Mimas: Small Moon with A Big Crater . ... Credit Copyright: NASA , Voyager 1 Explanation: Mimas is one of the smaller moons of Saturn but shows one of the largest impact craters! ... The large crater has been named Herschel after the 1789 discoverer of Mimas, Sir William Herschel . Mimas' low mass produces a surface gravity just strong enough to create a spherical body but weak enough to allow such relatively large surface features. ... NASA Web Site Statements, Warnings, and Disclaimers . ...