| Ultimi arrivi - Titan: The "Foggy" Moon |
Titan-PIA07878-Titan_sOddSpot.jpgThe "Odd-Spot" on Titan (detail mgnf)55 visiteLa 'Nuvola Permanente': una nuova ed incredibile scoperta su Titano che apre nuovi orizzonti ai panorami di pseudo-certezze che la maggior parte dei Ricercatori si stavano costruendo relativamente a questa "Terra in fieri" (una bella definizione per Titano, nata dopo che sono stati visionati i frames relativi ai primi passaggi ravvicinati della Sonda Cassini e dopo il landing dell'Huygens Probe).
Alla NASA hanno già fatto delle ipotesi; qualcuna plausibile - un uragano permanente - e qualche altra, diciamo così... , un pò "forzata" - tipo la vetta luminosa di una mega-montagna.
E se fosse un 'pennacchio' di fumo, ceneri e polveri - spesso e denso - proveniente da un vulcano attivo (il 'cuore caldo' del Pianeta...)?
E' così improponibile pensare ad un vulcano e, quindi, ad un Pianeta geologicamente attivo?!?Mag 27, 2005
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Titan-PIA07877.jpgA bright Red Spot on Titan (2)54 visiteThis dramatic color (but not true color) image was taken during the April 16, 2005, encounter with Titan. North is to the right. In the center it shows the dark lanes of the "H"-shaped feature discovered from Earth and first seen by Cassini last July shortly after it arrived in the Saturn system. At the southwestern edge of the "H" feature, near Titan's limb, is an area roughly 500 Km across. That area is 50% brighter when viewed using light with a wavelength of 5 microns, than the bright continent-sized area known as Xanadu. At wavelengths shorter than 5 microns, the spot is not unusually bright. The strange spectral character of this enigmatic feature has left the Team with 4 possibilities for its source: the spot could be a surface coloration, a mountain range, a cloud or a hot spot. The hot spot hypothesis will be tested during a Titan flyby on July 2, 2006, when the visual and infrared spectrometer will take nighttime images of this area. If it is hot, it will glow at night.Mag 26, 2005
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Titan-PIA07876.jpgA bright Red Spot on Titan (1)54 visiteThe recently discovered infrared-bright spot on Titan is the type of enigmatic feature that is best investigated by putting together as many different types of complementary information as possible. This montage shows the spot in infrared wavelengths from the visual and infrared mapping spectrometer on the left, from the imaging science subsystem in the center and a combination of both data sets on the right. When put together, the 2 different views show more than either does separately. The visual and infrared spectrometer team noted the bright region in the image on the left after March 31, 2004, Cassini's-Titan encounter. The strange, bright feature to the southeast of Xanadu was flagged as unusual and informally dubbed "The Smile" by imaging team members in December 2004. It seems clear that both instruments are detecting the same basic feature on Titan's surface. This bright patch may be due to an impact event, landslide, cryovolcanism, or atmospheric processes. Its distinct color and brightness suggest that it may have formed relatively recently".Mag 26, 2005
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Titan-Huygens_Landing_Site-13-PIA07871.jpgHuygens Landing Site56 visiteCaption NASA originale:"This mosaic from the Descent Imager/Spectral Radiometer camera on the European Space Agency's Huygens probe combines 17 image triplets, projected from an altitude of 800 mt (approx. 2.625 feet).
The area covered is approximately 1,3 Km across (North at the top of the image). The smallest visible objects visible are less than 5 mt across and the dark channels are 30 to 40 meters (approx. 98 to 131 feet) wide.
The images were then stitched together using one of several projection algorithms (in this case 'gnomonic') to produce a full mosaic. The images used to construct this mosaic were taken on Jan. 14, 2005".
Commento: a nostro parere si tratta di immagini complesse (e piuttosto confuse), estremamente difficili da interpretare in maniera convincente (almeno sulla base di ricostruzioni come queste due che Vi abbiamo proposto).Mag 14, 2005
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Titan-Huygens_Landing_Site-12-PIA07870-br500.jpgHuygens Landing Site56 visiteCaption NASA originale:"This stereographic projection of Descent Imager/Spectral Radiometer images from the European Space Agency's Huygens probe combines 60 images in 31 triplets, projected from a height of 3.000 mt (approx. 9.843 feet) above the black 'lakebed' surface. The bright area to the North (top of the image) and West is higher than the rest of the terrain and covered in dark lines that appear to be drainage channels.
The images were then stitched together using one of several projection algorithms (in this case 'stereographic') to produce a full mosaic. The images used to construct this mosaic were taken on Jan. 14, 2005. The Descent Imager/Spectral Radiometer is 1 of 2 NASA-funded instruments on the probe".Mag 14, 2005
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Titan-Atmosphere-PIA06236.jpgThe Atmosphere of Titan58 visiteCaption NASA originale:"This natural color image shows Titan's upper atmosphere: an active place where methane molecules are being broken apart by solar ultraviolet light and the byproducts combine to form compounds like ethane and acetylene. The haze preferentially scatters blue and ultraviolet wavelengths of light, making its complex layered structure more easily visible at the shorter wavelengths used in this image. Lower down in the atmosphere, the haze turns into a globe-enshrouding smog of complex organic molecules. This thick, orange-colored haze absorbs visible sunlight, allowing only perhaps 10% of the light to reach the surface. The thick haze is also inefficient at holding in and then re-radiating infrared (thermal) energy back down to the surface. Thus, despite the fact that Titan has a thicker atmosphere than Earth, the thick global haze causes the greenhouse effect there to be somewhat weaker than it is on Earth". Mag 03, 2005
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Titan-Craters-Unnamed_Crater-PIA07868_fig1.jpgTitan's most prominent Impact Crater59 visiteCaption NASA originale:"This 3-panel image shows one of Titan's most prominent impact craters in an infrared-wavelength image (left), radar image (center) and in the false-color image (right). The Cassini radar imaged this crater during Cassini's 3rd flyby of Titan, on Feb. 15, 2005. The Crater, located at 16° West, 11°North, is about 80 Km in diameter and is surrounded beyond that by a blanket of material thrown out of the crater during impact. In radar, brighter surfaces mean rougher terrains, or else terrains tilted toward the radar. The Crater has a dark floor and a small bright area in the center and it is surrounded by bright material, which has a very faint halo slightly darker than the surrounding dark material". Apr 28, 2005
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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'. Apr 26, 2005
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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".Apr 23, 2005
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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".
Apr 23, 2005
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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".
Apr 23, 2005
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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".Apr 23, 2005
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