Lysithea Transparent

Planet of Origin



Seth Barnes Nicholson

Date of Discovery

July 6, 1938

Place of Discovery

Mount Wilson Observatory

Surface Color

Brownish red

Alternate Name(s)

Jupiter X

Lysithea is one of the irregular-shaped prograde, or orbiting a planet from the western to eastern directions, satellites belonging to the outer planet, Jupiter. It was discovered by Seth Barnes Nicholson at the Mount Wilson Observatory on July 6, 1938. It is part of the Himalia group, a group of moons that travel the same direction as Himalia, and are nearly as large in size, since Himalia is the largest of the group. The other's include (arranged from distance from Jupiter): Leda, the furthest, Himalia, Lysithea, and Elara being the closest. Names of satellites ending in "a" is in this group, according to the International Astronomical Union (IAU) regulations.


Lysithea is thought to be a stray asteroid from the neighboring Asteroid belt that was pulled in by Jupiter's gravitational pull. Lysithea has a color spectrum similar to those of D-type asteroids, which is similar to that of Sinope, a moon belonging to the Pasiphae group.


Lysithea has a surface similar to that of Sinope, yet has a size and mass similar to that of Himalia, thus giving it its name and grouping. Lysithea is believed to be from the inner depths of the Asteroid belt, yet was still pulled in by Jupiter's gravitational pull after possibly being pushed into distant space. This history is the same hypothetical history of Sinope.