hm.. read up a couple of replies and you will see that it has already been adressed. all they need to do is take a picture of a certain area at nite, do the same with the others and put em together like a puzzle.. not too complicated how..
this isnt actually a picture of the world at night, its a picture of Electricity use worldwide....notice how the poor/unpopulated areas of the world have less lights......ive seen this before......