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    Re: "A Star To Steer Her BY"????
    From: FS
    Date: 2005 Jan 31, 21:00 -0800

    --- Joe Shields  wrote:
    > Chapter 2 has several diagrams
    > that are most
    > upsetting.  They show a FLAT earth with a celestial
    > object so close to the
    > earth surface as to suggest the difference in
    > measured angle with the
    > horizon (Ho) is due to the fact that the object's
    > rays are approaching at a
    > different angle instead of the object's parallel
    > rays hitting different
    > spots on the earth at different angles due to curved
    I don't have a newer version, but I do have this book
    and I would defend that diagram, a variation of the
    "very tall flagpole" analogy, as being quite useful
    for gently easing beginners into the concept of
    circles of equal altitude.  I am currently teaching a
    beginner-level celnav class and that is in fact the
    first diagram I draw to start explaining the
    underlying principle.  Then I explain how the diagram
    is flawed and present the "parallel light
    rays/corresponding angles" diagram as being much
    closer to the truth, but even it is still flawed by
    ignoring parallax, (which is in play for all Solar
    System bodies, not just the moon)
    I also have a large library and similar diagrams are
    in many similar books, including Hobbs, Wright,
    Cunliffe, Toghill, Turner, and (I think) the newer
    Schlereth.  Others do indeed avoid this diagram.
    Diagrams help authors to get points across, like the
    huge exaggerations in the typical diagrams
    illustrating elliptical orbits, dip of the horizon,
    and refraction.  It isn't necessary to be upset by too
    literal an interpretation.
    Hey Celestaire, I vote please don't phase out this
    book!  It is a fine beginner's text!  If there's one
    to get rid of, it's the new one by Meyrier!  Pretty
    color diagrams, but I found it useless.
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