| Piú votate - Titan: The "Foggy" Moon |
Titan-Shoreline_and_Drainage_Channels-02a.jpgShoreline and Drainage Channels56 visiteUn'altra istantanea di Titano ripresa durante la quieta discesa di Huygens verso la superficie di questo mondo ritenuto dagli Scienziati e dai Ricercatori di tutto il Mondo come una "versione gelida" (temperatura media di superficie: circa -180°C) di quello che era la Terra ai suoi albori.
L'atmosfera di Titano è prevalentemente costituita da azoto, con l'aggiunta di metano ed altri elementi di natura organica.
Si noti che alcuni di questi "organic compounds", se riscontrati nell'atmosfera di un corpo celeste simile alla Terra, sarebbero indici forti dell'esistenza di forma di vita indigene. Sulla Terra, infatti, la formazione del metano è legata all'esistenza di forme di vita nel senso che il metano stesso è un sottoprodotto ("by-product") del metabolismo di svariati organismi. E' la Vita stessa, insomma, che sulla Terra contribuisce a ricostituire continuamente le scorte di metano, sostituendo quello andato distrutto per ossidazione. Ma su Titano? Da dove viene tutto il metano che abbiamo scoperto?
(7 voti)
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Titan-W00002390.jpgThe "Dark Side" of Titan from about 107.000 Km68 visiteLa Sonda Cassini-Huygens è passata accanto a Titano ed ora se ne sta rapidamente allontanando. Questa immagine è stata ripresa quando Titano era già stato superato di oltre 100.000 Km. Si tratta, come potete intuire, di una ripresa del lato di Titano immerso nella notte, mentre la luce che emerge dal bordo del Pianeta - formando una sorta di "aureola" - è causata dai raggi del Sole che passano attraverso gli strati superiori della sua atmosfera, generando un curioso fenomeno di diffusione luminosa.
Questo tipo di immagine, oltre ad essere piuttosto suggestiva, ci permette anche di vedere abbastanza bene i vari sub-strati in cui si suddivide (o sembra suddividersi...) l'atmosfera di Titano.
(7 voti)
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Titan-Lakes-Unnamed_North_Polar_Lakes-07-PIA08363-1.jpgThe Great Lake of Titan (False Colors; elab. Lunexit)55 visiteCaption NASA:"This view of Titan taken on Feb. 25, 2007, reveals a giant lake-like feature in Titan's North Polar Region. It is approximately 1100 Km (about 680 miles) long and has a surface area slightly smaller than that of Earth's largest lake, the Caspian Sea".
(7 voti)
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Titan-PIA06987_modest.jpgTwo Views of Titan's Haze54 visiteCaption NASA originale:"These images show 2 views of Titan's planet-wide stratospheric haze just before (left) and after (right) Cassini's first close encounter with the Shrouded Moon. The image on the left was taken on Oct. 25, 2004, through an ultraviolet filter, which is sensitive to scattering of sunlight by small haze particles. It shows the high-altitude haze at the North Pole (top) illuminated above a surface blanketed in darkness during this winter season. Numerous striations are visible in the haze, indicating either waves passing through the layer or the presence of multiple layers.
The image on the right was taken on Oct. 26, 2004 and shows Titan's night-side backlit by the Sun, after Cassini's closest approach to the moon. The haze layer ringing the planet is illuminated because the small particles scatter significant sunlight in the forward direction. Variations in haze concentration and thickness around the globe are also evident and seem to be symmetric around the north pole (upper left)".
(12 voti)
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Titan-Regions-Adiri_Region-IMG002645.jpgAdiri Region73 visiteCaption NASA:"Bright mid-latitude clouds near the bottom of this view hint at the ongoing cycling of Methane on Titan. These cloud streaks are near the same latitude as similar clouds observed above different longitudes on Titan.
The view is centered on Titan's Trailing Hemisphere, over the 1.700 Km (such as about 1050 mile) wide bright Region known as "Adiri".
North on Titan is up and rotated 15° to the right.
This view was created by combining multiple images taken using a combination of spectral filters sensitive to wavelengths of infrared light centered at 939 and 742 nanometers
The images were taken with the Cassini spacecraft wide-angle camera on May 13, 2007 at a distance of approx. 104.000 Km (about 65.000 miles) from Titan. Image scale is roughly 12 Km (about 8 miles) per pixel. Due to scattering of light by Titan's hazy atmosphere, the sizes of surface features that can be resolved are a few times larger than the actual pixel scale".MareKromium
(5 voti)
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Titan-IMG001663-br500.jpgTitan from about 209.000 Km (FlyBy n. 6)56 visiteOriginal caption:"This is one of the first images returned from T6, such as the sixth Titan flyby. The image (W00010189.jpg) was taken on August 21, 2005 and received on Earth August 23, 2005. The camera was pointing toward Titan (approx. 209.379 Km away) and the image was taken using the CB3 and IRP90 filters. (...)".
