Edition: U.S. / Global  Third Moon Of Jupiter May Have Sea Under
Its Ice  Published: December 17, 2000  Scientists have found
evidence that Ganymede, a moon of Jupiter, has an ocean. That is
the third Jupiter moon that shows signs of water sloshing
beneath its frozen exterior.  NASA's Galileo spacecraft has
detected telltale undulations in Ganymede's magnetic field.
Planetary scientists had previously found indications of under-
ice oceans on Europa and Callisto, two other moons. Water is
considered a necessary ingredient for the development of life,
although no signs of life have yet been seen on any of the
moons.  ''It looks pretty persuasive to us,'' said Dr. Margaret
Kivelson, a professor of space physics at the University of
California at Los Angeles, who led the research. She was to
present her Ganymede findings Sunday at the fall meeting of the
American Geophysical Union here.  ''I think it's an exciting
result,'' said Dr. Robert Pappalardo, of Brown University. ''It
makes sense if Callisto has really r