I don't know, but I'll ask one. This follows on from a point that was raised earlier (possibly in this thread, I don't recall):
What are the respective sizes of the shadows which the Galilean satellites cast on Jupiter during transits?
(Diameters of the umbras [Edit: make that
shadows] to the nearest Km. Assume that the centres of Sun, moon, umbra and Jupiter are all in a line. Use average distances as given in the
Planetary Fact Sheets.)