Crater 308 on the moon
This photo was taken by the crew of Apollo 11 as they circled the far side of the moon. Since the moon is in synchronous rotation with Earth, we only see the same, smoother side from Earth. The far side of the moon is rough with craters and marks. Further, the moon's gravitational pull on Earth is weaker on the far side of the moon. Without the interplay of gravity between Earth and the moon, we wouldn't have the tidal forces at work in our oceans which are so important to life on our planet.