Astronomy according to Ptolemy was the popular theory until Copernicus turned it on its head. This lesson explores the theories of Copernicus and Brahe and how the two changed astronomical study.
Sixteenth century Europe saw many changes. A revival of humanist thought led many to broaden their ways of thinking about the world. Humanism is a philosophy that supports reason and respect. Humanists encouraged education as this was the basis of reason. They also believed each person deserved an equal amount of respect and the freedom to choose their beliefs. Humanism was a popular movement. As humanism spread through Europe, many universities held humanist scholars.
The Ancient Greeks and the Stars
Humanists studied the works of the ancient Greek philosophers. One philosopher was known for his observations regarding the universe. This philosopher's name was Ptolemy. Ptolemy believed that the Earth was the center of the universe. He also believed other heavenly bodies like the moon, the planets, and the sun moved in perfect circles around the Earth. Because he believed the heavenly bodies moved in perfect circles, he accounted for any discrepancies in their movement with epicycles. An epicycle was a smaller circle where planets moved as they moved around the larger circle. The larger circle was called a deferent.
At odds with the Bible, Copernicus believed that the Earth spun on an axis and moved around the sun
Nicolaus Copernicus was a mathematician and a clergyman from Poland. When he went to college to study canon law, he lived with an astronomer. He would have also come into contact with humanist scholars as he studied. At this time, he was introduced to both astronomy and the study of ancient Greeks.
Copernicus agreed with Ptolemy's idea of epicycles but disagreed with some of Ptolemy's theory. He proposed that the sun was the center of the universe and that the planets revolved around it. This theory is called the heliocentric system. He also said that the Earth not only moved around the sun, but it also spun on an axis.
Copernicus's theory appeared to some to conflict with the writings of the Christian Bible. They claimed that the scripture states that the Earth cannot be moved. Copernicus published his theory in a book called De Revolutionibus.
At this time, Europe was experiencing the Protestant Reformation. Protestants believed each person should hold authority to make decisions about religion based on the Bible. Catholics believed authority belonged to the clergy. However, both groups felt Copernicus' ideas went against scripture. Many copies of his book went unsold.
Brahe believed the sun and moon revolved around Earth, but other planets revolved around the sun
Tycho Brahe was a rich Danish man from a noble family. When he went to a university to study law, he also developed an interest in astronomy. Brahe was the last major astronomer to work without the use of a telescope. However, he worked hard to make sure he had the highest quality instruments. He basically enlarged and improved instruments that were already being used to help increase his accuracy.
Brahe wanted to find a way to merge Ptolemy's theories with those of Copernicus. He proposed that the Sun and the moon revolve around the Earth, allowing the Earth to remain the center of the universe. However, he also said that the other planets revolved around the sun.
When Copernicus and Brahe attended universities to study, they were introduced to the study of the ancient Greek philosophers. Astronomy had been understood until this point in the 16th century according to Ptolemy's theory that the Earth was the center of the universe. Copernicus suggested a new idea - that the sun was central to the orbiting planets. The idea was met with contempt from both Catholics and Protestants who believed his theory went against scripture. Brahe attempted to bridge the two theories, saying the planets orbited the sun which, together with the moon, orbited Earth. These theories were some of the earliest to challenge ancient ideals and inspire the modern study of astronomy.
After completing this lesson, you should be prepared to:
- Define humanism, epicycle, and the heliocentric system
- Compare and contrast the astronomical theories of Ptolemy, Copernicus, and Brahe