The Age of Astronomy

Copernicus' heliocentric model places the Sun
in the center of the universe

As time moved into the Renaissance, the thoughts on where Earth was located in the universe began to change. In the 2nd century, it was Ptolemy, who suggested that the Earth was situated in the center of the universe. Ptolemy also thought that the planets traveled around the Earth in circular orbits. This model of the universe was not challenged for more than a thousand years. A new age of astronomical thinking began when Copernicus placed the Sun at the center of the universe. This new development created a wave of astronomical observations from scientists like Brahe, Kepler, Galileo, and Newton, who all added ideas to how the planets orbit the Sun.

As you study the history of astronomy, notice the following two themes: the struggle to understand the placement of Earth in the universe and the struggle to understand planetary motion. As time passed, the use and reliance on technology subsequently increased, and so did the accuracy in predicting how the planets travel around the Sun.

Essential Questions

• What was the Age of Astronomy, and who were some important contributors?
• What is the difference between the heliocentric and geocentric models?
• What are Kepler’s Laws of Planetary Motion?
• What are Newton’s Laws of Motion?