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A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding
Re: Night moon sights
From: Peter Fogg
Date: 2004 Feb 3, 08:35 +1100
From: Peter Fogg
Date: 2004 Feb 3, 08:35 +1100
D'ohh! Just when that one seemed sorted out! Have never noticed a false horizon ABOVE the real horizon. But presumably I wouldn't? The first part made sense, we have probably all seen a sinking moon (or sun) with reflections right to the horizon. Tthe body partly hidden below the horizon makes that clear. Or does it? ----- Original Message ----- From: "Trevor J. Kenchington" >.......For any given sea > state and height of eye, there must be some altitude below which rays of > light from the Moon strike the observer's horizon and there reflect to > his eye. > > Presumably, it is when the Moon is below that altitude that the > irradiation effect becomes important and the false horizon rises above > the real horizon. At a guess, small boats and high latitudes tend to > make for reflected light reaching to the true horizon and hence a raised > false horizon while large heights of eye and low latitudes tend to give > the reverse -- though I have never attempted a sextant sight under > either set of conditions, so this is purely theoretical for my part.