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The Magnetosphere of Jupiter

1969; Annual Reviews; Volume: 7; Issue: 1 Linguagem: Inglês

10.1146/annurev.aa.07.090169.003045

1545-4282

Thomas D. Carr, S. Gulkis,

Solar and Space Plasma Dynamics

The only solar system objects known to possess magnetic fields are the Earth, the Sun, and Jupiter. The field of the Earth can be measured directly, while that of the Sun has been deduced from the observed Zeemann splitting of optical emission lines. The first evidence that Jupiter has a magnetic field, and thus far the only evidence, was provided by its polarized radio emissions. Jupiter's field is believed to be considerably stronger than that of the Earth. As in the case of the Earth, Jupiter's field does not extend in­ definitely into space, but is confined to a cavity of unknown size and shape around the planet. Outside this cavity and beyond a transition region, the ambient conditions are characteristic of the interplanetary medium. The region within the cavity, in the space above the ionosphere, is termed the magnetosphere. Inside the magnetosphere, the magnetic field has control over the fast charged particles responsible for much of the Jovian microwave emission, and presumably also a background plasma with a broad spectrum of particle energies extending down into the thermal region. Because of the relatively high rotation rate of the planet, its strong magnetic field, and the presence of a number of satellites orbiting within its magnetosphere, mag­ netic interactions are believed to play an even more important role in Jupi­ ter's magnetosphere than in that of the Earth. In this paper we shall discuss the observed radio emissions, the deductions from them regarding the mag­ netic field and the magnetosphere, and the results of theoretical investiga­ tions of interactions between the magnetic field and plasma in the Jovian magnetosphere.