| Descripción |
Es una Esfera armilar geocéntrica o astrolabio esférico que representa la tierra rodeada de "armillas" (procedente del latín "armilla" que significa círculo) representando los principales círculos de la esfera celeste basado en el sistema geocéntrico de Ptolomeo. Se pueden distinguir el ecuador celeste, la eclíptica, el horizonte y el zodiaco entre otras, todas con sus correspondientes escalas, para poder identificar las coordenadas celestes de las estrellas.
Impreso en Elzeviriana y editado por la Librería Cami, S.A.- Barcelona.
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| Bibliografía |
HUGGINS, Margaret Lindsay. Chisholm, Hugh. Armilla. Encyclopædia Britannica. 1911. ARMILLA, Armil or Armillary Sphere (from the Lat. armilla, a bracelet), an instrument used in astronomy. In its simplest form, consisting of a ring fixed in the plane of the equator, the armilla is one of the most ancient of astronomical instruments. Slightly developed, it was crossed by another ring fixed in the plane of the meridian. The first was an equinoctial, the second a solstitial armilla. Shadows were used as indices of the sun´s position, in combination with angular divisions. When several rings or circles were combined representing the great circles of the heavens, the instrument became an armillary sphere. Armillae are said to have been in early use in China. Eratosthenes (276-196 B.C.) used most probably a solstitial armilla for measuring the obliquity of the ecliptic. Hipparchus (160-125 B.C.) probably used an armillary sphere of four rings. Ptolemy ( c. A.D. 107-161) describes his instrument in the Syntaxis (book v. chap, i.), and it is of great interest as an example of the armillary sphere passing into the spherical astrolabe. It consisted of a graduated circle inside which another could slide, carrying two small tubes diametrically opposite, the instrument being kept vertical by a plumb-line.
No material advance was made on Ptolemy´s instrument until Tycho Brahe, whose elaborate armillary spheres passing into astrolabes are figured in his Astronomiae Instauratae Mechanica. 576 The armillary sphere survives as useful for teaching, and may be described as a skeleton celestial globe, the series of rings representing the great circles of the heavens, and revolving on an axis within a horizon. With the earth as centre such a sphere is known as Ptolemaic; with the sun as centre, as Copernican.. Disponible en: <http://www.gutenberg.org/files/34116/34116-h/34116-h.htm#ar140> Consulta: 04/05/2012.
Lorente Algora, María. La lección de las cosas. El patrimonio histórico educativo en Aragón. Aragón educa. Museo Pedagógico de Aragón, 09/2010, pp. 67-77.
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