Chapter 5 - 5

05 Astronomy

listen to a discussion in an astronomy class. fill in the diagram with the information that you hear.

M: Today we’re going to get started a little differently.

Do this: imagine you’re an astronomer.

You’ve seen Saturn in a telescope − and you all have, right?

You all know what Saturn looks like?

Rings… yes? OK. So you’ve seen the rings, but neither you, nor any other astronomer in the world, can come up with even the slightest clue of what they’re made of.

How… how frustrating would that be?

Well, luckily for us, a Scottish physicist named James Clerk Maxwell finally solved the mystery in 1857.

So my fellow astronomical sleuths, what do you think the rings are made of?

W: Can I guess? I’d have to say that they’re made of solid rock. I mean, how else would we be able to see them?

M: Well, that’s a very common guess, and that’s what many thought in the past, but that’s actually incorrect.

So, should I go ahead and cracked the mystery for you all?

OK. So, this Maxwell that I mentioned a minute ago, he decided that the rings had to be made of tiny particles that orbit around the planet.

W: Tiny particles? Tiny particles of what?

M: Would you like to guess?

W: OH, wow, I don’t know. Um, well, would they be little pieces of rock?

M: Nope, but that’s a good guess.

OK, I want you all to get this, so I’m going to help you out.

Think about this: you will know that the rings are really bright, right?

And they appear brighter at different points in the planet’s rotation.

OK, so, knowing that, what can you surmise? No one? Here’s another hint.

They reflect over eighty percent of the sunlight that hits them.

Now, what material is this starting to sound like to you?

W: What−no, um, ice?

M: That’s it! Great job, you just did in a few minutes what it took astronomers over two hundred years to do!

Of course, you had help. Anyway, you’re exactly right about the ice.

The particles are pieces of ice that range from, well, tiny, to as big as a large snowball that you might make during a snowball fight.

So, honestly, “particles” is almost misleading because it makes you think of something really small, but that’s what they call them.

Anyway, so where these particles come from?

W: Actually, before we move on to that, could you explain how they actually formed rings?

M: Good question. It is yet another mystery; the rings are really only about, the most, twenty or thirty meters thick.

That’s very thin. So how do they stay in such a thin pattern?

Well, astronomers believe it is because the particles tend to run into each other as they orbit.

After a while, they had collided so many times that they all just sort of fell into the same orbit.

No one particle could stray from its own orbit because it would just be knocked back by an adjacent particle.

Does that make sense? Let’s move on to how they formed.

1) How does the professor organize the information he presents to the class?

2) How does the professor introduce the topic to the class?

3) Why does the professor mention a snowball fight?