By Dr David Whitehouse
BBC News Online science editor
Jupiter's tally of moons now stands at 58, following the discovery of six more.
Probably just a few kilometres across
It means Jupiter has more moons than any other planet. They are mostly small irregularly shaped objects that are probably captured asteroids.
All the new satellites appear to have distant so-called retrograde orbits - their orbital movement is opposite to Jupiter's spin - like the majority of the irregular satellites already recorded in the Jovian system.
The majority of the new satellites were discovered in early February 2003 by Scott Sheppard and David Jewitt, from the Institute for Astronomy, University of Hawaii, US; along with Jan Kleyna, of Cambridge University, UK.
'We will get to 100'
The moons were found using the world's two largest digital cameras at the 8.3 metre Subaru and 3.6 metre Canada-France-Hawaii telescopes atop Mauna Kea in Hawaii.
Following the initial discoveries, the new moons were confirmed using the University of Hawaii 2.2 metre telescope with help from Yanga Fernandez and Henry Hsieh, also from the University of Hawaii.
Brian Marsden, of the Harvard-Smithsonian Center for Astrophysics, US, performed the calculations for determining the orbits of the new bodies.
More moons than any other planet
However, these orbits are still preliminary and may change as new observations are obtained.
Jewitt's team has found 18 Jupiter moons this year and expects to find more.
"We think if we keep on pushing it with the cameras and telescopes we have available, we'll get to about 100," he said.