A BRIEF-HISTORY OF MAGNETOSPHERIC PHYSICS DURING THE SPACE AGE

After 1958, when scientific satellites began exploring the Earth magne tic environment, many puzzling phenomena could be directly examined, e specially the polar aurora and disturbances of the Earth's magnetic he ld [see Stem, 1989a]. The notion of the solar wind, also introduced in 1958, helped clarify the role of the Sun in driving such phenomena. T he large-scale structure of the magnetosphere, the space region domina ted by the Earth's magnetic field, was gradually revealed within the n ext decade: its trapped particles, its boundary, and its long magnetic tail on the nightside. Inevitably, however, at a more fundamental lev el, the new discoveries led to new questions about the transfer of ene rgy, the flow patterns of plasmas and electric currents, the accelerat ion of the aurora, and transient events such as magnetic substorms and storms, which energized ions and electrons. Though significant progre ss has occurred in some of these areas, many unresolved issues still r emain. This review outlines the history of magnetospheric research, dr aws some general conclusions, and provides an extensive bibliography.