Sketch map on how the celestial navigation technology works

The celestial navigation technology refers to pinpointing the position and direction of a sailing boat by using the constellation's position, angle, and "height" (to be shortly explained) from a sea-level point of view.

Even as early as in the Qin (221-206BC) and Han (206BC-220) dynasties, Chinese people already knew how to identify a ship's sailing direction by watching the northern star.

Even after the invention of the marine compass in the Song Dynasty (960-1279), the navigators still partly relied on the position and height of certain constellations as a supplementary navigation method.

The Yuan (1271-1368) and Ming (1368-1644) dynasties witnessed huge progress in the celestial navigation technology, and the navigators in their time could pinpoint the geographical latitude by the height of certain constellations.

The tool used in the celestial navigation technology was the celestial navigation board, made from ebony. Altogether there were 12 square-shaped wooden boards, the largest and smallest of which were about 24 and 2 centimeters in length and width respectively.

When observing the northern star with a celestial navigation board, for instance, one would hold one end of the tool extended from his or her arm, and look into the sky. The upper edge of the celestial navigation board represented the northern star (the highest "height"), while the bottom equaled the sea level. Then the distance between the northern star and the place where the observation was carried out could be worked out.

Author: Jessie