Ali ibn Isa al-Asturlabi

Full name: 
ʿAlī ibn ʿĪsā al-Asṭurlābī
Arabic name: 
علي بن عيسى

He was an Astronomer. Together with khalid Ben Abdulmelik in 827, he measured the Earth's circumference, getting a result of 40,248 km (or, according to other sources, 41,436 km).