In the first half of the sixteenth century Nicolaus Copernicus developed the first thorough mathematical model of our solar system as a heliocentric arrangement. However, he was very aware of the resistance he would encounter from Church figures should his theory be published because it was in direct conflict with the traditional geocentric beliefs that are supported by scripture. Additionally, the science behind his theory was revolutionary for the period and Copernicus recognized that he would also be bombarded with criticisms from a variety of scholarly perspectives including philosophical inquiries. Despite his attempts to downplay the theory it would quickly spread by word throughout academic and related channels throughout Europe. Eventually Copernicus would consent to the publishing of his heliocentric model in his famous book De revolutionibus orbium coelestium. Copernicus would never have to face his fears of questioning as he died before it was released.
Galileo Galilei became a champion of the Copernican heliocentric model in the early seventeenth century, coming to the defense of the theory as it had become subject to much opposition as the original author had predicted. Galileo found support for the theory through observations using a telescope (Chaisson & McMillan, 2011), one of the most advanced scientific instruments of the time and a luxury not had by his predecessor. The first discovery made by Galileo that favors the heliocentric model over geocentric was made shortly after the dawn of the seventeenth century. He observed that a star later identified as Kepler’s supernova moved in a manner that was incompatible with the theory of an immutable universe as held by the Aristotelian geocentric perspective. A few years later Galileo identified objects moving in line around Jupiter. He saw them disappear and reappear from behind the gas giant and laid the ground for the planet/moon model, a major astronomical discovery that was extremely supportive of the Copernican heliocentric system in comparison to geocentric theories by demonstrating that these objects were orbiting something other than the Earth.
Further viewings of planets by Galileo gave even more evidence of deficiencies in non-heliocentric theories, though the astronomer may not have recognized much of it at the time. Saturn’s rings became a confusing mystery as they appeared to be orbiting moons from certain angles with some disappearing at apparently random intervals. Despite a lack of clarity about the nature of the objects, Saturn’s rings would come to represent another example of non-geocentric orbiting. Venus may have been the most significant of his planetary observations as it relates to support for the Copernican geocentric perspective. The existence of Venus’ perceived phases was in direct conflict with predictions from all forms of geocentric theories as well as other planetary models that were up for debate at the time. Accordingly, several transitional models emerged that combined both heliocentric and geocentric concepts to account for Galileo’s findings, each of which would eventually give way to purely heliocentric designs.
The extent of Galileo’s various contributions to astronomy and physics through telescopic observations cannot be understated. However, one of the most prominent of his findings is that the Copernican heliocentric system is vastly superior to geocentric models in accounting for repeatable and testable observations of heavenly bodies. Even some of his more local investigations uncovered aspects in the moon phases and sunspots that further reduced the feasibility of any theory other than heliocentric being apt, while extremely distant stars and the dense clouds of the Milky Way presented a seemingly unending testing ground for future research that would also support the theory.
Chaisson, E., & McMillan, S. (2011). Astronomy: A beginner’s guide to the universe. (6th ed.). Benjamin-Cummings Pub Co.