Magnetospheric interactions in the major planets

In its eighteen years of operation, 1978-1996, different aspects of the interaction of the upper atmospheres and magnetospheres of the gaseous planets Jupiter, Saturn and Uranus, and the Jovian satellite Io and associated plasma torus, were discovered and further studied with the International Ultraviolet Explorer (IUE). Given the intrinsic time-variable nature of these phenomena, IUE's stable capabilities and long-term availability provided extensive datasets that are still particularly useful for our understanding of these systems. The main results obtained with IUE are reviewed, with reference to other observations in particular by the Voyager spacecrafts, the Hubble Space Telescope (HST), and the Galileo spacecraft. Outstanding questions posed by the IUE observations are also discussed.