Key facts
- Scale fact
- 1,470 kmdiameter
- Composition
- Water ice and rock with dark carbon-rich surface material
Iapetus
1,470 kmdiameter
Visual creditCassini 2007 / NASA / JPL / Space Science Institute / Public domainSource: Wikimedia Commons
Details
Iapetus is Saturn's third-largest moon and one of its strangest, with a bright trailing hemisphere and a dark leading hemisphere. It also has a slow 79-day rotation, a distant orbit, and a giant ridge along much of its equator.
Iapetus keeps one face forward along its orbit. Dark dust preferentially coats that leading side; warmer dark areas then lose surface ice, which migrates and condenses on colder bright terrain, amplifying the original contrast. A separate puzzle is the broken mountain ridge along much of the equator: proposed origins include an early fast rotation or debris from a collapsed ring, and neither explanation is settled.
Links
- Universe journey
- Asteroid belt & Jupiter
- Wikipedia
- Iapetus on Wikipedia
Size neighbors
Objects near Iapetus on the scale
Sources
References for Iapetus
Measurements and descriptive context are compiled by the Scale of Space team from the references below. If you find an error, please let us know.
- Iapetus — Wikipedia
- Visual reference: Wikimedia Commons (Cassini 2007 / NASA / JPL / Space Science Institute, Public domain)
Continue with nearby objects or open the full scale.
About
Scale of Space is a scroll-based journey through the universe, placing objects on a single logarithmic scale so you can compare size across an unbroken range.
Guides explain selected parts of that range, while focused views filter the objects by subject.