Revisiting “Why the Earth does not Revolve Around You”

In a past Conceptual Objective, I read an article on entitled “How Fast is the Earth Moving?” In it is discussed that when observing the stars, Sun, and the planets the Earth seems to be the center of our galaxy. However, most obviously, as educated individuals on a lot of things space related, we know this is not true anymore.

As taught in class previously, the stars and Sun do appear to spin around our sky rising in the East and setting in the West, the Earth is actually spinning around the Sun. As explained in the article, inconsistencies of planetary movement of Mars when Earth passes it in orbit as well as the difference in height of the Sun as the seasons pass prove that the Earth is not the center of our solar system. In more recent class discussion, the Heliocentric Model of our Solar system came to being after disproving the preconceived ideas of our solar system being Geocentric. Beginning with Greek astronomer Aristarchus and furthered by Polish astronomer Mikołaj Kopernik, the model was transformed to a Sun centered system to account for the retrograde motion displayed by the other planets in our night sky. However, it was not until Tycho Brahe where the motion of the planets was perfected by his assistant Johannes Kepler. Until Kepler’s research, the world has only believed the planets must have a perfectly-circular orbit. However, through the use of measurements calculated by Tycho, Kepler noticed that in order for the data to be correct, the idea of perfectly circular orbits must be wrong. It was Kepler who found out that, for the retrograde motion to be accounted for, the orbits of the planets must be elliptical.

Yet, it was not until Galileo’s invention of the telescope that officially set the Heliocentric Model in stone. With his telescope, Galileo proved that the Earth cannot be the center of our solar system because of three large ideas, the first of which is that objects on a certain planet share its motion around the Sun unless forced to stop otherwise (a concept known at Newton’s first law of motion). Next, Galileo emphasized that the heavens could change, meaning they were not perfect. With his telescope, Galileo observed that the Sun had spots and the moon had mountains and valleys, meaning that if these astronomical beings could be imperfect, then the idea of elliptical orbits is not so far fetched. The third objection Galileo underscored was that there was no way to accurately measure distance to stars using naked-eye observations. He proved this with his telescope, seeing that stars were in fact farther than previously imagined. As icing on the cake of his discoveries, he observed 4 moons around Jupiter, not Earth, and that Venus’s seasons could only be explained if it were orbiting around the Sun, proving finally that our solar system is Heliocentric after all.

This idea of the Heliocentric Model relates to the understanding of the speed of our Earth discussed in the article, because if it were not for the scientific discovery of our solar system Heliocentric, the information we would have had thus far would be much different. First off, none on the planetary movements, not even the movement of the Sun, would make sense. I infer that if our solar system was indeed geocentric, we would not have an understanding as to why a star and many planets so massive in comparison to our Earth would revolve around it. There would be no discovery of gravity as a force outside of what it does on Earth. Most importantly, there would not have been a lot of advancement within this science, because a lot of what is know about astronomy is attributed to the way our solar system works and how it compares to other systems within the galaxy.

My biggest takeaway from this objective seems to be that I’m grateful to have grown up in a time where I can appreciate how far astronomy has come. From thinking we are the world to not knowing that our lifetime ultimately has no role in the billions of years in our universe is the most humbling idea. The greatest of all is knowing that there is so much more to find out, and that we could never know it all. Striving for an understanding is so influential and passionate that it just keeps me looking up.



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