In my previous post I referred to the 27 number and it's relation to the Moon. Here is more proof that the Grand Gallery encodes astronomic info of the Moon:
It is a Khufu pyramid cross section projection on to the geography of Greece using Google Earth and it's distance measurement tool. As one can see the length of the Gallery encodes the distance from Earth to the Moon. It is this distance - length that is divided into 27 slots - days, the rotation period.