A life of research
Born around the middle of the ninth century, at an uncertain date, he carried out much of his observing work in Raqqa. He belonged to the scientific tradition conducted in the Arabic language.
His observations extended across several decades, from the late ninth into the early tenth century. Such long records make it possible to compare positions and separate genuine variations from errors of measurement.
Understanding the contribution
He determined the length of the solar year and the inclination of the ecliptic with impressive accuracy for his period. He also investigated the apparent motions of the Sun and Moon and improved tables used to predict them.
His work employed trigonometric methods that made calculations more effective. It remained within geocentric astronomy; its importance does not depend on claiming that he anticipated modern cosmological models.