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]