MEDIA RELATIONS OFFICE
JET PROPULSION LABORATORY
CALIFORNIA INSTITUTE OF TECHNOLOGY
NATIONAL AERONAUTICS AND SPACE ADMINISTRATION
PASADENA, CALIF. 91109. TELEPHONE (818) 354-5011
Contact at JPL: Jane Platt (818) 354-0880
Contact at Cornell: David Brand (607) 255-3651
FOR IMMEDIATE RELEASE September 15, 1998
GALILEO FINDS JUPITER'S RINGS FORMED BY DUST BLASTED OFF SMALL MOONS
Jupiter's intricate, swirling ring system is formed by dust kicked up as
interplanetary meteoroids smash into the giant planet's four small inner
moons, according to scientists studying data from NASA's Galileo spacecraft.
Images sent by Galileo also reveal that the outermost ring is actually two
rings, one embedded within the other.
The findings were announced today by scientists from Cornell University,
Ithaca, NY, and the National Optical Astronomy Observatories (NOAO), Tucson, AZ, at a news briefing held at Cornell.
"We now know the source of Jupiter's ring system and how it works," said
Cornell astronomer Dr. Joseph Burns, who reported on the first detailed
analysis of a planet's ring system, along with Maureen Ockert-Bell and Dr.
Joseph Veverka of Cornell, and Dr. Michael Belton of NOAO.
"Rings are important dynamical laboratories to look at the processes that
probably went on billions of years ago when the Solar System was forming
from a flattened disk of dust and gas," Burns explained. Furthermore,
similar faint rings probably are associated with many small moons of the
Solar System's other giant planets. "I expect we will see similar processes
at Saturn and the other giant planets," Burns said.
In the late 1970s, NASA's two Voyager spacecraft first revealed the
structure of Jupiter's rings: a flattened main ring and an inner, , tiny Adrastea is "most perfectly suited for the job."
As dust particles are blasted off the moons, they enter orbits much like
those of their source satellites, both in their size and in their slight
tilt relative to Jupiter's equatorial plane. A tilted orbit wobbles around a
planet's equator, much like a hula hoop twirling around a person's waist.
This close to Jupiter, orbits wobble back and forth in only a few months.
Jupiter's diameter is approximately 143,000 kilometers (86,000 miles). The
ring system begins about 92,000 kilometers (55,000 miles) from Jupiter's
center and extends to about 250,000 kilometers (150,000 miles) from the
Galileo has been orbiting Jupiter and its moons for 2 1/2 years, and is
currently in the midst of a two-year extension, known as the Galileo Europa
Mission. JPL manages the Galileo mission for NASA's Office of Space Science, Washington, DC. JPL is a division of Caltech, Pasadena, CA. The new images, and further information on this discovery and the Galileo mission, are available on the Internet at the following websites: