Presentation: the astronomers

Three weeks into this semester, we've already covered motions and cycles of Earth, the moon, the sun, and the stars--are you freaked out enough as it is?

We just extended these spatial reasoning skills to locating planets in the night sky in the previous in-class activity. If your brain is hurting from applying these spatial reasoning skills, then that's not necessarily a bad thing, but we are now going to shift gears and look at the historical background of this model, which is story of science itself, as astronomy was the first science.

For many of you, this is good news! Instead of spatial reasoning skills, this chapter primarily reads like a history book, which is perhaps more like the type of conventional studying that you are used to. However, the history of astronomy makes for pretty heavy reading, and this material is not going to be discussed in this presentation--you are expected to read this on your own.

But in order to maximize your reading of this material, this presentation will do is summarize what is kind of important and what is really important, and two main categorization questions to answer as you read along. This slide is a bit overoptimistic perhaps, but with a targeted approach to reading this admittedly very dry material, you should be okay.

Astronomers: who's who, and more importantly, what did they do?

First is the boring but necessary part of tackling this chapter.

You are going to have to distinguish between seven important astronomers, and their contributions to developing astronomy as a science.

Seven bland astronomers that are going to blend into each other. Why should you care? How should you care?

Second, useful and more essential--categorization questions you should be concentrating on, going beyond differentiating between names, places and dates (well okay, at least the names are important).

When you read about each astronomer, ask yourself whether he is a mover or disprover, and ask yourself whether he is a non-scientist or scientist? These are somewhat subjective questions that may not have definitive answers based solely on the material in the textbook, but the important thing is being able to synthesize the material enough to argue in your own words how each astronomer should be classified as a mover/disprover and using a non-scientific or scientific approach. Let's define these terms, and these are the terms you should keep in your mind when you read and re-read the textbook--hmm, mover or disprover, non-scientific or scientific approach?

A "mover" is a builder--an astronomer who develops a model to explain why planets move the way they do across the night sky--all that prograde and retrograde motion stuff. When you classify an astronomer as a mover, you should also be able to describe and understand their model.

In contrast to a "mover" who builds something up, a "disprover" is someone who tears things down--an astronomer who argues against a model of planetary motion. When you classify an astronomer as a disprover, you should also be able to describe and understand their arguments. The history of astronomy is a cycle of movers followed by disprovers, subsequently culminating in more accurate models of planetary motion. (The disprover and mover categories are not meant to be mutually exclusive--it might be possible that someone refutes an older model by replacing it with a newer model.)

The second categorization question is distinguishing between a non-scientific approach and a scientific approach. A "non-scientific" approach is used by an astronomer who explains something with first principles--assumptions, intuitions, and common-sense arguments, in spite of, or with lack of evidence. Often a first principle sounds like a neat idea, such as explaining the prograde and retrograde motion of planets with epicycle and deferent gears, like a Spirograph^TM, despite there being no evidence that there are actually gears like this in space...

That's where a "scientific" approach comes in, where an astronomer first gathers evidence and makes observations, and then makes an explanation based only what the evidence says, without any assumptions or preconceived ideas. The history of astronomy is the replacement of non-scientific explanations with scientific explanations--in this sense, astronomy is the first science.

So when you go through the heavy lifting of reading through this history chapter, for each astronomer ask yourself: mover or disprover, non-scientific approach or scientific approach?