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| Ultimi arrivi - Saturn: the "Ringed Beauty" and His Moons |
Hyperion-PIA06527.jpgHyperion from approx. 2.200.000 Km57 visiteCaption NASA originale:"This image reveals the odd shape of Saturn's moon Hyperion and an intriguing variation in brightness across its surface (ndr: just like Japetus?!?).
The diameter of Hyperion is 266 Km.
The image was taken in visible light with the Cassini spacecraft narrow angle camera on Oct. 20, 2004, at a distance of about 2.2 MKM from Hyperion and at a Sun-Hyperion-spacecraft, or phase, angle of 50°. The image scale is 13 Km per pixel".Nov 26, 2004
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Tethys-PIA06140_modest.jpgTethys in natural colors60 visiteCaption NASA originale:"Having passed closer to Tethys than the Voyager 2 spacecraft, Cassini has returned the best-ever natural color view of this icy Saturnian moon.
As seen here, the battered surface of Tethys has a neutral hue. The image here is a mosaic of two footprints. Three images taken in the red, green and blue filters were taken to form a natural color composite. The result reveals a world nearly saturated with craters - many small craters lie on top of older, larger ones, suggesting an ancient surface. At the top and along the boundary between day and night, the moon's terrain has a grooved appearance.
This moon is known to have a density very close to that of water, indicating it is likely composed mainly of water ice. Its frozen mysteries await Cassini's planned close flyby in September 2005". Nov 24, 2004
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Tethys-PIA06526_modest.jpgTethys and the South Pole of Saturn65 visiteCaption NASA originale:"This dazzling view looks beyond gigantic storms near Saturn's South Pole to the small but clear disc of Tethys (1.060 Km across). Clouds and ribbons of gas swirl about in the planet's atmosphere in the foreground, while a tremendous chasm is visible on the icy moon. The image was taken with the Cassini spacecraft narrow angle camera on Oct. 18, 2004, at a distance of about 3.9 MKMs from Saturn and at a Sun-Saturn-spacecraft, or phase, angle of 61°. The view is in wavelengths of visible red light centered at 619 nanometers. The image scale is 23 Km per pixel". Nov 24, 2004
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Rhea-PIA06525_modest.jpgRhea from about 1.700.000 Km55 visiteCaption NASA originale:"Saturn's moon Rhea shows off the moon equivalent of a black eye: a bright, rayed crater near its eastern limb.
Rhea is about half the size of Earth's moon. At 1.528 Km across, it is the second-largest moon orbiting Saturn.
The image was taken in visible light with the Cassini spacecraft narrow angle camera on Oct. 24, 2004, at a distance of about 1.7 MKMs from Rhea and at a Sun-Rhea-spacecraft, or phase, angle of 40°. The image scale is approximately 10 Km per pixel. Cassini will image this hemisphere of Rhea again in mid-January 2005 with an approx. 1 Km resolution". Nov 24, 2004
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Atlas and others-PIA06522_modest.jpgSaturn's Rings + Atlas, Prometheus and Janus77 visiteCaption NASA originale: "Saturn hosts its own miniature solar system with an entourage of more than 30 moons. This image shows Saturn's "A" and "F" Rings, along with 3 of the moons that orbit close to them. From innermost to outermost, tiny Atlas (32 Km across) orbits just outside of the bright "A-Ring" and is seen above center in this view. Prometheus (102 Km across) is visible near lower right. Prometheus and its smaller cohort, Pandora, shepherd the thin, knotted F-Ring. Janus (181 Km across) can be seen near lower left. Janus shares its orbit with the moon Epimetheus. Density waves due to Janus cause some of the bright bands seen in the A-Ring in this image. Prometheus and Atlas also produce waves in the rings, but their wave regions are too narrow to be seen here. The planet's shadow stretches all the way across the main rings in this view. The shadow has an oval shape now but over the next few years it will become more rectangular as the planet orbits the Sun and the angle Sunlight-Rings decreases".Nov 19, 2004
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Atlas, Pandora and Janus-PIA06522_modest.jpgSaturn's Rings + Atlas, Pandora, Prometheus and Janus78 visiteCaption NASA originale: "Saturn hosts its own miniature solar system with an entourage of more than 30 moons. This image shows Saturn's "A" and "F" Rings, along with three of the moons that orbit close to them. From innermost to outermost, tiny Atlas (32 Km across) orbits just outside of the bright "A-Ring" and is seen above center in this view. Prometheus (102 Km across) is visible near lower right. Prometheus and its smaller cohort, Pandora, shepherd the thin, knotted F-Ring. Janus (181 Km across) can be seen near lower left. Janus shares its orbit with the moon Epimetheus. Density waves due to Janus cause some of the bright bands seen in the A-Ring in this image. Prometheus and Atlas also produce waves in the rings, but their wave regions are too narrow to be seen here. The planet's shadow stretches all the way across the main rings in this view. The shadow has an oval shape now but over the next few years it will become more rectangular as the planet orbits the Sun and the angle Sunlight-Rings decreases.Nov 19, 2004
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Japetus-PIA06521_modest.jpgThe "dark side" of Japetus63 visiteCaption NASA originale: "This image shows the dark, leading hemisphere of the mysterious moon Iapetus. The dark area is the Cassini region, named for Giovanni Cassini, who discovered the moon in 1672. The diameter of Iapetus is of approx. 1,436 Km (892 miles).
