Outer Limits The Sky at Night


Outer Limits

Patrick Moore discusses the ice giants Uranus and Neptune, while Arthur C Clarke talks about his vision of bases on the moon in a newly-found episode from 1963.


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Transcript


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Good evening.

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For this programme we're going to go right out

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to the edge of our known solar system.

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Beyond Jupiter and Saturn there are two more giant planets -

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Uranus

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and Neptune.

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We call them the ice giants because they're

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very different from the two gas giants, Jupiter and Saturn.

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With me, two experts, both from Oxford.

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Dr Leigh Fletcher and Chris Lintott.

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Can I ask you, Leigh, so what are the main

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differences between the ice giants and the gas giants?

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In fact, we knew very little about the ice giants before Voyager 2

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flew past in the late 1980s.

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Voyager flew past Uranus and saw a greenish disc with very little

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cloud activity taking place over the disc itself.

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It was a really boring planet, let's be honest about this!

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Lots of scientists looked at it and were disappointed -

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we were used to Jupiter and Saturn,

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-and seeing incredible storms and banded systems.

-You won't see storms and rings there.

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They happen, you won't see them.

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And in fact that's been revealed in the 25 years since Voyager 2

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that we've got a large data set of Hubble space telescope

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and ground-based observations of Uranus, which show that we simply

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flew past at a rather boring time

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and in fact it's become a lot more active now, with white spots,

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incredible colours around the north pole and the south pole.

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Uranus and Neptune are twins, they are dissimilar twins. Why?

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Voyager 2, when it flew past Uranus, gave us an idea of what we thought and ice giant should be like.

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When we got out to Neptune we realised those ideas were again wrong

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because Neptune has its own source of internal heat.

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It basically emits out more energy that it's receiving from the sun

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and that emission of heat is driving a really complicated weather pattern.

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We see incredible storms,

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such as the great dark spot which was present in Neptune

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when Voyager 2 flew past in 1989.

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But we haven't got that with Uranus.

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Apparently there there's little or no source of internal heat.

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Why not?

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Well, this has got something to do with the dim, distant past

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of our solar system and the way the ice giants formed in the first place.

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Something, back in Uranus's distant history,

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must have changed the planet into its present inclination.

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-Because it's really weird.

-It's extremely strange.

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What we should say is that Uranus has been tilted completely on its side.

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Now, the Earth, and Neptune in fact, have a tilt of about 23 degrees.

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-26 for Neptune.

-So if this is the sun and this is the Earth, you're there.

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There you go.

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It means that the planet is rotating like this

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so it suffers from seasons in the same way the Earth does.

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Uranus, on the other hand,

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has got such an extreme tilt that it spends many, many years

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with just one pole of the planet

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facing towards the sun and, in fact, when we flew past

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in 1986, the south pole of Uranus

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was pointing straight back towards the sun.

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What do you mean by the south pole?

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The south pole has been defined by the International Astronomical Union

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-as being the pole which we flew past.

-Yeah, so stop being awkward. Another point...

-Point taken!

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There's another critical point here, as well. If this is our...

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our Uranus, and the planet's spinning like this,

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all the moons are in line with that axis as well.

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So why do people think this is tilted?

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It can't be, surely?

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Well, one of the most popular theories out there today

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is that something in the past hit Uranus...

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-A large impact.

-Some kind of large impact.

-Where is it now?

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The impact would have melded the two planets together, such that

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what we see as Uranus today is the agglomeration

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of multiple impacting bodies.

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-You don't sound convinced.

-I'm not.

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So how would you tilt your axis?

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Years of planetary migration. Interaction with Uranus

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and the other giants gradually tilted it over.

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Well, during the migrational period, there is a very good chance

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that collisions of this sort were happening.

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In fact, the motions in these planets is causing gravitational instabilities

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and it's flinging material around all over the place.

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I have a silly question, which... You were talking earlier about ice giants, Patrick.

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-But we're not looking at ice, we're looking at gas.

-Of course.

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So why do we call them ice giants - why aren't they just gas giants?

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-Cos they're icy!

-Well, yes, but where's the ice?

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-It's an important point and it does confuse a lot of people.

-Confuses me!

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The reason we call these things ice giants

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is because the material they're actually made of, planetary scientists call ices.

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So things like methane, ammonia, water

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that have condensed to form solids in the outer solar system.

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Now, these have all been incorporated into the interiors of these

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two ice giants, but even then they're not ices

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as you would imagine water ice being.

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If I'd come through the atmosphere and stayed alive,

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would I hit a solid icy surface?

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You won't hit solid surfaces, you'll see these ices are slowly being pressure cooked.

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The pressure is so immense at the centre of these giant planets

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that the ices take on a very alien and exotic form.

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Now, in Jupiter and Saturn it's hydrogen and helium

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which consists of most of the bulk of these planets

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and hydrogen takes on something called a metallic form and this is conducting

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and that's where we believe we get the magnetic field of the giant planets from.

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Now, on Uranus and Neptune,

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there isn't as much hydrogen helium

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cos there simply wasn't as much available in the outer disc when it formed.

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So the thing that gets pressure cooked are these ices

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that you're talking about and those ices that are in a sort of molten,

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fluid state within the interior,

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they are still conducting,

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so Uranus and Neptune do have magnetic fields,

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but even those are extremely odd - tilted and offset.

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-There's a lot that we simply don't know about them.

-It occurs to me.

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I mean, we talked about the great dark spot a bit

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and you now tell me that Uranus is interesting again.

