NavList:
A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding
Re: Lunars - Even Easier
From: Andr�s Ruiz
Date: 2008 Jul 7, 12:39 +0200
From: Andr�s Ruiz
Date: 2008 Jul 7, 12:39 +0200
Very interesting Frank, This topic and your "Latitude by Lunar Distance" must be properly published. I am wondering, and I think other navlist members too, if You are planning to write any paper or book about it? Andr�s Ruiz Navigational Algorithms http://www.geocities.com/andresruizgonzalez -----Mensaje original----- De: NavList@fer3.com [mailto:NavList@fer3.com] En nombre de frankreed@HistoricalAtlas.net Enviado el: viernes, 04 de julio de 2008 21:54 Para: NavList@fer3.com Asunto: [NavList 5686] Re: Lunars - Even Easier I wrote previously: "But sometimes a miracle happens. Even when the objects aren't perfectly aligned, the same almost trivial math applies. The math doesn't care whether the objects are really aligned so long as there is an equivalent case where they are in fact aligned. For example, the two objects could be separated in azimuth by 170 or even 165 degrees instead of 180 degrees, and under the right conditions we can "pretend" that they are separated in azimuth by 180 degrees, and it all works out correctly. How can this be?! Some kind of crazy voodoo? No, just good old rigorous math. It works because the altitude of the Moon doesn't matter much, especially when the observed lunar distance is close to 90 degrees or the Moon's altitude is near the zenith." I thought a picture might help to see the variety of cases where this works properly. In the attached graphic, we see the surprisingly large region of the celestial sphere where "trig-free" clearing of a lunar distance would yield near-perfect results. Note that this diagram applies when the Moon's altitude is 40 degrees. At lower altitudes, the zones are a bit smaller. At higher altitudes, they expand greatly. When the Moon's altitude is 80 degrees, they cover half the sky. -FER www.HistoricalAtlas.com/lunars --~--~---------~--~----~------------~-------~--~----~ Navigation List archive: www.fer3.com/arc To post, email NavList@fer3.com To , email NavList-@fer3.com -~----------~----~----~----~------~----~------~--~---