[010] Lysithea

Lysithea /laɪˈsɪθiə/, also known as Jupiter X, is one of the larger irregular satellites of Jupiter.

Discovery and naming

Lysithea was discovered by Seth Barnes Nicholson in 1938 at Mount Wilson Observatory.^[1]

It is named after the mythological Lysithea, daughter of Oceanus and one of Zeus' lovers.^[9] Lysithea did not receive its present name until 1975; before then, it was simply known as Jupiter X. It was sometimes called "Demeter"^[10] from 1955 to 1975.

Orbit

Lysithea orbits Jupiter at an average distance of 11,700,710 km in 258,57 days, at an inclination of about 27° to the ecliptic, in a prograde direction and with an eccentricity of 0.148. Its orbit is continuously changing due to solar and planetary perturbations.

Lysithea belongs to the Himalia group, a prograde group of moons orbiting between 11 and 13 Gm from Jupiter at an inclinations between 27 and 30°, and eccentricities between 0.11 and 0.24.

Physical characteristics

Lysithea has a of diameter of about 42 kilometers, with a measured albedo of about 3.6%,^[5] making it the fifth largest irregular moon of Jupiter.

Like the other members of the Himalia group, the satellite appears gray (B−V=0.72, V−R=0.36, V−I=0.74) and intermediate between C-type and P-type asteroids.^[11][5]

The rotation period was found to be approximately 12 hours and 45,6 min.^[7] This was regarded by a later paper as uncertain due to the short observation periods.^[12]