astrolabe


astrolabe

/

Astrolabe, 11th century.—Oxford Science Archive/Heritage-Images

Type of early scientific instrument used for reckoning time and for observational purposes. Astrolabes can be traced to the 6th century AD; they came into wide use in Europe and the Islamic world in the early Middle Ages and were adopted by mariners by the mid-15th century. One widely used variety, the planispheric astrolabe, can be regarded as a rudimentary analog computer. It enabled astronomers to calculate the positions of the Sun and prominent stars with respect to both the horizon and the meridian.

This entry comes from Encyclopædia Britannica Concise.
For the full entry on astrolabe, visit Britannica.com.

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