Tycho Brahe’s Theory of Gravity Explained


The discovery of the theory of gravity is often attributed to Isaac Newtown. Some might point to a modernized version of the theory, the Theory of General Relativity by Albert Einstein, for credit purposes. These theories may not have been possible, however, without Tycho Brahe’s theory of gravity.

Brahe was born in 1546 and was part of Danish nobility. He was always fascinated with astronomy as a child. Based off these early observations of the night sky, he found that the various tables for planetary motion where in accurate at best and basic guesses at worst. That was when he decided that his life and whatever resources he had would be dedicated to documenting planetary positions with a much greater accuracy.

Brahe Had Numerous Resources at His Disposal

Brahe initially had some success in predicting planetary motion and location through pure observational research. After publishing some of this work, Brahe’s uncle would one day end up saving the life of the King of Denmark. For this act, the king rewarded the Brahe family with numerous financial and property-based resources.

Brahe would end up receiving property rights for an entire island and the money to build an observatory. He would also use the financial rewards to begin designing his own instruments, allowing for a more accurate study of the stars and planets. Brahe would also use multiple clocks and timekeeping devices.

This would all help him to achieve his primary goal: to measure one minute of arc.

What Is One Minute of Arc?

We know that a sphere has 360 degrees. This means one degree is essentially a 1/360 degree turn for a complete rotation. That means one minute of arc must be 1/60 of that 1/360 turn that occurs.

When Brahe was able to measure this, it would become possible to develop new technologies, such as the modern telescope, which would allow for deeper research into what the universe had to offer. It would also be an early confirmation that the Earth wasn’t the center of the universe – or even the center of the solar system.

It would, however, be an attempt to confirm Brahe’s own view of the universe. He felt that the sun rotated around the Earth, but that the other planets had an orbit which moved around the sun. Kepler would go on to use Brahe’s work to develop his own laws of planetary motion at a later time.

Without the calculations made by Tycho Brahe’s theory of gravity, the more accurate theories which would be developed over time may not have been as accurate.

Tycho Brahe Was Essentially an Observer

Brahe may have been able to do more with his theory of gravity if there were more tools and data available to him. He was able to take a large amount of data, combine it with his own observations, and be able to make basic conclusions about the nature of the universe. His one downfall may have been the fact that he refused to believe that anything but the Earth could be the center of the universe.

His idea was not a compromise between the ideas of Copernicus and Ptomley. They were evidence of the fact that he was forced to compromise with his own unyielding beliefs about the science of the universe at the time.

Brahe’s theory of gravity shows how important it is for a scientist to set aside belief systems so that raw data can be observed. The data which Brahe collected went on to become the foundation of the modern theories of gravity. His experimentation, however, was to create more of a geocentric model of the universe because that was the theory he was attempting to prove.

Johannes Kepler, however, was a student of Brahe and took on the task of simplifying the massive amount of data that had been collected. It would be Kepler, with more of an independent view, that would show Brahe’s data could create a powerful model of the universe. The only requirement was that the sun had to be in the middle for the equation to work.

Three empirical laws would eventually be developed from Brahe’s work. That the planets have elliptical orbits; that the planets move faster when closer to the sun within their orbits; and that the orbital period, or how long a planetary year would be, is directly related to the average distance between the sun and the planet.

Thanks to Tycho Brahe, we have a much greater knowledge of the universe. His theory of gravity may have been incorrect, but it was progress toward a deeper overall scientific understanding of how the universe works.