Tag Archives: Ananke

Astronomy Quick Facts – Ananke

Ananke is a small retrograde moon of Jupiter, and is a member of the Ananke group of moons. This group consists of retrograde irregular moons that orbit at a high inclination. Ananke’s also known as Jupiter XII. It was discovered in 1951 by Seth Barnes Nicholson at Mount Wilson Observatory.

Image copyright OHP/CNRS/IMCCE. Used under Creative Commons license from Wikimedia.


  • Mean radius: 14 km
  • Mass: 3.0×1016 kg
  • Density: 2.6 g/cm3 (estimated)
  • Surface gravity: 0.010 m/s2 (0.001 g)
  • Albedo: 0.04 (estimated)
  • Temperature: 124 K (-149°C)
  • Mean orbital radius: 21,280,000 km
  • Orbital period: 610.45 d
  • Inclination: 149.9° (to Jupiter’s equator)
  • Eccentricity: 0.24

Name Origin

Ananke was the personification of destiny, necessity, and fate. She is the mother of the Fates, whose father is Zeus. She’s a rather powerful figure in Greek mythology, being in total control of fate.

5 Interesting Facts

1. Ananke got its name in 1975. However, it was known as Adrastea from 1955 to 1975, which is the name of another moon of Jupiter.

2. Ananke is the largest member of the Ananke group, which may have been formed from the breakup of a larger moon.

3. It appears to be light red in the visible spectrum.

4. The infrared spectrum indicates it possibly has water (ice).

5. With a surface area of approximately 2,500 km2, it’s about the same size as Luxembourg.

This is a rather small satellite, and Galileo wasn’t able to get a picture of it. It’s a very minor target anyway, and orbits quite far from Jupiter.