Also known as astronavigation, is a position fixing(dead reckoning) to enable them to strike land. Celestial navigation uses angular measurements (sights) between common celestial objects or to the horizon. The Sun and the horizon are most often measured. Skilled navigators can use the Moon, planets or one of 57 navigational stars(nautical almanacs) technique that was devised to help sailors cross the featureless oceans without having to rely on whose coordinates are tabulated in
Celestial navigation is the process whereby angles between objects in the sky (celestial objects) and the horizon are used to locate one's position on the globe. At any given instant of time, any celestial object (e.g. the Moon, Jupiter, navigational star Spica) will be located directly over a particular geographic position on the Earth. This geographic position is known as the celestial object’s subpoint, and its location (e.g. its latitude and longitude) can be determined by referring to tables in a nautical or air almanac.
The measured angle between the celestial object and the horizon is directly related to the distance between the subpoint and the observer, and this measurement is used to define a circle on the surface of the Earth called a celestial line of position (LOP). The size and location of this circular line of position can be determined using mathematical or graphical methods (discussed below). The LOP is significant because the celestial object would be observed to be at the same angle above the horizon from any point along its circumference at that instant.
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