Voyager Encounters Jupiter

by United States. National Aeronautics and Space Administration

The Magnetosphere

Perhaps the largest structure in the solar system is the magnetosphere of Jupiter. This is the region of space which is filled with Jupiter’s magnetic field and is bounded by the interaction of that magnetic field with the solar wind, which is the Sun’s outward flow of charged particles. The plasma of electrically charged particles that exists in the magnetosphere is flattened into a large disk more than 4.8 million kilometers (3 million miles) in diameter, is coupled to the magnetic field, and rotates around Jupiter. The Galilean satellites are located in the inner regions of the magnetosphere where they are subjected to intense radiation bombardment. It appears that Io is a source of the sulfur and oxygen ions which fill the magnetosphere. Another magnetospheric interaction is the electrical connection between Io and Jupiter along the magnetic field lines that leave Jupiter and intersect Io. This magnetic flux tube was examined by Voyager 1 and a flow of about five million amperes of current was measured, which was considerably more than anticipated. Voyager also discovered a new low-frequency radio emission coming from Jupiter, which is possibly associated with the Io torus.