Ananke is one of the largest of the outer irregular satellites of Jupiter. Before 1975 it was known simply as Jupiter XI. It gives its name to the Ananke group of retrograde irregular satellites that follow similar orbits to Ananke and are thought to have a common origin. Their semi-major axes (distances from Jupiter) range between 19.3 and 22.7 million kilometers, their orbital inclinations between 145.7° and 154.8°, and their orbital eccentricities between 0.02 and 0.28.


discovery 1951, by Seth Barnes Nicholson
semimajor axis 21,455,000 km (13,334,000 mi)
diameter 28 km (17 mi)
mean density 2.6 g/cm3
escape velocity 0.017 km/s (61 km/h, 38 mph)
orbital period -642.02 days (retrograde)
orbital eccentricity 0.345
orbital inclination 151.56°