Dr. Owen Gingerich, an astronomer and historian of astronomy at Harvard, said he believed that Copernicus could have developed the ideas independently, but wrote in Scientific American that the whole idea of criticizing Ptolemy and reforming his model was part of ''the climate of opinion inherited by the Latin West from Islam.''

The Decline of the East

Despite their awareness of Ptolemy's flaws, Islamic astronomers were a long ways from throwing out his model: dismissing it would have required a philosophical as well as cosmological revolution. ''In some ways it was beginning to happen,'' said Dr. Ragep of the University of Oklahoma. But the East had no need of heliocentric models of the universe, said Dr. King of Frankfurt. All motion being relative, he said, it was irrelevant for the purposes of Muslim rituals whether the sun went around the Earth or vice versa.

From the 10th to the 13th century Europeans, especially in Spain, were translating Arabic works into Hebrew and Latin ''as fast as they could,'' said Dr. King. The result was a rebirth of learning that ultimately transformed Western civilization.

Why didn't Eastern science go forward as well? ''Nobody has answered that question satisfactorily,'' said Dr. Sabra of Harvard. Pressed, historians offer up a constellation of reasons. Among other things, the Islamic empire began to be whittled away in the 13th century by Crusaders from the West and Mongols from the East.

Christians reconquered Spain and its magnificent libraries in Córdoba and Toledo, full of Arab learning. As a result, Islamic centers of learning began to lose touch with one another and with the West, leading to a gradual erosion in two of the main pillars of science -- communication and financial support.

In the West, science was able to pay for itself in new technology like the steam engine and to attract financing from industry, but in the East it remained dependent on the patronage and curiosity of sultans and caliphs. Further, the Ottomans, who took over the Arabic lands in the 16th century, were builders and conquerors, not thinkers, said Dr. El-Baz of Boston University, and support waned. ''You cannot expect the science to be excellent while the society is not,'' he said.

Others argue, however, that Islamic science seems to decline only when viewed through Western, secular eyes. ''It's possible to live without an industrial revolution if you have enough camels and food,'' Dr. King said.