The level of Hellenistic achievement in astronomy and engineering is impressively shown by the Antikythera mechanism (150–100 BC). It is a 37-gear mechanical computer which computed the motions of the Sun and Moon, including lunar and solar eclipses predicted on the basis of astronomical periods believed to have been learned from the Babylonians. Devices of this sort are not found again until the 10th century, when a simpler eight-geared luni-solar calculator incorporated into an astrolabe was described by the Persian scholar, Al-Biruni.[not in citation given] Similarly complex devices were also developed by other Muslim engineers and astronomers during the Middle Ages.[not in citation given]