英語時差：月亮的黑暗面（下）

As the moon orbits the earth, the illumination from the sun gradually slides in and out of our view. Depending on the positions of the moon and sun, we on earth see the moon as waxing, full, or waning. During a new moon, the moon looks completely dark from earth. But that’s just because the light is now falling entirely on the other side. Another thing that confuses people is that the moon always shows us the same side. That’s because its rotation around the earth takes just as long as one complete spin: 27 and 1/3 days. The result is the moon as seen from earth seems not to spin. But it is spinning, just like the earth. So “the dark side of the moon” is only “dark” in the sense that we never see it. It gets just as much light as the side we can see.