| Ultimi arrivi - Neptune and His Moons |
Triton-PIA12185.jpgVolcanic Plains on Triton65 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".MareKromiumSet 08, 2009
|
|
Triton-PIA12187.jpgTritonian Terminator74 visitenessun commentoMareKromiumSet 08, 2009
|
|
Neptune_and_Despina-transit_combo_despinabrightened.jpgNeptune and Despina63 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)".MareKromiumSet 05, 2009
|
|
Neptune-PIA01982.jpgClouds near the "Eye" of Neptune (Natural Colors; credits: Lunexit)87 visiteCaption NASA:"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".MareKromiumLug 26, 2009
|
|
Neptune-PIA01995.jpgSouth Polar Clouds and Shadows (Natural Colors; credits: Lunexit)69 visiteCaption NASA:"This image of Neptune's South Polar Region was obtained by the NASA Voyager 2 Probe narrow-angle camera on Aug. 23, 1989, when it was at a distance of about 25 MKM (about 1,6 MMs).
The smallest cloud features are 45 Km (about 28 miles) in diameter. Also this image shows the discovery of shadows in Neptune's Atmosphere, shadows cast onto a deep cloud bank by small elevated clouds. Located at about 68° South Lat., they are the first cloud shadows ever seen by the Voyager on any Planet.
The dark regions adjacent to the small bright clouds are believed to be shadows, because they are on the side of the cloud that is opposite to the incoming Sunlight and also because they lengthen in places where the Sun lies closer to the horizon".MareKromiumLug 26, 2009
|
|
Neptune-PIA02220.jpgSouth Polar Clouds and Shadows (Natural Colors; credits: Lunexit)62 visiteCaption NASA:"This image of Neptune shows the discovery of shadows in Neptune's Upper Atmosphere, shadows cast onto a deep cloud band by small elevated clouds. They are the first cloud shadows ever seen by Voyager on any Planet. Estimates of the height of these discrete clouds above the underlying cloud bank can be obtained by careful analysis of this data".MareKromiumLug 26, 2009
|
|
Triton_Mosaic.JPGTriton (photo-mosaic - credits: NASA)62 visiteCaption NASA:"This picture of Triton is a mosaic of the highest resolution images taken by Voyager 2 on Aug. 25, 1989 from a distance of about 40.000 Km (approx. 24.800 miles). The mosaic is superimposed on the lower resolution mapping images taken about 2 hours earlier in order to fill in gaps between high resolution images. The smallest features that can be seen on the images are about 0,8 Km (approx. 0,5 miles) across.
The Terminator (such as the line separating the day from the night) is at the top of the picture and is centered at about 30° North Lat. and 330° East Longitude.
These highest resolution images were targeted for the Terminator Region to show details of the topography by the shadows it casts. Near the center of the picture is a depression filled with smooth plains that are probably ices which were once erupted in a fluid state. The depth of the depression is about 300 meters (900 feet) and the prominent fresh impact crater on its floor is about 20 Km (approx. 12 miles) in diameter and about 1 Km (such as approx. 0,6 mile) deep. On the right is an elongate crater with adjacent dark deposits above it. This feature may be an explosive eruption vent formed by gaps within the ice.
The linear structure on the left is probably a fracture along which fresh ice has been extruded".MareKromiumFeb 21, 2009
|
|
Neptune-StrechedNaturalColors.JPGNeptune and a few of His Moons (Voyager 2 - Natural, but enhanced, Colors; credits: NASA)78 visiteCaption NASA:"Voyager 2 was the first spacecraft to observe the planet Neptune and its two satellites: Triton, the largest, and Nereid.
The most obvious feature of the Planet is its blue color, the result of Methane in the Atmosphere. Research continues on Neptune's two largest satellites and the additional 6 that were discovered by Voyager 2's investigation". MareKromiumFeb 21, 2009
|
|
Triton.JPGNorthern Latitudes on Triton62 visiteVoyager 2 took this picture of Neptune's largest satellite, Triton, from less than 80.000 Km (about 50.000 miles). The image shows an area in Triton's Northern Hemisphere.
The Sun is just above the horizon, so features cast shadows that accentuate height differences. The large, smooth area in the right-hand side of the image shows a single, fresh, impact crater. Otherwise there is no evidence of impacts such as those that have pocked the faces of most of the satellites Voyager 2 has visited.
Many low cliffs in the area, bright where they face the Sun, and when they face away from it, suggest and intricate history for Triton. The cliffs might be due either to melting of surface materials or, possibly, caused by unusual fluid materials that flowed sometime in Triton's past.MareKromiumFeb 21, 2009
|
|
Neptune-HST1.JPGViews of Neptune (from Hubble Space Telescope)84 visitenessun commentoMareKromiumFeb 15, 2009
|
|
Neptune-HST2.JPGNeptune and a few of His Moons (HST; Natural Colors; credits: NASA)64 visitenessun commentoMareKromiumFeb 15, 2009
|
|
Neptune-HST4.JPGMoments of Neptune (HST - False Colors; credits: NASA, L. Sromovsky and P. Fry - University of Wisconsin-Madison)72 visitenessun commentoMareKromiumFeb 15, 2009
|
|
| 96 immagini su 8 pagina(e) |
2 |  |
|
|
|
|
|
