Megaclite’s stretched, backward orbit

Why Megaclite’s distance from Jupiter swings by around 20 million km.

Published 2026-10-23

Megaclite’s orbit is unusual even among Jupiter’s irregular moons.^[3]

Backwards

It travels retrograde — opposite to Jupiter’s rotation — on an orbit inclined about 150°.^[3][1]

Stretched

JPL’s mean elements give an eccentricity of about 0.42. That means it moves between roughly 13.7 and 33.6 million km from Jupiter over one orbit of about 743 days.^[3]

Constantly changing

At such distances the Sun’s gravity strongly perturbs a moon’s orbit. Mean elements are averages; the actual orbit changes continuously.^[4]

A family resemblance

Pasiphae group moons average around 23.4 million km, inclinations near 148° and eccentricities near 0.34 — but with large spread, partly attributed to resonances with Jupiter’s orbit around the Sun.^[5] Megaclite fits that broad, scattered picture.^[3]

Numbered citations link to the sources list on the Megaclite overview page.