MEDIA RELATIONS OFFICE
JET PROPULSION LABORATORY
CALIFORNIA INSTITUTE OF TECHNOLOGY
NATIONAL AERONAUTICS AND SPACE ADMINISTRATION
PASADENA, CALIF. 91109.  TELEPHONE (818) 354-5011
http://www.jpl.nasa.gov

IMAGE CAPTION                       P50087               
                                    September 15, 1998
                                    Jupiter's Main and Gossamer 
                                    Ring Structures

The schematic structures of Jupiter's main and gossamer rings are 
depicted here.  Scientists studying data from NASA's Galileo 
spacecraft have found that the ring system is made up of impact 
debris created when meteoroids, which are fragments of comets and 
asteroids, slam into Jupiter's four smallest satellites.

The top panel shows that the main ring (red) is formed mostly from 
meteoroid impact debris kicked up from the innermost moons, Metis (m) 
and Adrastea (a).  Since both satellites orbit in paths not inclined 
to Jupiter's equator, the main ring appears as a narrow line.  

The middle panel shows the additional effect of dust ejected from the 
satellite Amalthea (A), responsible for producing one of the two moon 
components of the gossamer ring.  Amalthea's orbit is inclined to 
Jupiter's equatorial plane, and at different times the satellite's 
vertical position can range anywhere between the two extreme limits 
shown.  Dust ejected from Amalthea (orange) produces a ring whose 
thickness equals Amalthea's vertical projections beyond Jupiter's 
equatorial plane.  

The lower panel shows the additional effect of dust ejected from 
Thebe (T), which makes up the second component (shown in green) of 
the gossamer ring.  Again, the two positions shown represent the 
maximum projections of Thebe from Jupiter's equatorial plane.  This 
component of the gossamer ring is thicker than the component due to 
Amalthea's dust because Thebe's orbit is more inclined than that of 
Amalthea.

The Jupiter image was created from a map based on data obtained by 
the Hubble Space Telescope.  The Jet Propulsion Laboratory, Pasadena, 
CA manages the Galileo mission for NASA's Office of Space Science, 
Washington, DC. 

JPL manages the Galileo mission for NASA's Office of Space Science, 
Washington, DC.  The images are posted on the Internet at 
http://photojournal.jpl.nasa.gov/  and at 
http://www.jpl.nasa.gov/galileo . Background information and 
educational context for the images can be found at: 
http://www.jpl.nasa.gov/galileo/sepo . 

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9/9/98 JP