S/2003 J 2

S/2003 J 2 is a natural satellite of Jupiter. It was discovered by a team of astronomers from the University of Hawaii led by Scott S. Sheppard, et al. in 2003. It is Jupiter's outermost known moon. S/2003 J 2 is about 2 kilometres in diameter, and orbits Jupiter at an average distance of 30,291 Mm in 1077.018 days, at an inclination of 176° to the ecliptic (152° to Jupiter's equator), in a retrograde direction and with an eccentricity of 0.188.

It seems to belong to a group all of its own, with semi-major axis ~30 Gm and inclination ~150°.

The limits of Jupiter's gravitational influence are defined by the Hill sphere, whose radius is

<math>\approx a_j \sqrt[3]{\frac{m_j}{3 M_s}}<math>,

where <math>a_j<math> and <math>m_j<math> are Jupiter's semi-major axis and mass, and <math>M_s<math> is the Sun's mass. This comes out as about 52 gigametres. S/2003 J 2 reaches 36 Gm during its orbit; it is therefore possible that yet farther out moons of Jupiter are left to discover.