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| Piú viste - Titan: The "Foggy" Moon |
Titan-Mountains-PIA10654.jpgTitanian Tectonics - radio-image; credits: NASA56 visiteOvviamente la "linea" è un ovvio image-artifact, come la NASA stessa ci riferisce e spiega NELLE ULTIME DUE RIGHE DEI COMMENTI UFFICIALI, ma noi abbiamo lasciato la sovraimpressione "evocativa di Mistero" sul frame al SOLO scopo di farVi capire - caso mai ce ne fosse stato ancora bisogno - QUANTO SIA FACILE CREARE BUFALE!
Soprattutto allorchè NON si presta la dovuta attenzione alle note "ufficiali" di commento ed allorchè non si è molto familiari con la Fotografia Spaziale in generale e con le Radio-Immagini in particolare.
Caption NASA:"A set of three parallel ridges was seen by the Cassini Spacecraft's Radar Instrument during the latest Titan flyby on May 12, 2008. This combination is unlikely to be a coincidence -- the best explanation for these features is that they are tilted or separated blocks of broken or faulted crust, now exposed as high ridges. Their regular spacing is typical of regions that have been compressed or extended over large areas; as an example, the western United States Basin and Range Province was formed by extension. Such interactions are called "Tectonics", although they do not happen in the same way as plate tectonics, which is a process unique to Earth.
The ridges, which appear on the left side of the image, are rugged features and are elevated above surrounding terrain. The brightness patterns mean that the materials are fractured or blocky at the radar wavelength (2,17 cm, or about 1" - one inch). Along the south sides of the ridges are prominent cliffs, or scarps, present as thin, radar-dark lines trending West-to-East, and interpreted as faults.
These features are dark due to shadowing from the radar illumination, and have heights up to a few hundred meters (several hundred feet), based on preliminary estimates of slopes.
The area shown here is located in the mountainous region called Xanadu.
The ridges are similar in many ways to mountain chains seen at similar latitude but about 90° to the West, just West of Shangri-La (observed during a flyby in October 2005, and showin a Sea of Sand-like Dunes).
Both Regions have mountain chains or ridges that are oriented West-to-East and are spaced about 50 Km (or about 30 miles) apart. This indicates tectonic forces have acted in a North to South direction at Titan's Equatorial Region and have resulted in regular effects in Titan's crust, evidence that will help scientists better understand Titan's crust and interior.
Other linear features, probably related to the formation of the ridges, and circular features, perhaps eroded impact craters now filled with radar-dark (smooth) material, are also seen in the image. The largest circular feature, at bottom center, is about 20 Km in diameter.
The image is centered at 2° South Lat. and 127° West Long. and was obtained on May 12, 2008, with a resolution of about 300 meters (980 feet). The open arrow indicates the direction of radar illumination.
The dashed white line in the upper portion is an artifact of the SAR processing and will be removed in later versions".MareKromium
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Titan-Channels-Unnamed_Channels-PIA10956.jpgXanadu's Channels (false colors; credits: Lunexit)56 visiteOn the final flyby of Cassini's original 4-year tour, its radar mapper captured these unusual channels on Titan at the edge of Xanadu, the widest seen in this area (For a radar image of Xanadu, see PIA08428). These might be active rivers carrying methane or debris, or they might be dry riverbeds similar to earthly "arroyos".
Past Cassini radar images have revealed different types of channels on Titan's surface (see PIA03565 and PIA07366). They vary from bright to dark in radar (rough to smooth), and from fan-shaped to braided to meandering.
Some, drain into lakes; others disappear. Some of these channels may be several hundred meters, or feet, deep.
This image, taken from the flyby on May 28, 2008, shows the border of Xanadu as the bright-dark boundary running from the upper left to lower right. Southward from that boundary is an unusual set of channels. While these are brighter (more roughly textured) than the surrounding terrain, some are only slightly brighter, and some are as wide as 5 Km (about 3 miles) — about the size of the River Thames at its mouth east of London.
They appear to flow out of the rough Region of Xanadu.
Careful inspection reveals smaller tributaries that wind through the brighter and apparently rougher terrain to the north. A close-up of one of the widest channels is shown at the lower left.
