A sextant is an optical instrument used to measure the angle between two observed objects. Primarily employed in celestial navigation, it determines the angular altitude of celestial bodies—such as the Sun, Moon, or visible planets—relative to the observer’s horizon. The device operates by allowing the measurement of angular separation using a combination of mirrors and an adjustable arc. By comparing the observed angular separation with established astronomical tables, maritime users can calculate their approximate latitude and longitude, providing essential data for determining position when terrestrial landmarks are unavailable.