So (Mom, you'll be interested in this), I learned today why pictures seem to have rings in them sometimes. wikipedia has info (http://en.wikipedia.org/wiki/Moir%C3%A9_pattern), but basically, when you line up parallel lines in one space, and cross them with parallel lines that are slightly askew, a pattern forms from where they intersect. The small version of this picture shows them; the larger one might not (it has to do, in digital imagery, with pixelation).