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Encyclopedia > Saturn > Satellites > Mimas


Credit : C. J. Hamilton/NASA

Mimas (Saturn I) was discovered by Herschel in 1789. 

Mimas is the smallest spherical satellites. It is a "big ball of dirty ice", riddled with impact craters including a large one bordered by the "walls of Herschel." Its orbital period is 22 hours and 30 minutes.

Origin of the name : click here.

Characteristics Values
Semi-major axis in km  185 540 
Revolution period  0.942 days 
Rotation period  0.942 days
Orbital velocity 14 km/s
Inclination on the equator of Saturn 1.56
Eccentricity of the orbit 0.019
Equatorial diameter (Earth=1)  0.031 
Equatorial diameter 418 km
Visual magnitude of the opposition 12.9
Mass (Saturn=1)  8/100 000 000 
Density (Water=1)  1.4 
Escape velocity 161 m/s
Reflectivity (geometric albedo) 0.5
The highest peak 7000m
Deepest pit 2000m
Temperature at the surface -200C
Atmosphere no
Composition ice