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00-Titan.JPGTitan in possible True Colors (credits: NASA)62 visiteAttraverso l’oculare di un (anche) modesto telescopio, Titano, il più grande satellite naturale del pianeta Saturno, appare come un corpo puntiforme che splende debolmente di un delicato color giallo-pallido.
Si tratta di un oggetto celeste reso affascinante dalla sua posizione – apparentemente assai prossima – rispetto al Gigante Anellato (la sua distanza angolare da Saturno non supera mai i 20 raggi saturniani), ma certo non si può dire che Titano, in sé, riesca a suggerire particolari interessi e curiosità visive, anzi: nessun rilievo superficiale di questo Mondo, infatti, risulta discernibile nelle osservazioni effettuate da Terra (nemmeno usando le più sofisticate ed avanzate tecniche fotografiche) e, come abbiamo appreso grazie alle immagini ottenute dalle Sonde Voyager prima e dall’Orbiter Cassini poi, anche da distanza (relativamente) ravvicinata questo mondo risulta alquanto indecifrabile (anche se occorre dire che, già dalla metà degli Anni ’70, l’effettuazione di una serie di osservazioni ripetute di Titano – effettuate usando i più grandi telescopi terrestri al tempo disponibili – aveva, peraltro correttamente, suggerito agli Astronomi una sostanziale NON uniformità, in termini di albedo, della sua superficie la quale venne ben interpretata, sin d’allora, come indice della possibile presenza di aree superficiali sensibilmente disomogenee ed equiparabili a continenti).
MareKromium
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Titan from Voyager.jpgTitan from Voyager 2 (in HR)57 visiteTitan Data and Statistics
Discovered by = Christiaan Huygens
Date of discovery = 1655
Mass (kg) = 1.35e+23
Mass (Earth = 1) = 2.2590e-02
Equatorial radius = 2.575 Km
Equatorial radius (Earth = 1) = 4.0373e-01
Mean density (gm/cm^3) = 1,88
Mean distance from Saturn = 1.221.850 Km
Rotational period (days) = 15,94542
Orbital period (days) = 15,94542
Mean orbital velocity (km/sec) = 5,58
Orbital inclination = 0,33°
Escape velocity (km/sec) = 2,65
Visual geometric albedo = 0,21
Magnitude (Vo) = 8,28
Mean surface temperature = -178°C
Atmospheric pressure (bars) = 1,5
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Titan-1-PIA06228.jpgTitan in three different wavelenghts: the monochrome Titan (1)58 visiteCaption NASA originale:"This image composite was created with images taken during the Cassini spacecraft's closest flyby of Titan on April 16, 2005. Cassini's cameras have numerous filters that reveal features above and beneath the shroud of Titan's atmosphere.
This monochrome view shows what Titan looks like at 938 nnmts, a near-infrared wavelength that allows Cassini to see through the hazy atmosphere and down to the surface. The view was created by combining 3 separate images taken with this filter, in order to improve the visibility of surface features. The variations in brightness on the surface are real differences in the reflectivity of the materials on Titan. North on Titan is up and tilted 30° to the right".
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Titan-2-PIA06230.jpgTitan in three different wavelenghts: the natural Titan (2)57 visiteCaption NASA originale:"This natural color composite was taken during the Cassini spacecraft's April 16, 2005, flyby of Titan. It is a combination of images taken through three filters that are sensitive to red, green and violet light.
It shows approximately what Titan would look like to the human eye: a hazy orange globe surrounded by a tenuous, bluish haze. The orange color is due to the hydrocarbon particles which make up Titan's atmospheric haze. This obscuring haze was particularly frustrating for planetary scientists following the NASA Voyager 1 and 2 mission encounters in 1980-81. Fortunately, Cassini is able to pierce Titan's veil at infrared wavelengths (see also PIA06228). North on Titan is up and tilted 30° to the right".
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Titan-3-PIA06229.jpgTitan in three different wavelenghts: the strange Titan (3)57 visiteCaption NASA originale:"This false-color composite was created with images taken during the Cassini spacecraft's closest flyby of Titan on April 16, 2005.
It was created by combining 2 infrared images (taken at 938 and 889 nnmts) with a visible light image (taken at 420 nnmts). Green represents areas where Cassini is able to see down to the surface. Red represents areas high in Titan's stratosphere where atmospheric methane is absorbing sunlight. Blue along the moon's outer edge represents visible violet wavelengths at which the upper atmosphere and detached hazes are better seen.
