Astronomy 101

08 Smart people studying big ideas

Aristotle (300s BC)

Aristotle is still famous for many cool things, one of them being that he’s considered the granddaddy of Science. He was super big into observing the natural world, which is a great example for anyone interested in science. Or people. Or understanding pretty much any part of the world. He was an observer. He observed things, and after studying under Plato, he developed his own beliefs on all kinds of things, including the planets and stars and how they worked together.

Aristotle the Greek came up with a lot of wrong assumptions that lasted for hundreds of years. For example, he asserted, like many, that the other planets and the sun revolved around the earth. An earth-centric  view  that we know now is false. So he was wrong about all kinds of things. But, BUT, he helped set the groundwork for studying science. Things such as:

  1. Observe

  2. Experiment

  3. Study

  4. Develop logical ways of thinking about, organizing, and classifying the physical universe.

This was a super big deal, and even though he was wrong about so many things, the ways he learned about the world set a foundation for science that is still followed today.

Eratosthenes (200s BC)

Greek fellow far ahead of his time who came up with the idea of using the sun to calculate Earth’s measurement. Think that’s no big deal? Pay attention to these two little facts: One, he made his calculations over 2,000 years ago. Before Jesus was birthed, before electricity and telescopes and Instagram. And two, he was only 200 miles off the correct measurement. Wow.

Claudius Ptolemy (AD 100s)

Ptol was a Greek-born Roman citizen who lived in Egypt and got super good at both astronomy and mathematics. Several hundred years after Aristotle, he kept the idea going that the earth is the center of the universe. Which it’s not. But all the smart people of the time believed it. Even though he was wrong about it, he used his mad math skills to track the planets’ movements and propose a model where everything revolved around earth.. He used math to prove his theories and predictions, and his (incorrect) theories - primarily the Ptolemaic System  were accepted for a long time. Cool thing though, he inspired other astronomers to study planetary motion, and probably many politicians to aggressively try and make the facts fit their agendas.

Also, score him some points for archiving: he hung onto the star charts of Hipparchus, the Greek astronomer, and these, along with his work in calculating the relative positions of celestial bodies, were extremely important to later Renaissance-era astronomers in developing the field.

Western civilization borrowed many ideas from the Greeks that we still use today, some better than others. Ptolemy and his Earth-centered system probably represents the high point of Greek astronomy. Incidentally, he was the last great astronomer in the Western world before the hordes plunged the hemisphere into what proper historians have decided to not call the Dark Ages.

Abd al-Rahman al-Sufi (AD 900s)

Sufi, also known as Azophi, was a Persian - what is now Iran - who astronomer who made the first known observation of a group of stars outside the Milky Way. The Andromeda galaxy. Wow.

Nicolaus Copernicus (1400-1500s)

Aah, the Renaissance. The rebirth and rediscovery of old ideas that woulda been great to hang onto if the hordes hadn’t overrun Europe and plunged Earth into the Middle Ages. Copernicus was a Prussian who posed the radical idea that maybe we live in a heliocentric system where the sun is the center.

“Heresy,” shrieks the Catholic Church. “It cannot be!” The reasons they had such a strong reaction are many, but basically come down to the fact that they felt it ran counter to a strict and literal interpretation of the Bible and therefore was...heresy.

Copi wasn’t the first fellow to pose this theory. But Cop brought a fresh look and examination of it as the Renaissance kicked off after people had forgotten to even think about that possibility for oh...ten centuries or so. He was a radical, and this heliocentric idea was just the beginning. He also *gasp* believed that Earth rotated on its axis. What an idiot. He inspired people...but a lot of them in secret. The kind of support where people don’t raise their hand in public, but quietly shuffle off to secretly check out his ideas and do their own research based on them. He was inspiring to a certain gentleman with the greatest name in all of science. His name was...

Galileo Galilei (1500-1600s)

Besides being one of the great scientists of all time, he has inarguably the greatest name in all of science history. Galileo Galilei. Say it over and over. Anyone named that was destined for greatness.

