Alī ibn Khalaf (Arabic: علي بن خلف الأندلسي) was an Andalusian astronomer[1] who belonged to the scientific circle of Ṣāʿid al- Andalusī.
[2] He devised, with help from al-Zarqali, the universal astrolabe.
[3] Both Khalaf and al-Zarqali's design were included in the Libros del Saber (1227) of Alfonso X of Castile.
[4]