Marek Kukula and Richard Dunn take a closer look at telescopes

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Marek Kukula and Richard Dunn take a closer look at telescopes

Telescopes aren’t just for gazing at the stars, as Marek Kukula and Richard Dunn find out. Join them on tour of a new display of telescopes at the Royal Observatory.

Marek:
Hi, I’m Marek Kukula. I’m here at the Royal Observatory with my colleague Richard Dunn.

Richard:
Hi.

Marek:
And we’re here to see a new telescope exhibition. Richard, why do we have an exhibition of telescopes now? What’s the significance of right now?

Richard:
Well, right now is the 400th birthday of the telescope, or at least we know that 400 years ago a man named Hans Lipperhey appeared in The Hague and said, ‘Hey, I’ve got this new invention!’ And that’s what started it all.

Marek:
Well, I’m an astronomer. I’m used to using telescopes like the Hubble. Looking at the things in the glass case some of them look a little bit unfamiliar to me. Are they all astronomical instruments?

Richard:
No, far from it. I mean, one of things we’re trying to get over in this exhibition is that most of the telescopes ever made are about doing other things than astronomy. They’re about navigating on ships at sea; they’re about armies on land; they’re about personal accessories; spying on your neighbours; things like that.

Marek:
OK, so it’s not all about astronomy then. But we do have a portrait of Galileo on the wall. And I guess the significance of that is that a year after the first recorded incidence of the telescope Galileo modified it and used it for his famous observations of the Moon and of Jupiter.

Richard:
Yeah, that’s right. A lot of people think that Galileo invented the telescope and that’s one thing I’d love people to take away, he didn’t. But what he did though was make it into a scientific instrument, into an instrument for astronomy.

Marek: Do you have a favourite out of all the instruments that we have on display?

Richard:
Yeah, I think I do. In fact, our earliest dated telescope from 1661, which is still 50 years after the invention. It’s a very beautiful but very unusual trumpet-shaped telescope and there’s only about half a dozen surviving in the world and it’s just one I’m particularly drawn to.

Marek:
It certainly looks very striking.

If we move around further along into the exhibition there’s a bit that we can actually get our hands on and play with. And as an astronomer I’m particularly interested in this because it’s a comparison between a refracting telescope, which uses lenses to focus the light, and a reflecting telescope, which uses mirrors to focus it and to produce an image.

Just to try and explain what’s there, we’ve got some little model planets set up and you can look through each of the two telescopes and see the quality of the image that you get through both.

It’s interesting to me because as a modern astronomer we tend to use entirely reflecting telescopes so it’s very interesting to be able to compare them in real life.

Richard:
Yeah, absolutely. Well, you know, visitors have got to be able to look through telescopes because that’s what they’re there for. That’s why we’ve put that in, just to get over that simple idea of the different telescopes. It’s interesting, you say, the difference from nowadays. I mean, how do they differ to you as a modern astronomer?

Marek:
Well, as I said, most of the telescopes that we use now are reflecting telescopes that use mirrors. And the reason for that is it’s much easier to make a very large mirror than it is to make a very large lens and still preserve the optical integrity of the instrument.

But it’s also quite interesting for me to actually look through a telescope because actually as a modern astronomer you very rarely get the chance to do that. These telescopes are so big and so expensive that you wouldn’t waste the light by shining it onto the retina of an astronomer, you send it straight into an electronic detector and then analyse on a computer.

Richard:
So, exactly how big are they?

Marek:
Well, the telescopes that you hear about in the news at the moment, the biggest ones tend to be on islands like Hawaii or in the Andes in Chile, and they tend to have mirrors which are eight to ten metres across. So, if you compare that to the largest mirrors in the exhibition at the moment, I don’t know, probably you’re talking 10 or 15 centimetres. The reason for this is that they can collect huge amounts more light and therefore image much, much fainter and more distant objects.

Richard:
Yeah, they obviously are very different. There must be similarities too.

Marek:
I guess the greatest similarity is that, just as in Galileo’s time, 399 years ago, the observations that we’re making with telescopes like Hubble and Gemini and the very large telescope in Chile are still revolutionising our view of the Universe that we live in.

Richard:
Yeah, so in some sense not a lot has changed.

Marek:
No, I think there are great similarities there.

Well, thanks very much Richard for showing us around the exhibition. The exhibition is on at the Royal Observatory right now. It’s open from 10 till 5 every day and it’s absolutely free.

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