The asterisks are only put at the top and bottom of the pages b/c there is a break in the story. Usually if a part of the story stops, it stops in the middle of the page and Stephenie puts a large space or break to show u that it is a little later in the story.
Hope that helps...
and i think sometimes they were used like when a crtain period of time has passed so instead of writing a whole day she used asterisks to show its a new day or scene or something - i think :s
