Maggie: Who are we talking about today?
John: A great astronomer named Tycho Brahe.
Before we discuss his theories, though, we need to recall a point from an earlier discussion about the development of science.
Maggie: I know, I know. Scientists build on the ideas of previous scientists, and that is how science grows and develops. So, unless a scientist is so creative that her ideas create a paradigm shift, she is always indebted to previous thinkers.
John: You really get this stuff. It makes me happy.
Maggie: I enjoy our conversations.
John: Me too. And with that out of the way, we can get back to Tycho Brahe.
Brahe was born in 1546, shortly after the publication of Copernicus’s famous book On the Revolutions of the Heavenly Spheresin 1543. He died in 1601.
Maggie: I read a little bit about his life. Can I share what struck me as interesting?
Maggie: It is interesting to me that he came from a wealthy and noble family.
John: Why do you think that is important?
Maggie: He became interested in astronomy when he was just a teenager. And because he was from a noble family, he didn’t have to get a job right away. So he spent his time attending different universities, until he was 30 years old, just learning about astronomy. I like that. He was able to travel around and study with different scholars for many years, just learning and developing his interests.
John: I like that too. He was very driven as a young man. And it paid off.
Maggie: Didn’t he discover a new star?
John: Kinda, sorta. In 1572, a Nova appeared in the sky.
Maggie: Wait. Before you go on, can you tell me what a Nova is?
John: Sure. There are many stars that are not visible to the naked eye. These stars will occasionally re-ignite and become so bright that they are easily seen, even in the daytime. These stars are called Novae. And here is something interesting.
If you recall, Aristotle believed that the planets and stars were fixed in the universe. In other words, he believed that what you saw in the sky was all that existed. And many people during Brahe’s time still believed this theory.
So then this Nova appears, which was unseen before. Scholars, including Brahe, thought it was a new star. A new star, Tycho Brahe would later write, proves that the heavens are not fixed and unchanging.
Maggie: That must have blown peoples’ minds.
John: It did. And then he made one more radical discovery.
In 1577, he observed a comet streaking across the sky. That wasn’t unusual. People had seen comets before. But…
Maggie: There is always a “but…”
John: Brahe loved measurements and scientific observations. And his calculations showed that the comet was racing around the planets and the stars; it was not just flying around in the sky above earth.
Maggie: Oooh, radical.
John: It was…
Maggie: I was being sarcastic. I really have no idea why that is significant.
John: Think about it. People used to think that comets flew through the sky right above the earth. But Brahe showed that they were actually much higher, among the planets and stars. Based on what we just discussed, why is that significant?
Maggie: (Thinking…) If a comet was flying around with the planets and stars, it shows that the objects in the heavens are not fix. Like the nova, this once again challenged the idea that the planets and stars are fixed. What do you think?
John: Perfect. Both the nova and the comet proved that stars and the planets were not fixed and immutable. This was a radical idea.
Tycho Brahe wrote about these events and these two works greatly advanced astronomy. So cool.
Maggie: So what did he do after these two discoveries?
John: He focused on creating new observation facilities and equipment. In 1576, the king of Denmark made Brahe a lord, giving him an island in the Danish Sound on which to build observation platforms. He in fact built two observatories, the first of their kind in Europe, with advanced measurement tools.
Here is a picture of one of his observatories, where he studied planetary motion and made exact measurements of the stars:
And this is also very cool: he accumulated a very extensive catalogue of the stars and their positions, which was later used by Johannes Kepler to further advance astronomy.
Maggie: He sounds awesome.
John: Well, hang on. It is hard for some people to give up long-standing traditions, and this is true even for scientists.
Maggie: What did he cling to, the theory that the earth was the center of the universe?
Maggie: No way! Even after Copernicus?
John: Yes. Brahe just couldn’t accept Copernicus’s theory that all the planets revolved around the sun. So he came up with an elaborate new idea, and backed it up with the math to prove it.
He theorized that all the planets revolved around the sun, except the earth, which was fixed at the center of the universe. The sun and the other planets, while still in their own motion, revolved around the earth. Here is a picture of his universe:
Maggie: That seems goofy to me.
John: Well, now it does. But remember, he had the math to back it up.
Maggie: I get it, science advances step by step, and his steps were necessary.
Who’s next in our discussion?
John: Kepler, of course.
Maggie: Can’t wait.