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A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding
Where on earth are lunar distances the same?
From: Jim Thompson
Date: 2005 Mar 14, 07:09 -0400
From: Jim Thompson
Date: 2005 Mar 14, 07:09 -0400
I understand clearly how a body's altitude is the same anywhere on a circle on the surface of the earth around the GP of the body at a given instant of time, but I cannot picture the set of places on the surface of the earth from where a navigator would find the same lunar distance for a given Moon-Body pair at a given instant of time. Is it one unique point, or a line of points? If the latter, what does it look like? (This is why I get beaten at chess so routinely.) Using Frank's predictor at http://www.clockwk.com/lunars/lunars_pre_v5.html, I played around by changing latitude or longitude. The lunar distances for each hour of GMT did not seem to change until longitude changed by several degrees (using a start position of 47d 11m N, 63d 07m W). Jim Thompson www.jimthompson.net -------------------- Outgoing email scanned by Norton Antivirus