Mimas (moon)

Mimas /ˈmaɪməs/, also designated Saturn I, is a moon of Saturn discovered in 1789 by William Herschel.[11] It is named after Mimas, a son of Gaia in Greek mythology.

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Mimas

Mimas with its large crater Herschel. Other bright-walled craters include Ban just left of center near top, and Percivale two thirds of the way left of Herschel. (Cassini, 2010)
Discovery
Discovered by	William Herschel
Discovery date	17 September 1789[1]
Designations
Designation	Saturn I
Pronunciation	/ˈmaɪməs/[2] or as Greco-Latin Mimas (approximated /ˈmiːməs/)
Named after	Μίμας Mimās
Adjectives	Mimantean,[3] Mimantian[4] (both /mɪˈmæntiən/)
Orbital characteristics [5]
Periapsis	181902 km
Apoapsis	189176 km
Semi-major axis	185539 km
Eccentricity	0.0196
Orbital period (sidereal)	0.942421959 d
Average orbital speed	14.28 km/s (calculated)
Inclination	1.574° (to Saturn's equator)
Satellite of	Saturn
Physical characteristics
Dimensions	415.6 × 393.4 × 381.2 km (0.0311 Earths)[6]
Mean radius	198.2±0.4 km [6]
Surface area	490000–500000 km2
Volume	32600000±200000 km3
Mass	(3.7493±0.0031)×1019 kg [7][8] (6.3×10−6 Earths)
Mean density	1.1479±0.007 g/cm3 [6]
Surface gravity	0.064 m/s2 (0.00648 g)
Escape velocity	0.159 km/s
Synodic rotation period	synchronous
Axial tilt	zero
Albedo	0.962±0.004 (geometric)[9]
Temperature	≈ 64 K
Apparent magnitude	12.9 [10]

With a diameter of 396 kilometres (246 mi), it is the smallest astronomical body that is known to still be rounded in shape because of self-gravitation. However, Mimas is not actually in hydrostatic equilibrium for its current rotation.^{[citation needed]}