Gal, besides inspiring the future name of the Wonder Woman actress, was an Italian who was maddeningly precocious as a kid. He could invent like nobody else. He had Aristotle’s talent for observing, and an incredible ability to come up with ideas to test out theories based on his observations. For example, he invented a telescope that he used to confirm Copernicicus’ theory about a heliocentric system and how planetary motion really worked. He used evidence-based methods to prove the accuracy of his ideas, and this got him huge commendations from the Church…

...wait. No. It did not get him major awards from the Church. After he published his ideas, they were seriously peeved. Peeved enough to put him on trial, charge him with blasphemy, heresy, and a bunch of bad stuff (but mostly those) and eventually get him to recant...sort of.

Recant is a fancy way of saying he said “I was wrong and I confess.” Sad. He was such a cool dude. It doesn’t seem right that he’d cow to peer pressure, or rather peer pressure, or rather pressure from a massive institutional system that would in a best case scenario simply execute him if he didn’t recant and worse case scenario, torture him a bunch until he eventually recanted, then burn all his writings, and probably put him to death anyway. They did this to a whole bunch of people later on when they got seriously peeved and started the whole Inquisition. Not cool.

Anyway, Gal recanted and went on house arrest for the rest of his life, which is sad. But the revolution he started - or perhaps Copernicus started and Gal got really moving - was already at critical mass and there was no stuffing these new ideas and evidence back into the box. So he was stuck in his house, but there’s one last really great little snippet that he allegedly sneaked in when he confessed and recanted. Supposedly, he murmured:

E pur si muove

Which means: “It still moves.” Or something of the sort. This was in reference to heliocentric theory he had proved and the Church wanted to shut down. It’s a wonderful phrase to use, because it means even if you’re powerless or getting bullied or getting pressured to do something, you always have that phrase to fall back in if the evidence and facts are on your side: E pur si muove. No matter what you say, and no matter what you force me to say, the facts remain the same and you can’t change them.  

Johannes Keppler (1500-1600s)

This German chap and contemporary of Galileo was important because he discovered and articulated basic laws of planetary motion. He didn’t call them laws, he referred to them as celestial harmonies, which is a rather beautiful and elegant description. His observations were based on mathematics as well and helped provide exciting context for Copernicus’s sun-centered system - he showed how there was an order and design to how they revolved and the mathematical framework for their relationships not only with the sun, but with each other. He was able to show how the sun was actively involved in moving the planets around via the process we now call orbit. This helped give arguably the greatest scientist of all time, Sir Isaac Newton (stay tuned) a foundation for developing his ideas that later became pillars of modern science. Also known as Laws.

One of the reasons Keppler is fascinating is the way he combined ideas from different disciplines. Even though we often look at his work now as existing within the framework of astronomy, he was interested in optics, vision, philosophy, religion, astrology, mathematics, and the natural world in general, so he drew upon all these in formulating his ideas about heavenly bodies. He wasn’t simply a big idea guy though, he had a strong ability to come up with novel explanations for natural phenomena, such as his descriptions of how light and vision work.  

Isaac Newton (1600s)

Oh Isaac. Where to begin? This is specifically addressing his role in astronomy, but it goes down the rabbit’s hole fast, because much of Isaac’s work involved motion, which laid the framework for understanding how celestial systems work together.

Short version, he did a bunch of cool stuff and basically invented the fields that later became physical optics and calculus, but he is best known for the work he did involving force and motion: the three Laws he came up with to explain motion became the discipline known as Physics, and these in turn helped to explain how gravity works. Amazing.

The fancy word for “motion” is “classical mechanics.” In his big work, which I won’t write here because you probably won’t remember and the title isn’t that important, he wrote out his famous Three Laws of Motion, in which he riffed off the ideas of a certain Johannes K and went on to mathematically describe gravity.

  1. First Law. The Inertia one. This one basically says that if something isn’t moving, it will stay not moving until something makes it move, as well as saying that if something is moving, it will stay moving in the same direction at the same speed until something makes it slow down or stop.

  2. Second Law. The Acceleration one. This one basically says that the bigger something is, the the more force is required to move it and make it go faster.

  3. Third Law. The Equal and Opposite one. This one basically says that there is - wait for it - an equal and opposite reaction for every action.

