Iapetus


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Iapetus,

in Greek mythology, a Titan. By the nymph Clymene he fathered Atlas, Prometheus, Epimetheus, and Menoetius.

Iapetus

(īăp`ĭtəs), in astronomy, one of the named moons, or natural satellites, of SaturnSaturn,
in astronomy, 6th planet from the sun. Astronomical and Physical Characteristics of Saturn

Saturn's orbit lies between those of Jupiter and Uranus; its mean distance from the sun is c.886 million mi (1.
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. Also known as Saturn VIII (or S8), Iapetus is 907 mi (1460 km) in diameter, orbits Saturn at a mean distance of 2,212,885 mi (3,561,300 km), and has equal orbital and rotational periods of 79.33 earth days. Saturn's third largest moon, it was discovered in 1671 by the Italian-French astronomer Gian Domenico CassiniCassini
, name of a family of Italian-French astronomers, four generations of whom were directors of the Paris Observatory. Gian Domenico Cassini, 1625–1712, was born in Italy and distinguished himself while at Bologna by his studies of the sun and planets,
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. With a density of only 1.1, Iapetus is believed to consist almost completely of water ice. A notable surface feature is a ridge that encircles it along its equator and rises as high as 12 mi (20 km). The reflectivity and surface features of Iapetus's leading and trailing hemispheres are noticeably different. The leading hemisphere is remarkably dark, while the trailing hemisphere is light—the asymmetry is so marked that Cassini wrote that he could see Iapetus on one side of Saturn but not on the other. The difference in reflectivity is due in part to the accumulation of dust on the leading hemisphere; this dust is believed to come from the enormous but faint ring of Saturn discovered in 2009. Much of the difference in reflectivity, however, is believed to be due to residue left behind by the sublimation of ice. The trailing hemisphere is also heavily cratered, while the leading hemisphere is not. Unlike all the other moons but PhoebePhoebe
, in astronomy, one of the named moons, or natural satellites, of Saturn. Also known as Saturn IX (or S9), Phoebe is 137 mi (220 km) in diameter, orbits Saturn at a mean distance of 8,047,985 mi (12,952,000 km), has an orbital period of 550.
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, Iapetus's orbit is inclined to the plane of Saturn's equator.

Iapetus

(ÿ-ap -ĕ-tŭs) A satellite of Saturn, discovered in 1671 by Giovanni Domenico Cassini. The diameter of Iapetus is 1440 km so that in size it is the twin of the satellite Rhea but its density, 1.21 g cm–3, is much lower. It is a strange satellite with a dark leading hemisphere (albedo 0.04–0.05) compared with a bright trailing edge of albedo 0.6. The dark hemisphere carries the name Cassini Regio. It appears to be coated with some dark material. The demarcation between the dark and light regions is not abrupt and there is a transition region 200–300 km in width with a meandering boundary. The bright trailing edge is most heavily cratered; some of the craters have dark floors but it is not known if the dark material in them is the same as that covering Cassini Regio. The material on the leading edge is thought to be carbon-based, but it is unclear whether it was emitted from the interior of Iapetus or was debris from eruptions on other Saturnian satellites swept up by Iapetus from space.

Iapetus was photographed by Voyager 2 in 1981 and by Cassini–Huygens in 2004. The Cassini images revealed some new features not seen on the Voyager images, in particular a vast ancient impact basin over 400 km across, which has been heavily overprinted with more recent smaller craters, and a curious and extraordinary ridge that almost exactly coincides with Iapetus' equator. It appears as a 20-km-wide band, 1300 km long, that seems to girdle the whole satellite, extending above the surface of Iapetus to a height of up to 13 km. The equatorial ridge may be a mountain belt that has folded upward, or perhaps it was formed when material from inside Iapetus erupted onto the surface through a crack and accumulated locally.

See also Table 2, backmatter.

Iapetus

 

a satellite of Saturn, approximately 1,800 km in diameter and located at a mean distance of 3,563,000 km from the center of Saturn. It was discovered in 1671 by G. D. Cassini.

Iapetus

[‚yap·əd·əs]
(astronomy)
A satellite of Saturn that orbits at a mean distance of 2.207 × 106 miles (3.560×106 kilometers) and has a diameter of about 900 miles (1500 kilometers).
References in periodicals archive ?
Professor Danny Donoghue, academic lead for IAPETUS at Durham University, said: "The shared expertise, resources and facilities that will be offered through the IAPETUS and our breadth of disciplines means that our doctoral training partnership is considerably greater than the sum of its parts and we welcome this exciting opportunity to support excellence in training the next generation of environmental and earth scientists.
Palaeo-oceanography and biogeography in the Tremadoc (Ordovician) Iapetus Ocean and the origin of the chemostratigraphy of Dictyonema flabelliforme black shales.
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The two nations were originally separated by a vast ocean called Iapetus before crashing together around 450million years ago.
Phoebe, one of Saturn's outer moons and an object thought to originate in the far-off Kuiper Belt, seems to be shedding reddish dust that eventually rouges the surface of nearby moons, such as Hyperion and Iapetus.
Louis, "but Saturn's icy moon Iapetus has more giant landslides than any body other than Mars.
The cluster analysis of the large satellites of Saturn reveals that they belonged to three groups: (1) Mimas and Enceledus; (2) Tethys, Dione, Iapetus and Rhea; and (3) Titan by itself.
Eyles and I also found most informative the IGC field guide by Neale (1972), because this booklet contains the first fully-formed plate-tectonic reconstruction of the island, in which the opening and closure of the Iapetus Ocean and the obduction of the Bay of Islands Ophiolite are well described (see also Geological Survey of Canada 1992).
Because Iapetus doesn't rotate relative to Saturn, the same face continually catches the dark moon flakes.
While the Scottish Borders region is best known for its colorful history, it's also famous for its rocks, which tell the story of the death of the ancient Iapetus Ocean.
Iapetus has a strange appearance--one side is bright and the other is really dark.