Geocentric and Heliocentric Models

Plato and Aristotle both believed in geocentric model - earth is the center of the universe. Ptolemy was the first one to give a detailed account of this model where the earth did not move, and half the stars were above the horizon and half were below, and all the stars (sun, moon, Mercury, Venus, etc.) move around the earth, and were equidistant from it. In 1953, Copernican posited that instead of the earth, the sun was at the center of the universe. He was soon joined by Galileo and Kepler. What I found interesting are:

1. The stars that looked equidistant from the earth, as Ptolemy believed, are actually a lot farther than he could have imagined. Because the shapes of the constellations did not change and seemed to be at the fixed position over the course of the year, he concluded that the earth could not have moved. But in reality, the earth moves and the stars are so much farther beyond our comprehension, (hence we are so much smaller in Ptolemy's estimation of the size of the cosmos). No wonder Pascal exclaimed: “When I consider the short duration of my life, swallowed up in the eternity before and after, the little space I fill, and even can see, engulfed in the infinite immensity of space of which I am ignorant, and which knows me not, I am frightened, and am astonished at being here rather than there, why now rather than then?”


2. Having the earth at the center of the universe was not considered a privileged position in ancient times. The earth was considered to be "heavy" and it was the cosmic sump where the "universe's filth and ephemera collect". Having realized that the earth is not at the center of the universe actually elevates us to the position that we are no longer "excluded from the dance of the stars" as Galileo pointed out. So it is with us that sometimes we may have thought that being at the center of the universe is a privileged position, but it also carries its weight and filth that we may not realize!