The planet Jupiter has been an object of interest since antiquity. In the 17th century Galileo discovered the large moons, named by Cassini for the various lovers of Zeus in Greek mythology including Io and Ganymede). In 1962, the modulation of the Jovian decametric radiation by Io was discovered, in 1975, Yuri Mekler, Irena Kupo and I found the cold Io plasma torus from the ground and 1979 the phenomenal volcanic activity of Io was observed for the first time by Voyager 1 along with the observations of the hot plasma torus by the PLS team and the ultraviolet instrument. Since then, the Jovian system has been the subject of intense research and I have had the privilege of making some small contribution to it.
Our early Jupiter studies at TAU , the Ph.D. dissertation work of Ron Schreier, were focused
primarily on the outer part of the Io torus and its interface with the mid-
magnetosphere plasma, i.e. we considered the region between the
planetocentric radial distances of 7 to 20 
. This region is of great interest since it contains the sharp
gradient in flux tube content region where precipitation of particles into
the atmosphere to create the aurora takes place. The urgent question
resolved in this region, with the aid of the data
analysis and theoretical modeling in our group, is the establishment of the
roles of the various components of the plasma. The significance of this
determination lies in its contribution to our understanding of the coupling
of the various components of the
atmosphere-ionosphere-magnetosphere-satellites system. The rate of radial
transport, which must supply the nearly 30 Terawatt energy consumption of
the auroral zone, depends on the ionospheric conductivity and the
gradients of the inward and outward going plasmas.The conductivity depends
in turn on the rate of precipitation. In general, the system is extremely
non-linear and an understanding of each of the components and its
interaction with the others is needed in order to derive a coherent picture
of how the Jovian magnetosphere and its attendant plasma function. We have
also looked at the possible role of the satellite Europa and found that it
is not extremely significant in populating the magnetosphere with plasma.
The latter phase of my Jupiter work began with my involvement in the work of the EPD team on Galileo. The discovery that the satellite Ganymede has an intrinsic magnetic field of sufficient magnitude to create a mini-magnetosphere inside the magnetosphere of Jupiter opened up totally new vistas of research. I have investigated the morphology of the energetic electron population, flow patterns around Ganymede, the structure of the ionosphere and the excitation of the aurora of Ganymede. I have also not ignored Io and Europa and have looked at the results of Galileo flybys and the phenomena discovered.
