Celestial Navigation is the art and science of finding your way by the sun, moon, stars, and planets, and, in one form or another, is one of the oldest practices in human history. Steering by the stars, finding routes and locations by them, and orienting oneself from the positions of celestial bodies is the ancient art of Wayfinding,or non-instrument navigation. People have been wayfinding since the beginning of history because the stars are (relatively) fixed markers. This page will concentrate on the theory behind modern celestial navigation, what is called “modern,” “mathematical,” or “instrument” celestial navigation.
This is fairly easy to do on land or on the coast, where we can find our position from known landmarks on charts and maps. On the open ocean, it’s a different story, as there are no landmarks. We can’t take a bearing from an object as distant as the sun or a planet, because the compass is too clumsy an instrument. It measures in degrees, while a sextant measures in degrees, minutes, and seconds (there are 3600 seconds in a degree). [The sextant does not give us a bearing, or azimuth, to a celestial body, but gives us information that helps us find the azimuth].