If Jupiter’s moons are visible in the evening sky, observe them with a small telescope on five consecutive clear nights. Record their positions by making nightly drawings, just as the Jesuit priests...

If Jupiter’s moons are visible in the evening sky, observe them with a small telescope on five consecutive clear nights. Record their positions by making nightly drawings, just as the Jesuit priests did in 1620 (see Figure 2-11a). From your drawings, can you tell which moon orbits closest to Jupiter and which orbits farthest? Are there nights when you saw fewer than four of the Galilean moons? What happened to the other moons on those nights?

Figure 2-11a