Last evening's Io/Ganymede event was really neat. I had my 4" refractor out checking out a new drive corrector and doing an accurate polar align. I took a break and looked at Jupiter through the trees. It was obvious that two of the moons were very close so I checked the S&T chart for Jovian moon events. Sure enough they were heading for a collision (well, it looked that way through the eyepiece!). The 4" showed them merge and then some 10's of minutes later began to seperate again. Then about 40 minutes later Io's shadow darkened Ganymede to the point it was dimmer than Io, but not by much. I was quite taken by how quickly these "real time" events transpired.
Walt
Walt