Scientists think that many of the channels on Titan are carved by methane deposited on the surface from strong but infrequent rainstorms. A bright channel may be dry, with the rough riverbed of icy particles (like those seen at the Huygens Landing Site) producing the radar brightness. The darker channels in this image resemble the dry lakes seen in the North Polar area of Titan, so they may be dry as well, with their smoother (radar-dark) surfaces caused by finer-grained sediment deposits on the channel floors.
This image shows an area located at 15° South Latitude and 121° West Longitude. It is about 450 Km (about 280 miles) across, and has approximately 1 Km (0,62-mile) resolution.
North is up.MareKromium
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Titan-N00121492.jpgTitan (natural colors; credits: Lunexit)56 visitenessun commentoMareKromium
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Titan-W00049900.jpgLost in the Space of Saturn... (natural colors; credits: Lunexit)56 visiteTitano: il disco, appena percettibile, splende di un leggero color giallo. Siamo a circa 1,8 MKM dalla "Luna Nebbiosa".MareKromium
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Titan-N00124864.jpgTitan in possible True Colors (credits by Lunar Explorer Italia)56 visiteCaption NASA:"N00124864.jpg was taken on December 05, 2008 and received on Earth December 06, 2008. The camera was pointing toward TITAN that, at the time, was approximately 171.534 Km away.
The image was taken using the CL1 and CB3 filters".MareKromium
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Titan-W00051725.jpgCrescent Titan (possible True Colors; credits: Lunar Explorer Italia)56 visiteCrescent Titan (possible True Colors; credits: Lunar Explorer Italia)
Caption NASA:"W00051725.jpg was taken on December 05, 2008 and received on Earth December 06, 2008. The camera was pointing toward TITAN that, at the time, was approx. 147.760 Km away.
The image was taken using the CB3 and CL2 filters".
MareKromium
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Titan-W00051746.jpgCrescent Titan (possible True Colors; credits: Lunar Explorer Italia)56 visiteCaption NASA:"W00051746.jpg was taken on December 06, 2008 and received on Earth December 06, 2008. The camera was pointing toward TITAN that, at the time, was approx. 313.546 Km away.
The image was taken using the CL1 and CL2 filters".MareKromium
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Titan-Surface-38.gifOn the way down... - Sol 1 (GIF-Movie; credits: Dr G. Barca)56 visiteLe Condizioni di Illuminazione
Innanzitutto, ed a dispetto di quanto mostrato dalle immagini ESA-Huygens (e da tante altre “visioni artistiche” di Titano made by NASA, la nostra prima considerazione attiene le condizioni medie di illuminazione di questo mondo.
Le fotografie ESA (ottenute sia durante la discesa, sia dalla superficie di Titano), al pari delle interpretazioni artistiche NASA, ci danno l’impressione di un mondo, ancora una volta, alquanto luminoso…
MareKromium
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Titan-Surface-40.gifOn the Surface... - Sol 1 (GIF-Movie; credits: Dr G. Barca)56 visiteIl quantitativo di luce solare e di calore che raggiunge la superficie di Titano (la cui temperatura superficiale media, lo ricordiamo, si aggira, per quanto si sa e si suppone, intorno ai -175° Celsius) infatti, è talmente esiguo (diciamo pure “trascurabile”) da non permettere – se non altro sulla base di quelle che sono le nostre attuali conoscenze scientifiche – lo sviluppo di alcuna reazione assimilabile, ad esempio, alla fotosintesi.
Questo significa, tra le altre cose, che l’eventuale sviluppo di Forme Vitali indigene su Titano potrebbe derivare esclusivamente da interazioni chimiche o da processi esotici di carattere assolutamente locale. A quest’ultimo proposito, infine, si è detto e scritto che Titano, in fondo, rappresenta la versione “gelida” di una Terra Primordiale (un parallelo nato, probabilmente, dalla considerazione relativa al quantitativo di Nitrogeno esistente nell’atmosfera della Luna Nebbiosa nonché in riferimento a quella che sembra essere la morfologia attuale del pianeta in rapporto a quella che si suppone possa essere stata la morfologia della Terra Primordiale).
A nostro parere, però, la realtà è diversa e Titano potrebbe rappresentare, oggi, l’espressione di un Mondo “vivo e vitale” per nulla simile od assimilabile al nostro Pianeta Azzurro.
Un mondo che NON assomiglia affatto alla nostra Terra e che NON assomiglierà MAI alla nostra Terra.
