measured the motion of the sun's shadow (http://johnburridge.blogspot.com/2009/03/measuring-suns-darkness.html).
Wow. Five years.
Anyway, the shadow is about to point due north, as figured using the the circles in yellow and bisecting the angle where the shadow's tip touches. I like the contrasts between the shadow and the pencil, and between the lines in the wood, the yellow circles and the black circles.