(9 voti)
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Titan_and_Dione-PIA07644.jpgTitan & Co.57 visiteOriginal caption:"In a rare moment, the Cassini spacecraft captured this enduring portrait of a near-alignment of four of Saturn's restless moons. Timing is critical when trying to capture a view of multiple bodies, like this one. All four of the moons seen here were on the far side of the Rings from the spacecraft when this image was taken; and about an hour later, all four had disappeared behind Saturn.
Seen here are Titan (5.150 Km, or 3.200 miles across) and Dione (1.126 Km, or 700 miles across) at bottom; Prometheus (102 Km, or 63 miles across) hugs the Rings at center; Telesto (24 Km, or 15 miles across) is a mere speck in the darkness above center.
The image was taken in visible light with the Cassini narrow-angle camera on Oct. 17, 2005 at a distance of approx. 3,4 MKM (2,1 MMs) from Dione and 2,5 MKM (about 1,6 MMs) from Titan. The image scale is 16 Km (10 miles) per pixel on Dione and 21 Km (about 13 miles) per pixel on Titan".
(8 voti)
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Titan-PIA10546.jpgNorth Polar Haze (Saturated Natural Colors; credits for the additional process. and color.: Dr Paolo C. Fienga - Lunexit Team)55 visiteCaption NASA:"Titan's globally distributed detached haze layer and the moon's North Polar hood, both notable details of its thick atmosphere, are clearly seen in this image from the Cassini Spacecraft.
Titan is about 5150 Km (approx. 3200 miles) across, and therefore slightly larger than Mercury.
The image was taken with the Cassini Spacecraft narrow-angle camera using a combination of spectral filters sensitive to wavelengths of polarized ultraviolet light centered at 338 nanometers. The view was obtained at a distance of approx. 1,7 MKM (about 1,08 MMs) from Titan and at a Sun-Titan-Spacecraft, or Phase, Angle of 50°.
Image scale is roughly 10 Km (about 6 miles) per pixel".MareKromium
(4 voti)
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Titan-PIA06186.jpgTitan (almost) naked, from 2,5 MKM56 visiteCaption NASA originale:"Titan's surface and atmospheric features are shown here in this processed, visible-light image taken by Cassini. Cassini's visible-light spectral filter is sensitive to a broad range of light, from ultraviolet to near-infrared. Imaging scientists normally use a narrow-band filter centered at 938 nanometers to look at Titan's surface and cloud features. Most images of Titan taken between flybys are in visible light and are used to navigate the spacecraft. Views like these demonstrate that the surface, as well atmospheric features (such as the haze banding seen near the northern limb of Titan), can indeed be seen through this filter. Although the clear filter is not the best way to view the surface, this observation demonstrates that with sufficient processing, this filter can be used to keep track of cloud features during periods between flybys in order to provide a better understanding of the evolution of Titan's atmosphere as the moon nears spring in the northern hemisphere".
(4 voti)
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Titan-N00023130.jpgTitan56 visiteDue immagini di Titano, riprese da una distanza di circa 1,5 milioni di Km. Alcune caratteristiche superficiali di Titano incominciano a distinguersi con una certa chiarezza ed il giorno del "contatto" si avvicina. Certo è che, ancora oggi, fra le tante lune di Saturno, Titano, perennemente avvolto in una spessa coltre di nuvole di colore giallastro, sembra essere davvero la più enigmatica. Se la Sonda Huygens sarà fortunata, forse riusciremo a vedere ed a scoprire qualcosa. Titano ci sta aspettando...
(12 voti)
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Titan-PIA07626.jpgThe "haze" of Titan59 visiteOriginal caption:"Looking back toward the sun brings out the thin haze that hovers 500 Km (310 miles) above Saturn's moon Titan.
The haze is composed of small particles whose diameter is comparable to the wavelength of light, which is ultraviolet light centered at 338 nnmts. Particles of this scale scatter sunlight most effectively in the direction opposite to the direction of sunlight itself.
Scientists are still trying to understand what processes produce this thin, high-altitude haze layer.
Picture data: North on Titan is up and tilted 10° to the right. The image was taken with the Cassini spacecraft narrow-angle camera on Sept. 24, 2005, at a distance of approx. 917.000 Km (about 570.000 miles) from Titan and at a Sun-Titan-spacecraft angle of 145°. Image scale is 5 Km (about 3 miles) per pixel".
(6 voti)
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Titan-Close Up 3.jpgTitan's fly-by "A" - Close-up 355 visiteQualche altra immagine di Titano e delle sue dense nuvole grigio-gialle, come potete vedere nelle immagini a colori. A questo punto dobbiamo solo aspettare le immagini ancora più ravvicinate e poi vedremo cosa succederà al secondo passaggio ravvicinato (fly-by "B"), fra circa un mese e mezzo. Inutile dire che, già a questo punto, la discesa della Sonda Huygens su Titano diventa un evento di importanza storica.
(3 voti)
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