Mimas (moon)

(0.0311 Earths) (6.4 Earths)

**Mimas**
Discovery
Discovered by	William Herschel
Discovered on	September 17, 1789
Orbital characteristics
Semimajor axis	185,404 km
Eccentricity	0.0202 ^{^*}
Orbital period	0.9424218 d ^{^*}
Inclination	1.51° (to Saturn's equator)
Is a satellite of	Saturn
Physical characteristics
Mean diameter	396.6 km (414.8×394.4×381.4 km)^*
Surface area	~1,990,000 km²
Volume	~32,900,000 km³
Mass	3.84 kg
Mean density	1.17 g/cm³
Surface gravity	~0.065 m/s²
Escape velocity	~0.16 km/s
Rotation period	synchronous
Axial tilt	zero
Albedo	0.77
Surface temp.

min	mean	max
? K	~64 K	? K

Atmosphere none Mimas (mye'-məs, IPA , Greek Μίμᾱς, rarely Μίμανς) is a moon of Saturn that was discovered in 1789 by William Herschel. It is named after Mimas, a son of Gaia in Greek mythology, and is also designated Saturn I.

Name

Mimas was one of the Titans of Greek mythology. The name "Mimas", indeed the names of all seven then-known satellites of Saturn, were suggested by Herschel's son John Herschel in his 1847 publication Results of Astronomical Observations made at the Cape of Good Hope ^*. He named them after Titans specifically because Saturn, known as Kronos in Greek mythology, was the leader of the Titans.

According to Liddell and Scott's Greek-English Lexicon, the adjectival form of Mimas/Mimans would be Mimantean (the genitive case is Mimantis, Greek Μῑμάντις). In practice, anglicisms such as Mimasian and Mimian are very occasionally seen, but more commonly writers simply use the phrase 'of Mimas'.

Physical characteristics

Mimas' low density (1.17) indicates that it is composed mostly of water ice with only a small amount of rock. Due to the tidal forces acting on it, the moon is not perfectly spherical; its longest axis is about 10% longer than the shortest. The somewhat ovoid shape of Mimas is especially noticeable in recent images from the Cassini probe.

Mimas (NASA) PIA06176.jpg Mimas' most distinctive feature is a colossal impact crater 130 km across, named Herschel after the moon's discoverer. Herschel's diameter is almost a third of the moon's own diameter; its walls are approximately 5 km high, parts of its floor measure 10 km deep, and its central peak rises 6 km above the crater floor. If there were a crater of an equivalent scale on Earth it would be over 4,000 km in diameter, wider than Canada. The impact that made this crater must have nearly shattered Mimas: fractures can be seen on the opposite side of Mimas that may have been created by shock waves from the impact travelling through the moon's body.

The surface is saturated with smaller impact craters, but no others are anywhere near the size of Herschel. Although Mimas is heavily cratered, the cratering is not uniform. Most of the surface is covered with craters greater than 40 km in diameter, but in the south polar region, craters greater than 20 km are generally lacking. This suggests that some process removed the larger craters from these areas.

Scientists officially recognise two types of geological features on Mimas: craters and chasmata (chasms). See also: List of geological features on Mimas.

Mimas is responsible for clearing the material from the Cassini Division, the gap between Saturn's two widest rings, A Ring and B Ring.

Mimas in fiction and film

Comparisons have been made between Mimas' appearance and the appearance of the Death Star from the movie A New Hope (see picture). The appearance is merely a coincidence, as Mimas was not photographed until three years after the release of the film; it was this similarity that led to Mimas sometimes being called "the Death Star moon".
In the novels of Rob Grant and Doug Naylor based on their sitcom Red Dwarf, Mimas is the site of a large, congested spaceport where Dave Lister takes shore leave to get over being dumped by his girlfriend Kristine Kochanski, adopts a cat, escapes as a stowaway and begins his journey on the Red Dwarf. Both the book and the series refer to the local delicacy "Mimean Bladderfish".
An episode of The Next Generation features Mimas as the site of an evacuation station to which four Starfleet cadets, including Wesley Crusher, transport after their vessels collide.
In the 1958 novel Lucky Starr and the Rings of Saturn (one of Isaac Asimov's famous Lucky Starr juvenile space opera series, which were originally published under the pseudonym of Paul French) the hero, knowing that Mimas is almost entirely made of ice, guides his ship on a collision course toward it, melts its surface with his weapons, and thus hides the ship underwater in order to escape from his enemies, the people from the Sirius System.

External links

(Saturn's natural satellite navigator) | Mimas | Enceladus | ...

Saturn's moons

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Name

Physical characteristics

Mimas in fiction and film

External links