The Day the Universe Changed - James Burke [61]
Ptolemy’s universe, illustrated in 1559. Artistic licence has added scenery and the figure of Atlas supporting the structure. Strictly speaking there was held to be nothing beyond the outermost sphere but God’s invisible presence.
The Copernican planetary system of 1543, with the sun at its centre. To account for the apparent alterations in speed and movement of the planets, Copernicus was obliged to use as many as ninety Ptolemaic epicycles (right).
The problem of calendar reform involved all these phenomena and the accepted explanations of why they occurred, since the cosmos and everything in it was a manifestation of God’s plan. Belief in Aristotle and Ptolemy was the bedrock of social stability.
In 1514 the secretary to the Pope asked a relatively unknown mathematician, who was also Canon of Frombork, in Poland, to look at the problem of calendar reform. The priest, called Niklas Koppernigk, replied that nothing could be done about the calendar until the matter of the relationship between the sun and moon had been resolved.
Koppernigk had attended the university of Cracow and had then visited Italy, where he had studied at Padua and Bologna. In 1503 he had received his doctorate in canon law at Ferrara. During these years he had absorbed much of the contemporary Renaissance thinking about astronomy, which placed a high value on mathematics and observation. In his spare time in Frombork, to which he returned in 1503, Koppernigk studied astronomy.
His principal aim was to explain the apparent anomalies in the motions of the planets with a simpler version of events than was currently held, closer in concept to the original, circular plan adopted by Aristotle. Koppernigk came to the conclusion that there was a better explanation of the anomalies in planetary motion. On 1 May 1514 Copernicus, the name by which Koppernigk is better known today, circulated a manuscript called The Little Commentary which questioned the entire Aristotelian system and suggested a sun-centred system with a moving earth. The fully developed heliocentric argument was not published until Copernicus died, in 1543. This might be evidence of Copernicus’ awareness of the effect his new theory would have, or it maybe that he simply felt it would be misinterpreted.
In the theory he proposed a system heliocentric in nature, with the earth orbiting the sun and spinning once a day on its axis. He avoided the charge of heresy by quoting sources such as Pythagoras and Aristarchus, both classical writers favoured by the Italian humanists, thus admitting that he himself had not originated the idea. The work, published in 1543, was called On the Revolution of the Celestial Spheres. It stated that the centre of the universe was a spot somewhere near the sun. It also answered the question of stellar parallax—which posed that if the earth were orbiting the sun, the stars ought to seem to change their positions - by stating that their distance was so vast that parallax would be too small to measure. Copernicus avoided the question of why objects thrown into the air from a revolving earth did not fall to ground to the west.
The scheme met the requirements of philosophical and theological belief in circular motion. In every other respect, however, Copernicus struck at the heart of Aristotelian and Christian belief. He removed the earth from the centre of the universe and so from the focus of God’s purpose. In the new scheme man was no longer the creature for whose use and elucidation the cosmos had been created. His system also placed the earth in the heavens, and in doing so removed the barrier separating the incorruptible from the corruptible. But if this made