Johannes Kepler and Planetary Motion

September 19, 2017November 23, 2022 / Emma / 10 Comments

Thales and Pythagoras suggested that the natural world could be understood. Aristotle dared to imagine what was beyond the Earth. Plato encouraged thought about the universe, even if he did take astronomy one step forward and two steps backward.

Copernicus followed in Ptolemy’s wake, devising the revolutionary heliocentric (sun-centric) model of the universe. Tycho Brahe may have (incorrectly) rejected that model, but he did make some of the most detailed night sky observations yet.

What’s more, by Johannes Kepler’s time, Tycho had cast doubt on the idea of uniform circular motion that had plagued astronomy for centuries.

At last, the world was ready for a more mathematical take on a question that had confounded philosophers, mathematicians, and classical astronomers alike: how do the planets truly move through space?

By standing on the shoulders of giants, Johannes Kepler was finally able to devise his three laws of planetary motion, which are still the leading mathematical theory today.

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Tycho Brahe, the Observer

September 18, 2017November 23, 2022 / Emma / 2 Comments

It is surprisingly difficult to find a flattering image of Tycho Brahe.

Honestly. Do me a favor and do a Google image search for the guy. It’ll come up with all sorts of disfigured images, mostly because his nose got messed up in a sword fight…

I know what you’re thinking. A classical astronomer in a sword fight? Suddenly these people seem less like heroes of modern-day science and more like human beings with lives of their own.

Tycho certainly fits the trend. He’s known for being quite the unpopular sort. Bad-tempered and vain, there were few who respected him for more than just his astronomical accomplishments—and even those were few.

So why is he even important, then?

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The Copernican Revolution

September 17, 2017November 23, 2022 / Emma / 2 Comments

Nicolaus Copernicus lived from 1473-1543, a time when rebellion against the Church was at its height. And unfortunately for the astronomy of the time, it had gotten inextricably tied up with Christian teachings.

In that time, heaven and hell weren’t just parts of our personal religions and beliefs—the Church held some of the highest authority over the land, and questioning heaven and hell just wasn’t done.

The way astronomers of the time pictured the universe fell right in sync with the heaven and hell geometry—Earth was the imperfect center of the universe, with hell nested deep below. Heaven was a place of perfection, and it was where all the heavenly bodies—the moon, sun, planets and stars—all moved.

Problem was, the Ptolemaic model of the universe really couldn’t explain detailed observations. It used epicycles to explain why the planets moved backwards sometimes. And no matter what people tried, they couldn’t get it to be accurate…

But then along came Copernicus, who would be the first to challenge the Ptolemaic universe and be believed.

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Aristotle’s Universe

September 15, 2017November 23, 2022 / Emma / 11 Comments

You might have heard of Aristotle. He’s the guy who said that we are what we repeatedly do. His words are often interpreted to mean that, for instance, a person who farms is therefore a farmer—or a person who writes science posts is, therefore, a science writer.

He also contributed a lot to the arenas of politics, philosophy, and basically every other field of study the Greeks could think of. His teachings were almost as widely accepted as Plato’s. And, like Plato, he had a few ideas about astronomy.

Well, most of what he taught about astronomy was dead wrong. But he had his moments. And his failures illustrate an important concept of science. No level of understanding is beyond our reach, and sometimes it takes pure imagination and guesswork to get there.

Aristotle may have been wrong most of the time, but he dared to imagine. And that’s something all scientists must do.

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From Classical Beginnings

September 14, 2017November 23, 2022 / Emma / Leave a comment

The universe as we know it was born out of chaos.

We have a pretty good idea of the scale of our universe and how it began—as an infinitely dense point of matter that blew apart in what we call the Big Bang. That’s chaos for you, right there.

And chaos continues to define our daily lives.

Stars are born out of the complete chaos of gravity, and nothing in the universe forms gently. Our moon was born out of a violent collision with the Earth. And I’m sure you’ve noticed how easy it is to let a room get disorganized.

All these are examples of chaos—known as entropy in science. Everything tends toward chaos. But the ancient Greeks rebelled against this idea.

In their view, everything in the cosmos had to be perfect. It was a somewhat spiritual way of looking at the universe, if you think about it. And even as they developed the groundwork for science as we know it today, one idea hindered them…

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