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Skathi: Overview
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Skathi is a member of the Norse group of moons, which orbit Saturn at mean distances ranging from 12 to 24 million km, at inclinations between 136 and 176 degrees from the plane of Saturn's equator, and with eccentricities between 0.12 and 0.77. (A satellite's eccentricity is a number between 0 and 1 which describes the shape of the orbit. The closer to 0, the more circular it is; the closer to 1, the more elongated.)

The Norse moons all have retrograde orbits (they travel around Saturn in the opposite direction from the planet's rotation). That and their deviations from circular orbits and from the plane of Saturn's equator classify them as "irregular" satellites. Like Saturn's other irregular moons, they are thought to be objects that were captured by Saturn's gravity, rather than having accreted from the dusty disk that surrounded the newly formed planet as the regular satellites are thought to have done.

Unlike the Gallic and Inuit groups of Saturn's moons, the wide range of distances, inclinations and eccentricities among moons in the Norse group suggest that they are not the pieces of a single original object that shattered in a collision, but they may be the pieces of several such "original" objects. Skathi appears to be a member of a subgroup that also includes Skoll, Hyrrokkin, S/2006 S1, Bergelmir, Farbauti, S/2006 S3, and Kari.

Skathi, and another member of the Norse group, Ymir, may be the sources of material that coats the dark side of Iapetus and, to a lesser extent, the surface of Hyperion.

Skathi has a mean radius of about 4 km, assuming an albedo of 0.06. It orbits Saturn at an inclination of about 151degrees and an eccentricity of about 0.3. At a mean distance of 15.6 million km from Saturn, the satellite takes about 728 Earth days to complete one orbit.

Discovery:
Skathi was discovered on 23 September 2000 by Brett J. Gladman, John J. Kavelaars, Jean-Marc Petit, Hans Scholl, Matthew J. Holman, Brian G. Marsden, Phillip D. Nicholson, and Joseph A. Burns using the 3.6-m Canada-France-Hawaii reflector on Mauna Kea, Hawaii, with adaptive optics. They discovered seven other Saturnian moons at the same time: Tarvos, Ijiraq, Thrymr, Siarnaq, Mundilfari, Erriapus, and Suttungr.

How Skathi Got its Name:
Originally called S/2000 S8, Skathi was named for Skadi, a giantess in Norse mythology. Skadi donned armor and traveled to Asgard, home of the Norse gods, to avenge her father's death at their hands. However, she settled for an agreement that she could pick a husband from their ranks by inspecting only their feet, and that the gods would make her laugh. The latter was accomplished when Loki engaged in a tug of war with a goat, using a cord tied to the goat's beard and to a particularly sensitive part of Loki's anatomy.

Just the Facts
Orbit Size (semi-major axis):  15,614,300 km
Mean Radius:  4.0 (assuming an albedo of 0.06) km
Volume:  268 km3
Mass:  314,720,370,950,411 kg
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Last Updated: 11 Apr 2011