Vintage ship's sextant

A sextant is a navigation tool used to measure the angle between two objects, typically the horizon and a celestial object such as the sun, moon, or stars. It consists of an optical system with a small mirror mounted on a graduated arc, which allows the user to align the image of the celestial object with the horizon and measure the angle between them. By measuring the angle between the horizon and a celestial object, navigators can determine their latitude (their position north or south of the equator) and, by comparing measurements taken at different times, can calculate their longitude (their position east or west of a reference meridian, usually Greenwich, England). The sextant was an essential tool for celestial navigation.