This angular observation combined with knowing its simultaneous precise time referred to the time at the prime meridian directly renders a latitude and longitude fix at the time and place of the observation by simple mathematical reduction.
Celestial navigation can also take advantage of measurements between celestial bodies without reference to the earth horizon, such as when the moon and other selected bodies are utilized in the practice called "Lunars" or lunar distance method, used for determining precise time when time is unknown.Ĭelestial navigation using the Sun and the horizon whilst on the surface of the earth is commonly used, providing various methods of determining position, one of which is the popular and simple method called "noon sight navigation"-being a single observation of the exact altitude of the sun and the exact time of that altitude (known as "local noon")-the highest point of the sun above the horizon from the position of the observer in any single day. the Sun, the Moon, a planet, or a star) and the visible horizon.
A diagram of a typical nautical sextant, a tool used in celestial navigation to measure the angle between two objects viewed by means of its optical sight.Ĭelestial navigation, also known as astronavigation, is the ancient and continuing modern practice of position fixing using stars and other celestial bodies that enables a navigator to accurately determine his or her actual current physical position in space (or on the surface of the earth) without having to rely solely on estimated positional calculations, commonly known as " dead reckoning", made in the absence of GPS or other similar modern electronic or digital means.Ĭelestial navigation uses "sights", or timed angular measurements, taken typically between a celestial body (e.g.
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