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| Ultimi arrivi - Saturn: the "Ringed Beauty" and His Moons |
PHOEBE-PIA06064_modest.jpgPhoebe (Extremely Ehnanced and Saturated Natural Colors; credits: Lunexit Team)58 visitenessun commentoMareKromiumAgo 20, 2008
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Janus-PIA10447-1.jpgJanus (possible True Colors; credits: Lunexit)58 visiteCaption NASA:"This shadowy scene is one of the Cassini Spacecraft's closest views of Saturn's moon Janus.
The slopes of some craters here display hints of the darker material better seen on Epimetheus. A bright linear feature runs up the wall of the large crater at bottom center.
This view looks toward Southern Latitudes on Janus (about 179 kilometers, or 111 miles across). North is toward the top of the image and rotated 58° to the right.
The image was taken in visible light with the Cassini Spacecraft narrow-angle camera on June 30, 2008. The view was obtained at a distance of approx. 33.000 Km (such as about 21.000 miles) from Janus and at a Sun-Janus-Spacecraft, or Phase, Angle of 120°. Image scale is roughly 200 meters (656 feet) per pixel".MareKromiumAgo 15, 2008
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Enceladus-PIA11113.jpgDamascus Sulcus (possible True Colors; credits: Lunexit)58 visiteCaption NASA:"The yellow circles on this mosaic, showing the fracture known as Damascus Sulcus, indicate the Jets' Source Locations II and III, as identified in PIA08385.
This mosaic consists of two images obtained with the clear spectral filters on Cassini's narrow-angle camera. The view is an orthographic projection with an image scale of 24 meters (79 feet) per pixel. The area shown here is centered on 81,2° South Latitude and 309,9° West Longitude. The original images ranged in resolution from 27 to 30 meters (89 to 98 feet) per pixel and were taken at distances ranging from 4200 to 4742 Km (such as from about 2610 to approx. 2947 miles) from Enceladus".MareKromiumAgo 15, 2008
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Enceladus-PIA11114.jpgBaghdad and Cairo Sulci on Enceladus (possible True Colors; credits: Lunexit)61 visiteCaption NASA:"Cassini shot past the surface of Saturn's moon Enceladus on Aug. 11, 2008, acquiring a set of 7 HR images targeting known hot spot locations on the moon's "Tiger Stripe" fractures, or Sulci.
Five of those images are presented in this mosaic.
Features on Enceladus are named for characters and places from "The Arabian Nights", and the four most prominent Sulci are named Alexandria, Cairo, Baghdad and Damascus. Here, Baghdad Sulcus runs across the top mosaic tile, from lower left to upper right. Cairo Sulcus runs from left to right just beneath the center tile.
One highly anticipated result of this flyby was to pinpoint previously identified source locations for the jets that blast icy particles, water vapor and trace organics into space.
The yellow circles indicate the Jets' Source Locations I and V, as identified in PIA08385" .
Scientists are using these new images to study geologic activity associated with the sulci, and effects on the surrounding terrain. This information, coupled with observations by Cassini's other instruments, may answer the question of whether reservoirs of liquid water exist beneath the surface.
The mosaic consists of five images taken with the clear spectral filters on Cassini's narrow-angle camera. The view is an orthographic projection with an image scale of 14,5 meters (47,5 feet) per pixel. The area shown here is centered on 81,6° South Latitude and 56,5° West Longitude. The original images ranged in resolution from 10 to 24 meters (33 to 79 feet) per pixel and were taken at distances ranging from 1288 to 3600 Km (such as from about 800 to approx. 2237 miles) from Enceladus".MareKromiumAgo 15, 2008
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Enceladus-PIA11112.jpgThe (possible) True Colors of Enceladus (credits: Lunexit)58 visiteQuesta colorizzazione in possibili Colori Veri è la risposta ad un quesito postoci dal nostro Amico "Alby56", il quale ci domanda - appunto - quali sìano (possano essere) i colori di Encelado.
Come ovvio, una risposta che abbia valore assoluto non possiamo darla, però possiamo provare a ragionarci sopra e vedere che cosa si riesce a stabilire...Dunque:
1) Encelado, a quanto pare, è completamente ricoperto da uno (spesso) strato di ghiaccio d'acqua ed esso - per motivi ancora non noti, ma che potremmo rinvenire, ad esempio, in un "riscaldamento periodico" dell'intero globo causato da "frizionamento mareale" con Saturno, si rinnova, nel tempo, rimuovendo i segni classici che dimostrano l'invecchiamento di un Corpo Celeste (su tutti: i crateri da impatto, i quali vengono - letteralmente - "cancellati", se sono piccoli, oppure "riempiti e parzialmente nascosti", se di medio-grandi dimensioni);
2) il ghiaccio d'acqua, allorchè illuminato dal Sole, risplende di color bianco, con riflessi azzurri;
3) il Sole, visto da Encelado, dovrebbe apparire non molto più grande di una qualsiasi delle altre stelle visibili dalla sua superficie e questo ci spinge a ritenere che la sua capacità di illuminare questo piccolo mondo sia trascurabile;
4) su Encelado, non esistendo un'atmosfera e dunque non sussistendo le condizioni per la diffusione della luce solare (anche se ci è possibile ipotizzare una diffusione minima e meramente stagionale - grazie alle particelle di ghiaccio e di vapore acqueo che restano, per un certo tempo, in sospensione nello spazio circum-Enceladiano), riteniamo che il panorama visibile ad occhi umani risulti, globalmente, piuttosto buio.
