Sunday, August 25, 2013

Walking Gnomon

 Every sunny day as I walk back and forth in our neighbor's lane, I marvel at my shadow. I watch it bob along as I pace back and forth and note its length, from an ungainly long shadow early (and late in the day) to one that is nearly as short as my feet at noon at summer's start.

 I am, in effect, a walking gnomon.

 This morning, at about 8 am, my shadow stretched perfectly parallel with Sam's lane (the lane runs roughly east/west). Early in the summer, at the same hour, my shadow would have traced off to the left, owing to the sun's location farther north at the same time. As the season's progress towards winter, my shadow will move slowly right.

 To make myself into an accurate sundial, I would have to lean towards the true north, 39.7° above horizontal, to compensate for my latitude. If I then marked off the hours on the ground, my shadow would fairly accurately tell the time. Every hour the sun moves 15° westward, the shadow projecting the solar time onto the ground.

 But is time itself real or just an illusion? Is all we measure no more than change? In any case, I measure the change daily as I walk, my shadow drifting this way and that, proving, at least, I live on a rotating sphere, orbiting an inconsequential star.

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