An artist's sketch of the development of the main Jovian ring and halo.
Particles in the main ring are believed to be impact debris coming off
the small moons Adrastea and Metis. Adrastea (shown in the sketch)
skims along the outer edge of the ring and Metis orbits roughly
in the middle of the main ring. The orbits of the debris spiral inward
due to the absorption of sunlight. At 1.7 Jupiter radii (121,400 kilometers
or 75,300 miles), this debris reaches a resonance where electromagnetic forces
push the particles up and down at a rate that is exactly one third
their orbital rate around Jupiter. The systematic forcing at this resonance
pushes the particles out of the equatorial plane, leading to the development
of the vertically extended (lightbulb-shaped) halo. An even stronger resonance
is located at 1.4 Jupiter radii (100,000 kilometers or 62,000 miles),
where the particles are pushed upward on every second orbit. Their paths
become so tilted and elongated that they hit Jupiter's atmosphere where they
are lost, thereby terminating the ring halo.
The Jet Propulsion Laboratory, Pasadena, CA manages the Galileo mission
for NASA's Office of Space Science, Washington, DC.
This image and other images and data received from Galileo are posted
on the World Wide Web, on the Galileo mission home page at URL
http://galileo.jpl.nasa.gov/.
Background information and educational context for the images can be found at:
http://www.jpl.nasa.gov/galileo/sepo.
