English Planispheric Astrolabe


The astrolabe is an astronomical calculating device used from ancient times into the eighteenth century. Measuring the height of a star using the back of the instrument, and knowing the latitude, one could find the time of night and the position of other stars. The openwork piece on the front, called the rete, is a star map of the northern sky. Pointers on the rete correspond to stars; the outermost circle is the Tropic of Capricorn, and the circle that is off-center represents the zodiac, the apparent annual motion of the sun. This brass astrolabe has a body and throne plate (there are no separate plates), a handle, ring, rete, alidade, pin, wedge, and index arm. It is signed d (/) q pnel in Gothic script – this may be an owner’s mark.

This isnstrument is sometimes referred to as "Parnel's astrolabe."


For a detailed description of this object, see Sharon Gibbs with George Saliba, Planispheric Astrolabes from the National Museum of American History, Washington, D.C.: Smithsonian Institution Press, 1984, pp. 13, 150-151. The object is referred to in the catalog as CCA No. 304.

Robert T. Gunther, Astrolabes of the World, vol II, Oxford: Oxford University Press, 1932, p. 483.

John Davis, "Two Medieval English Astrolabes in the Smithsonian Museum," Bulletin of the Scientific Instrument Society, 2023, #157, pp. 2-17. Davis dates this instrument to second quarter of the fourteenth century.

Date Made: ca 1300-1450ca 1325-1450ca 1450

Location: Currently not on view

See more items in: Medicine and Science: Mathematics


Exhibition Location:

Credit Line: Gift of International Business Machines Corporation

Data Source: National Museum of American History

Id Number: MA.316758Catalog Number: 316758Accession Number: 215454

Object Name: astrolabe

Physical Description: brass (overall material)Measurements: overall: 18.6 cm x 14.5 cm x 1.5 cm; 7 5/16 in x 5 23/32 in x 19/32 in

Guid: http://n2t.net/ark:/65665/ng49ca746b4-f1a7-704b-e053-15f76fa0b4fa

Record Id: nmah_997133

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