The shadows of Jupiterís Galilean satellites #1 Io and #3 Ganymede will simultaneously transit Jupiter during the evening of 2012 MAR 22 in North American time zones. Io itself will be transiting at the same time. This will be the last dual shadow transit until the predawn hours of 2012 JUL 21.
Iíve created four preview graphics. One as viewed from above Jupiterís north pole and a second as viewed from Earth. The third is an event timetable. The fourth displays the dance of the satellites and shadows with Jupiter at 90-minute intervals. They can be seen by clicking http://www.curtrenz.com/jupiter
Photos and descriptions of the event would be welcome additions to this thread.