So Isaac used a bunch of his calculus wizardry to show the idea of universal gravitation and how it works. Five hundred years ago and I still have trouble understanding his calculations. He showed mathematically how movements in the natural world occurred, from the rhythm of equinoxes to the changing of tides to the orbits of planets. This last was particularly important because it finally proved, beyond a doubt’s shadow, that that the heliocentric theory was correct and that the Sun was indeed the center of our system. Perhaps even more importantly, the fundamental principles he developed helped show how many - all? - motion on Earth could be explained scientifically.

He also did a bunch of important work in mathematics and optics, but it is his work in physics - the field he invented - that changed the science world forever and helped us to finally begin to fully explain and understand the way motion, force, and gravity work together both on Earth and in the context of Earth’s relationship with all other objects in the solar system. The only other scientist who might come to close to his level of of genius might be Albert Einstein. However, neither of them were smart enough to invent a time machine, so to my knowledge they never met. Sad.

Edmond Halley (1600-1700s)

British chap with an eye for detail and ability to find patterns in the skies. By reviewing historical data of reported comet sightings, he correctly predicted when the next one would appear. He died before it happened, but it was posthumously named in his honor. For those of you to lazy to punch it into Google, it’s coming back around in 2061. Stick around.

William and Caroline Herschel (1700s-1800s)

Brother and sister duo. Will was another one of those super patient fellows with an Aristotelian-interest in organizing and classifying. He discovered a bunch of stuff, like Uranus, some moons around Saturn, Martian ice caps, stuff like that, and ended up cataloging over 2,500 deep space objects.. But even more awesome, he trained his sister and she became the first woman to identify a planet, and later went on to identify several more.

Albert Einstein (1900s)

The only serious competitor to Newton in the Greatest Scientist Ever contest would be Einstein. He proposed a mindblowing idea - backed by mathematics and physics - that fundamentally changed the way people even think about astronomy. The basic gist is that physical laws are consistent throughout the universe, that light speed traveling in a vacuum is constant, and that gravity does a weird thing to warp the relationship between space and time. He forced the world to rethink how the universe functions, in a fundamental way, in a manner that no one else had done. Since Newton.

Yet he never invented a working time machine. Pathetic.

Edwin Hubble (1900s)

One of the greatest television series ever is the five-season run of Fringe, whose idea of parallel multiverses would not exist without the work of Mr. Hubble. So thank you. Also, before his observations and research, there was great debate over whether there was more than one galaxy. Ed not only calculated that umm, yes, definitely but also figured out that the universe itself is expanding; a calculation that came to be known as Hubble’s Law.

Carl Sagan (1900s)

Sagan was a good astronomer, but inarguably an even better astronomy educator. He did some important astronomy-ish stuff, but his lasting achievement was in getting people excited about astronomy. He did for astronomy what great teachers in any discipline do: they broke down very complicated ideas and topics down so people could actually understand them. That takes mad skills. Props.

Stephen Hawking (1900s-2000s)

Cosmologist and Simpsons guest star who cheerfully suggested that since the universe had a beginning, it probably would have an end, thereby raising blood pressures all across the world. Fortunately, most people who bought his massive and popular book, A Brief History of Time, didn’t actually read it and kick the worry into hyperdrive, but it always look good on a bookshelf and it helped popularize and simplify complicated theories for the layperson masses. Supposedly it’s simple. It still have trouble understanding.

He also suggested that the universe doesn’t have borders or boundaries, something that President Trump would surely take issue with, as it removes the opportunity to erect a wall to keep super smart and aggressive aliens out.

Frank Drake (1900s - 2000s)

Which one of these astronomers do I most identify with? Easy. Frank Drake. Why? Uh, he’s one of the great pioneers of the search for extraterrestrial intelligence. What else is there to say?

next chapter - vocabulary >


  • Newton’s magnum opus on the topic was Philosophiæ Naturalis Principia Mathematica (“Mathematical Principles of Natural Philosophy”)

  • Today, the phrase Newtonian is used to describe fields or disciplines that owe their existence to the theories he discovered, invented, or created. Like Calculus.