[natphil] Natural Philosophers - a Conundrum

[Paul Bassett]

Hi Ed,
In case I can't get to the next meeting, the attached PowerPoint slides capture what I recently set myself thinking about during periods at night when I had trouble falling to sleep. It's all trigonometry. The attached Excel spreadsheet compares my day-night formula with the official data for 2013. I simplified by assuming a circular orbit, so my values vary from the official ones, but by less than 10 minutes. Orbital eccentricity probably also explains the anomalous sunrises. The Earth reaches the narrowest point in its elliptical orbit (perihelion) in early January (and 6 mo. later). If the precise moment of the winter/summer solstice occurs at other than noon for our longitude, it's possible for the longest/shortest night to occur on an adjacent date from the exact solstice date. Similarly, the increasing/decreasing sunrise times may get out of sync for a day or so due to the changing distance to the sun (which changes fastest near perihelion and aphelion).

I regret missing many of the meetings, but commuting from Barrie forces me to give local events and weather higher priority.

Cheers,
Paul
----- Original Message ----- 
From: ED 
To: natphil at listserv.physics.utoronto.ca 
Sent: Thursday, January 16, 2014 4:05 PM
Subject: [natphil] Natural Philosophers - a Conundrum




Greetings,


This is not another rant about poor attendance, although those who missed this week's lecture missed a great one, this is a genuine plea for assistance in understanding a natural phenomenon.


The winter solstice occurred Dec. 21 as usual and we had 8 hrs. 55 mins. of sunlight, from 7:49 A.M to 4:44 P.M.  The days are supposed to start getting longer with the sun rising earlier and setting later. Pretty basic so far, however...


On Dec. 31 we had 9 hrs. 1 min. of sunlight, from 7:51 (!) A.M. to 4:52 P.M. Then...


Today, Jan.16, we have 9 hrs. 21 mins. of sunlight, from 7:49 A.M. to 5:08 P.M.


Although we have gained 26 mins. of sunlight since the solstice, 26 days ago, the sun still hasn't risen sooner!


Explanations will be gratefully received at our next meeting on Feb. 4th.


Ed Morrison






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