The Dark Side of the Moon was not always hidden
There was a time when you could see the dark side of the moon. You do not remember it because it was there are three, perhaps four billion years.
According to a team from the Institute of Physics of the Earth in Paris, a very violent collision with one or more meteorites have sufficiently disrupted the rotation of the Moon that, within a few tens of thousands of years, the face it turns towards the Earth moves gradually, until the situation stabilizes.
The Moon always turns the same face to us, because it turns on itself at the same speed that it revolves around us (one round every 28 days).
