Celestial navigation Celestial navigation 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.
Dynamics of the celestial spheres bodies are moved by angelic spirits, which govern and move them. He maintained, instead, that "celestial bodies are moved by their own natural inclinations similar to weight". Just as heavy bodies are naturally moved by their own weight, which is an intrinsic active principle, so the celestial bodies are naturally moved by a similar intrinsic principle. Since the heavens are spherical, the only motion that could be natural to them is rotation. Kilwardby's idea had been earlier held by another Oxford scholar, John Blund (c. 1175–1248). In two slightly different discussions, John Buridan (c.1295–1358) suggested that when God created the