A retrograde satellite of Jupiter, 21 254 000 km from the planet; also known as Jupiter XII. Ananke orbits Jupiter in 629.8 days at an inclination of almost 149° to Jupiter’s equator. It is about 28 km in diameter, and was discovered in 1951 by the American astronomer Seth Barnes Nicholson (1891–1963). Ananke is the largest member of the so-called Ananke retrograde irregular group of Jovian satellites which all have similar orbital eccentricity, inclination, and semimajor axis: Euporie, Orthosie, Euanthe, Thyone, Mneme, Harpalyke, Hermippe, Praxidike, Thelxinoe, and Iocaste.