Astrolabe facts for kids
The astrolabe is a tool using the positions of the stars or sun. It was formerly used in navigation to help explorers and sailors figure out where they were. They found their distance north and south of the equator by measuring the distance of the sun and stars above the horizon. Astronomers used other kinds of astrolabes, usually larger ones.
An early astrolabe was made in the Hellenistic world in 150 BC. It is often attributed to Hipparchus. The astrolabe was a marriage of the planisphere (a star chart analog computing instrument) and dioptra (a tool to measure angles). It was a calculator able to work out many kinds of problems in astronomy. Theon of Alexandria wrote a complex book on the astrolabe. Lewis says that Ptolemy used an astrolabe to make the astronomical observations recorded in the Tetrabiblos.
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Images for kids
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A modern astrolabe made in Tabriz, Iran in 2013.
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Amerigo Vespucci observing the Southern Cross with an Astrolabium, by Jan Collaert II. Museum Plantin-Moretus, Antwerp, Belgium.
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A spherical astrolabe from medieval Islamic astronomy, c. 1480, most likely Syria or Egypt, in the Museum of the History of Science, Oxford
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An astrolabe from the Mamluk Sultanate dated 1282.
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The Canterbury Astrolabe Quadrant, England, 1388.
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A 16th-century astrolabe showing a tulip rete and rule.
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The Hartmann astrolabe in Yale collection. This instrument shows its rete and rule.
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Celestial Globe, Isfahan (?), Iran 1144. Shown at the Louvre Museum, this globe is the third oldest surviving in the world.
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Computer-generated planispheric astrolabe
