| Piú viste - Neptune and His Moons |
Neptune-clouds-PIA00047_modest.jpgThe clouds of Neptune (b/w) - 159 visiteCaption NASA originale:"The bright cirrus-like clouds of Neptune change rapidly, often forming and dissipating over periods of several to tens of hours. In this sequence Voyager 2 observed cloud evolution in the region around the Great Dark Spot (GDS). The surprisingly rapid changes which occur separating each panel shows that in this region Neptune's weather is perhaps as dynamic and variable as that of the Earth. However, the scale is immense by our standards - the Earth and the GDS are of similar size... - and in Neptune's frigid atmosphere, where temperatures are as low as 55 degrees Kelvin (-360 F), the cirrus clouds are composed of frozen methane rather than Earth's crystals of water ice".
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ZA-Neptune_s Rings-PIA01996_modest.jpgThe Rings of Neptune (closest approach)58 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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AAA-NeptuneandTriton-CJH.gifNeptune and Triton in natural colors - from Voyager 258 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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A_-_Neptune.jpgDo you see any difference?58 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...MareKromium
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Triton-PIA12185.jpgVolcanic Plains on Triton58 visiteCaption NASA:"This view of the Volcanic Plains of Neptune's moon Triton was produced using topographic maps derived from images acquired by NASA's Voyager Spacecraft during its August 1989 flyby, 20 years ago this week (August 2009).
Triton, Neptune's largest natural moon, was the last solid object visited by the Voyager 2 Spacecraft on its epic 10-year tour of the Outer Solar System. This view shows a close-up of a prominent chain of Volcanic Features surrounded by smooth Volcanic Plains formed by lavas or ash deposits of water or other ices, such as Methane or Ammonia.
The smaller pits and domes are typically 10 Km (about 6 miles) across and have relief of no more than a few hundred meters (several hundred feet).
The large depressions at the far left and right of the chain are 50 to 80 Km (about 31 to 50 miles) across.
The Surface of Triton is very rugged, scarred by rising blobs of ice (diapirs), faults and volcanic pits and lava flows composed of water and other ices. The Surface is also extremely young and sparsely cratered and could be geologically active today.
This scene is on the order of 500 Km (about 310 miles) across and is taken from a new flyover movie across the Equatorial Regions of Triton commemorating the Voyager anniversary of the Triton flyby.
Vertical relief has been exaggerated by a factor of 25 to aid interpretation".MareKromium
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ZB-Neptune_s Partial Rings-PIA02200_modest.jpgNeptune's "Partial Rings" (or "Ring Arcs")57 visiteCaption NASA originale:"One of two new ring arcs, or partial rings, discovered by NASA's Voyager 2 spacecraft, is faintly visible here just outside the orbit of the Neptunian moon 1989N4, also discovered by Voyager 2.
The 155 second exposure taken by Voyager's narrow-angle camera shows the glare of an overexposed Neptune to the right of the moon and ring arc.
The two bright streaks below the moon and ring arc are stars.
The ring arc is approximately 50.000 Km (or 30.000 miles) long".
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AA-Neptune-HST-PIA01285_modest.jpgNeptune from HST57 visitePer incominciare il nostro breve viaggio verso l'ultimo dei Giganti Gassosi, ci sembra giusto mostrarVi due serie di immagini del "Re dei Mari" che sono state ottenute dall'Hubble Space Telescope. Nettuno ci appare come un disco dal colorito azzurro vivo, sul quale spiccano - ora bianche, ora con colori e sfumature diverse - le grandi formazioni nuvolose che attraversano rapidamente gli strati alti dell'atmosfera del Pianeta.
Nettuno, per gli amanti della fotografia spaziale, è un obbiettivo difficile ed al confine estremo di visibilità dalla Terra, allorchè si faccia uso di strumenti amatoriali. A "fuoco diretto", usando un buon telescopio (tipo C-8), esso appare leggermente più definito di una stella, la forma sferica è appena percepibile ed il colorito, purtroppo, grigio-azzurrato, molto lontano - purtroppo - dal suo colore naturale, come vedremo sia nelle foto HST, sia nelle foto Voyager.
