This dockapp shows you the actual distance of Jupiter in astronomical units
(AE) and when the red spot crosses (which is a weather feature on Jupiter).
The four Galileo Moons are displayed too but only when they are near the
planet (Io, Europa, Ganymede, and Callisto).  The position of the red spot
changes on the surface so you need to change that value within few months
or so.  The current position can be found on the Internet.  It was 80 deg.
as of 11th Jan 2002.