Exploring the Planets

The Renaissance

Copernicus

Nicolaus Copernicus

From a portrait in the Torun Town Museum.

A rigid code of respect for ancient cultures and thought governed the early Renaissance, a period during which resistance to traditional concepts was met with hostility. Therefore, the Polish astronomer, Nicolaus Copernicus, whose ideas changed the course of astronomy forever, did not release his manuscript for publication until he was on his deathbed.

"The apparent....motion of the planets arises not from their motion but from the Earth's. The motion of the Earth alone, therefore, suffices to explain so many apparent inequalities in the heavens."

— Nicolaus Copernicus, Commentariolus, about 1510.

Copernicus Stopped the Sun and Moved the Earth
Copernicus broke with centuries of tradition by showing that the Sun — and not the Earth — was the center of the planetary system. The Greek astronomer Aristarchus had this idea about 1100 years earlier, but because it was rejected by Ptolemy he was largely ignored.

The Copernican System

Copernicus arranged the Earth and the five planets that were known in the correct order. The planets were shown to revolve around the Sun in circular orbits. It was not until 1609 that the German astronomer, Johannes Kepler, described planetary paths correctly as ellipses. Other than this, the planetary system of Copernicus is correct.