Vega and Altair, the flying eagles
Two bird-shaped pointers on this early 13th-century Persian astrolabe indicate the positions of the stars Vega and Altair, representing two birds of prey. Vega, just above centre, is shown with wings folded in an apparent dive, while Altair, at top left, is shown soaring with wings extended. The shapes of the icons are derived from the Arabic names for the stars: Vega comes from the Arabic al-nasr al-wāqiʻ, ‘the swooping eagle’, while Altair comes from al-nasr al-ṭāʼir, meaning ‘the flying eagle’. These Arabic names arose from the fact that Vega and its two nearby stars Epsilon and Zeta Lyrae form a V-shape, like a bird with folded wings, whereas Altair and the stars Beta and Gamma Aquilae either side of it form a line, giving the impression of outstretched wings.
A third pointer at left, shaped like the head and neck of a horse, indicates the position of the star Beta Pegasi. Such animal-shaped icons are called zoomorphs.
This astrolabe was made around 1221/2 in Iṣfahān by Muḥammad ibn Abī Bakr and is now in the History of Science Museum, Oxford. For more about this astrolabe on the Museum’s website, see here.
(Image: History of Science Museum, Oxford.)