A similar false-color image showing the opposite hemisphere of Titan was created from images taken during Cassini's first close flyby of the smoggy moon in October 2004 (see PIA06139). At that time, clouds could be seen near Titan's South Pole, but in these more recent observations no clouds are seen. North on Titan is up and tilted 30° to the right".
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Titan-4-PIA06227.jpgTitan in three different wavelenghts: is it always Titan?57 visiteCaption NASA originale:"All of these images were taken with the Cassini spacecraft wide angle camera on April 16, 2005, at distances ranging from approximately 173.000 to 168.200 Km (such as approx. 107.500 to 104.500 miles) from Titan and from a Sun-Titan-spacecraft angle of 56°.
Resolution in the images approximately 10 Km per pixel".
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Titan-Atmosphere-IMG001498-br500.jpgComplex Hydrocarbons in Titan's upper atmosphere57 visiteCaption NASA originale:"During its closest flyby of Saturn's moon Titan on April 16, the Cassini spacecraft came within 1.025 Km of the moon's surface and found that the outer layer of the thick, hazy atmosphere is brimming with complex hydrocarbons.
This figure shows a mass spectrum of Titan's ionosphere near 1.200 Km above its surface. The mass range covered goes from Hydrogen at 1 atomic mass unit per elementary charge (Dalton) to 99 Daltons. This mass range includes compounds with 1, 2, 3, 4, 5, 6 and 7 carbons as the base structure (as indicated in the figure label). The identified compounds include multiple carbon molecules and carbon-nitrogen bearing species as well".
Un'atmosfera "primordiale", dunque, ma teoricamente idonea per lo sviluppo di forme di vita 'prossime' (in termini di fondamenta chimiche e chimico/fisiche) alle nostre concezioni di 'forme vitali'.
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Titan-Atmosphere-N00027972.jpgThe "Foggy" Limb of Titan56 visitenessun commento
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Titan-Atmosphere-N00031071.jpgThe "Foggy" Limb of Titan55 visiteIl 4° fly-by di Titano si è compiuto e dalla Sonda Cassini, come al solito, ci arrivano una marea di frames completamente (o quasi) inesplicabili. Gli artifacts fotografici, come vedete in questo frame che abbiamo scelto fra tantissimi uguali, sono tanti (e la pulitura elettronica delle immagini avverrà solo in un futuro imprecisato); i rilievi della superficie di Titano - come ovvio - sono assolutamente impossibili da cogliere senza l'ausilio di attrezzature e tecniche all'avanguardia. Il risultato, purtroppo, è che noi non siamo in grado di dirVi nulla di "nuovo" su questa comunque affascinante Luna "Nebbiosa". La NASA, come sapete, esprime - di tanto in tanto - qualche commento a riguardo, ma il tutto si esaurisce (come per Marte) in grandi bolle di sapone: pillole di Scienza "usa & getta" che possono essere utili a dei Divulgatori (come noi, per esempio), ma che non servono quasi a nulla nel momento in cui si intendessero fare degli studi e delle ricerche un pò più profondi/e e dettagliati/e.
Peccato...
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Titan-Atmosphere-N00091073.jpgIn the Night of Titan - (possible natural colors; elab. Lunexit)55 visiteCaption NASA:"N00091073.jpg was taken on August 30, 2007 and received on Earth September 01, 2007. The camera was pointing toward TITAN that, at the time, was approx. 138.726 Km away, and the image was taken using the CL1 and UV3 filters. This image has not been validated or calibrated".MareKromium
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Titan-Atmosphere-N00098823.jpgThe "Multi-Layered" Atmosphere of Titan (MULTISPECTRUM - Overexposed; credits for the additional process. and color.: Lunexit)57 visiteCaption NASA:"N00098823.jpg was taken on December 20, 2007 and received on Earth December 22, 2007. The camera was pointing toward TITAN that, at the time, was approx. 186.227 Km away, and the image was taken using the CL1 and UV3 filters. This image has not been validated or calibrated".MareKromium
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Titan-Atmosphere-PIA06160_modest.jpgThe many layers of Titan's Atmosphere56 visiteCaption NASA originale:"Cassini has found Titan's upper atmosphere to consist of a surprising number of layers of haze, as shown in this ultraviolet image of Titan's night side limb, colorized to look like true color. The many fine haze layers extend several hundred kilometers above the surface. Although this is a night side view, with only a thin crescent receiving direct sunlight, the haze layers are bright from light scattered through the atmosphere. The image was taken with the Cassini spacecraft narrow angle camera. About 12 distinct haze layers can be seen in this image, with a scale of 0.7 Km (0.43 miles) per pixel. The limb shown here is at about 10° south latitude, in the equatorial region".
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