Overview

Megaclite (Jupiter XIX, designation S/2000 J 8) is one of Jupiter's many irregular satellites. It is small — roughly 5.4 kilometres in diameter — and follows a distant, inclined, retrograde orbit around the planet. Like other irregular moons, Megaclite is thought to be a captured object or a fragment produced by collisions, rather than a body that formed in place with the regular satellites.

Discovery and designation

Megaclite was discovered in 2000 by a team of astronomers led by Scott S. Sheppard. The discovery was made by observers associated with the discovery team at the University of Hawaii, with Scott S. Sheppard credited as the lead investigator (Sheppard). Upon confirmation it received the temporary designation S/2000 J 8 and later the permanent name Megaclite.

Orbit and group membership

Megaclite orbits Jupiter at an average distance of about 24,687,000 kilometres and completes one orbit in approximately 792.437 days. Its orbital plane is steeply inclined: about 150° to the ecliptic (roughly 148° relative to Jupiter's equator), which means it moves in a retrograde direction opposite the planet's rotation. The orbit is notably elliptical, with an eccentricity of about 0.308.

It is classified as a member of the Pasiphaë group (Pasiphaë group), a collection of irregular, retrograde moons that share similar orbital distances and inclinations. The members of this group typically orbit between roughly 22,800,000 and 24,100,000 kilometres from Jupiter and have inclinations between about 144.5° and 158.3°.

Physical properties

Megaclite is non-spherical in shape and therefore irregular, a common characteristic among small outer satellites (non-spherical). Its small size implies it has insufficient gravity to pull itself into a rounded shape. Little is known about its surface composition or colour from ground-based observations; many Pasiphaë-group members show dark, reddish surfaces consistent with primitive, carbon-rich material.

Name and mythological background

The moon was given the name Megaclite in October 2002. In Greek mythology Megaclite is described as a consort of Zeus (the counterpart of Jupiter) and in some traditions the mother of figures such as Thebe and Locrus. As with many planetary names, the choice reflects the convention of using mythological characters associated with Jupiter/Zeus for Jovian satellites (Zeus).

Significance and context

Megaclite and satellites like it help astronomers study the population of small bodies in the Jovian system and the processes that shaped it. Their varied orbits and physical properties provide clues about past capture events, collisional fragmentation, and the dynamical evolution of the outer satellite system. Although individually small and faint, together these irregular moons record a complex history of interactions around the giant planet.

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