Magnetospheres of Jovian Panets

JUPITER'S MAGNETOSPHERE 
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.
SATURN'S MAGNETOSPHERE 
Saturn's magnetic field also defines a zone about it, or a magnetosphere in which it can control the motions of subatomic particles. The Saturnian magnetosphere is intermediate, in size and in the intensity of the mag­netic field, between that of jupiter and the earth. AI three are based on a common framework of physica principles; yet each possesses its own distinctive char­acter.
Prior to the late summer of 1979 astronomers could only speculate on the magnetic field and radiation belts around Saturn. During that summer Pioneer 11 detected the boundary of the magnetosphere lying some 24 Saturnian radii from the planet (its rings ex­tend about six radii from the center of the planet). Saturn's magnetosphere is apparently more disklike than that of the earth, which is more spherical but less so than Jupiter's larger magnetosphere.
Beyond Saturn we expect to find that Uranus and Neptune possess magnetic fields to create magneto­spheres about themselves as do Jupiter and Saturn. However, until Voyager 2 makes its pass by Uranus in 1986 and Neptune in 1989, we shall not have confirm­ing evidence for their existence.