Here are 12 frames, cropped at precisely the same place in each frame, taken at 30 second intervals beginning at 05:27 UT on Sept. 3. They show Europa's shadow on Jupiter and a second shadow, presumed to be of Ganymede during a double transit. Yet, Ganymede's shadow was not supposed to cross Jupiter's face until 06:46 UT, according to a published predictions. The second shadow, I found out later, was Ganymede itself, and not the shadow. I had not thought that a moon of Jupiter would appear so dark against the big planet's cloud surface.