<P> Celestial navigation, also known as astronavigation, is the ancient and modern practice of position fixing that enables a navigator to transition through a space without having to rely on estimated calculations, or dead reckoning, to know their position . Celestial navigation uses "sights", or angular measurements taken between a celestial body (e.g. the Sun, the Moon, a planet, or a star) and the visible horizon . The Sun is most commonly used, but navigators can also use the Moon, a planet, Polaris, or one of 57 other navigational stars whose coordinates are tabulated in the nautical almanac and air almanacs . </P> <P> Celestial navigation is the use of angular measurements (sights) between celestial bodies and the visible horizon to locate one's position in the world, on land as well as at sea . At a given time, any celestial body is located directly over one point on the Earth's surface . The latitude and longitude of that point is known as the celestial body's geographic position (GP), the location of which can be determined from tables in the nautical or air almanac for that year . </P>

Explorers who used celestial navigation plotted their courses according to