Herschel (Mimantean crater)
Largest impact crater on Saturn's moon Mimas.
Herschel is the biggest impact crater on Saturn’s moon Mimas, sitting on the moon’s leading side at the equator, centered at 112° longitude. It takes its name from William Herschel, the 18th-century astronomer who found Mimas in 1789. Among all equilibrium planetary moons in the Solar System, Herschel ranks as the second-largest crater relative to its parent body, trailing only Tethys’s crater Odysseus. The crater spans 139 kilometers (86 miles) across—nearly a third of Mimas’s own diameter. Its walls rise about 5 kilometers (3 miles) high, while parts of the floor plunge 10 to 12 kilometers (6 to 7 miles) deep, and a central peak juts 6 to 8 kilometers (3.5 to 5 miles) above the floor. The impact that carved Herschel must have nearly torn Mimas apart. On the moon’s opposite side, large chasms called chasmata appear, likely stress fractures from shock waves that traveled through Mimas and focused there. The impact may also relate to Mimas’s current “Pac-Man”‑shaped temperature pattern. Herschel is estimated to be about 4.1 billion years old, and the impactor is thought to have been roughly 4.8 kilometers (3 miles) in diameter, hitting at 15 kilometers per second. Because of Herschel’s size, Mimas’s appearance has often been compared to the Death Star from *Star Wars: Episode IV*—both in the press and in NASA/JPL releases. This is a coincidence, though: the crater’s resemblance wasn’t noticed until 1980, when Voyager 1 got a clear view, three years after the movie came out.
Quick Facts
- Diameter
- 139 km
- Depth
- 10 -
- Discoverer
- Voyager 1 in 1980
- Eponym
- William Herschel
- Location
- Leading hemisphere, Mimas
- Age
- 4.1 billion years
- Imp Size
- 4.8 km
Facts from the source article.
Lore & Background
Herschel measures 139 kilometres across, almost one third the diameter of Mimas. Its walls are approximately 5 km high, parts of its floor are 10–12 km deep, and its central peak rises 6–8 km 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'–shaped temperature pattern on Mimas. Herschel has an estimated age of around 4.1 billion years. It is also estimated that the impactor had a mean diameter of 4.8 kilometers (3 mi), and had a speed of 15 km/s.
Reader's Guide
Herschel is significant because it is the largest crater on Mimas and the second-largest crater relative to its parent body of any equilibrium planetary moon in the Solar System. Astronomers have expressed surprise that Mimas was not shattered by the impact that caused it, given the crater's size. The crater's similarity to the Death Star in Star Wars: Episode 4 has often been noted in the press and in NASA/JPL press releases, though this is a coincidence, as the similarities were not discovered until 1980 when Voyager 1 gained line of sight, three years after the movie was made. The impact is also suspected of being related to the 'Pac-Man'–shaped temperature pattern on Mimas. Large chasms on the opposite side of Mimas may be stress fractures from the impact's shock waves.
Did You Know?
- The impactor that formed Herschel is estimated to have had a mean diameter of 4.8 kilometers and a speed of 15 km/s.
- Herschel's similarity to the Death Star was not discovered until 1980, three years after the movie was made.
- The crater is named after William Herschel, who discovered Mimas in 1789.
Frequently Asked Questions
What is Herschel crater and who is it named after?
Herschel is the largest impact crater on Saturn's moon Mimas, stretching 139 kilometers (86 miles) across. It honors William Herschel, the 18th-century astronomer who first discovered Mimas in 1789.
How big is Herschel relative to Mimas itself?
The crater spans nearly a third of Mimas's total diameter, with walls climbing roughly 5 kilometers (3 miles) and a floor that plunges 10 to 12 kilometers (6–7 miles) deep in places. Among all equilibrium moons in the Solar System, it ranks second-largest relative to its parent body, trailing only Odysseus on Tethys.
Where exactly is Herschel situated on Mimas?
It sits on the moon's leading hemisphere, centered right on the equator at 112° longitude. That orientation means it faces the direction Mimas travels along its orbit around Saturn.
What does the interior of Herschel look like?
A prominent central peak rises 6 to 8 kilometers (3½–5 miles) above the crater floor, standing out against the deeply excavated basin. The steep walls, about 5 kilometers high, enclose this rugged, multi-level interior.
Why is Herschel such a fan-favorite among Saturn-moon enthusiasts?
Because the crater is so enormous compared to its tiny host, Mimas has long been nicknamed the "Death Star" in fan communities. Herschel is the feature responsible for that instantly recognizable, battle-scarred look in every spacecraft image of the moon.
More in Moons of Saturn, Part 2 1-24
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