In the popular story of astronomy the 1,400 years between the geocentric system of Claudius Ptolemy and the heliocentric model of Nicholas Copernicus was a period of no great consequence. Muslim astronomers translated the Almagest, the Handy Tables, and the Tetrabibios from Greek into Arabic in eighth century Baghdad and, after a few editorial comments and suggestions, saw the Arabic versions translated into Latin in eleventh century Spain and passed on to the fledgling scholars of late medieval Europe. In this account Muslim astronomers and mathematicians functioned primarily as conduits, transmitting a relatively untouched version of the famous Alexandrian, adding little to a model that was questioned, criticised, and finally overturned by the astronomer/mathematicians of Renaissance Europe – Nicholas Copernicus, Tycho Brahe, Johannes Kepler, and finally Isaac Newton.

Although this cartoon version has been challenged by serious scholars of Islamic history and science, a non-technical account of the Muslim contributions to astronomy and astrology has not been available. To fill that void and to highlight the crucial role that Islamic scientists played in the transition from Ptolemy to Copernicus and Newton has been the goal of this essay. Astronomy was in many ways the first science and the effort to untangle the mysteries of the heavens led to a number of important discoveries in mathematics, geometry, trigonometry, and physics. Because of the complex gravitational forces in the solar system – the massive Sun acting on the five smaller but distant planets – the task was incredibly difficult. And it was the effort to decipher the riddles of the heavens that spurred the earliest efforts to understand the world in a systematic, proto-scientific manner – to count, model, and predict.

In the wider context of Eurasian science the Islamic achievement was central, connecting the first century Greeks and their predecessors (the Egyptians and the Babylonians) to the Renaissance world of sixteenth-century Europe. And from this perspective, the breakthroughs in European astronomy, mathematics, and physics would not have been possible without the work of the Muslim astronomers and mathematicians who went before – men like Abu Ja‘far Muhammad al-Khwarizmi, Nasir al-Din Tusi, and Jamshid al-Kashi.

Of the early Muslim astronomer/astrologers the most important were al- Khwarizmi and Abu Ma‘shar.