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Tethys moon of Saturn
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Updated February 01, 2013
|Tethys In the Greek mythology, Tethys is one of the essential divinities of the Hellenic theologies. She personifies the "feminine" fertility of the sea. Born of the courtship of Ouranos and Gaia, she is the youngest of Titanides. She married Ocean, one of her brothers, of whom she had one very children's large number, more than three thousand, which are all the rivers of the world. Tethys raised Hera, whom confided her Rhea (too a titanide), during the fight of Zeus against Cronos. As a mark of gratitude, Hera succeeded in reconciler Tethys and Ocean, which had fallen out. The house of Tethys is generally placed in the extreme West, beyond the country of Hesperidia, in the region where, every evening, the sun ends its running. is an ice-cold body, similar to Dione and Rhea. Its density indicates that it mainly consists of ice. |
The surface of Tethys is covered with craters and counts numerous cracks in the ice.
There are two types of ground on Tethys: the one consists of regions strongly craterised; other one consists of a belt of dark color and little craterised which crosses the moon throughout.
The weak number of craters on this region indicates that Tethys certainly had formerly an internal activity, causing a partial ascent of the oldest ground.
In orbit synchronous around Saturn, Tethys always presents the same hemisphere to its planet, quite as the Moon in the Earth and of numerous satellites with regard to their planet mother.
It is necessary to Tethys a little less than 2 days to make the tour of Saturn.
Tethys is accompanied on his orbit by two other satellites of Saturn : Telesto early of 60° and Calypso late of 60° what creates a point of "Lagrange" A point of Lagrange (noted Li), or of libration, is a position of the space where the fields of gravity of two bodies in orbit the one around the other one, and around the substantial masses, harmonize so as to supply a point of balance to the third body of unimportant mass, such as the relative positions of three bodies are fixed..
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|Tethys|| || |
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|diameter|| ||1072×1056×1052 km|
|mass|| ||6,176×1020 kg|
|distance of Saturn|| ||295 000 km|
|Period of revolution|| ||1,888 jour|
|gravity|| ||0,15 m/s2|
|discovered in|| ||21 mars 1684|
|discovered by|| ||Jean-Dominique Cassini|
|temperature|| ||-187°C (86 K)|
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Face hidden from Tethys
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|Since the beginning of its mission in the system of Saturn, the space probe Cassini had repeatedly the occasion to observe the procession of the moons which revolve around the huge planet. Tethys is dominated by an enormous crater of impact named Odyssey, 400 km in diameters of which represent near 2/5 of Tethys. |
Tethys being a ball of ice in-187°C, this crater became level during ages.
The most visible second structure of Tethys is the gigantic valley Ithaca Chasma, 100 km wide, deep from 3 to 5 km and 2000 km long, covering near 3/4 of the circumference of Tethys. This scar is maybe the mark of the impact which is at the origin of the big crater Odyssey.
This one was able to provoke a shock wave which crossed Tethys, breaking the fragile ice-cold surface of the opposite face.
It presents us here the face "hidden" from the fifth biggest moon of Saturn.
The edge of the immense pond of impact Odysseus (450 kilometers wide) is visible on the oriental limb, on the upper right of the image, and seems to flatten in this place the curvature of the moon.
| ||Other big very visible craters here are Penelope (to the left of the center) and Melanthius (under the center). |
The region between craters Penelope and Odysseus had been photographed never again with such a resolution.
Image : The face was hidden from Tethys in natural colors, this image was taken by the probe Cassini on December 31st, 2006 at a distance about 414000 kilometers of Tethys. The resolution is 2 kilometers by pixel. Source: NASA
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