Selenology:
Luna rotates one time per lunar month, the same face always presents to the earth (Terra). As would be obvious to anyone going out on clear nights to observe the earth's moon, over a month the light falls on varying amounts of the face visible to the Terran observer, waxing and waning.
Since a hemisphere of Luna is always illuminated, as the visible (near) face wanes in illumination, the nonvisible (far) face waxes (increases) in illumination. When there is "no moon," the sun completely illuminates the far side.
Hence, there is NO dark side.
[nyah-na-NA-na-na]
S&F