Old instruments
Astrolabe
Direct answer
Astrolabe: An Astrolabe is a historical astronomical instrument that combines a star map, coordinate projection, sighting scale, and rotating parts to solve problems involving altitude, direction, and time.
An Astrolabe is a portable analog model and calculator for the sky.
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At a glance
- Found in
- Historical Almanacs & Instruments
- Related
- Almanac, Astronomical Almanac, Nautical Almanac, Armillary Sphere
An Astrolabe is a portable analog model and calculator for the sky.
An engraved functional orientation; the page explains the real instrument, method, or publication.
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The story behind Astrolabe
Planispheric astrolabes were developed and refined across Hellenistic, Islamic, European, and other scholarly and craft traditions over many centuries.
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The Book of the Sky
How people learned to read the sky, from Babylon to the day you were born.
Why Astrolabe matters
Astrolabe compresses celestial geometry into a hand-held instrument and illustrates how observation and mathematical design worked together before electronic computation.
Where readings of Astrolabe go wrong
It is a mistake to see every astrolabe as a marine navigation instrument or imply that one surviving object represents all regional forms and uses.
Sources and editorial method
Research references used for this entry include:
- Smithsonian National Museum of American History: English Planispheric Astrolabe - Museum explanation of the astrolabe as an astronomical calculating and observing instrument.
- Royal Museums Greenwich: Astronomical and Navigational Instruments - Museum reference collection for astrolabes, armillary spheres, quadrants, nocturnals, sundials, and navigation instruments.
- Source
- The Great Almanac Dictionary
- Category
- Historical Almanacs & Instruments
- Last updated
- 2026-09-26
Explore how an astrolabe works
A definition tells you what it is; your own birth chart tells you what it means for you. The Oracle casts your real chart and answers for your love, your work, and your year ahead, in conversation. It opens with the 7-day Seeker trial.
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More in Historical Almanacs & Instruments
- Celestial Navigation
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- Nocturnal Instrument
- Plumb Line
- Sight Reduction
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Common questions
What is an Astrolabe?
An Astrolabe is a historical astronomical instrument that combines a star map, coordinate projection, sighting scale, and rotating parts to solve problems involving altitude, direction, and time.
What do people get wrong about an Astrolabe?
It is a mistake to see every astrolabe as a marine navigation instrument or imply that one surviving object represents all regional forms and uses.
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