spheres in orbit in spring

"It was one day as I listened to baseball that it occurred to me how the moon actually moves, in a spiral, because while it orbits the earth it also follows the orbit of the earth around the sun.  This is obvious, but the realization pleased me.  There was a full moon outside my window, icy white in the blue sky, and the Cubs were playing Cincinnati."

-from Gilead by Marilynne Robinson