The Heliocentric Solar System: Humanity's Place In The Universe

A Science Story

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Many people sacrificed everything to make humanity aware that the universe doesn't revolve around us. At the time, this idea was revolutionary. With any revolutionary idea comes those who are willing to do anything to stop it.

Show Notes/Transcription Below

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Show Notes/Transcription

When we go about our day to day lives, it is all too easy to think that the world revolves around us, but what about the entire solar system and the rest of the universe? Well, it may seem preposterous to think that, but when you put yourself into the shoes of the ancients, its not as outlandish as you may have first thought.

Imagine that there was no such thing as modern technology. There is no internet, no electricity, no space shuttles, and no telescopes for that matter. You live a simple life consisting of taking care of yourself and your family and most likely a majority of your spare time is spent consumed with your birth religion.

Why would you ever doubt that the Earth wasn’t the center of the universe? You probably wouldn’t even be too concerned with it. Even if you were, when you look into the night sky, it kind of does look like everything revolves around the earth.

Today we are going to learn about the story of a few people that were concerned with it and because of their hard work and sacrifice, humanity was changed forever.

Is The Earth At The Center? First Ideas Otherwise

Speculation that the earth may not be the center of the Universe goes all the way back to the 9th century BC and the Indian philosopher Yajnavalkya. This philosopher used math and geometry heavily in his study of philosophy which may have led to this interesting conclusion.

He included the idea that the earth may not be the center of the universe in a sacred Hindu text which states “The sun strings these worlds – the earth, the planets, the atmosphere – to himself on a thread.”

Other written texts by Yajnavalkya state "The Sun never sets nor rises thats right. When people think the sun is setting, it is not so; they are mistaken."

Much of this belief is thought to have come from the sage’s idea that the sun was much larger earth which instilled an idea that maybe the sun was more important astronomically. He was also able to calculate the Earth’s distance from the moon and the sun.

This is one of the first written texts and teachings referring to the solar system as heliocentric, but this idea was a bit too radical in India and gained little traction.

We have to wait about 600 years until we meet Aristarchus. Around 300BC, it was common knowledge that the solar system was the entirety of the universe with the earth placed at its center. You’d have to be crazy to think otherwise, right?

Well, not to Aristarchus. While his complete work on astronomy didn’t survive history, it has been pieced back together by many other renowned Greeks. It is thought that he also independently came to the conclusion that the sun is much larger than the earth, so it makes sense to have the earth move around the sun and not the other way around.

Greek mathematician Archemides is a well-known figure and wrote on aristachus: “His hypotheses are that the fixed stars and the Sun remain unmoved, and that the Earth revolves about the Sun in the circumference of a circle, the Sun lying in the middle of the orbit.”

Although Aristarchus came to this conclusion, it was met with fierce opposition especially from religions that believed ‘god’ or ‘the gods’ created humanity to be at the center of the universe. Remember that at this point in history, many still thought that the sun could possibly be a god itself. Setting it among the stars diminished the sun’s importance and would not be tolerated.

While this was a subjective argument against the heliocentric model, there were mathematicians making arguments as well. They argued that we can’t possibly orbit the sun because there is no observable parallax when we look at the stars at opposite times of the year.

The Common Arguments Against The Sun Centered Model

Now, you may be wondering what stellar parallax is, and for good reason. In short, stellar parallax is a shift in the position of nearby stars in the night sky against a far away background as we orbit the sun. So, the position of closer stars should move back and forth more than that of the background as we move around.

What those doubting mathematicians got wrong was that there actually is stellar parallax, but we can’t see it with the naked eye because the stars are too far away. It wasn’t until 1838 that Friedrich Bessel used an instrument that was comprised of a refracting telescope with multiple lenses that gave us the ability to measure the angle between stars, but that’s a story for another day.

Aristarchus did say that the stars were very large distances away, but it is not known if this was to dispute the arguments put forth by his fellow astronomers and philosophers or simply his own beliefs.

Unfortunately for the heliocentric hypothesis from Aristarchus, three of the biggest names in ancient philosophy and astronomy solidified the geocentric model. Almost immediately before Aristarchus, Plato and Aristotle both spread the word of the geocentric model. Those are two names that couldn’t be competed with at the time. Then, Ptolemy, an astronomy powerhouse, further pushed the earth as the center of the universe and put it into the permanent dogma for which would last for 14 centuries.

More People Taking On The Heliocentric Model

So, in Europe it seems the earth centered solar system and universe is there to stay for a while, but things aren’t the same back in India. Between 476-550 AD an Indian astronomer and mathematician named Aryabhata figured out that the light coming off the moon and planets was reflected from the sun.

From this he decided that the earth was spinning on an axis and that the orbits of the planets were dependent upon the sun. Incredibly , Arybhata was also able to calculate some astronomical constants such as when solar and lunar eclipses would occur as well as the motion of the moon.

