NavList:
A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding
Re: Where on earth are lunar distances the same?
From: Ken Muldrew
Date: 2005 Mar 14, 09:41 -0700
From: Ken Muldrew
Date: 2005 Mar 14, 09:41 -0700
On 14 Mar 2005 at 7:09, Jim Thompson wrote: > 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? The true distance will be the same for everyone who can see the moon and the other body (of course) but the apparent distance will change from point to point due to changes in refraction and parallax. Usually these will change pretty slowly with changes in geographic position, so for a particular point there will be no measureable change in apparent distance over some area. The size and shape of that area will depend upon the location of the moon and the other body. Ken Muldrew.
