Mimas is the seventh-largest natural satellite of Saturn. With a mean diameter of 396.4 kilometres or 246.3 miles, Mimas is the smallest astronomical body known to be roughly rounded in shape due to i
Mimas in 2013 as imaged by the Cassini orbiter
Portrait of William Herschel, 1785. William Herschel, discoverer of Mimas
Mimas compared to Ceres and the Moon
A high-relief image of Mimas by Cassini on January 30, 2017. The shapes and the texture of its many overlapping craters can be seen clearly.
Saturn has the most extensive and complex ring system of any planet in the Solar System. The rings consist of particles in orbit around the planet, ranging from micrometers to meters in size, and are
Mimas
…impact event. The crater is named after William Herschel, who discovered Mimas in 1789. The moon's presence has created one of the largest 'gaps' in Saturn's ring, named the Cassini Division, due to orbital resonance destabilising the particles' orbit there. Mimas was discovered by the astronomer William Herschel…
The full set of rings, imaged on 19 July 2013, as Saturn eclipses the Sun from the vantage of the Cassini orbiter, which is 1.2 million kilometres (0.75 million miles) from Saturn. Earth appears as a dot at 5 o'clock, between the G and E rings – with its brightness artificially exaggerated in this photograph.
Huygens' ring hypothesis in Systema Saturnium (1659)
Simulated image using color to present radio-occultation-derived particle size data. The attenuation of 0.94-, 3.6-, and 13-cm signals sent by Cassini through the rings to Earth shows abundance of particles of sizes similar to or larger than those wavelengths. Purple (B, inner A Ring) means few particles are < 5 cm (all signals similarly attenuated). Green and blue (C, outer A Ring) mean particles < 5 cm and < 1 cm, respectively, are common. White areas (B Ring) are too dense to transmit adequate signal. Other evidence shows rings A to C have a broad range of particle sizes, up to m across.
Cassini space probe view of the unilluminated side of Saturn's rings (October 10, 2013).