Ma attenzione: potrebbe essere ragionevole ipotizzare una dominante bianca (provocata dal Sole e dal ghiaccio) durante il "Giorno" di Encelado - ed a cielo sgombro - oppure, allorchè Saturno splende nel cielo di Encelado in tutta la sua pienezza, si potrebbe ipotizzare, sempre per una visione "umana", un paesaggio illuminato da una colorazione dominante giallo-arancio, la quale - al suolo - potrebbe tradursi in un colorito giallo pallido dei rilievi maggiori, con riflessi bianchi, azzurri e, forse - in alcune zone - anche verdastri.
Conclusioni: da una certa distanza (supponiamo tra i 500 ed i 25000 Km), Encelado - ad occhi umani - dovrebbe apparire, allorchè illuminato congiuntamente dal Sole e da Saturno (come in questo frame), di color giallo pallido, con riflessi bianchi ed azzurri (e quindi, in alcune regioni ed in determinate ore del giorno, non è assurdo ipotizzare la visione/percezione di delicate sfumature di color grigio e rosa).
Oltre i 25000/30000 Km di distanza, infine, Encelado dovrebbe apparire, ad un Osservatore che lo scrutasse "ad occhio nudo", di color bianco brillante, con debolissime (diremmo quasi impercettibili) sfumature di colore giallo e rosa.MareKromiumAgo 15, 2008
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The_Rings-PIA10446.jpgIn the Sunlight... (natural colors; credits: NASA)58 visiteCaption NASA:"Saturn's icy Rings shine in scattered sunlight in this view, which looks toward the unilluminated northern side of the Rings from about 15° above the Ring-Plane. The Sun currently illuminates the Rings from the South. Some of the sunlight not reflected from the Rings' southern face is scattered through the countless particles, setting the Rings aglow. The inner F-Ring shepherd moon Prometheus (86 Km, or about 53 miles across at its widest point) appears at lower left.
Images taken using red, green and blue spectral filters were combined to create this natural color view. Bright clumps of material in the narrow F-Ring moved in their orbits between each of the color exposures, creating a chromatic misalignment in several places that provides some sense of the continuous motion within the Ring System.
The images were obtained with the Spacecraft wide-angle camera on July 4, 2008 at a distance of approx. 1,2 MKM (about 770.000 miles) from Saturn. The Phase Angle was 28°.
Image scale is roughly 70 Km per pixel".MareKromiumAgo 14, 2008
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Enceladus-PIA11105.jpgSouth Polar Terrain near Cairo Sulcus63 visiteCaption NASA:"This image is the 1st skeet-shoot image taken during Cassini's very close flyby of Enceladus on Aug. 11, 2008. It captures a Region near the Cairo Sulcus on Enceladus' South Polar Terrain - that is littered with blocks of ice.
The image was taken with the Cassini spacecraft narrow-angle camera on Aug. 11, 2008, a distance of approx. 1288 Km (about 800 miles) above the surface of Enceladus.
Image scale is approximately 10 meters (33 feet) per pixel. MareKromiumAgo 14, 2008
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Enceladus-PIA11106.jpgCairo Sulcus61 visiteCaption NASA:"This image is the 3rd skeet-shoot image taken during Cassini's very close flyby of Enceladus on Aug. 11, 2008.
Cairo Sulcus is crossing the southern part of the image. The terrain is littered with blocks of ice.
The image was taken with the Cassini Spacecraft narrow-angle camera on Aug. 11, 2008, a distance of approx. 2446 Km (such as about 1396 miles) above the surface of Enceladus.
Image scale is approximately 18 meters (59 feet) per pixel". MareKromiumAgo 14, 2008
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Enceladus-PIA11107.jpgDamascus Sulcus59 visiteCaption NASA:"This image is the 7th skeet-shoot image taken during Cassini's very close flyby of Enceladus on Aug. 11, 2008. Damascus Sulcus is crossing the upper part of the image.
The image was taken with the Cassini Spacecraft narrow-angle camera on Aug. 11, 2008, a distance of approx. 4742 Km (such as about 2947 miles) above the surface of Enceladus.
Image scale is approximately 30 meters (98 feet) per pixel". MareKromiumAgo 14, 2008
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Enceladus-PIA11109.jpgCairo Sulcus58 visiteCaption NASA:"This image is the 4th skeet-shoot footprint taken during Cassini's very close flyby of Enceladus on Aug. 11, 2008. Cairo Sulcus is shown crossing the upper left portion of the image. An unnamed fracture curves around the lower right corner.
The image was taken with the Cassini Spacecraft narrow-angle camera on Aug. 11, 2008, a distance of approx. 3027 Km (such as about 1881 miles) above the surface of Enceladus.
Image scale is approximately 20 meters (66 feet) per pixel". MareKromiumAgo 14, 2008
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Enceladus-W00048468.jpgApproaching Enceladus (natural colors; credits: Lunexit)58 visiteCaption NASA:"W00048468.jpg was taken on August 11, 2008 and received on Earth August 12, 2008. The camera was pointing toward ENCELADUS that, at the time, was approximately 4748 kilometers away.
The image was taken using the CL1 and CL2 filters and it has not been validated or calibrated".MareKromiumAgo 13, 2008
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Enceladus-W00048467.jpgThe Unbelievable Surface of Enceladus, from ONLY 545 Km: the bright (and icy) walls of a Canyon57 visiteCaption NASA:"W00048467.jpg was taken on August 11, 2008 and received on Earth August 12, 2008. The camera was pointing toward ENCELADUS that, at the time, was approximately 545 kilometers away.
The image was taken using the CL1 and CL2 filters and it has not been validated or calibrated". MareKromiumAgo 13, 2008
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