Jupiter is the strongest radio emitter in the solar system after the sun. It emits both thermal and nonthermal radiation. At times its radio emission exceeds even the sun's in intensity. The nonthermal radiation is a type of synchrotron radiation, and it results from jupiter's having a magnetic field and energetic, free electrons in radiation belts analogous to the earth's Van Allen radiation belts.
There are also occasional bursts having energies up to 10 million kilowatts. The bursts are more intense when the nearest Galilean satellite, 10, appears on one side of jupiter as viewed from the earth. Why should the position of 10 make a difference? We suspect that it is due to the motion of 10 through jupiter's magnetic field, disturbing the field and the electrons trapped in it.
Pioneer space probes ran into the bow shock wave formed by the solar wind's interacting with jupiter's magnetic field as far out as 108 jupiter radii. Data from the two Pioneer craft and the two Voyagers indicate that the boundary of the magnetosphere in the direction of the su n varies between about 50 and 100 jupiter radii. The planet's inner radiation region is like earth's Van Mien belts but from 5000 to 10,000 times more intense.
Far out the magnetic field flattens into a disk extending several million kilometers from the planet, and its long tail, flowing out opposite to the direction of the sun, extends an unknown distance beyond the orbit of Saturn. The shape is influenced by the large centrifugal force that results from the planet's rapid rotation.
