Cadet Competition Written Practice Exam

Who developed the geocentric theory?

1. Ptolemy

2. Copernicus

3. Galileo

4. Kepler

The correct answer is: Ptolemy

The geocentric theory, which posits that Earth is at the center of the universe and that all celestial bodies, including the sun and stars, revolve around it, was primarily developed by the ancient Greek philosopher Claudius Ptolemy in the 2nd century AD. His model provided a comprehensive explanation of the positions and movements of celestial bodies and was widely accepted for many centuries until the heliocentric model proposed by Copernicus gained prominence. Ptolemy's work, particularly the "Almagest," laid the foundation for astronomical thought in Western civilization. It combined observational data with mathematical models to predict planetary positions and was influential in the fields of astronomy and navigation. Each of the other figures mentioned played significant roles in the history of astronomy but did not develop the geocentric theory. Copernicus introduced the heliocentric model, suggesting that the sun was the center of the universe. Galileo made critical observations that supported this heliocentric model, while Kepler formulated laws of planetary motion that further substantiated the ideas of Copernicus.