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Hewitt Schlereth wrote-

"I'm not sure I understand your table. It seems to say that for a given
declination the sunrise bearings would be different for folks in
different hemispheres. On any given day doesn't the sun rise in the
same direction, no matter whether you're looking at it from the
Southern hemisphere or the Northern?"

and on 3 June, I cast some doubt on that, writing-

"To me, that notion of Hewitt's seemed wrong, and five minutes spent with a
blow-up Earth globe and a piece of string convinced me further that it was.
But perhaps I'm just misunderstanding what he is saying, and ask him to
spell it out a bit further, if he wishes to defend it."

Some rejoinders have caused me to think again, and to repeat my tests with
a blowup Earth globe and a piece of string, with a bit more care. I am now
happy to confirm that Hewitt's statement is correct, and that I was wrong,
and that my tests that indicated otherwise were too crude.

On further thought, it's that very anti-symmetry in the azimuth that allows
such a simple table of amplitudes as its result, as long as the moment of
rise or fall of a body is taken to be when its centre is on the true (not
the apparent) horizontal.

contact George Huxtable, at  george@hux.me.uk
or at +44 1865 820222 (from UK, 01865 820222)
or at 1 Sandy Lane, Southmoor, Abingdon, Oxon OX13 5HX, UK.

   

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