Mimas

Moons of Saturn

Mimas is a moon of Saturn, discovered in 1979 by William Herschel.
Mimas is one of the smallest spheroid bodies that we know in the solar system. It orbits at just under 200,000 km from Saturn and is about 400 km in diameter. The orbital period of Mimas is extremely short (0942 days), the order of 22h30mn, so it rotates at full speed around the planet Saturn.
Mimas is mostly made of ice water mixed with rock debris. Saturn has 61 known moons in 2008, including Titan. In reality, the total number of satellites of Saturn is unknown, because there are a lot of objects in orbit around the giant planet in the solar system.
Twelve moons have been discovered since the end of 2000 on unusual orbits, probably fragments of larger bodies captured by Saturn.

Some have even been recently discovered through the rings of Saturn by the Cassini spacecraft. Ripples in the rings, photographed by the probe, have puzzled scientists. They have little insight into issues that have proved to be tiny moons.

NB: In Greek mythology, Mimas was a giant, son of Uranus (Heaven) and Gaia (Earth).

Mimas Saturn's moon

Mimas is made mostly of water ice mixed with rocks. Like all solar system objects, Mimas is covered with craters, but the first thing one notices on Mimas is the huge impact crater 130 km in diameter and is named after the discoverer of Mimas, Sir William Herschel.
Its slopes are about 5 km high with depths of 10 km depth and a central peak that rises 6 km above the crater floor.
These characteristics make it an almost perfect example of the impact crater.
A crater on Earth would not equal less than 4000 km in diameter, is larger than Canada.
The impact that produced this crater has narrowly missed total destruction of Mimas since the object is broken up the side opposite the impact point, probably because of the shock wave had completely through the body.
The thermal map of Mimas shows that the highest temperatures are in the range of -180 ° C, while lower temperatures are in the range of -200 ° C.

Image: This picture was taken by NASA's Cassini spacecraft when it flew Mimas at approximately 9500 kilometers (5.900 miles) in altitude, February 13, 2010.
The large crater Herschel, 130 km in diameter, dominates Mimas, catching the eye on the object 396 km in diameter.
The eye of Cyclops seems to look interstellar space. The low density of Mimas (1.17) indicates that it consists mainly of water ice and some rock.
The Herschel crater floor is made of molten liquid material that is solidified, which probably explains the relative lack of craters on the basin floor of Herschel. This phenomenon, common objects with no atmosphere on the solar system, Mimas is accentuated because of the large size of Herschel in comparison to the size of Mimas.
Credit NASA.

Mimas and Pandora

Saturn's moons, Mimas and Pandora taken together on this photo from the Cassini spacecraft, we show how they are different. Of course Pandora is much smaller (104 × 81 × 64 km) Mimas (415 × 393 × 381 km), but above the moon does not accrete enough material to obtain a spherical shape. Pandora has remained a small irregular satellite and heavily cratered. Its low density and high albedo seem to indicate that Pandora is a very porous icy planet. Pandora acts as an outer shepherd satellite of Saturn's F ring.


NB: A "shepherd" satellite is an object of modest size that orbit close to the edge of a ring (unstable structure composed of a multitude of tiny objects) and acting as guardian of the structure. The gravity generated by the satellite confines the ring and it defines a specific board. Indeed, the materials that are moving away, are either returned to the ring, either ejected from one or captured by the satellite. This effect explains the existence of narrow rings confined by two satellites "shepherds", as is the case for Saturn's F ring.

The image was taken in blue light with a narrow-angle camera Cassini May 14, 2013. This view was captured at a distance of approximately 1.1 million km from Mimas and 1.2 million km from Pandora. The scale of the image of Mimas and Pandora is 7 kilometers per pixel. Pandora was discovered in 1980 from photos taken by Voyager 1. It was not until the end of 1985 it was officially named Pandora, it is also designated Saturn XVII. The orbit of Pandora appears to be chaotic, because of resonances with Prometheus. The most notable changes in their orbits occur approximately every 6.2 years, when the perigee Pandora aligns with the apogee of Prometheus, the moons approach each other within 1400 kilometers. Pandora is also in 2:3 resonance with Mimas.

Image: Mimas and Pandora (moon of Saturn) are taken together in light blue with narrow-angle camera of the Cassini probe May 14, 2013. Image Credit: NASA / JPL-Caltech / Space Science Institute.