Greek mathematics began during the 6th century B.C.E. However, we do not know much about why people did mathematics during that time. There are no records of mathematicians’ thoughts about their work, their goals, or their methods (Hodgkin, 40). Regardless of the motivation for pursuing mathematical astronomy, we see some impressive mathematical books written by Hippocrates, Plato, Eudoxus, Euclid, Archimedes, Apollonius, Hipparchus, Heron and Ptolemy. I will argue that Ptolemy was the most integral part of the history of Greek astronomy.
Mathematics and astronomy are very closely related. It is the mathematical procedures which help define time and space. However, Greek culture plays a role too. With a Greek mindset one would be restricted to believing that the universe is composed of perfect circles. This idea is rooted in Plato and Aristotle’s work. Plato believed that the celestial bodies were godly because their motion was consistent, whereas the Earth is always changing. Plato believed that the Earth was at the centre of the universe and all the celestial bodies orbited around it on perfect uniform circular paths. He chose a circular path because circles have no corners or edges. They are continuous like the motion of the planets (Cassidy, 9).
Similarly, Aristotle believed that the circle was a symbol of continuity. He applied this idea of continuity to the notion of time, which has no beginning or end. (Aristotle, IV) He also said that the circle is “the perfect, first, most beautiful form.” (Wikipedia, Perfection)
Ptolemy lived from approximately 90 A.D. to 168 A.D (Wikipedia, Ptolemy) and grew up in Alexandria, Egypt. Throughout his life time he studied astronomy and worked a great deal on astrology, geography, physics, and optics as well (Sprague).
When Ptolemy started to study astronomy, he had a strong bias based on the surrounding Greek culture. With this in mind, it is easy to see how the basis for his model had a false premise. All the previous theories had been taken as true for so long. Such as Aristotle’s geocentric model of the universe – the idea that the Earth is the centre of the universe and all other celestial bodies revolve around it. This model held up for 500 years. Thus it is no surprise that Ptolemy assumed that it was accurate and used it as the basis for all of his work. This was one of the Greek values Ptolemy had impressed upon him. Another core Greek value is that of perfect circles naturally occurring in our universe. (Big Site of Amazing Facts, What) The restriction of only using circular motion to calculate planetary motion had a practical aspect as well – perfect circles were easier to work with (Hodgkin, 66). Along with internal Greek values, Ptolemy also had a lot of external tools at his disposal. He had access to Babylonian astronomical observations from as distant as 721 B.C. ( Big Site of Amazing Facts, Why), and he used a lot of information from other early Greek...