S/2003 J 9

S/2003 J 9 is a retrograde irregular satellite of Jupiter. It was discovered by a team of astronomers from the University of Hawaii led by Scott S. Sheppard in 2003.^[1]

S/2003 J 9

S/2003 J 9 imaged by the Canada-France-Hawaii Telescope during follow-up observations in February 2003
Discovery [1]
Discovered by	Scott S. Sheppard David C. Jewitt Jan T. Kleyna Yanga R. Fernández
Discovery site	Mauna Kea Obs.
Discovery date	6 February 2003
Orbital characteristics [2]
Epoch 17 December 2020 (JD 2459200.5)
Observation arc	15.19 yr (5,545 d)
Semi-major axis	0.1615575 AU (24,168,660 km)
Eccentricity	0.1701900
Orbital period (sidereal)	2.10 yr (767.60 d)
Mean anomaly	109.89836°
Mean motion	0° 28m 8.381s / day
Inclination	166.33403° (to ecliptic) 13.66597° (retrograde)
Longitude of ascending node	130.59522°
Argument of perihelion	45.62861°
Satellite of	Jupiter
Group	Carme group
Physical characteristics
Mean diameter	≈1 km[3]
Albedo	0.04 (assumed)[3]
Apparent magnitude	23.7[3]
Absolute magnitude (H)	16.9[2]

S/2003 J 9 is about 1 kilometre in diameter, and orbits Jupiter at an average distance of 0.162 AU (24,200,000 km) in 767.60 days, at an inclination of 166.3° to the ecliptic (166° to Jupiter's equator), in a retrograde direction and with an eccentricity of 0.17.

It belongs to the Carme group, made up of irregular retrograde moons orbiting Jupiter at a distance ranging between 23 and 24 Gm and at an inclination of about 165°.

This moon was once considered lost^[4][5][6][7] until November 2020, when the Minor Planet Center announced the recovery of S/2003 J 9 by Scott Sheppard in observations from September 2011 to April 2018.^[2]