Lysithea (moon)

Lysithea is one of the larger irregular moons of the giant planet Jupiter. It is also known as Jupiter X. Moons like Lysithea help scientists learn more about how our solar system formed and how planets grow by capturing smaller objects into their orbits. Studying these distant moons gives us clues about the early days of our solar neighborhood.

Discovery and Naming

Lysithea was found by Seth Barnes Nicholson in 1938 at Mount Wilson Observatory.

The moon is named after the mythological Lysithea, who was the daughter of Oceanus and one of Zeus’s lovers. Lysithea did not get its current name until 1975. Before that, it was known as Jupiter X and was sometimes called "Demeter" from 1955 to 1975.

Orbit

Lysithea travels around Jupiter at an average distance of 11,700,710 km. It completes one orbit in 258.57 days and moves in a forward direction, tilted about 27° compared to the plane where Earth orbits the Sun. The path of its orbit changes because of the pull of the Sun and other planets.

Lysithea is part of a group of moons called the Himalia group. These moons orbit Jupiter between 11 and 13 million kilometers away, with tilts between 27 and 30°, and their paths are not perfect circles.

Physical characteristics

Lysithea is a moon of Jupiter with a diameter of about 42 kilometers. It has a measured brightness, called albedo, of about 3.6%. It is the fifth largest irregular moon of Jupiter.

Like other moons in the Himalia group, Lysithea appears gray and has colors between certain types of asteroids. It completes a rotation roughly every 12 hours and 45.6 minutes.

Origin

Lysithea likely did not form close to Jupiter. Instead, it was probably pulled in by Jupiter's gravity at a later time. It is similar to other moons in a group called the Himalia group, which share similar paths around Jupiter. Scientists think Lysithea might be a piece of an asteroid that broke apart and was captured by Jupiter.