Sextant
Definition
A sextant is a navigational instrument used to measure the angle between any two visible objects. Its primary use is to determine the angle between a celestial object and the horizon which, along with the time of measurement, can be used to calculate a position line on a nautical or aeronautical chart.
Analogy
Think of using a sextant like playing an augmented reality game on your phone. Just as you might aim your phone at an object in real life to interact with it in the game, sailors would aim their sextants at stars or other landmarks to figure out where they were in relation to those points.
Related terms
Celestial Navigation: This is navigation by observation of celestial bodies (like stars, sun, moon etc.). It's like using nature's own landmarks when there are no man-made ones around.
Astrolabe: An astrolabe is another ancient device for solving problems relating to time and the positions of stars and planets. You could think of it as an older cousin of the sextant.
Longitude: Longitude refers to geographic coordinates that specify east-west positioning on Earth. If you're standing on one longitude line and looking at another, you're essentially seeing into either your past or future travel path!
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