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    Re: Pear shaped Earth
    From: Dave Weilacher
    Date: 2002 Oct 2, 05:11 -0700

    My conclusion from this is that a pear shaped earth has a negligible effect on
    the accuracy of sight reduction.  It doesn't matter what distance you are from
    the center of the earth (well there is an over-simplification) as long as the
    horizon is also at the same level.  Since the horizon is likely to be only 4
    to 10 nm away, this pear shape notion becomes moot because you and the horizon
    are at the same height.
    
    On Wed, 2 Oct 2002 16:28:29 +1000 Peter Fogg  wrote:
    
    > David Weilacher wrote:
    >
    > > Can anyone give me a numerical representation
    > of the shape of earth?  I'm
    > > thinking something like the length of a line
    > of latitude for each 10 degrees
    > > north and south of the equator.
    >
    > I'm told that Meridional Distances do indicate
    > this:
    >
    > 10 d lat  597.11
    > 20        1194.58
    > 30        1792.72
    > 40        2391.75
    > 50        2991.82
    > 60        3592.91
    > 70        4194.91
    > 80        4797.59
    > 90        5400.63
    >
    > so, if I've understood correctly, a degree at
    > 10d of lat.is 59.71 nm, and a
    > degree at 90d of lat. is 60.007 nm.
    >
    
    
    
    Dave Weilacher
    .US Coast Guard licensed captain
    .    #889968
    .ASA certified sailing and celestial
    .    navigation instructor #990800
    .IBM AS400 RPG contract programmer
    
    
    

       
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