The low density of Iapetus indicates that it is mostly composed of ice, with only a small (~20%) amount of rocky materials.
Unlike most of the large moons, its overall shape is neither spherical nor ellipsoid, but has a bulging waistline and squashed poles; also, its unique equatorial ridge (see below) is so high that it visibly distorts the moon's shape even when viewed from a distance. These features often lead it to be characterized as walnut-shaped.
Iapetus is heavily cratered, and Cassini images have revealed large impact basins, at least five of which are over 350 km wide. The largest, Turgis, has a diameter of 580 km; its rim is extremely steep and includes a scarp about 15 km high. Iapetus is known to support long-runout landslides or sturzstroms, possibly supported by ice sliding.
Read more about this topic: Iapetus (moon)
Other articles related to "physical characteristics":
... At time of closure, the line connected with Southeastern mainline services at New Cross and Southern at New Cross Gate ... Underground connections were at Canada Water (Jubilee line) and Whitechapel (District and Hammersmith City Lines) ...
Famous quotes containing the word physical:
“Unfortunately, moral beauty in artlike physical beauty in a personis extremely perishable. It is nowhere so durable as artistic or intellectual beauty. Moral beauty has a tendency to decay very rapidly into sententiousness or untimeliness.”
—Susan Sontag (b. 1933)