Why Copernicus, Kepler, and Galileo Preferred the Heliocentric System Over Tycho’s Geocentric Model

For centuries, we have understood that planets orbit the Sun, and that Tycho Brahe's geocentric model does not align with reality. Tycho may have had the best astronomical records of his time, but his methods were flawed. He did not apply the scientific method and instead tried to fit the data to a preconceived religious view. In 2022, can one seriously support Tycho Brahe's geocentric model?

The Role of Gravity and the Mass Distribution in the Solar System

While it is true that gravity pulls towards the center of the Earth for us, Sir Isaac Newton’s universal law of gravitation demonstrates that gravity is universal and proportional to the mass of the objects divided by the square of the distance between them. The Earth is not the only massive object in our solar system; in fact, the Sun accounts for 99% of the total mass. This fact alone makes geocentric views unsupported by reality.

Observational Equivalences and Diurnal Motions

Both heliocentric and geocentric models are observationally equivalent to some degree. Tycho's model does explain certain observations such as why Venus was never observed to move away from the Sun in the Ptolemaic system. However, the main issue was the diurnal motion of stars. The apparent fast rotation of stars, which were distant, once a day, was unexpected. Furthermore, the fact that the Sun, the planets, and the stars all participate in this rapid motion was highly impractical.

Any theory that could explain these observations and eliminate the diurnal motion of stars would be more convincing to astronomers. While this is not a logical argument, the aesthetics and practicality of a theory matter a great deal.

Tycho Brahe’s Model as an Alternative

Despite his precise observations, Tycho’s model never truly became a viable alternative to Ptolemy's. The idea of having the Sun as the center of the solar system and the Sun orbiting the Earth, a much smaller and insignificant object, was cumbersome. Astronomers were usually left to choose between Ptolemy’s and Copernicus’ models.

One key advantage of the heliocentric model was that many Ptolemaic epicycles had a period of one year, which was unexplainable in geocentric terms but trivial in the heliocentric case. This allowed for a simpler and more logical explanation of planetary motion.

Conclusion

While both heliocentric and geocentric models have their merits, the historical preference of astronomers like Copernicus, Kepler, and Galileo for the heliocentric model lies in its logical consistency, simplicity, and the ability to explain planetary motion without the impractical complications of the geocentric model. The heliocentric system is supported not only by the observations of modern science but also by the fundamental laws of physics.