Earthquake climaxed when the world was about ten billion years old. At that time a massive stone rock came to the earth. Later this stone was named Theia. Theia size and size are equal to Mars. In the face of confrontation with Theia, a large part of one side of the earth broke down, Theia got crushed. Earth rotation did not stop but a little bit. Theia debris and the parts scattered from the earth began to rotate around the earth, becoming a pandal mixed with the force of gravitational force. This round pind is the only natural satellite in the world - the moon. 