NavList:
A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding
Re: Moon Horizon
From: Frank Reed
Date: 2009 May 12, 13:47 -0700
From: Frank Reed
Date: 2009 May 12, 13:47 -0700
Thomas, you wrote: "In several works on celnav the authors had stated the bright reflection of the moon on oceans surface would obscure the visible horizon at night and create a line below it, called moon horizon (at least by some of them)." Imagine an idealized model of ocean waves as a long row of saucers sitting edge-to-edge extending out to the horizon. Each one has a reflective interior surface so the light from a celestial body can bounce from the right spot in the saucer to the eye of an observer at some height above the waves. Each saucer reflects a spot of light from a slightly different point within it and so altogether we see a "road" of light beneath that celestial body extending out into the distance. But at a certain distance from the observer, not as far as the true horizon, the spot that would reflect light to the observer is hidden behind the lip of the saucer just in front of it. The road would come to an end. This is presumably why the Moon has that false horizon below the true horizon. Incidentally, I agree with Peter and others who have said that you can still see the true horizon if you look carefully. I find that this is especially true when the sky is a bit hazy. Then you see that bright illuminated road of reflected light below the Moon. It ends at that "moon horizon". Then there's a narrow dark band. And then the somewhat brighter sky above it. The true horizon is the top of the narrow dark band. -FER --~--~---------~--~----~------------~-------~--~----~ Navigation List archive: www.fer3.com/arc To post, email NavList@fer3.com To , email NavList-@fer3.com -~----------~----~----~----~------~----~------~--~---