NavList:
A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding
Re: Visibility at rising and setting
From: Philip Ouvry
Date: 2000 Apr 25, 11:00 AM
From: Philip Ouvry
Date: 2000 Apr 25, 11:00 AM
This sort of theoretical aspect of astro-navigation comes up from time to time but is really completely impractible. It depends on how well you can see the horizon in dark conditions. It is a similar problem to taking star sights using the light of the moon to illuminate the horizon. False horizons are a strong possibility. It is rather similar to the problem of navigation whislt adrift in a liferaft with nothing but a watch and a simple compass. By observing when a planet or major star such as Sirius rises and sets each day it is possible to forecast the exact moment and position on the horizon of the rising and setting. By measuring the amount by which the rising or setting is early or late one can work out the distance run over 24 hours or so and hence ones approximate longitude. Latitude is a bit more difficult without some way of measuring angles. HTH Philip Ouvry
