alignment of linear patches of dark material shown in the lower and left part of the image suggests that the patches are structurally controlled".
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ZC-Neptune_s Rings-PIA01493_modest.jpgThe Rings of Neptune68 visiteCaption NASA originale:"In Neptune's outermost ring, 39.000 miles out, material mysteriously clumps into 3 arcs.
Voyager 2 acquired this image as it encountered Neptune in August 1989".
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s Rings-PIA02207_modest.jpgNeptune's Rings (and a crescent Neptune) from 1,1 MKM68 visiteCaption NASA originale:"This wide-angle Voyager 2 image, taken through the camera's clear filter, is the first to show Neptune's rings in detail. The 2 main rings, about 53.000 Km and 63.000 Km from Neptune, are 5 to 10 times brighter than in earlier images and the difference is due to lighting and viewing geometry. In approach images, the rings were seen in light scattered backward toward the spacecraft at a 15° phase angle. However, this image was taken at a 135° phase angle as Voyager 2 left the planet. That geometry is ideal for detecting microscopic particles that forward-scatter light preferentially. The fact that Neptune's Rings are so much brighter at that angle means the particle-size distribution is quite different from most of Uranus' and Saturn's rings, which contain fewer dust-size grains. However, a few components of the Saturnian and Uranian ring systems exhibit forward-scattering behavior: the F-Ring and the Encke Gap ringlet at Saturn, and 1986U1R at Uranus".
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Neq-Neptune-PIA00051.jpgNeptune in false colors68 visiteCaption NASA originale:"In this false color image of Neptune, objects that are deep in the atmosphere are blue, while those at higher altitudes are white. The image was taken by Voyager 2's wide-angle camera through an orange filter and two different methane filters. Light at methane wavelengths is mostly absorbed in the deeper atmosphere. The bright, white feature is a high altitude cloud just south of the Great Dark Spot. The hard, sharp inner boundary within the bright cloud is an artifact of computer processing on Earth. Other, smaller clouds associated with the Great Dark Spot are white or pink, and are also at high altitudes. Neptune's limb looks reddish because Voyager 2 is viewing it tangentially, and the sunlight is scattered back to space before it can be absorbed by the methane. A long, narrow band of high altitude clouds near the top of the image is located at 25° north latitude and faint hazes mark the equator and polar regions".
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AAA-NeptuneandTriton-CJH.gifNeptune and Triton in natural colors - from Voyager 268 visiteNon si possono fare commenti ad immagini suggestive come questa: Vi lasciamo con la Vostra Fantasia ed Immaginazione, per provare a sentire che cosa questa "corsa infinita" del Voyager 2 Vi suggerisce...
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Neptune-HST2.JPGNeptune and a few of His Moons (HST; Natural Colors; credits: NASA)68 visitenessun commentoMareKromium
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ZA-Neptune_s Rings-PIA02202_modest.jpgThe Rings of Neptune (full system) 267 visiteCaption NASA originale:"This pair of Voyager 2 images (FDS 11446.21 and 11448.10), two 591-s exposures obtained through the clear filter of the wide angle camera, show the full ring system with the highest sensitivity. Visible in this figure are the bright, narrow N53 and N63 rings, the diffuse N42 ring, and (faintly) the plateau outside of the N53 ring (with its slight brightening near 57.500 Km)".
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ZA-Neptune_s Rings-PIA01996_modest.jpgThe Rings of Neptune (closest approach)67 visiteCaption NASA originale:"The Voyager 2 spacecraft took this picture after closest approach to Neptune on Aug. 25 1989, using the clear filter of the wide-angle camera with an exposure time of 255 seconds. The view back towards Neptune at a phase angle of 135° found the 2 known rings to be 5 to 10 times brighter than seen in backscattering during Voyager approach at much lower phase angle. This brightness increase implies a large percentage of microscopic particles within the rings".
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Neptune and Triton - PIA01491_modest.jpgNeptune and Triton67 visiteCaption NASA originale:"This image was returned by the Voyager 2 spacecraft on July 3, 1989, when it was 76 MKM from Neptune. The planet and its largest satellite, Triton, are captured in the field of view of Voyager's narrow-angle camera through violet, clear and orange filters. Triton appears in the lower right corner at about 5 o'clock relative to Neptune.
Recent measurements from Voyager images show Triton to be between 1.400 and 1.800 Km in radius with a surface that is about as bright as freshly fallen snow".
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Triton-PIA00317_modest.jpgTriton (False Colors; credits: NASA/JPL/USGS)67 visiteCaption NASA originale:"The color was synthesized by combining HR images taken through orange, violet and ultraviolet filters; these images were displayed as red, green and blue images and combined to create this color version. With a radius of 1.350 Km, about 22% smaller than Earth's Moon, Triton is by far the largest satellite of Neptune. It is 1 of only 3 objects in the Solar System known to have a nitrogen-dominated atmosphere (the others are Earth and Saturn's giant moon, Titan). Triton has the coldest surface known anywhere in the Solar System (38 K, about -391 degrees F); it is so cold that most of Triton's nitrogen is condensed as frost, making it the only satellite in the Solar System known to have a surface made mainly of nitrogen ice. The pinkish deposits constitute a vast south polar cap believed to contain methane ice, which would have reacted under sunlight to form pink or red compounds. The dark streaks overlying these pink ices are believed to be an icy and perhaps carbonaceous dust deposited from huge geyser-like plumes, some of which were found to be active during the Voyager 2 flyby. The bluish-green band visible in this image extends all the way around Triton near the equator; it may consist of relatively fresh nitrogen frost deposits. The greenish areas includes what is called the cantaloupe terrain, whose origin is unknown, and a set of "cryovolcanic" landscapes apparently produced by icy-cold liquids (now frozen) erupted from Triton's interior".
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Neptune-crescent-PIA02204_modest.jpgNeptune's bright crescent67 visiteCaption NASA originale:"Neptune's bright crescent taken in six filters (from bottom to top: UV, violet, blue, clear, green, orange) on August, 31, 1989. The images were shuttered in temporal order: violet, blue, UV, clear, green, orange. These images how the bright core of D2, the South Polar feature, and the symmetric structure immediately surrounding the South Pole. The relatively high contrast of the features in these images indicates that they extend above most of the scattering haze and absorbing methane gas in Neptune's atmosphere. [Image processing by D.A. Alexander]"
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t Neptune Space.jpgNeptune's System67 visiteUn magnifico e realistico collage che ci mostra Nettuno e le sue Lune maggiori, insieme, per una "Foto Ricordo" di un viaggio indimenticabile...
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