Building a Model Astrolabe

This paper presents a hands-on introduction to the medieval astrolabe, based around a working model which can be constructed from photocopies of the supplied figures. As well as describing how to assemble the model, I also provide a brief explanation of how each of its various parts might be used. The printed version of this paper includes only the parts needed to build a single model prepared for use at latitudes around 52{\deg}N, but an accompanying electronic file archive includes equivalent images which can be used to build models prepared for use at any other latitude. The vector graphics scripts used to generate the models are also available for download, allowing customised astrolabes to be made.

💡 Research Summary

The paper presents a practical, low‑cost approach to teaching the medieval astrolabe by providing a fully printable paper model that can be assembled with common office tools. The author begins by outlining the historical significance of the astrolabe as a multifunctional instrument for astronomy, navigation, and timekeeping, and notes the pedagogical gap in modern curricula where the complex geometry of the device is rarely experienced hands‑on. To fill this gap, a complete set of printable figures is supplied, optimized for a latitude of 52° N, along with an online archive containing equivalent files for any latitude.

The core of the work is divided into four sections. First, the design files (PDF and SVG) include the mother plate, alidade (rotating rule), rete (star map), hour scale, altitude/azimuth grid, and a radian scale. All components are sized for A4 paper and printed at 100 % scale to preserve geometric accuracy. Second, a step‑by‑step assembly guide walks the reader through cutting, folding, and fastening each part. Critical alignment points—such as matching the hour marks on the rete with the mother plate, and ensuring the radian scale lies precisely along the alidade—are illustrated with photographs and tolerance notes that address common sources of error like paper thickness and ink bleed.

Third, the author demonstrates how the finished model can be used for a range of astronomical calculations. By rotating the rete, users can determine local solar time, estimate sunrise and sunset, and locate stars or planets on the altitude‑azimuth grid. The radian scale enables direct measurement of angular separations, facilitating manual solutions to spherical trigonometry problems. The paper emphasizes that these activities give learners tactile feedback while they explore the relationship between the celestial sphere and its planar projection, reinforcing concepts that are otherwise abstract in textbook form.

Fourth, the paper highlights the extensibility of the project. The accompanying digital archive contains pre‑generated templates for latitudes from 0° to 90° in 5° increments, and the author provides an open‑source Inkscape‑compatible Python script that automatically generates a custom set of files for any user‑specified latitude. The script computes the necessary adjustments to the rete’s star positions, the altitude grid curvature, and the radian scale length based on spherical geometry formulas. All source code is released under an MIT license, encouraging educators, makers, and hobbyists to adapt, improve, or integrate the model into broader curricula.

In conclusion, the paper argues that the paper astrolabe serves as an effective “hands‑on” learning tool that bridges historical scientific instrumentation with contemporary STEM education. By combining low‑tech construction with open‑source digital resources, the project offers a scalable solution for classrooms, makerspaces, and informal learning environments. The author suggests future work could involve more durable materials such as thin plastic or wood, as well as augmented‑reality overlays that provide interactive guidance and real‑time feedback during use.