From: mff@hypatia.unh.edu   
      
   Greg D. Moore \(Strider\)  wrote:   
   >"I_am_on_Saturn"  wrote:   
   >>   
   >> Is Sun positioned at the center of the elliptical orbits of all the   
   >> planets?   
   >   
   >Keep in mind an ellipse has two "centers" positioned along the semi-major   
   >axis.   
   >   
   >The sun is at ONE of these centers.   
      
        Thanks for putting "centers" in quotes.  What Strider is referring to   
   are the *foci* of the ellipse.  They are removed from the actual *center*   
   by a distance equal to one half of the major axis' length times the   
   eccentricity of the ellipse.  For an ellipse that happens to be a perfect   
   circle, the foci and the center are the same point.   
        (The "eccentricity" is a measure of the "flatness" of the ellipse.   
   For ellipses, the eccentricity is a number between zero and one.  The   
   larger the number, the more "squashed" the ellipse.  An eccentricity of   
   zero gives a circle.)   
   --   
                                -- With Best Regards,   
                                   Matthew Funke (mff@hopper.unh.edu)   
      
   --- SoupGate-Win32 v1.05   
    * Origin: you cannot sedate... all the things you hate (1:229/2)