5 centuries later, a scholar by the name of Bhaskara expanded on this work and mentioned the law of gravity which led to the discovery that planets don’t orbit the sun at the same velocity.

This all happened before many of the revelations back in Europe, and it isn’t known if European scholars came to their ideas that I’ll talk about soon independently or if they intermingled with the Indians. It is known that the Greeks and Indians did exchange quite a bit culturally.

The Copernican Revolution In Europe

The Renaissance was a period of intense change and radical ideas. It was during this period that astronomer and mathematician Nicolaus Copernicus tried to revive the works of Aristarchus. He came up with a new model for the universe that worked perfectly with the sun at the center.

He was able to solve the problem of retrograde motion of the planets closer to the sun. If you don’t know what retrograde motion is, don’t worry, it’s more simple than it sounds.

If you were to track the location of all the planets that travel around the sun in the same direction as the earth in the sky day after day, you would see them move across the sky, then make what looks like a loop, and then continue across the sky.

The Ancient astronomers came up with pretty complex ideas as to why it happens, but Copernicus figured out that it is because some planets either move faster or slower than the earth around the sun. At some point, the paths will cross and it looks like the planet moves backwards in the sky.

If that doesn’t make sense, there are a ton of great resources out there showing gifs or short videos of how that works. If only I could zap the videos into your minds, but that’s not how podcasting works.

Here is a mind blowing quote for the time from Copernicus: “We revolve around the Sun like any other planet”. Pretty crazy, right?

However, he was afraid of being labeled a heretic by the church so he waited until his death in 1543 to release his work. In an attempt to maintain order and the power structure of the time, the Church banned the manuscript in 1616 and did everything in their power to make sure that the heliocentric model was suppressed.

Pushing Past Suppression By The Church

I want to interject here and remind everyone, no matter what your beliefs may be, that this isn’t meant to offend anybody or attack anyone’s beliefs. This is history. This suppression did happen, but it isn’t to say that people and beliefs like those held by the church can’t evolve over time and modernize. However, it should serve as a warning against the dangers of being too dogmatic.

Even though the Church tried to suppress the heliocentric model, the work of Copernicus was able to spread and turned into the Copernican Revolution. One of the people it spread to was someone named Galileo around 1610 AD.

There were some arguments such as ‘if the earth is spinning, why doesn’t everything fall off?’ or ‘if an object is dropped from a tower, wouldn’t it fall behind the tower?’ These semmed like common sense at the time, but this would start to change with characters like Galileo and the advancement of physics.

Galileo was able to expand on the heliocentric model with the help of the newly invented refracting telescope. He was able to see all the way to Jupiter and noticed four moons orbiting it. He noticed that the smaller bodies orbited the larger body.

I can imagine him thinking “huh, that’s kind of weird considering we know about the earth and the sun...”

A View Of Saturn Yields More Evidence

Although this was insightful, the real kicker was when he took a peek at Saturn. What he noticed is that as Saturn moved through the night sky, the portion that was lit and dark would change in congruence with where the sun was.

He came out with a book called “The Dialogue Concerning the Two Chief World Systems” that outlined his beliefs, but unfortunately he was placed under house arrest by the church for the rest of his life.

He essentially gave his life to move science forward for the rest of humanity which is something that I respect a lot.

Isaac Newton Delivers The Knockout Punch

The final stages in moving into the acceptance of the heliocentric model of the universe was the discovery of the reflective telescope by Sir Isaac Newton. This allowed a much more clear view of our universe.

This led to the publication called Principia Mathematica around 1680 by Newton where he proves that the solar system is heliocentric. The publication was one of the final dagger moments where it was clear that the solar system revolved around the sun. In the writing, Newton explained why the planets move around the sun and named the force that kept them in place ‘gravity’.

After this, scientists began predicting events in space using Newton’s Equations which further proved its legitimacy. The study of physics kept moving forward as well which dispelled the common sense arguments against the heliocentric model and also further validated earlier findings.

Also stemming from the heliocentric model was a bunch of other earthly phenomena that started to make more sense and allowed them to be studied. So events such as night turning into day, changing seasons, the duration of days, tidal strength, phases of the moon and much more become infinitely more understandable.

We Now Know Our Place

The discovery of the heliocentric universe was a paradigm shift for the mindset of humanity. We went from being the sole purpose of the universe to just a small part of it. But with that paradigm shift came an explosion of self-awareness and a more accurate perspective that ultimately allowed us to become what we are today.

And remember that this model of the universe was only agreed upon less than about 300 years ago. That’s about as long as the United States has been a country. While we have come a long way since then, we still have much farther to go. So, never get to dogmatic with your beliefs, and as always, keep learning.