Jupiter's New Moons

Jupiter XVII, XVIII, ...?


   A dozen small irregular jovian satellites have been discovered recently. Many new moons of Saturn and Uranus are also showing up.

   S/1999 J1 was discovered by the Spacewatch project and the Minor Planet Center in 2000 from images taken in 1999.

   Observations with the VLT in July 2000 confirmed the existence of S/1999 J1 and refined our knowledge of its size and orbit.

   S/2000 J11 has an orbit similar to Leda, Himalia, Lysithea and Elara (direct, inclination about 30 degrees).

   S/2000 J1 seems to be in a class by itself.

   The other new ones have orbits similar to Ananke, Carme, Pasiphae and Sinope.

   We usually say that these irregular satellites are "captured asteroids". But the mechanism of their capture is unclear. The truth is we don't really know how they came to be where they are.

Preliminary Data

IAU Name Distance Period Inclination Eccentricity Brightness Radius Discoverer Date aka
  [x1000 km] [days] [degrees]   [magnitudes]        
Callisto 1883 17 0 0.01 5.6 2403.0 Galileo 1610  
S/2000 J1 7435 130 46 0.20 21.0 4.0 Sheppard et al 2000 S/1975 J1
Leda 11094 239 27 0.15 20.2 8.0 Kowal 1974  
Himalia 11480 251 28 0.16 15.0 93.0 Perrine 1904  
Lysithea 11720 259 29 0.11 18.2 18.0 Nicholson 1938  
Elara 11737 260 28 0.21 16.6 38.0 Perrine 1905  
S/2000 J11 12654 290 29 0.22 22.4 2.0 Sheppard et al 2000  
S/2000 J10 20375 591 166 0.16 22.5 1.9 Sheppard et al 2000  
S/2000 J3 20733 605 150 0.27 21.8 2.6 Sheppard et al 2000  
S/2000 J5 21019 618 149 0.20 22.2 2.2 Sheppard et al 2000  
S/2000 J7 21162 626 146 0.15 21.2 3.4 Sheppard et al 2000  
Ananke 21200 631 147 0.17 18.9 15.0 Nicholson 1951  
S/2000 J9 21734 652 164 0.25 21.9 2.5 Sheppard et al 2000  
S/2000 J4 21948 661 161 0.35 22.8 1.6 Sheppard et al 2000  
Carme 22600 692 163 0.21 17.9 20.0 Nicholson 1938  
S/2000 J6 22806 704 165 0.28 22.5 1.9 Sheppard et al 2000  
Pasiphae 23500 735 147 0.38 16.9 25.0 Melotte 1908  
S/2000 J8 23521 733 152 0.53 21.7 2.7 Sheppard et al 2000  
Sinope 23700 758 153 0.28 18.0 18.0 Nicholson 1914  
S/2000 J2 24164 766 166 0.32 21.8 2.6 Sheppard et al 2000  
S/1999 J1 24296 774 143 0.13   2.4 Spacewatch 1999 1999 UX18
The above is probably not very accurate. (Previously known satellites are shown in bold.)

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Bill Arnett; last updated: 2001 Jan 9