NOTICE: The project that is the subject of this report was approved by the Governing Board of the National Research Council, whose members are drawn from the councils of the National Academy of Sciences, the National Academy of Engineering, and the Institute of Medicine. The members of the committee responsible for the report were chosen for their special competences and with regard for appropriate balance.

Support for this project was provided by Contract NASW 96013 and NASW 01001 between the National Academy of Sciences and the National Aeronautics and Space Administration, National Oceanic and Atmospheric Administration Purchase Order No. 40-AA-NR-111308, National Science Foundation Grant No. ATM-0109283, Office of Naval Research Grant No. N00014-01-1-0753, and Air Force Office of Scientific Research Purchase Order No. FQ8671-0101168. Any opinions, findings, conclusions, or recommendations expressed in this material are those of the authors and do not necessarily reflect the views of the sponsors.

Cover: The background photo is of the aurora borealis as viewed from the vicinity of Fairbanks, Alaska. The three figures in the inset show the magnetically structured plasma of the Sun’s million-degree corona (left); the plasmasphere, a cloud of low-energy plasma that surrounds Earth and co-rotates with it (top right); and an artist’s conception of Jupiter’s inner magnetosphere, with the Io plasma torus and the magnetic flux tubes that couple the planet’s upper atmosphere with the magnetosphere. Ground-based aurora photo courtesy of Jan Curtis; coronal image courtesy of the Stanford-Lockheed Institute for Space Research and NASA; plasmasphere image courtesy of the IMAGE EUV team and NASA; rendering of the jovian magnetosphere courtesy of J.R. Spencer (Lowell Observatory).

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