Assignment 2. The Copernican revolution

The Copernican Revolution

First, a little introduction about Nicolaus Copernicus, who is a famous Mathematician and Astronomer in Poland [1]. He is famous for his establishment of the "On the Revolutions of the Celestial Spheres", which includes the concept of a heliocentric solar system.

Before the copernican revolution, the astronomy was dominated by Ptolemy's geocentric cosmology system, which assumes Earth is stationary and the centre of the Universe. And all the stars and planets travel along the circle around the Earth.One reason why the geocentric cosmology is widely spreaded and accepted is becasue the Christianity can find the place of Heaven in the scientific model. Even though Ptolmey add several principles on the original Aristotle's modle, it is still have many problems in explaining the planet positions.

In fifthteen and sixthteen century, the problem exasperated. Tha sailors needed the Eclipse table to keep track of their postition when sailing in the deep sea. However, the calendar table based on the geocenter therom can no longer provide an accurate discribtion of the enquinox [3]. 

After years of research, ironically, Copernicus, as an church official,  published his work before he died - "De Revolutionibus Orbium Coelestium Libri VI" (On the Revolutions of Celecstial Spheres), which mainly include three findings [2]:

  1. The Earth is spining around its axis 
  2. The Earth is not the centre of the univers, and its a planet orbiting the Sun once a year
  3. The Sun is the centre of the planetary system and remain motionless
The retrograde motion of the planets was the proof of Copernican theory. In his theory, the planet outside the Earth is moving slower than the Earth. So when both planets circling around the Sun, the Earth periodically overtakes and passes these planets. And when the Earth pass the slower planets, like the Mars, from the Earth's reference system, Mars slows down and move backwards.

Copernicus' model is not perfect. In his model, it still need epicycles to slove the position problem. Also, he have a strong belief on the uniform cicular motion, which have been proved wrong nowadays (the orbit is ellitical, neither uniform nor circular).

What is interesting is that even though heliocentric model is a radical idea for Copernicus' time, he is not actually the first one to recognize that the earth is not the center of the universe. The acient Greek astronomer Aristarchus of Samos, was acctually believed to be the first person puposed a Sun-centered solar system[4].

From my opinion, the most important statement that Copernicus made is that the Earth is a planet,  like others, obiting around the Sun. This statement is not only an opening of the Astonomy, but also in philosophy. 


[1]https://www.biography.com/people/nicolaus-copernicus-9256984
[2]http://planets.utsc.utoronto.ca/~pawel/ASTB03/
[3]https://io9.gizmodo.com/how-we-came-to-recognize-the-sun-as-the-center-of-our-s-1681558043
[4]https://sixdayscience.com/2013/04/04/christianity-and-the-center-of-the-universe/

评论

  1. Vince2018年2月13日 06:08

    Thanks for this.

    Some comments:
    1- Where are the images from? They have no references in their captions (and no captions, making it impossible to reference them in the main text).
    2- Your answer to "which statement is most important and why?" is insufficient.
    3- Overall, you really could've expanded.
    4- References should be used in increasing order ([1], then [2], then [3], etc.).

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