Earth has only one natural satellite, called the Moon. Many scientists have given different hypothesis for the formation of the Moon. One class of theories states that after the formation of the Earth, a Meteorite hit the Earth and a part of the Earth was broken up to form the Moon. But another theory states that the formation of the Moon was similar to that of the Earth. Nowadays, the second class of theories is widely accepted. The Lunar mountains in the Hadley-apennine area were explored by the Apollo 15 mission. Covering about 23 km, the Lunar Rowing Vehicle was used to help collect rock samples. These showed a maximum age of about 4.5 billion years. When the Moon formed by the accretion , it was initially molten, and no permanent surface features had formed. Compared with other satellites of the Solar System, the Moon is large in relation to the Earth.
If you look at the surface of the Moon even with a small telescope, you will be able to see the craters clearly. These craters are huge pits on the surface of the Moon. They were possibly caused by collision of the Meteorites on the Lunar surface. Moon has a gravity of one-sixth that of the Earth and is about 4 times smaller than the Earth. The Moon has no atmosphere. Hence when Meteorites move towards the Moon, there is no opposing force to stop them, they directly hit the surface creating huge pits called - impact craters.

Image : Moon
Source: NASA/NSSDC

Image : Apollo Rover
Source: NASA/NSSDC

These craters are more in number on the 'Far side' of the moon, the face of the Moon we cannot see from the Earth. But on the near side, there are patches called 'Seas of the moon'. Neil Armstrong was the first man to land on the Moon on 20th July, 1969 and till today 12 men have landed on the Moon. We cannot see the other side of the moon for the simple reason that the period of rotation of the Moon about its own axis and the period of revolution of the Moon around the earth is one and the same (27 days, 7 hours, 43 mins and 11 sec. This means that one side always faces the Earth and the other side never faces the Earth.
The lunar landing module Eagle ascends from the surface of the Moon after Apollo 11 mission in July 1969. For the first time, the human race had established a foothold on a world beyond its own. In the view of some scientists, the appearance of intelligent life and its colonization of the universe was designing into the laws of the cosmos from the very beginning.