Tuesday, November 02, 2004

Clockwise and otherwise

I just thought of this in response to a comment in an APA I contribute to.

MH. ct (comment to) LG: Now I'm trying to decide whether sundials would run "clockwise" in Australia (or south of the equator in general). Let's see. North of the equator, the sun rises in the east, so the shadow points west. At solar noon, the sun has moved around to the south, so the shadow has moved to point north. At sundown, the sun is in the west, so the shadow points east. The shadow of the gnomon traces a circle from west, through north, to east. South of the equator, the sun rises in the east, so the shadow points west. So far, so good. At solar noon, the sun has moved around to the north. Finally, at sunset, it has moved to the west. The gnomon's shadow moves from west to east via south. A sundial in Australia would run counter-clockwise. I wonder if anyone has ever written a story with a new immigrant to Australia, New Zealand, South Africa or any other land well south of the equator, complaining that his or her sundial is "broken".

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