Our nearest neighbor

The moon's orbital period around the earth is approximately 27 days (27 days, 7 hours 43 min 11.5 sec), it rotates on its own axis in exactly the same time and therefore we never see the back of the moon. The distance to the moon is approx. 384,400 km and increases by approx. 4 cm per year, this causes the tidal forces and the Earth's rotation speed to decrease gradually over time. There are visible signs of past volcanic activity on the moon's surface, in addition, the moon is believed to contain large amounts of frozen water. 12 American astronauts have walked on the surface of the moon from 1969-1972. It is the plan that man will visit the moon again and establish a permanent lunar base, including the USA, China and Russia etc.