Environment Man measures his existence on the orbit of the Moon around the earth and on the rotation of the Moon. Of course, it is extremely difficult for the average human to calculate the number of Moon years of one's existence. The mystery of Eman continues.
The rotation of the Moon – or a lunar day – lasts around 27.3 days. This is the same amount of time the Moon takes to complete one orbit around the Earth. Because the rotation of the Moon and the length of its orbit are exactly the same, the Moon always presents the same face to the Earth.
Imagine that the Moon and the Earth are connected with an imaginary cable. The cable is bolted down on the Moon, but it’s connected to a ring around the Earth. So, the Earth can rotate at its own speed of turning once every 24 hours, and the Moon can go around it once every 27 days. But the Moon always shows the same face towards the Earth. (Universe Today, 8/23/2011)