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Thanks for taking the first stab Ken. I too am not sure that I understand
what Jim but was ashamed to admit it.

Jim, do you have a diagram to illustrate your method?

Ken, I am going to take a stab at yours. Sounds interesting.

Robert

----- Original Message -----
From: "Ken Gebhart" 
To: 
Sent: Wednesday, May 19, 2004 10:25 PM
Subject: Re: Emergency sun declination


> on 5/19/04 4:37 PM, Jim Thompson at jim2@JIMTHOMPSON.NET wrote:
>
> > What about this method for emergency calcuation of declination?
> >
> > 1. Label a compass rose June 22 at 000o, Sept 23 at 090o, Dec 22 at 180o
and
> > March 21 at 270o.
> > 2. The radius on the vertical axis is the declination of the sun. A
> > horizontal line from any date around the circle intersects that vertical
> > radius.
> > 3. Measure the length of the vertical axis from the center to the
> > intersection of the horizontal line, divide that length by the full
radius,
> > and multiply that ratio by 22.5o.
> > 4. Error is +/- 0.5o.
> >
> > Jim Thompson
> > jim2@jimthompson.net
> > www.jimthompson.net
> > Outgoing mail scanned by Norton Antivirus
> > -----------------------------------------
> >
> I am not sure I understand what Jim is saying, but here is what I have
been
> preaching for many years.  I would very much appreciate someone telling me
> if I am wrong, and if so, how much wrong!
> I tell people to take a piece of paper and draw horizontal lines, each
> separated by an equal amount.  Label them +30, +20,+10,0,-10,-20,-30.
Draw
> a circle centered on the 0 line so that the top of the circle is on 23.5,
> and the bottom is on -23.5. Label the cardinal points June 21, Sept 23,
Dec
> 22, and March 21.  Then I tell them to fill in the dates around the circle
> (easier said than done), and read the declination directly.
>
> I am guessing that if the Earth were in a circular orbit around the sun
> instead of elliptical, then my analogue would be OK. Does the ellipticity
of
> the orbit make this wrong?
>
> Ken Gebhart
>
>

   

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