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Subject: Re: About Lunars, part 3 (correction)
From: George Huxtable (george@XXX.XXX)
Date: Fri Feb 15 2002 - 18:42:36 EST
In my reply to Chuck Griffiths, sent a few minutes ago, there was an error
which needs correcting.
What I said was-
"Try this out on a globe of the world, in exaggerated form. Forget about
the continent-markings on it, we aren't using it as a model of the World,
just as a sphere to show up the spherical geometry. In fact, we only need
the upper hemisphere.
The equator represents the plane of the observer's horizon, and the
observer is at the centre of the globe.
Mark a spot at say zero longitude, 30 N latitude, and another at 90
longitude, 30N latitude. These spots represent the two stars, in GHA and
altitude. Measure the distance between the spots (the interstellar
distance) with a piece of string, along the shortest path (a great circle).
This length corresponds to the length of the ars between the two stars as
seen by the observer..."
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Where I referred to the spots representing two stars "in GHA and altitude",
I should have said "in azimuth and altitude". The globe, as a model, makes
more sense that way.
Oh, and where I aid ars, it should have been arc, of course!
Sorry about that.
George.
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george@XXX.XXX
George Huxtable, 1 Sandy Lane, Southmoor, Abingdon, Oxon OX13 5HX, UK.
Tel. 01865 820222 or (int.) +44 1865 820222.
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