0800 – astrolabe

The astrolabe is an astronomical calculator used to solve problems related to the position of the Sun and the stars in the sky. It enables an accurate estimation of the position of the astrolabe on the surface of the Earth by creating a flat projection map of astronomical objects.

The principles of mathematics and astronomy and projection that are used with an astrolabe were developed over a period of time before the instrument came into common use. Hipparchus worked on projection theory and the trigonometry involved around -150. Ptolemy wrote extensively on the same subjects around 300 years later (+150) and refined the geometry further. While astrolabes existed prior to 800 in various forms, they have been documented to have been in wide use by this date at the latest.

PRECURSOR:
-0575 – Pythagorus
-0325 – Euclid
-0225 – Apollonius
-0190 – Hipparchus
0085 – Ptolemy
0335 – Theon
0370 – Hypatia
0378 – Synesius
0490 – Philoponus

SUBSEQUENT:
1295 – mariner’s astrolabe

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