Galileo sees all four again

15 January 1610. Galileo can't wait for evening twilight. He was clouded out last night, but tonight, three hours after sunset, he points his spyglass at Jupiter once again and sees all four of the companions, all to the west of Jupiter. Four hours later ('the seventh hour', after midnight) the visible companions are three in number. He stays up another hour and spies two of the companions in conjunction

I keep having toremind myself that the diagrawms in Sidereus Nuncius are the telescope view, which is inverted -- east is right and west is left in Galileo's thumbnails

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