Figure 3-4:

The Moon’s Rotation These diagrams show the Moon at four points in its orbit as viewed from high above Earth’s north pole. (a) The wrong model: If the Moon did not rotate, then at various times the red crater would be visible from Earth while at other times the blue crater would be visible. Over a complete orbit, the entire surface of the Moon would be visible. (b) In reality, the Moon rotates on its north-south axis. Because the Moon makes one rotation in exactly the same time that it makes one orbit around Earth, we see only one face of the Moon.