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Triton-PIA01536_modest.jpgTriton (through green, violet and ultraviolet filters)57 visiteCaption NASA originale:"This color photo of Neptune's large satellite Triton was obtained on Aug. 24 1989 at a range of 530.000 Km (or 330.000 miles). The resolution is about 10 Km (6,2 miles), sufficient to begin to show topographic detail. The image was made from pictures taken through the green, violet and ultraviolet filters. In this technique, regions that are highly reflective in the ultraviolet appear blue in color. In reality, there is no part of Triton that would appear blue to the eye. The bright southern hemisphere of Triton, which fills most of this frame, is generally pink in tone as is the even brighter equatorial band. The darker regions north of the equator also tend to be pink or reddish in color".
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Neptune-HST2.JPGNeptune and a few of His Moons (HST; Natural Colors; credits: NASA)57 visitenessun commentoMareKromium
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Neptune_and_Despina-transit_combo_despinabrightened.jpgNeptune and Despina57 visiteDalla Rubrica "NASA - Picture of the Day", del giorno 3 Settembre 2009:"Despina is a tiny moon of Neptune. A mere 148 Km across, diminutive Despina was discovered in 1989, in images from the Voyager 2 Spacecraft taken during its encounter with the Solar System's most distant Gas Giant Planet. But looking through the Voyager 2 data 20 years later, amateur image processor (and philosophy professor) Ted Stryk discovered something no one had recognized before -- images that show the shadow of Despina in transit across Neptune's blue cloud tops.
His composite view of Despina and its shadow is composed of four archival frames taken on August 24, 1989, separated by 9 minutes. Despina itself has been artificially brightened to make it easier to see.
In ancient Greek mythology, Despina is a daughter of Poseidon (the Roman god Neptune)".MareKromium
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Triton-PIA12184.jpgVolcanic Plains on Triton (possible Natural Colors; credits: Lunexit)57 visiteCaption NASA:"This view of the Volcanic Plains of Neptune's moon Triton was produced using topographic maps derived from images acquired by NASA's Voyager Spacecraft during its August 1989 flyby, 20 years ago this week (August 2009).
Triton, Neptune's largest moon, was the last solid object visited by the Voyager 2 Spacecraft on its epic 10-year tour of the Outer Solar System.
This regional view shows a variety of Terrains on Triton, including the smooth Volcanic Plains in the foreground, formed by icy lavas. Parts of this Surface have been eroded, forming mounds and depressions with relief of tens to a few hundred meters (several hundred feet). The round pits and mounds across the center of the scene are probably volcanic explosion or collapse craters, the largest of which (at bottom center) is approx. 250 meters deep (820 feet) and approx. 15 Km (about 9 miles) across.
Many of these pits are aligned in chains similar to those seen in basaltic volcanic areas on Earth, such as Craters of the Moon National Monument in Idaho, except the lavas on Triton are water and other ices that erupted onto the Surface.
In the distance is one of two large walled smooth plains of unknown origin. These plains are roughly 200 Km (about 124 miles) across.
The Surface of Triton is very rugged, scarred by rising blobs of ice (Diapirs), Faults and Volcanic Pits and Lava Flows composed of water and other ices. The Surface is also extremely young and sparsely cratered. It may even be younger than the Surface of Europa, one of the first objects visited by the Voyager Spacecraft and could be geologically active today.
Although locally very rugged, Triton has no large mountains or deep basins and regional relief is low, a consequence of its high internal heat and the low strength of most ices. This scene is on the order of 500 Km (about 310 miles) across and is taken from a new flyover movie across the Equatorial Regions of Triton commemorating the Voyager 20-year anniversary of this flyby.
Vertical relief has been exaggerated by a factor of 25 to aid interpretation".MareKromium
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Triton-PIA02234~0.jpgTriton (possible Natural Colors; credits for the additional process. and color.: Dr Paolo C. Fienga - Lunexit Team)57 visitenessun commentoMareKromium
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