* Astronomy

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RE: Titan

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This image of Titan taken by the Cassini spaceprobe on January 29, 2007, when it was approximately 64,522 kilometres away.

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Credit: NASA/JPL/Space Science Institute

The image was taken using the CB3 and CL2 filters.

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This image of Titan taken by the Cassini spaceprobe on January 29, 2007, when it was approximately 3,203 kilometres away.

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Credit: NASA/JPL/Space Science Institute

The image was taken using the CB3 and CL2 filters.

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This image of Titan taken by the Cassini spaceprobe on January 29, 2007, when it was approximately 139,047 kilometres away.

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Credit: NASA/JPL/Space Science Institute

The image was taken using the CB3 and CL2 filters.

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This image of Titan taken by the Cassini spaceprobe on January 28, 2007, when it was approximately 335,282 kilometres away.

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Credit: NASA/JPL/Space Science Institute

The image was taken using the CL1 and CL2 filters.

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Two stars far across the galaxy have helped scientists discover secrets of a world in our own solar system. Saturn's biggest moon Titan - which is thought to resemble a primitive Earth - was observed as it passed in front of the distant stars.
The rare celestial alignments allowed astronomers to study winds in Titan's thick atmosphere as starlight shone through it.
They discovered that Titan has its own fast moving jet stream blowing at 450mph more than 125 miles above its surface.

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This radar image of Titan's well-known dunes is distinctive because it may show an age relationship between different classes of features on the surface of this frigid world.
Taken by Cassini's radar mapper on Jan. 13, 2007, during a flyby of Titan, three kinds of terrain can be seen. Throughout the image, the fine striping has been identified as dunes, possibly made from organic material and formed by wind activity. Dunes are a common landform on Titan. The dark material at the lower right of the image is interpreted as being topographically higher than the dunes that go around it, and several circular features seen at the top centre may be craters that are slowly being buried by the dunes. Since the dunes seem to lie over the craters, the dune activity probably occurred later in time.

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Credit NASA

Blobrana · L

This artist's impression shows the 'light curve' produced by a star passing behind Titan, Saturn's biggest moon.
When such occultation events take place, the light from the star is blocked out. Because Titan has a thick atmosphere, the light does not 'turn off' straight away. Instead, it drops gradually as the blankets of atmosphere slide in front of the star, as the light-curve drawn here shows. The way the light drops tells astronomers about the atmosphere of Titan.
The peak at the centre of the light curve represents the bright flash occurring at the very middle of the occultation. This is due to the fact that Titan's atmosphere acts as a lens, making the light emitted by the star passing behind converge into a focal point and produce the flash.

Credits: ESA. Image by C.Carreau

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A pair of rare celestial alignments that occurred in November 2003 helped an international team of astronomers investigate the far-off world of Titan. In particular, the alignments helped validate the atmospheric model used to design the entry trajectory for ESA's Huygens probe.
Now the unique results are helping to place the descent of Huygens in a global context, and to investigate the upper layers of Titan’s atmosphere.
Occasionally Titan passes directly in front of a distant star. When it does so, the light from the star is blocked out. Because Titan has a thick atmosphere, the light does not 'turn off' straight away. Instead, it drops gradually as the blankets of atmosphere slide in front of the star. The way the light drops tells astronomers about the atmosphere of Titan.
By pure chance on 14 November 2003, fourteen months before Huygens’ historic descent through Titan's atmosphere, Titan passed in front of two stars, just seven and a half hours apart. Bruno Sicardy, Observatoire de Paris, France, organised expeditions to record the occultations, as such events are called.

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Titan Flyby - Jan. 29, 2007