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Perturbations of the external magnetic fields around Europa and Callisto, Jupiter satellites, are reported. They are believed to arise from induced magnetic fields, generated in response to the varying plasma environment. It is likely that there significant layers of electrical conductivity just under the surfaces of both moons, and that the conducting layers can be explained by the presence of salty liquid-water oceans.

The encounter of Galileo spacecraft with Ganymede, Jupiter's largest moon reveals the the presence of an internal magnetic field. The data agrees with the observation of an equatorial surface field strength of 750 nT and a 10 degree tilt of Ganymede-centered magnetic dipole with respect to the spin axis. The magnetic field is strong enough to produce a magnetosphere with well-defined boundaries in Ganymede. The observations fail to indicate the source of the internal magnetic field.

The dust in the dust streams detected by the Galileo spacecraft near Jupiter originate from either the jovian gossamer ring or volcanoes on Io. The dust does not originate from the Shoemaker-Levy 9 comet as the comet has no stream activity. The dust storms detected by the Galileo dust detector are more intense and longer than those observed by the Ulysses spacecraft. The dust stream activity changes with time and there are significant differences between the intensity of the strongest and the weakest streams.

Two types of dust particles were detected by the Ulysses spacecraft during its passage near Jupiter last Feb 8, 1992. The first type occured at periodic bursts and measured in the submicrometer range. The streams were narrow, collimated and concentrated near Jupiter. These grains are hypothesized to be of Jovian origin, which escaped Jupiter's influence by a combined action of the plantet's intense magnetic field and the high solar wind speed. The second type of dust particles were interstellar dust. This was indicated by the retrograde motion of the particles which moved at speeds comparable to interstellar gas.