6 The Sun Is the Center of the Universe
Copernicus hoped to use “modern” (sixteenth-century) technology to improve on Ptolemy’s measurements and, hopefully, eliminate some of the epi-circles.
For almost 20 years Copernicus painstakingly measured the position of the planets
each night. But his tables of findings still made no sense in Ptolemy’s model.
Over the years, Copernicus began to wonder what the movement of the planets would
look like from another moving planet. When his calculations based on this idea more accurately predicted the planets’ actual movements, he began to wonder what the motion of the
planets would look like if the earth moved. Immediately, the logic of this notion became
apparent.
Each planet appeared at different distances from the earth at different times throughout
a year. Copernicus realized that this meant Earth could not lie at the center of the planets’
circular paths.
From 20 years of observations he knew that only the sun did not vary in apparent size
over the course of a year. This meant that the distance from Earth to the sun had to always
remain the same. If the earth was not at the center, then the sun had to be. He quickly calculated that if he placed the sun at the universe’s center and had the earth orbit around it, he
could completely eliminate all epi-circles and have the known planets travel in simple circles around the sun.
But would anyone believe Copernicus’s new model of the universe? The whole
world—and especially the all-powerful Catholic Church—believed in an Earth-centered
universe.
For fear of retribution from the Church, Copernicus dared not release his findings during his lifetime. They were made public in 1543, and even then they were consistently
scorned and ridiculed by the Church, astronomers, and universities alike. Finally, 60 years
later, first Johannes Kepler and then Galileo Galilei proved that Copernicus was right.
Fun Facts: Approximately one million Earths can fit inside the sun. But
that is slowly changing. Some 4.5 pounds of sunlight hit the earth each
second.
More to Explore
Crowe, Michael. Theories of the World from Antiquity to the Copernican Revolution.
New York: Dover, 1994.
Dreyer, J. A History of Astronomy from Thales to Kepler. New York: Dover, 1998
Fradin, Dennis. Nicolaus Copernicus: The Earth Is a Planet. New York: Mondo Publishing, 2004.
Goble, Todd. Nicolaus Copernicus and the Founding of Modern Astornomy. Greensboro, NC: Morgan Reynolds, 2003.
Knight, David C. Copernicus: Titan of Modern Astronomy. New York: Franklin
Watts, 1996
Vollman, William. Uncentering the Earth: Copernicus and the Revolutions of the
Heavenly Spheres. New York: W. W. Norton, 2006.