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More an astronomy question, but Physics is the closest stack exchange category I could find and Google doesn't have the answer.

Granted, the sun's elevation changes for a given time of day throughout the year, easily explained by the earth's axial tilt.

Does it's bearing vary, by how much, and by what mechanism(s)?

Unless my admittedly crude observations are flawed, I believe that the sun's bearing for a given time of day has increased since earlier in the year (my crude observations being its angle to my street at the consistent times that I leave to and return from work).

Have raised the question with my cousin who is a navigator in the Royal Navy, after a couple of pints and a pitcher of Pimms, and we're now very much eager to hear an intelligent answer!

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Astronomy is on topic here (except maybe equipment recommendations and such). As for the question itself, just one clarification question: By "bearing" do you mean "direction" (i.e. degrees clockwise from North) aka "azimuth" in astronomical parlance? –  Chris White Aug 29 '13 at 17:26
    
Yes that is what I am referring to. –  Toby Wilson Aug 29 '13 at 17:42
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up vote 2 down vote accepted

Yes

What : The Sun's bearing oscillates around a mean point throughout the year. Along with the change in elevation, a time-lapse throughout the year gives a shape of 8 in the sky known as Analemma.

analemma at 14:00 UTC

Why : You already know the reason for the change in elevation. So let me come to the point. Why should the azimuth change? This is due to the fact that Earth's orbit around the Sun is elliptical, and speed of Earth in its orbit changes throughout the year. So, the Sun might not come back at the same position after 24 hrs, because it was either slow or fast. The difference is known as Equation of Time(EoT). It is important because we need to correct for it when predicting the time of astronomical events and etc.

EoT

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Good answer, thanks! –  Toby Wilson Sep 5 '13 at 8:23
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