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    Re: Delta-T: was [NAV-L] Tycho Brahe Mars oppositions
    From: Alexandre Eremenko
    Date: 2004 Dec 2, 13:54 -0500

    Dear George,
    I think this statement needs some comments/corrections.
    
    On Thu, 2 Dec 2004, George Huxtable wrote:
    
    > Not everything in astronomy is deterministic. Even in a system, such as the
    > solar system, in which more than two bodies have a mutual gravitational
    > interaction, there's a limit to the long-term predictability of it all.
    > This is the famous "three-body problem".
    
    This is not a problem for modern astronomy.
    If we are talking of "predictions" (forward or backward)
    for the period of few thousand years, this will cause no problems
    (in principle). As I understand you were talking of Tycho Brahe
    observations.
    
    The algorithm of such calculations is contained in the book
    of Meeus "Astronomical Algorithms". I doubt that these calculations
    can be easily done by hand, but they can be done with a computer
    and I suppose that Frank Reed's program can do this.
    
    The "long term" prediction is indeed impossible, (because the
    many-body problem of celestial mechanics has no simple solution)
    but "long term" in this sentence refers to billions years.
    For all "practical purposes" such prediction can be done.
    
    Alex.
    
    
    

       
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