Updated June 01, 2013

Tethys

Tethys moon of Saturn

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 cratered; other one consists of a belt of dark color and little cratered 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..

Tethys	Moon of Saturn

Dimensions	1072×1056×1052 km
Mass	6,176×10²⁰ kg
Mean density	984 kg/m³
Semi-major axis	294 619 km
Orbital period	1,887802 d
Eccentricity	0.0001
Gravity	0,15 m/s2
Inclination	0,168°
Discovered	March 21, 1684
Discovered by	Jean-Dominique Cassini

Image: Conversion Kelvin The Kelvin is a measure absolved from the temperature which was introduced thanks to the third principle of the thermodynamics. The temperature of 0 K is equal in-273,15°C and corresponds to the absolute zero. In degrees Celsius: °C = K - 273,15
gravity of the Earth (g = 9,81 m/s2)
g = GM/R2
G (gravitational constant)
M (mass of the object)
R (beam of the object)

Face hidden from Tethys

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.