WAT?! 12 hours for a 99% black image? :] Please justify your efforts - did you model atmosphere? :]
Yup i modeled it. Used as i remember 3 layers with different density and collor . Earth itself is blend material composed from light mtl and default corona mtl using bw mask for city lights.
And i used real scale of the objekts in 1 to 10000 to achive realistic result. (i tried to fake it firs bud i have not sucseded in it)
And 12 hrs was overkill it actualy was ready by the morning ( i have finished the scene at 0400 and woke up at 0900 but i was in a haze and forgot to stop render so 12 hrs it is ) Actualy sample/s number was 100k wich is very good for this pice of crap i got at home.