MALE PROFESSOR:So your reading assignment focused on the technology… telescopes… and how they’ve changed astronomy.

And there was a section on the Hooker telescope… So why was the Hooker telescope so important?

Let’s talk about that before we move on to some of the newer technologies.

Now back in the 1920s, the Hooker telescope was the most powerful telescope in the world.

And through it we could see, see for the first time, that the universe extends far, far beyond the Milky Way galaxy.

We could see that there are multiple galaxies beyond it… and all these galaxies are moving away from one another.

So multiple galaxies… moving away from each other… led to the theory…

MALE STUDENT：The big bang theory?

MALE PROFESSOR：Exactly. And that theory, that 15 billion years ago an explosion started the expansion of the universe, well, at the time that was a pretty revolutionary idea.

MALE STUDENT：And the Hooker telescope was responsible for that?

MALE PROFESSOR：Yes, because it allowed us to see that far, and being able to see that far led to, well it led to the big bang theory…

But let’s move on. The reading assignment discussed another tool for scanning the universe: the interferometer.

Claudia, what can you tell me about interferometers?

FEMALE STUDENT：OK. An interferometer is a machine, made of two or more conventional telescopes.

I think the example they gave in the book was made from six?

And they’re spread out; they’re not right next to each other.

And then the light, the starlight that those telescopes gather, travels through pipes to some computers, and then the computers put all the light together to make one image.

MALE PROFESSOR：OK. Good. Although, maybe that explanation is a bit simplistic.

There may be a thousand or so meters of pipe carrying the starlight from the telescopes to the computers.

And then getting all those components to work together, to synchronize, so the light from all the different telescopes reaches the computers at exactly the same time, that’s the challenge of working with interferometers.

What else can you tell me, what’s the advantage here, Paul?

MALE STUDENT：Alright, I think the idea isn’t that it sees farther, but that the image you see is a lot sharper. There’s more detail.

MALE PROFESSOR：A lot more detail. The image we get is something like 50 times finer than what you get with a single-mirror, conventional telescope.

So, why is that important?Now, think back a minute.

A couple weeks ago we looked at Castor, in the Gemini constellation. What do you remember about that?

FEMALE STUDENT：Well, through our telescope here, a conventional telescope, Castor looked like a single star, but you told us that it wasn’t.

It’s actually six stars orbiting, kind of dancing, around each other. Oh, I get it.

MALE STUDENT：And an interferometer would be able to see six separate stars?

MALE PROFESSOR：Yes. Remember, single stars like our Sun are the exception, not the rule. So more often than not you have two, three, or more stars clustered around each other, like Castor.

Not only that, but even a star’s dimensions, um, a conventional telescope won’t tell you, you can’t determine a star’s dimension because you can’t tell exactly how far away it is.

And there are other things as well: How do stars behave as they age?

Why do they cluster together? What was our Sun like in the past? Can we predict giant flares or periods of dimming?

And interferometers will certainly help us find planets, and of course the more planets you find, the greater the possibility of finding planets that may support life.

MALE STUDENT：So do you think interferometers will have the kind of impact the Hooker telescope had?

MALE PROFESSOR：I doubt it. Remember, big bang was a really revolutionary theory.

But then again, if an interferometer is used to locate a planet that supports life… well that’s another story altogether.