Stow it, William, I said to myself; you’ll be building a whole house out of glass next. After Papa Schultz left I spoke to George about it. “Look,” I said, “about this view window idea. It’s a good notion, especially for Peggy’s room, but the question is: can we afford it?”
“I think we can,” he answered.
“I mean can we afford it without your going back to work in town? You’ve been working yourself to death —and there’s no need to. The farm can support us now.”
He nodded. “I had been meaning to speak about that. I’ve about decided to give up the town work, Bill—except for a class I’ll teach on Saturdays.”
“Do you have to do that?”
“Happens that I like to teach engineering, Bill And don’t worry about the price of the glass; well get it free—a spot of cumshaw coining to your old man for designing the glass works. “The kine who tread the grain,'” he quoted. “Now you and I had better get busy; there is a rain scheduled for fifteen o’clock.’
It was maybe three weeks later that the moons lined up. This is an event that almost never happens, Ganymede, Callisto, Io, and Europa, all perfectly lined up and all on the same side of Jupiter. They come close to lining up every seven hundred and two days, but they don’t quite make it ordinarily. You see, their periods are all different, from less than two days for Io to more than two weeks for Callisto and the fractions don’t work out evenly. Besides that they have different eccentricities to their orbits and their orbits aren’t exactly in the same plane.
As you can see, a real line up hardly ever happens.
Besides that, this line up was a line up with the Sun, too; it would occur at Jupiter full phase. Mr. Hooker, the chief meteorologist, announced that it had been calculated that such a perfect line up would not occur again for more than two hundred thousand years. You can bet we were all waiting to see it. The Project Jove scientists were excited about it, too, and special arrangements had been made to observe it.
Having it occur at Jupiter full phase meant not only that a sixth heavenly body—the Sun—would be in the line up, but that we would be able to see it. The shadows of Ganymede and Callisto would be centered on Jupiter just as Io and Europa reached mid transit.
Full phase is at six o’clock Saturday morning; we all got up about four-thirty and were outside by five. George and I carried Peggy out in her bubble stretcher. We were just in time.
It was a fine, clear summer night, light as could be, with old Jupiter blazing overhead like a balloon on fire. Io had just barely kissed the eastern edge of Jupiter—”first contact” they call it. Europa was already a bit inside the eastern edge and I had to look sharp to see it. When a moon is not in full phase it is no trouble to pick it out while it’s making its transit, but at full phase it tends to blend into the background. However, both Ioand Europa are just a hair brighter than Jupiter. Besides that, they break up the pattern of Jupiter’s bands and that lets you see them, too.
Well inside, but still in the eastern half—say about half way to Jupiter’s center point—were the shadows of Ganymede and Callisto. I could not have told them apart, if I hadn’t known that the one further east had to be Ganymede’s. They were just little round black dots; three thousand miles or so isn’t anything when it’s plastered against Jupiter’s eighty-nine thousand mile width.
Io looked a bit bigger than the shadows; Europa looked more than half again as big, about the way the Moon looks from Earth.
We felt a slight quake but it wasn’t even enough to make us nervous; we were used to quakes. Besides that, about then Io”kissed” Europa. From then on, throughout the rest of the show, Io gradually slid underneath, or behind, Europa.
They crawled across the face of Jupiter; the moons fairly fast, the shadows in a slow creep. When we had been outside a little less than half an hour the two shadows kissed and started to merge. Io had slid halfway under Europa and looked like a big tumor on its side. They were almost halfway to center and the shadows were even closer.