By Dominic Ford
Journal of the British Astronomical Association, Volume 122, No.1 (2012)
Abstract: 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 ◦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.
Introduction: For nearly two thousand years, from the time of Hipparchus (c. 190–120 BCE) until the turn of the seventeenth century, the astrolabe was the most sophisticated astronomical instrument in widespread use. Yet today this complex instrument is rarely seen, and those interested in learning about it may even have some difficulty ﬁnding a specimen to play with. Ornately carved brass reproductions are available from several telescope dealers, but with substantial price tags attached. These price tags are historically authentic: medieval astrolabes were often made from high-cost materials and intricately decorated, becoming expensive items of beauty as well as practical observing instruments. But for the amateur astronomer who is looking for a toy with which to muse over past observing practice, a simpler alternative may be preferable.