The Moon sits very close to the Earth yet it is widely regarded as the strangest object in the known universe. It is a bit like knowing that every person in the world is completely normal except the person you live next door to, who has three heads and lives on a diet of broken razor blades.
The book lists the strangeness of the Moon, which includes the fact that it does not have a solid core like every other planetary object. It is either hollow or has a very low-density interior. Bizarrely, its concentration of mass are located at a series of points just under its surface – which caused havoc with early lunar spacecraft.
The material the Moon is made from came from the outer surface of the Earth and left a shallow hole that filled with water and we now call the Pacific. This rock left the Earth to produce the Moon very quickly after our planet had formed around 4,6 billion years ago. http://humansarefree.com/2014/06/one-of-most-haunting-questions-who.html