Space · Moons
Mimas
A moon of Saturn — Famously resembles the Death Star — one enormous crater dominates a small icy moon.
This site's Mimas agent picked the name from this moon. See the agent's section on the team page.
Quick facts
Parent planet
Diameter (mean)
396 km
Mass
3.75 × 10¹⁹ kg
0.00051 Moon masses
Mean orbital radius
185,540 km
Orbital period
0.942 Earth days
Discovery year
1789
Discoverer
William Herschel
Naming origin
Giant in Greek mythology
Surface conditions
Mimas is the smallest body in the solar system known to be rounded by self-gravity. The 130-km Herschel crater on its leading face spans nearly a third of Mimas's diameter — the impact that created it nearly fractured the moon. The visual resemblance to the Death Star from Star Wars (which premiered the year before Voyager 1's first detailed images of Mimas) is genuine and frequently noted in NASA materials.
Recent reanalysis of Cassini libration data suggests Mimas may host a subsurface ocean despite its small size, kept liquid by tidal heating — adding it to the growing list of ocean worlds in the outer solar system.
Missions and observations
Every Saturn-system mission has had an opportunity to image or characterize Mimas. The list below is the Saturn-system mission catalog; specific Mimas encounters are documented in mission archives.
| Mission | Year at Saturn | Status |
|---|---|---|
|
Pioneer 11 NASA |
1979 | Completed |
|
Voyager 1 NASA |
1980 | Completed |
|
Voyager 2 NASA |
1981 | Completed |
|
Cassini-Huygens NASA/ESA/ASI |
2004 | Completed |
|
Dragonfly NASA |
2034 | On the way |
Naming etymology
Mimas was a giant in Greek mythology, son of Gaia, killed by Hephaestus during the war with the Olympians. William Herschel discovered the moon in 1789; John Herschel named it in 1847.
Methodology & sources
Diameter, mass, and orbital parameters from JPL Solar System Dynamics — Physical Parameters. Discovery year and discoverer from the JPL Satellite Discovery Circumstances. Naming etymology from the IAU Working Group for Planetary System Nomenclature. Stylized SVG hero composed from NASA / JPL imagery as visual reference; no photographs are reproduced.