“The Father of Modern Astronomy”


April 28, 2004

Physics Period 5

From the first time children are introduced to astronomy in second grade, they are told that the sun is the center of the solar system. This was not always the case. For centuries, civilization believed the whole universe revolved around the earth. This was easy to believe since all the astral bodies seemed to make an arch across the sky, and, in relativity to the people on the ground, it was the sky that was moving, and not the earth itself. This whole misconception was questioned in 1514 when a man named Nicholas Copernicus distributed a book called Little Commentary and then completely shattered in 1543, in his book De Revolutionibus Orbium Coelestium Libri VI (Six Books Concerning the Revolutions of the Heavenly Orbs).

Nicholas Copernicus was born on February 19, 1473 in Torun, Poland with the name Mikolaj Kopernik. He was born into a wealthy merchant family and was the youngest of four children. After his father\'s death in 1485, his uncle Lucas Watzenrode took his nephew under his care. Watzenrode, the bishop of the chapter of Varmia, sponsored Nicolas\' education and his future career as a church canon.

Between 1491 and 1494 Copernicus studied liberal arts, including astronomy and astrology, at the University of Krakow. The astronomy courses that Copernicus studied were scientific courses in the modern sense. Instead, they were mathematics courses that introduced Aristotle and Ptolemy\'s view of the universe so that students could understand the calendar, calculate the dates of holy days, and also have skills that would enable those who would follow a more practical profession to navigate at sea. Also taught as a major part of astronomy was what today we would call astrology, teaching students to calculate horoscopes of people from the exact time of their birth.

However, he left before completing his degree, resuming his studies in Italy at the University of Bologna, where his uncle had obtained a doctorate in canon law in 1473. During his stay at Bologna, Copernicus lived in the same house as the principal astronomer at the university, Domenico Maria de Novara. Novara had the responsibility of issuing annual astrological prognostications for the city, forecasts that included all social groups but gave special attention to the fate of the Italian princes and their enemies. Copernicus was "assistant and witness" to some of Novara\'s observations, and his involvement with the production of the annual forecasts means that he was intimately familiar with the practice of astrology.

Copernicus\'s astronomical work took place in his spare time, apart from these other obligations. There are only 27 recorded observations are known for Copernicus\'s life, most of them concerning eclipses, alignments, and conjunctions of planets and stars. On 9 March 1497 he observed the Moon eclipse the star Aldebaran. It was during his years of study at the University of Krakow that he noticed the contradictory hypotheses between Aristotle and Ptolemy and began to wonder if either was actually correct in his claim.

Aristotle’s astronomic model held that the planets are carried around the center of the universe, fixed in unchangeable, invisible spheres at fixed distances. According to his model, since all planets have the same center of motion, the universe is made of nested, concentric spheres with no gaps between them. Among other things, it had the distinct disadvantage that it could not account for variations in the apparent brightness of the planets since the distances from the center were always the same.

A second tradition, deriving from Claudius Ptolemy, solved this problem by hypothesizing three mechanisms: uniformly revolving eccentrics, epicycles, and equants. The equant, however, broke with the main assumption of ancient astronomy because it separated the condition of uniform motion from that of constant distance from the center. A planet viewed from the center of its orbit would appear to move sometimes faster, sometimes slower. As seen from the Earth, the planet would also appear to move inconsistently. There was general agreement that the Moon and Sun encircled the motionless Earth and that Mars, Jupiter, and Saturn were situated beyond the Sun in that order. However, Ptolemy placed Venus closest to the Sun and Mercury to the Moon, while others claimed that Mercury and Venus were beyond the Sun.

Copernicus’ observations led him to