Astronomic Astrolabe

Astrolabes are astronomical instruments with a range of functions. They allow you to find stars based on the coordinates of your location; measure the altitude of the sun and the stars; determine the time based on the altitude of the sun or another star (making these tools clocks which can be used by day or night); work out the date and time that the seasons start; and can be used as a calculator, with a series of overlaid abacuses.

Astrolabes have a base with a plate on top containing coordinate lines, a "rete" (rotating disc) showing the stars and position indicators, a rule, and an "alidade" (turning board). The upper part contains the face and a ring for hanging up the instrument. The plates can be swapped in and out as each corresponds to different latitudes.

This astrolabe was made by Michiel Coignet, a scholar and scientist working for Archduke Albert and Archduchess Isabella Clara Eugenia, who ruled the Southern Netherlands. His studies brought improvements to a variety of disciplines such as cosmography, cartography, and navigation, as can be seen in his work "Nieuwe Onderwijsinghe op de principaelste Puncten der Zeevaert" (New Instructions on the Principal Points of Navigation), published in 1580 as an appendix to Pedro de Medina's book The Art of Navigation.