HELIOCENTRIC VS. GEOCENTRIC

Heliocentric vs. Geocentric

Heliocentric vs. Geocentric

Introduction

During the second century, Greek-Egyptian astronomer and mathematician Ptolemy (100-170) summarized eight centuries of Greek geocentric (earth-centered) thought about the nature of the cosmos. Despite the heliocentric (sun-centered) theories of Aristarchus of Samos (320-250 B.C.) and a few others, Ptolemaic geocentrism dominated Western astronomy until Nicolaus Copernicus (1473-1543) proposed his heliocentric theory in the sixteenth century.

Geocentric Theory

In the 16th century, a Polish mathematician Nicolaus Copernicus presented the first challenge to the geocentric theory. He claimed that the sun stood at the center of the universe and that the earth moved around the sun. He worked for twenty-five years to develop what he called the heliocentric model, or sun-centered. In 1543, the year of his death, his book, On the Revolution of the Heavenly Spheres, was published. Many scientists, and both Protestant and Catholic churchmen denounced Copernicus's theory, charging that it was illogical, un biblical, and un-Christian (Goldstein, 1985).

In 1632, Galileo Galilei published his book. He wrote the work in Italian in order to reach a wide audience. Galileo was quick to defend his work; he showed how the rotation of the earth on its axis produced the rotation of the heavens. He was able to say this because he used the telescope to document his findings. The Roman Catholic Church supported the geocentric theory, and would have tolerated the heliocentric model as a hypothesis, not as proven fact. Galileo proved his theories and the Church quickly summoned him before the Inquisition in Rome. He was charged with teaching a doctrine contrary to Holy Scripture, and he was forcefully compelled to recant. His book was placed on the Index of Forbidden Works and remained there until 1822 (Gingerich, 1993).

Heliocentric Model

The heliocentric model is the theory which states that the Sun is the centre of the universe and the planets which orbit around it. The heliocentric model replaced geocentricism. Geocentrism is the belief that the Earth is the centre of the universe. The word 'helios' is Greek and means 'Sun'. With heliocentric meaning that the Sun is at the centre, a heliocentric system is one which the planets revolve around a fixed Sun. Therefore, Mercury, Venus, Earth, Mars, Jupiter and Saturn all revolve around the Sun. In this system, the Moon is the only celestial sphere which revolves round the Earth and together with the Earth, revolves around the Sun.

The geocentric model (otherwise known as the Ptolemaic system) was the dominant theory in Ancient Greece, throughout Europe and many other parts of the world for centuries. This theory was developed by philosophers and was named after Claudius Ptolemy who lived circa 90 to 168 A.D. It was developed to explain how planets, the Sun and stars, orbit around the Earth. But this theory is said to have existed long before Ptolemy voiced his opinion. Greek manuscripts, as early as the fifteenth century, show that Plato and Aristotle were writing about the geocentric model back then (Evans, 1998).

It was not until the 16th century that the ...