Herschel () is the largest impact crater on the Saturnian moon Mimas. It is located on Mimas's leading hemisphere, centered on the equator at 112ð longitude. It is named after the 18th-century astronomer William Herschel, who discovered Mimas in 1789.
Herschel is the second-largest crater relative to its parent body of any equilibrium planetary moon in the Solar System after Tethys's crater Odysseus. It is so large that astronomers have expressed surprise that Mimas was not shattered by the impact that caused it. It measures across, almost one third the diameter of Mimas. Its walls are approximately high, parts of its floor are deep, and its central peak rises above the crater floor.
The impact that formed Herschel must have nearly disrupted Mimas entirely. Large chasms (termed chasmata) that may be stress fractures due to shock waves from the impact traveling through it and focusing there can be seen on the opposite side of Mimas. The impact is also suspected of having something to do with the current "Pac-Man"âÂÂshaped temperature pattern on Mimas. Herschel has an estimated age of around 4.1 billion years.
The similarity between Mimas's appearance and the Death Star in Star Wars due to the large size of Herschel has often been noted, both in the press and in NASA/JPL press releases. This is a coincidence, however, as the crater's similarities were not discovered until 1980 when Voyager 1 gained line of sight, three years after the film was made.