Theoretical reconstruction of an ancient astrolabe
The Roman re-enactment scene serves as a framework where people from different educational backgrounds and interests can meet. People who look at the same text or object, but from a different perspective. And this can produce fascinating results.
In the astrolabe, technology and aesthetics blend into each other. I was fascinated by this technical art object because of its elegant symmetrical lines, long time before I understood how this instrument was created and how it functioned. To create this Greek invention, mathematical operations are performed and a good understanding of the celestial bodies and their relative movements is required.
This research is a collaboration between an architect from Kiev, an engineer from Rome and myself. We wondered: how would an ancient Greek astrolabe have looked like? Which archaeological sources are available? This was the start of our research, which lasted several years. Just a few more months of sleep, and our research document will become available. Be sure to let me know if you want to read/review this document.
Because the reproduction is already finished, you can find the visual results in the below.
The main parts of an astrolabe are:
Rete (top, left): the pointed triangles on this metal skeleton reflect the star positions. By turning the rete, the movement of the stars is simulated.
Three tympans (bottom): on both sides of a tympan the stereographic projection of a certain latitude is engraved.
Mater (top, middle): this is where the three tympans and the rete fit into.
Alidade (top, right): allows you to measure the angle of the sun (during the day) or a star (at night).
This is the operational reproduction of the astrolabe.
This mechanical computer from antiquity allows you to solve an equation with four variables:
- the latitude
- the position of a star (the sun is also a star)
- the calendar day in the solar year (translated towards the zodiac)
- the hour
Once you know the values of three of these variables and set them on the astrolabe, you can read the value of the fourth variable.
The design decisions of our theoretical reconstruction are based on various sources:
- Islamic astrolabe (8th century AD)
- Byzantine astrolabe (11th century AD)
- portable sundials
- ancient and Arabic manuscripts
- Antikythera mechanism
- ...
The astrolabe is an astronomical and mathematical puzzle.
Plans and diagrams on parchment help to visualize the construction and operation of the astrolabe.
The astrolabe in use. The alidade can be used to measure the angle of a star.
This angle can then be set by aligning the pointer of that star on the rete with the measured latitude line.
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