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Solar System Exploration
Harpalyke: Overview
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Harpalyke is a member of the Ananke group, a family of Jovian satellites which have similar orbits and are therefore thought to have a common origin. The group probably began as an asteroid that was captured by Jupiter's gravity and then suffered a collision, which broke off a number of pieces. The largest remaining chunk was named "Ananke," and the smaller pieces became the other 15 moons in the Ananke group.

All of the Ananke moons are retrograde, which means that they orbit Jupiter in the opposite direction from the planet's rotation. Their orbits are also eccentric (elliptical rather than circular) and rather highly inclined with respect to Jupiter's equatorial plane. All of these characteristics support the idea that the Ananke satellites began as a captured asteroid, rather than forming as part of the original Jupiter system. None of the Ananke members is massive enough to pull itself into a sphere, so they are probably all irregularly shaped.

Harpalyke has a mean radius of about 2.2 km (assuming an albedo of 0.04). It is colored a similar gray to two other moons in the Ananke family: Praxidike and Iocaste. At a mean distance of about 21.1 million km from Jupiter, Harpalyke takes about 623 Earth days to complete one orbit.

Harpalyke was discovered 23 November 2000 by Scott S. Sheppard, David C. Jewitt, Yanga R. Fernandez, and Eugene Magnier at the Mauna Kea Observatory in Hawaii.

How Harpalyke Got its Name:
Originally called S/2000 J5, Harpalyke was named for a woman in Greek mythology who was transformed into a night bird called Chalcis. According to one version of the story, this transformation happened after she had intercourse with Zeus, the Greek equivalent of the Roman god Jupiter. In another version, she had incestuous relations with her father. In revenge, she killed her younger brother or her son (depending on the account), carved him up, cooked the meat and served it to her father, who ultimately kills himself.

A name ending in "e" was chosen in accordance with the International Astronomical Union's policy for designating outer moons with retrograde orbits.

Just the Facts
Orbit Size (semi-major axis):  13,113,418 miles
Mean Radius:  1.4 miles
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Last Updated: 8 Mar 2011