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NASA's Cassini Sees Abrupt Turn in Titan's Atmosphere

Data from NASA's Cassini spacecraft tie a shift in seasonal sunlight to a wholesale reversal, at unexpected altitudes, in the circulation of the atmosphere of Saturn's moon Titan. At the south pole, the data show definitive evidence for sinking air where it was upwelling earlier in the mission. So the key to circulation in the atmosphere of Saturn's moon Titan turned out to be a certain slant of light. The paper was published today in the journal Nature.
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The International Astronomical Union (IAU) has approved new names for eight features on Titan.

Mohini Fluctus for a 347-km-wide fluctus located at -11.78°, 38.53°.
The feature was named in honour of an Indian goddess of beauty and magic.

Doom Mons for a 63-km-wide mountain located at -14.65°, 40.42°.
The feature was named in honour of a mountain from Middle-earth.

Erebor Mons for a 50-km-wide mountain located at -4.97°, 36.23°.
The feature was named in honour of a mountain from Middle-earth.

Irensaga Montes for a 194-km-wide mountain located at -5.68°, 212.71°.
The feature was named in honour of a mountain from Middle-earth.

Mindolluin Montes for a 340-km-wide mountain range located at -3.3°, 208.96°.
The feature was named in honour of a mountain range from Middle-earth.

Misty Montes for a 73-km-wide mountain range located at 56.8°, 62.44°.
The feature was named in honour of a mountain range from Middle-earth.

Mithrim Montes for a 147-km-wide mountain range located at -2.16°, 127.42°.
The feature was named in honour of a mountain range from Middle-earth.

Taniquetil Montes for a 130-km-wide mountain range located at -3.67°, 213.26°.
The feature was named in honour of a mountain range from Middle-earth.



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Cassini Halloween Treat: Titan Glows in the Dark

pia16177-640.jpg

A literal shot in the dark by imaging cameras on NASA's Cassini spacecraft has yielded an image of a visible glow from Titan, emanating not just from the top of Titan's atmosphere, but also - surprisingly - from deep in the atmosphere through the moon's haze. A person in a balloon in Titan's haze layer wouldn't see the glow because it's too faint - something like a millionth of a watt. Scientists were able to detect it with Cassini because the spacecraft's cameras are able to take long-exposure images.
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What's Baking on Titan?

Radar images from NASA's Cassini spacecraft reveal some new curiosities on the surface of Saturn's mysterious moon Titan, including a nearly circular feature that resembles a giant hot cross bun and shorelines of ancient seas. The results were presented today at the American Astronomical Society's Division of Planetary Sciences conference in Reno, Nev.
Steam from baking often causes the top of bread to lift and crack. Scientists think some similar process involving heat may be at play on Titan.

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Titan River networks
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River networks on Titan point to a puzzling geologic history


Findings suggest the surface of Saturn's largest moon may have undergone a recent transformation.

In 2004, the Cassini-Huygens spacecraft - a probe that flies by Titan as it orbits Saturn - penetrated Titan's haze, providing scientists with their first detailed images of the surface. Radar images revealed an icy terrain carved out over millions of years by rivers of liquid methane, similar to how rivers of water have etched into Earth's rocky continents.
While images of Titan have revealed its present landscape, very little is known about its geologic past. Now researchers at MIT and the University of Tennessee at Knoxville have analysed images of Titan's river networks and determined that in some regions, rivers have created surprisingly little erosion. The researchers say there are two possible explanations: either erosion on Titan is extremely slow, or some other recent phenomena may have wiped out older riverbeds and landforms.

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The Titanian Seasons Turn

Images from NASA's Cassini spacecraft show a concentration of high-altitude haze and a vortex materialising at the south pole of Saturn's moon Titan, signs that the seasons are turning on Saturn's largest moon.
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Buried ocean lends insight into Titan's dense, methane-rich atmosphere

To better understand Saturn's moon Titan, scientists must study the methane in its atmosphere, the persistence of which was likely influenced by an ocean of water recently discovered 100 kilometres below the moon's surface, said Jonathan Lunine, Cornell's David C. Duncan Professor in the Physical Sciences.
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Titans tides point to hidden ocean

Nothing like it has been seen before beyond our own planet: large tides have been found on Saturn's moon Titan that point to a liquid ocean - most likely water - swirling around below the surface.
On Earth, we are familiar with the combined gravitational effects of the Moon and Sun creating the twice-daily tidal rise and fall of our oceans. Less obvious are the tides of a few tens of centimetres in our planet's crust and underlying mantle, which floats on a liquid core.
But now the international Cassini mission to Saturn has found that Titan experiences large tides in its surface.

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Title: Titan's transport-driven methane cycle
Authors: Jonathan L. Mitchell

The strength of Titan's methane cycle, as measured by precipitation and evaporation, is key to interpreting fluvial erosion and other indicators of the surface-atmosphere exchange of liquids. But the mechanisms behind the occurrence of large cloud outbursts and precipitation on Titan have been disputed. A gobal- and annual-mean estimate of surface fluxes indicated only 1% of the insolation, or ~0.04 W/m², is exchanged as sensible and/or latent fluxes. Since these fluxes are responsible for driving atmospheric convection, it has been argued that moist convection should be quite rare and precipitation even rarer, even if evaporation globally dominates the surface-atmosphere energy exchange. In contrast, climate simulations that allow atmospheric motion indicate a robust methane cycle with substantial cloud formation and/or precipitation. We argue the top-of-atmosphere radiative imbalance -- a readily observable quantity -- is diagnostic of horizontal heat transport by Titan's atmosphere, and thus constrains the strength of the methane cycle. Simple calculations show the top-of-atmosphere radiative imbalance is ~0.5-1 W/m² in Titan's equatorial region, which implies 2-3 MW of latitudinal heat transport by the atmosphere. Our simulation of Titan's climate suggests this transport may occur primarily as latent heat, with net evaporation at the equator and net accumulation at higher latitudes. Thus the methane cycle could be 10-20 times previous estimates. Opposing seasonal transport at solstices, compensation by sensible heat transport, and focusing of precipitation by large-scale dynamics could further enhance the local, instantaneous strength of Titan's methane cycle by a factor of several.

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Cassini Sees Tropical Lakes on Saturn Moon

Saturn's rings lie in the distance as the Cassini spacecraft looks toward TitanSaturn's rings lie in the distance as the Cassini spacecraft looks toward Titan and its dark region called Shangri-La, east of the landing site of the Huygens Probe. Image Credit: NASA/JPL-Caltech/Space Science Institute  

NASA's Cassini spacecraft has spied long-standing methane lakes, or puddles, in the "tropics" of Saturn's moon Titan. One of the tropical lakes appears to be about half the size of Utah's Great Salt Lake, with a depth of at least 1 metre.
The result, which is a new analysis of Cassini data, is unexpected because models had assumed the long-standing bodies of liquid would only exist at the poles. The findings appear in this week's issue of the journal Nature.
The latest results come from Cassini's visual and infrared mapping spectrometer, which detected the dark areas in the tropical region known as Shangri-La, near the spot where the European Space Agency's Huygens probe landed in 2005. When Huygens landed, the heat of the probe's lamp vaporized some methane from the ground, indicating it had landed in a damp area.

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