User: What is the significance of the moon's hidden face?
Assistant: The Moon's hidden face is the hemisphere of this satellite that is not visible from Earth because the Moon always shows the same face. This is because the moon takes the same amount of time to rotate on its own axis (rotation) as it does to orbit the Earth (translation). Tidal coupling is the term used to describe this phenomenon. The first images of the Moon's far side were sent by the Soviet spacecraft Luna 3, the third spacecraft launched to the Moon, on October 7, 1959.