Sunday, October 26, 2014

The Sun Also Rises…

…to the south and to the north of due East. Indeed the sun rises in the East only on two days of the year, March 20 and September 23, the vernal and autumnal equinoxes.

This subject came up yesterday when, discussing the tilted wind-rose on our newly acquired gazebo, I kept insisting that what Brigitte called East was really West. She kept insisting that the sun rose in the East—and never mind which way the wind-rose was pointing. I kept arguing feebly for a while until she said: “If you are right, Arsen, the sun is right now setting in the East—and you can see it for yourself by looking out the window!” Sure enough. Some windstorm had managed to turn our wind-rose helter-skelter.

Another fix-it chore goes on my list, but I rather dread having to climb up there just to correct that problem. I am as challenged by heights as I am by spherical geometry.

Herewith a graphic that shows the rather considerable deviations of sunrise from due East for the North 42nd Latitude where Detroit lies on the map.

I have this diagram from a paper published by the Griffith Observatory in Los Angeles in 1948 and accessible here. One of the reassuring aspects of astronomy is that what was true in 1948 is still true in 2014—and will presumably still hold in 3014. Until the skies go into disarray, all’s well with the world.

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