Mimas


Mimas
/muy"mas, mee"-/, n.
1. Astron. one of the moons of Saturn.
2. Class. Myth. one of the Gigantes, killed by Hercules.
3. Rom. Legend. a companion of Aeneas, killed by Mezentius.

* * *

 smallest and innermost of the major regular moons of Saturn. It was discovered in 1789 by the English astronomer William Herschel (Herschel, Sir William) and named for one of the giants (Gigantes) of Greek mythology.

      Mimas measures about 400 km (250 miles) in diameter and revolves around the planet in a prograde, near-circular orbit at a mean distance of 185,520 km (115,277 miles). Because of tidal interactions with Saturn, the moon rotates synchronously with its orbital motion, always keeping the same hemisphere toward Saturn and always leading with the same hemisphere in orbit.

      The mean density of Mimas is only 1.1 times that of water, and its surface shows characteristics of water frost. For these reasons, Mimas is believed to be composed principally of ice. Its surface is bright and heavily marked with deep, bowl-shaped impact craters. The depth of the craters appears to be a consequence of the low surface gravity, which apparently is not strong enough to cause slumping. In spite of Mimas's small size, it shows some evidence of resurfacing, possibly resulting from a partial melting of the icy crust. Its most noteworthy feature is a 130-km- (80-mile-) diameter crater named Herschel, which is near the centre of the leading hemisphere. The crater's outer walls are 5 km (3 miles) high, its floor 10 km (6 miles) deep, and the central peak 6 km (4 miles) high. Herschel is one of the largest impact structures, relative to the size of the body, known in the solar system.

      Mimas is in an orbital resonance with the more distant Saturnian moon Tethys—its 22.6-hour circuit of Saturn is half that of Tethys—and the two bodies always make their closest approach to each other on the same side of Saturn. Clearly this resonance is not accidental. In general terms, it could have arisen from a gradual process, such as the slowing of Saturn's rotation because of tidal friction, that—due to conservation of momentum (momentum, conservation of)—expanded the orbits of both moons, Mimas's more than Tethys's, over geologic time. Mimas also is in orbital resonance with a number of observed structures in Saturn's ring system. The inner edge of the Cassini division, a prominent gap of lowered particle density in the main rings, has an orbital period close to one-half of that of Mimas, and this gap is thought to be formed at least in part by resonant interactions of ring particles with the moon. Other ring orbits that are in resonance with Mimas display bending waves, tightly wound spiral waves of ring material displaced upward or downward from the ring plane.

William B. Hubbard
 

* * *


Universalium. 2010.

Look at other dictionaries:

  • Mimas — steht für: Mimas (Mythologie), einen der Giganten, sowie die Berge, unter denen er begraben liegen soll Mimas (Sohn des Aiolos), Sohn des griechischen Stammvaters Aiolos Mimas (Sohn des Amykos), Sohn des Amykos und der Theano Mimas (Kentaur),… …   Deutsch Wikipedia

  • Mimas — may refer to: Mimas (giant), son of Gaia in Greek mythology, one of the Gigantes slain by Hephaistos Mimas (Aeneid), a son of Amycus and Theona, who escorted Aeneas to Italy Karaburun, a town and district in Turkey, formerly called Mimas in… …   Wikipedia

  • Mimas [1] — Mimas, einer der Giganten; die Insel Prochyte wurde im Gigantenkriege auf ihn geschleudert …   Pierer's Universal-Lexikon

  • Mimas [2] — Mimas (a. Geogr.), ein Zweig des Tmolos in Lydien, läuft westlich zwischen Smyrna u. Kolophon u. bildet die Vorgebirge Korykeion, Argennon u. Meläna; er heißt noch jetzt M …   Pierer's Universal-Lexikon

  • Mimas — Mimas, ein Trabant des Saturn, s.d. 2) …   Pierer's Universal-Lexikon

  • Mimas — Mimas, innerster Saturntrabant (s. Saturn) …   Meyers Großes Konversations-Lexikon

  • Mimas — MIMAS, antis, (⇒ Tab. V.) einer der Riesen, welcher in dem Streite mit den Göttern die Insel Lemnus, mit sammt des Vulcans Schmiedestatt, nahm, und nach dem Mars werfen wollte, dem aber Mars darüber den Spieß durch den Kopf stieß, und Pallas… …   Gründliches mythologisches Lexikon

  • Mimas [1] — MIMAS, antis, (⇒ Tab. XIV.) einer der Centauren, der sich auf des Pirithous Beylager befand. Hefiod. Scut. Herc. v. 186 …   Gründliches mythologisches Lexikon

  • Mimas [2] — MIMAS, antis, (⇒ Tab. XXV.) einer von des Aeolus Söhnen, welcher endlich als König in Aeolis regierete. Diod. Sic. l. IV. c. 69. p. 187 …   Gründliches mythologisches Lexikon

  • Mimas [3] — MIMAS, antis, des Amykus und der Theano Sohn, welcher in einer Nacht mit dem Paris geboren wurde, hernach mit dem Aeneas in Italien gieng, hieselbst von dem Mezentius erleget und endlich, als ein Fremder und Unbekannter, in dem Laurentischen… …   Gründliches mythologisches Lexikon

  • Mimas —   [nach einem Giganten der griechischen Sage], ein Mond des Planeten Saturn …   Universal-Lexikon


Share the article and excerpts

Direct link
Do a right-click on the link above
and select “Copy Link”

We are using cookies for the best presentation of our site. Continuing to use this site, you agree with this.