Sextant, instrument for determining the angle between the horizon and a celestial body such as the sun, the moon, or a star, used in celestial navigation to determine latitude and longitude.
What Does a Sextant Do?
A sextant is an instrument used for measuring the angular distance between two visible objects. The primary use of a sextant is to determine the latitude of a ship or plane.
It can also be used to measure the altitude of objects, such as mountains. The sextant is a relatively simple instrument. It consists of two mirrors, a horizon mirror and a index mirror, mounted on a frame.
The index mirror is fixed, while the horizon mirror is movable. The mirrors are positioned so that they reflect light from the object being observed into the user‘s eye.
To use the sextant, the user first aligns the horizon mirror with the horizon. The index mirror is then adjusted until the object being observed is seen in both the horizon mirror and the index mirror.
The angular distance between the object and the horizon is then read off of the index mirror. The sextant was invented in the early 18th century by John Hadley.
It was an improvement over the existing instruments for measuring angular distance, which were less accurate and more difficult to use.
The sextant quickly became the standard instrument for navigation and was used by sailors and explorers for centuries. Today, the sextant is still used