September 23, 2007

Autumn

Summer is over! Officially, anyway; we've already had a couple of cool snaps and school's been back in session for some weeks now. And on the other hand, since it doesn't actually feel like night until well into twilight, it will be a while yet before it actually feels like the night and day are equal in length. (A quick loop in XEphem tells me that, if I use nautical dawn to nautical dusk for Minneapolis, light-dark equality occurs on November 10th and nautical darkness thereafter will exceed the daylight until February 1st1. Which sounds about right; early November is about when the days begin to feel noticeably short, and in early February it starts to feel like the winter darkness is lessening.) Nevertheless, today the sun will have traversed a path almost exactly midway between its northern and southern annual extremes, most notable for the fact that it will have risen at due east and set at due west -- much to the chagrin of rush-hour drivers in the many cities that have street grids aligned to the cardinal directions.

Incidentally: Jessica, was I not just saying that this thing must exist? Although, contrary to my proposal, I don't think you could actually play this in a cassette deck. There's no room for the drive spindles to pass through.

1However, if we're talking about cute dates gleaned from playing around with XEphem, my favorite is September 8th -- this is the first day that the sun sets less than 6° north of west; for the rest of the year the sun will not shine into my lab and make it stifling hot in the afternoon.

Posted by Milligan at September 23, 2007 08:51 PM | TrackBack
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