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Sextant. Artwork of an historical sextant used to measure the position of heavenly bodies to aid in navigation and astronomy. The sextant's user can see a reflected image of the Sun or a star by looking in the eyepiece (at right). By aligning the sextant so that the image touches the visible horizon, the user can measure the angle between the horizon and the heavenly body. This aids navigation because the exact position in the sky of the Sun & stars depends upon the observer's location. The sextant was invented in about 1730 due to independent work by English mathematician John Hadley and American inventor Thomas Godfrey. Artwork of a sextant from the early 18th century.
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