Kepler’s findings provided strong evidence for the heliocentric theory by demonstrating that planets do not move in perfect circles around the sun, but rather in elliptical orbits. This was a significant departure from the previously accepted geocentric model, which held that the Earth was at the center of the universe and that celestial bodies moved in circular paths.
Kepler formulated three fundamental laws of planetary motion:
- Kepler’s First Law: Planets move in elliptical orbits with the Sun at one focus of the ellipse.
- Kepler’s Second Law: A line segment joining a planet and the Sun sweeps out equal areas during equal intervals of time, meaning that planets move faster when they are closer to the Sun and slower when they are farther away.
- Kepler’s Third Law: The square of the orbital period of a planet is directly proportional to the cube of the semi-major axis of its orbit.
By applying these laws, Kepler was able to accurately predict the positions of planets in the sky, aligning with the heliocentric model proposed by Copernicus. This shift not only provided a more accurate framework for understanding planetary motion but also laid the groundwork for Isaac Newton’s later work on gravity. Therefore, Kepler’s findings were instrumental in legitimizing the heliocentric theory, showing that it could explain the observable motions of celestial bodies more effectively than the geocentric model.