1947 words - 8 pages

Our Place in the Universe

Our fascination with the Solar System has preceded astronomical antiquity, in a process of conceptualising the cosmos. Fundamental theories of Ptolemy, Copernicus, Brahé, Kepler, Galileo and Newton, have dominated history, stimulating a constant re-evaluation of the nature of the Solar System. In particular, the theories postulated by Copernicus and Kepler had a fundamental influence on the interpretation of the Solar System through challenging the prevailing orthodoxy of Aristotelian physics; thus paving the way for revolutionary challenges to the medieval worldview to prevail. There are a myriad of ideas which have refined the Solar System, however, this article focuses on the two predominant, overarching theories which redefined contemporary society’s understanding of the Solar System: Copernicus’ heliocentric model and Kepler’s elliptical orbit of plants.

History of the Solar System: The evolution

Ptolemy’s model of the Solar System, in the second century, was the first conceptualisation of a standard model of the cosmos. The Ptolemaic model outlined the mathematical representation of the known Solar System, which was inherently rooted in Aristotelian physics[1]. This dictated the key elements of the model, especially the axiom of geocentrism[2][3]. This model is encapsulated in figure 1. Moreover, the convoluted system of epicycles, to account for the apparent retrograde motion, was extremely problematic in forming mathematical representations, due to its complexity[4]. This model prevailed for over a century, however, there were fundamental irreconcilable faults in the model, in particular, geocentrism.

Copernican’s model in 1543 exemplified a paradigm shift from the prevalent geocentric perspective of the Solar System to heliocentrism[5]. Copernican retained the circular orbits and epicycles of Ptolemaic’s system, while incorporating new, empirical observations[6]. Additionally, Copernican deduced that this model significantly simplified Ptolemy’s model through compounding epicycle orbits, establishing the symmetry of the Universe and harmonious linkage of planets, and postulating the Earth’s predominant motions: uniform motion around a displaced circle and a smaller epicycle[7][8][9]. This reconstructed model is exhibited in figure 2. The model explained the daily motion of the cosmos through Earth spinning on its axis, the annual drifting motion of the Sun from Earth’s perspective due to its orbit of the sun, the seasons as a consequence of Earth’s tilt and retrograde motion by Earth passing an outer planet[10]. Therefore, the change in the reverse frame of reference accounted for, and simplified, problems in Ptolemy’s model, however, the assumed circular orbit of plants perpetuated inaccuracies.

Copernican’s explicit contradiction of Aristotelian physics prevented the model from achieving scientific recognition, which allowed Brahé to conceptualise geo-heliocentrism. Brahé merged dominant elements from...

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