Astrolabe
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An astrolabe is an astronomical instrument dating to ancient times. It serves as a star chart and physical model of the visible half-dome of the sky. Its various functions also make it an elaborate in
North African, 9th century ce, planispheric astrolabe. Khalili Collection.
A modern astrolabe made in 2013, in Tabriz, Iran.
16th-century woodcut of the measurement of a building's height with an astrolabe
A modern reconstruction of the spherical astrolabe of Ptolemy, 2nd C.E., in Kotsanas Museum of Ancient Greek Technology, Athens.
Sextant
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A sextant is a doubly reflecting navigation instrument that measures the angular distance between two visible objects. Its primary use is to measure the angle between an astronomical object and the ho
Astrolabe
…Empire, the Islamic Golden Age, the European Middle Ages and the Age of Discovery for all these purposes. The astrolabe, which is a precursor to the sextant, is effective for determining latitude on land or calm seas. Although it is less reliable on the heaving deck of a ship in rough seas, the mariner's…
A sextant
Sextants can also be used by navigators to measure horizontal angles between objects.