Ananke (moon)
Ananke also known as , is a one of larger retrograde irregular moon of Jupiter.
Discovery and Naming
It was discovered by Seth [Barnes Nicholson] at Mount [Wilson Observatory] in 1951.It is named after the Greek mythological Ananke, the personification of necessity, and the mother of the Moirai by Zeus. Ananke did not receive its present name until 1975; before then, it was simply known as . It was sometimes called "Adrastea" between 1955 and 1975.
Orbit
Ananke orbits Jupiter on a high-eccentricity and high-inclination retrograde orbit. They are continuously changing due to solar and planetary perturbations.Ananke gives its name to the Ananke group, of irregular retrograde moons orbiting Jupiter at a distance ranging between 19–22 million km, inclinations between 144 and 156°, and eccentricities between 0.10 and 0.30.
Physical characteristics
From infrared thermal measurements by the WISE spacecraft, Ananke's albedo is measured at 3,8 %, corresponding to a diameter of 29,1 kilometres.In the visible spectrum, Ananke appears neutral to light-red. The infrared spectrum is similar to P-type asteroids but with a possible indication of water.
The rotation period is approximately 8 hours and 18,6 minutes with a peak amplitude of about ∼0.4 magnitudes.