https://www.youtube.com/watch?v=gxJ4M7tyLRE&feature=youtube_gdata"]Why is it Dark at Night? - YouTube
https://www.youtube.com/watch?v=Cey35bBWXls&feature=player_detailpage"]Can she be THAT stupid? - YouTube
I think it gets dark because god puts a big blanket over Earth so we'll all go to sleep - it's the same principle as a birdcage.
This reminds me of my father's high school friend, who ended up committing suicide, who was a druggie and stated "The cars don't move along the road, rather the road moves."