Cassini noted that he was able to see the moon on one side of its orbit around Saturn, but not on the other side. From this, he correctly deduced that one hemisphere must be dark while the other is much brighter".Nov 17, 2004
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Saturn-W00003147.jpgSaturn's Rings overexposed (4)55 visiteUn'ennesima - curiosissima, dobbiamo ammetterlo - versione degli Anelli di Saturno ampiamente sovraesposti. Che cosa sia il "raggio" di luce che sembra avere origine dagli Anelli stessi, ci è impossibile dirlo. Se andate a guardare il Sito dedicato alla Sonda Cassini-Huygens e, in particolare, quella sua sezione dedicata alle "last 500 raw images" della Sonda, avrete l'opportunità di notare il quantitativo sempre crescente, negli ultimi tempi, di questo tipo di immagine sovraesposta la quale, come ha fatto con noi, ha tratto in inganno tanti Ricercatori ed Appassionati. Questo tipo di immagini "strane" ed "ingannevoli", dunque, è salito (molto), ma il quantitativo globale di immagini in arrivo da Saturno si è paurosamente abbassato. Per questa volta evitiamo speculazioni che sarebbero (forse) troppo ovvie, però non possiamo non notare che questo nuovo trend è decisamente inusuale. Nov 14, 2004
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Tethys-PIA06518_modest.jpgTethys from approx. 7.900.000 Km55 visiteCaption NASA originale: "Two large craters and hints of several smaller ones are visible in this Cassini image of Saturn's icy moon Tethys (1060 Km across).
The image was taken in visible light with the Cassini spacecraft narrow angle camera on Sept. 23, 2004, at a distance of 7.9 MKMs from Tethys and at a Sun- Tethys-spacecraft, or phase, angle of 80°. The image scale is 48 Km per pixel. The image has been contrast-enhanced and magnified by a factor of four to aid visibility". Nov 12, 2004
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Saturn-W00003055.jpgSaturn and his shadow (1)56 visiteUn'immagine molto bella, ma incompleta: l'abbiamo scelta fra le tante perchè simboleggia abbastanza bene quello che molti di noi, da qualche tempo, stanno pensando.
Che cosa? Che la pagina dedicata alle "istantanee di Saturno" (http://saturn.jpl.nasa.gov/multimedia/images/raw/raw-images), da qualche tempo, non venga aggiornata mediante l'inserimento di TUTTE le fotografie scattate da Cassini-Huygens, come invece accadeva durante i primi tempi della Missione. Ad ogni modo, non appena avuto questo sospetto, abbiamo iniziato a controllare - e lo abbiamo fatto per 10 giorni - i codici alfanumerici identificativi delle 2 (solo2?!?) telecamere dalle quali le foto vengono scattate e, quindi, di tutte le immagini ricevute. Risultato? Ci sono dei "buchi" colossali! EccoVi le possibili spiegazioni di questo fatto:
1) forse le immagini da inserire sono troppe ed allora viene fatta una cernita - fra quali inserire e quali non - alla "sorgente" (già, ma da chi è fatta questa cernita, ed in base a quali parametri?); Nov 10, 2004
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Saturn-W00003106.jpgSaturn and his shadow (4)56 visiteCosa significa, in fondo, quello che dice la "caption" che abbiamo integralmente riportato e che viene apposta alla fine di ogni immagine NASA commentata? Vuol dire che Cassini-Huygens è un Progetto che coinvolge, oltre alla NASA, anche altre due Agenzie Spaziali, ma che tutto ciò che riguarda le immagini viene gestito da Washington. Il che, in altre - e forse più crude - parole, vuol dire che il "peso" delle tre Agenzie coinvolte NON è, nè potrebbe essere mai - ovviamente - lo stesso.
Questo è un argomento profondamente scabroso e ci piacerebbe sentire l'opinione anche di qualche altro Amico di Lunar Explorer che ci legge (quasi) tutti i giorni.
Aspettiamo le Vostre comunicazioni ed opinioni quindi!...Nov 10, 2004
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Saturn-W00003105.jpgSaturn and his shadow (3)57 visite...tutte le nuove immagini che, per un motivo o per l'altro, potevano prestarsi a far sorgere nuove domande, nuovi dubbi, nuovi interrogativi - più o meno scabrosi - e che, comunque, potevano "imbarazzare" la National Aeronautics and Space Administration. Detto in un altro modo, stiamo parlando di "CENSURA". Però, come ben sapete, la NASA non gestisce questa Missione da sola: c'è di mezzo anche l'European Space Agency e l'Agenzia Spaziale Italiana. Leggete:
"The Cassini-Huygens mission is a cooperative project of NASA, the European Space Agency and the Italian Space Agency. The Jet Propulsion Laboratory, a division of the California Institute of Technology in Pasadena, manages the Cassini-Huygens mission for NASA's Science Mission Directorate, Washington, D.C. The Cassini orbiter and its two onboard cameras were designed, developed and assembled at JPL. The imaging team is based at the Space Science Institute, Boulder, Colo".
Nov 10, 2004
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