There is a day/night cycle provided by the reflected light of the moon within the polar day/night cycle provided by the orbital surface rotation.

http://www.usap.gov/videoclipsandmaps/spwebcam.cfm

In a few weeks it will return to darkness once more for the last time as polar dawn begins to appear at the South pole with the Sun appearing for the first time since March.

https://www.youtube.com/watch?v=okw6Mu3mxdM

This is all going to be expanded on and worked out in detail.