| Ultimi arrivi - Neptune and His Moons |
Neptune-PIA09927.jpgThe "Hot" South Pole of Neptune85 visiteCaption NASA:"These thermal images show a "hot" South Pole on the Planet Neptune. These warmer temperatures provide an avenue for Methane to escape out of the deep atmosphere.
The images were obtained with the Very Large Telescope in Chile, using an imager/spectrometer for mid-infrared wavelengths on Sept. 1 and 2, 2006.
The telescope is operated by the European Organization for Astronomical Research in the Southern Hemisphere (known as ESO).
Scientists say Neptune's South Pole is "hotter" than anywhere else on the Planet by about 10° Celsius (50 degrees Fahrenheit). The average temperature on Neptune is about -200° Celsius (-392 degrees Fahrenheit).
The upper left image samples temperatures near the top of Neptune's troposphere (near 100 millibar pressure, which is 1/10th the Earth atmospheric pressure at sea level). The hottest temperatures are indicated at the lower part of the image, at Neptune's south pole (see the graphic at the upper right).
The lower two images, taken 6.3 hours apart, sample temperatures at higher altitudes in Neptune's stratosphere. They do show generally warmer temperatures near, but not at, the south pole. They also show a distinct warm area which can be seen in the lower left image and rotated completely around the back of the planet and returned to the earth-facing hemisphere in the lower right image".MareKromiumDic 18, 2007
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Triton-PIA02213-moe-ELEI.jpgThe limb of Triton (natural colors - elab. Lunexit)75 visitenessun commentoMareKromiumLug 24, 2007
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Triton-PIA00329.jpgViews of Triton (natural colors - elab. NASA)67 visiteTriton Voyager 2 approach sequence with latitude-longitude grid superposed. The color image was reconstructed by making a computer composite of three black and white images taken through red, green and blue filters. Details on Triton's surface unfold dramatically in this sequence of approach images. South Pole near the bottom of the images at the convergence of lines of longitude. Resolution changes from about 60 Km/pixel (37 mi/pixel) in the image at upper left taken from a distance of 500.000 Km to about 5 Km/pixel (3,1 mi/pixel) for the image at lower right. Global and regional albedo features are visible in all of the images. The albedo features can be tracked in successive images and show that Triton has undergone about 3/4 of a rotation during the 4.3-day interval over which these images were obtained.
A Southern Polar Cap of bright pink, yellow and white materials covers nearly all of the Southern Hemisphere; these materials consist of Nitrogen ice with traces of other substances, including frozen CH4 and CO2. Feeble ultraviolet radiation from the Sun is thought to act on methane to cause chemical reactions to the pinkish yellowish substances. At the time of the Voyager 2 flyby (Jan. 1989) Triton's Southern Hemisphere was starting the Summer Season and the South Pole was canted toward the Sun day and night, such that the Polar Cap was sublimating under the relatively 'hot' summer Sun (surface temperature about 38 K, about -391 degree F). Numerous dark streaks on the Southern Polar Nitrogen-ice cap are thought to consist of dark dust deposited by prevailing winds in Triton's tenuous Nitrogen Atmosphere. A bluish band, seen in all of the images, nearly circumstances Triton's Equator; this band is thought to consist of fairly Nitrogen frost, perhaps deposited in the decade prior to Voyager 2's flyby.MareKromiumLug 23, 2007
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Triton-PIA02234.jpgTriton, from 530.000 Km!71 visiteCaption NASA:"Voyager 2 was 530.000 Km (330,000 miles) from Neptune's largest satellite, Triton, when this photo was taken, Aug. 24, 1989. With a resolution of 10 Km (about 6 miles), this is the first photo of Triton to reveal surface topography. The South Pole, continuously illuminated by sunlight at this season, is at bottom left. The boundary between the bright Southern Hemisphere and the darker Northern Hemisphere is clearly visible. Both the darker regions to the north and the very bright sub-equatorial band show a complex pattern of irregular topography that somewhat resembles "fretted terrain" on parts of Venus and Mars.
The pattern of dark and light Regions over most of the Southern Hemisphere will require HR images for interpretation. Also evident are long, straight lines that appear to be surface expressions of internal, tectonic processes. No large impact craters are visible, suggesting that the crust of Triton has been renewed relatively recently that is, within the past billion years or less".MareKromiumLug 23, 2007
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A_-_Neptune.jpgDo you see any difference?76 visiteAllora, che ne dite? I "true colors" di Nettuno secondo la NASA ed i "true colors" di Nettuno secondo Lunexit: vedete qualche (significativa) differenza?
Secondo noi non c'è (praticamente) alcuna differenza ed il motivo è semplice: Nettuno è lontano, freddo e dimenticato.
Nettuno non è una "minaccia" e non serve trasformarlo in qualcosa che non è. Marte, invece...Marte è vicino, terribilmente vicino e, forse, esistono almeno un milione di buoni motivi per "trasfigurarlo".
Forse.
O forse - come molti pensano - la NASA e l'ESA ci fanno vedere le cose per quello che sono (su Nettuno e su Marte ed ovunque nel Sistema Solare) e siamo noi a sbagliare, a fraintendere ed a trasfigurare...MareKromiumGen 02, 2007
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t Neptune Space.jpgNeptune's System63 visiteUn magnifico e realistico collage che ci mostra Nettuno e le sue Lune maggiori, insieme, per una "Foto Ricordo" di un viaggio indimenticabile...Set 28, 2006
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Triton-vg2_p34665.jpgTriton (in natural colors and HR)72 visitenessun commentoAgo 11, 2006
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Triton-vg2_1138639.jpgTriton (HR)62 visitenessun commentoAgo 11, 2006
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Nereid-vg2_1138148.jpgNereid (HR)72 visitenessun commentoAgo 11, 2006
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Proteus-vg2_1138920.jpgProteus (HR)73 visitenessun commentoAgo 10, 2006
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Neptune-PIA01998.jpgNeptune, from FAR away...71 visiteCaption NASA originale:"This image of Neptune was taken through the clear filter of the narrow-angle camera, when the Voyager 2 spacecraft was at a range of 57 MKM (about 35 MMs). The image was processed by computer to show the newly resolved dark oval feature embedded in the middle of the dusky southern collar. The large dark spot nearer the equator is also prominent on the left edge of the disk. The new small dark spot rotates faster than the large dark spot indicating that the winds on Neptune have different velocities at different latitudes as is the case for Jupiter, Saturn and Uranus".Lug 05, 2006
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Triton-PIA01994.jpgStrange "surface features" on Triton (clouds?!?)62 visiteCaption NASA originale"Already intriguing patterns of unknown origin appear on the surface of Neptune's largest satellite, Triton, in this image returned by Voyager 2. The image was taken Aug. 22, 1989, from a distance of about 4 MKM (approx. 2.5 MMs). Voyager images show that Triton's diameter is about 2.720 Km (approx. 1.690 miles) and that it is one of the brightest objects in the Solar System, reflecting about 70% of the sunlight that strikes it. This is the Hemisphere of Triton that always faces away from Neptune. The South Pole is near the bottom of the image. Triton's rotation axis is tilted so that the latitude at the center of the disk is 55° South. Dark regions at the top of the disk extend from roughly the equator to beyond 20° North. The margin between the bright and dark regions varies with longitude around the satellite. The gray, featureless area just to the right of the center of the disk is due to a reseau (reticule mark) in the camera".Lug 05, 2006
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