Kepler's Laws and Planetary Movement

By the turn of the 1600's, the way in which the solar system and the universe as a whole was viewed began to change. With the controversial conclusions of Copernicus, scientists already began to adopt the idea of a heliocentric solar system. Further advancements in astronomy came about through the research of Tycho Brahe and his assistant Johannes Kepler. The three planetary laws developed by Kepler with the data gathered by Brahe shaped the way in which science viewed the structure and motion of the planets of the solar system in profound ways, lasting to this day.

A Brief History of Johannes Kepler

Johannes Kepler began his studies in astronomy as an assistant to the astronomer Tycho Brahe, whom, by his own right, was a formidable observer of the heavens, despite his rather illogical conclusions about the Earth and the movement of other celestial bodies. Brahe’s observations were phenomenally accurate, especially considering the technology available at the time, often accurate to less than half of a minute of arc. In hindsight, however; Brahe’s creditability as an astronomer is diminished due to his lack of acceptance of the idea of a heliocentric solar system created by Copernicus. He agreed that the other five known planets revolved around the sun, but that the Earth would be incapable of such movement and would certainly be detectable by the inhabitants of the Earth if that were the case.

Kepler's First Law

Since his introduction into astronomy, Kepler had held a strong faith in the accuracy of the theories of Copernicus. Under Copernican theory, all planets traveled in perfectly circular orbits around the sun. However, Kepler’s observations, especially in regards to the orbit of Mars, suggested that planets trave...

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...'s Third Law. What else should be noted is that the constant (4π^2/Gm) is included in the equation. thus creating an equation that not only proves Kepler's Third Law, but is also far reaching in its practical applications. For instance, if the peroid and distance from the sun of a planet were known, the mass of the planet could easily be calculated.

Conclusion

The remarkable aspect to Kepler’s Laws is that they were able to unify the seemingly complicated motion of the planets in the heavens with relatively simple concepts. The conclusion that the orbits of planets are elliptical rather than circular paved the way into developing concise relationships between all the planets by explaining the variance in the velocity of a planet as it travels through its orbit. This proportional relationship, T^2 = KR^3, unified the motions of the planets beautifully.