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Astronomical navigation is a method of terrain association, based on information about the positions of luminaries in the sky at any given time. At night, the latitude of a place is determined by the altitude of the polar star above the horizon, and longitude – by the moments of rising, culmination or setting of the luminaries. During the day, latitude is determined by the height of the Sun above the horizon at the moment of its upper culmination, and longitude is calculated by the time difference between this event and noon at a point with known longitude. For this purpose, chronometers are used that keep the current time of a geographic point.
