National Maritime Museum
Hegira 729 / AD 1329
Scientific instrument, metalwork
Ahmad ibn Ali al-Sharfi.
Diameter 12.2 cm
Alcalá (near Sevilla), Spain.
The astrolabe is an astronomical instrument consisting of several parts. The main part is the circular body, called the mater, which is composed of a limb (outer edge) fastened to a plate. The limb of the mater bears a 360° scale, numbered clockwise at intervals of five degrees. Every fifteen degrees is punctuated by a dotted line. Above, a handle is attached to the body. The ring that normally passes through the handle is missing. It served to fix a cord since the astrolabe was used suspended. Seven thin plates and the rete, a skeleton-like plate which indicates the stars, are fitted into the mater. A pin, passing through a hole at the centre, holds the several parts together.
The planispheric astrolabe is based on the principle of stereographic projection. The circles on the plates present the spherical surface of the earth at particular geographical latitude. The circles of the rete correspond to the vault of the fixed stars. Because the rete is the movable part, originally turned around by four knobs that are now missing, both the earth and the firmament can be set in combination with each other. The stars are indicated by the star-pointers. The 29 star-pointers of this astrolabe have bulbous bases, which are perforated with holes. The names of the stars are engraved in kufic letters below the pointer. The attraction of Western Arabic astrolabes derives from the curvatures and decorations of these star pointers. Another important part of the rete is the ecliptic, the circle of the zodiac. The Arabic names of the zodiacal signs are engraved in kufic.
On the back of the astrolabe are several circles representing the zodiac or the months of the Julian calendar with their Arabic names and two shadow squares. Above the east–west line are engraved the name of Ahmad ibn Ali al-Sharfi, the craftsman who made the astrolabe, and the date and place of manufacture.
An astrolabe was used for various purposes such as the measuring of the altitude of the sun or the stars to determine the times of sunrise, sunset or prayer.
The year of its manufacture is given on the back.
The astrolabe was bought by a Major Arvid Mörner in Fez, Morocco in 1907. In December 1931 the National Maritime Museum acquired the astrolabe from the property of Count Otto Hamilton.
The place of manufacture, which is incised together with the name of the craftsman on the back of the astrolabe, is given as Alcalá.
Gunther, R. T., The Astrolabes of the World, 2 vols. London (reprint), 1976.
King, D. A., Islamic Astronomical Instruments, London, 1987.
Maddison, F. and Savage-Smith, E., in Science, Tools and Magic, Part 1, Vol. 12 of the Nasser D. Khalili Collection of Islamic Art (ed. J. Raby), London, New York, 1997.
Sjöhistoriska Museet Årsbok, 108, 1988/9.
Stautz, B., Die Astrolabiensammlungen des Deutschen Museums und des Bayrischen Nationalmuseums, Munich 1999.
Friederike Voigt (on the basis of information about the object given by Susanna Allesson Nyberg). "Planispheric astrolabe" in Discover Islamic Art , Museum With No Frontiers, 2017. http://www.museumwnf.org/thematicgallery/thg_galleries/database_item.php?itemId=objects;ISL;se;Mus01_A;33;en&id=scientific_objects
Prepared by: Friederike Voigt (on the basis of information about the object given by Susanna Allesson Nyberg).Friederike Voigt (on the basis of information about the object given by Susanna Allesson Nyberg).
Friederike Voigt has an MA in Iranian studies, history of art and social science and is currently working on her doctoral thesis on wall tiles in architectural decoration of Qajar Iran. Since 2004 she has been a project-related curator at the Museum for Mediterranean and Near Eastern Antiquities in Stockholm for Museum With No Frontiers. She studied at Humboldt University in Berlin, at the University of Tehran and archaeology at the University of Halle-Wittenberg. She taught Persian language at several universities in Germany. She was an assistant curator at the Department of Near and Middle Eastern Cultures at the Museum of Ethnology, State Museums of Berlin. Her main fields of interest are the material culture of Iran, especially of the Qajar period, and contemporary Iranian art.
Copyedited by: Monica Allen
MWNF Working Number: SE 35