Pensate: se la regola fondamentale della “Vita”, nel suo senso più ampio e profondo, è esprimibile nel concetto di “ADATTAMENTO NEL TEMPO”, allora è ragionevole pensare che su Titano, in fondo (e riflettendoci bene), potrebbero essere in corso da ere ed ere (!) processi tali da aver consentito la nascita e lo sviluppo di Forme di Vita indigene assolutamente peculiari, per noi inimmaginabili e, per ovvi motivi, completamente diverse da quelle che caratterizzano la Terra e gli ipotetici ambienti alieni di tipo simil-terrestre.
Il fatto che la ricerca (talvolta esasperata) di similitudini fra altri mondi ed il “nostro” mondo costituisca una caratteristica peculiare e propria della Scienza (Astronomica e non solo) Moderna e dell’atteggiamento degli scienziati che la praticano è indubitabile; ma che un simile approccio, alla fine, non possa venirsi a caratterizzare se non per la sua intrinseca limitatezza (e per lo strabismo scientifico che geneticamente lo affligge), ci sembra un elemento sul quale si dovrebbe riflettere meglio e maggiormente.
MareKromium
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Titan-Cryovolcanism_Map-PIA11702.jpgActive Cryovolcanism on Titan?56 visiteCaption NASA:"The Cassini Radar Mapper imaged Titan on Feb. 22, 2008 (as shown on the left) and April 30, 2006 (as shown on the right).
These radar images show the outlines of Regions "1" and "2" identified by Cassini's VIMS (such as the Visual and Infrared Mapping Spectrometer) and inferred to be variable (see VIMS flat map, PIA11701), and which have been hypothesized to be due to cryovolcanic activity. The lobate, flow-like features in Region 1 are consistent with this interpretation.
Region 1 is just north of the feature named Hotei Arcus and is centered on 28° South Lat. by 78° West Long.
The Region is about 400 Km (approx. 249 miles) across. Region 2 is on the western part of Xanadu and is centered on 7° South Lat. by 135° West Long. This region is about 900 Km (approx. 560 miles) across. In both cases, North is up, and features as small as 300-500 meters can be resolved".MareKromium
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Titan-Cryovolcanism_Map-PIA11701.jpgIR Map of Titan's Active (Cryovolcanic) Regions56 visiteThis infrared projection map of Titan was composed from images taken by NASA's Cassini Spacecraft, Visual and Infrared Mapping Spectrometer. The location of two regions that changed in brightness are labeled. These regions are hypothesized by some to be areas of cryovolcanic activity on Titan.
Rather than erupting molten rock, it is theorized that the cryovolcanoes of Titan would erupt volatiles such as Water, Ammonia and Methane. Scientists have suspected cryovolcanoes might be on Titan, and the Cassini mission has collected data on several previous passes of the moon that suggest their existence. Imagery of the moon has included a suspect haze hovering over flow-like surface formations, which are plausibly the result of icy volcanism.
Some Cassini scientists indicate that such volcanism could release Methane from the interior, which explains Titan's seemingly continuous supply of fresh Methane. Without replenishment, scientists say, Titan's original Atmospheric Methane should have been exhausted long ago.
This image is an overlay of all the high-resolution images from the first 45 flybys, up through last February 2007. The map was created using what 2,1 micron wavelength. Image scale is about 25 Km (approx. 16 miles) per pixel or 1,8 pixels per degree".MareKromium
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Titan-Clouds-Noctilucent_Clouds-GIFMovie-N00023443-N00023924.gifNoctilucent Clouds over Titan (GIF-Movie; credits: Dr G. Barca)56 visiteSu Titano è notte, ma come queste immagini (ottimamente montate a formare un GIF-Movie dal nostro Dr Gianluigi Barca) dimostrano piuttosto chiaramente, delle grandi e vaporose formazioni nuvolose passano attraverso gli occhi elettronici di Cassini e si rendono palesi.
Magia delle riprese IR?
No, perchè queste immagini sono state ottenute nello Spettro della Luce Visibile.
E allora, come spiegare la (ripetiamo: EVIDENTE) luminosità delle nuvole di Titano?
Beh, esistono almeno tre modi per provare a spiegare (sensatamente) questo intrigante ed affascinante fenomeno, ma la soluzione (puramente ed assolutamente teorica e speculativa, lo sappiamo) che ci piace privilegiare la potete trovare descritta nell'articolo "Oltre la Nebbia", pubblicato sul nostro Blog "True Planets"...MareKromium
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