Planispheric Astrolabe from Muslim Spain
date: label: date made
content: 1691
notes: label: Description
content: The astrolabe is an astronomical calculating device used from ancient times into the nineteenth century. Measuring the height of a star using the alidade on 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. Engraved plates that fit below the rete have scales of altitude and azimuth (arc of the horizon) for specific latitudes. This brass metal astrolabe has backplate with throne, handle, ring, the end of a cord, an alidade with pin, a rete, five plates, a ringlet, and a wedge at the front that holds the instrument together. The instrument is signed: [. . .]ana ‘ahu al-[. . .]asan ben A[. . .]mad al-Ba[. . .] [. . .]u[. . .]i.
label: Description
content: Reference:
label: Description
content: For a detailed description of this object, see Sharon Gibbs with George Saliba, <a href="https://repository.si.edu/handle/10088/2444"><I>Planispheric Astrolabes from the National Museum of American History</I></a>, Washington, D.C.: Smithsonian Institution Press, 1984, pp. 17, 160, 163-165. The object is referred to in the catalog as CCA No. 2568.
label: Location
content: Currently not on view
setName: label: See more items in
content: Medicine and Science: Mathematics
creditLine: label: Credit Line
content: Gift of International Business Machines Corporation
dataSource: label: Data Source
content: National Museum of American History
identifier: label: ID Number
content: MA.316751
label: catalog number
content: 316751
label: accession number
content: 215454
objectType: label: Object Name
content: astrolabe
physicalDescription: label: Physical Description
content: brass (overall material)
label: Measurements
content: overall: 22 cm x 13.3 cm x 3.7 cm; 8 21/32 in x 5 1/4 in x 1 15/32 in