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I know I've been abusing Uranus so maybe I should stop being cruel to it.

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So over the last quarter century, Uranus, which was dull and bland

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at the beginning, seems to have taken on a more Neptune-like appearance.

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By that I mean it's become a lot more active.

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So it must now be, what, autumn or spring on different bits of Uranus?

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So the north pole of Uranus is slowly coming into sunlight

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for the first time in 40 years. It takes eight years to go round

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so it's springtime in the northern hemisphere and that means

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suddenly you've got energy being deposited from the sun into Uranus's atmosphere,

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which is triggering all these fantastic weather-like systems.

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And that's why I believe we must ultimately send another space craft back to Uranus

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other than Voyager 2. Voyager 2 flew past so quickly, it gave us just a snapshot

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-of the dynamics...

-We want a Uranus orbiter.

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We would love to see something going into orbit around Uranus

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to explore the moons and to explore the rings of Uranus

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and the atmosphere and interior,

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but I think the big step change in our understanding of ice giants in general

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would be if we were to send a probe into Uranus.

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Now, we did this once with Jupiter, back in 1995.

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The Galileo probe went in and sampled the gases and figured out what the chemical make-up of Jupiter was.

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But if we did that for an ice giant as well,

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it would be a wonderful advance for our science.

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Both Uranus and Neptune have rings and satellites, so what about them?

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I think the most interesting out of all of the Uranus and Neptunian moons

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is a moon called Triton. Now, Triton is a big moon in orbit around Neptune.

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-Not a genuine moon, though.

-But it's not a genuine moon.

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By that we mean that instead of forming from the same disc that Neptune formed from,

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it looks like it's been captured by Neptune's gravitational pull.

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-We know that cos it's going backwards.

-It's going in a different direction to all of the other moons.

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Very like Pluto.

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That's right, in fact, the surfaces of both Pluto and Triton -

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if they did form in the same place, this shouldn't be a surprise -

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they're covered in surfaces of nitrogen and possibly methane

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and carbon monoxide, condensed onto the surface.

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Now, the interesting thing about that

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is that when Pluto and Triton get close to the sun,

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the sun's energy heats them up

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and it causes them to sublimate off - basically they form a gas

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which forms a very, very thin tenuous atmosphere around these moons.

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The last thing to say about Triton is that with Voyager's fly-by,

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we actually saw active geysers on the moon itself,

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and that makes Triton one of the most interesting places

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in our solar system in having some sort of volcanic activity.

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It's a bit like the moon is being flexed by the gravity

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of Neptune, I would assume.

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What they saw with the geysers themselves is that most of them

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were clustered around where the sun's energy was the greatest,

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so it looks like the influence of solar radiation has some effect

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on destabilising the surface,

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and that's why you see these amazing plumes in the old Voyager movies.

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Well, we've come a long way, and thank you both very much.

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Uranus was discovered in 1781 by William Herschel.

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There's a Herschel museum in Bath and Paul Abel went there.

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The Herschel Museum is in the heart of Bath

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and this beautiful Georgian house was once home

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to the great William Herschel and his sister Caroline.

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German-born Herschel arrived in England fleeing the Prussian War.

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He was penniless and made the spa town of Bath his home,

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earning his living teaching young ladies music.

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He brought over his sister Caroline to run his household,

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and together they became two of our greatest astronomers.

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Well, this is Herschel's piano because he was first a musician,

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then he became a rather prominent astronomer, and look at this -

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this is brilliant - a picture of

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the "distinguished men of science of Great Britain living in 1807"

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and there's Herschel, right on the end.

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'Wandering thought the museum,

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'you really feel Herschel's passion for astronomy.

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'These are his original telescope eyepieces.

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'Just think, Herschel would have looked through these

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'to map the night sky.'

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'Herschel also made his own mirrors,

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'striving to improve the magnification

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'so he could see further into the heavens.'

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Well, here we are in Herschel's workshop

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and it's here that he made the telescope mirrors,

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not just for himself, but for other astronomers as well.

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Back then, telescope mirrors were made of metal

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and he'd take the blank, put it in this device and spend

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many, many hours polishing the mirror until it gained the desired shape.

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It's here that he made the telescope mirror for his famous

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seven-foot telescope, which is upstairs.

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The one he used to discover Uranus. So let's go upstairs and take a look.

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Herschel was eventually to become famous for his enormous 40-foot telescope in Slough.

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But in Bath, he had a more modest reflector.

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Here it is, a replica of the seven-foot telescope

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used by Herschel to discover the planet Uranus.

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In doing so, he became the first person in human history

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to discover the existence of another large planet

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far beyond the orbit of Saturn,

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thus opening up the icy depths of the solar system to us.

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With the discovery of Uranus,

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the Herschels became overnight 18th-century celebrities.

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The King and many others came calling.

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Jonathan Hall is one of the resident astronomers helping to promote and preserve

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the work of William and his sister Caroline.

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Back in the 18th century, Herschel's night-time activities

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were viewed by the good people of Bath as unusual.

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His local reputation as being a little bit eccentric

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and very keen on the sciences and mathematics and optics.

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He would set his early telescopes up in the street

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and the horse and carriages were obliged to go round him.

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He wasn't what today we might think of as a professional scientist.

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He was purely amateur

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and he was building these telescopes

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with the aid of his brother and local craftsmen

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to arguably the best standard of the time.

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And he made mirrors for other people as well,

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-many other prominent astronomers.

-He did indeed. Yes.

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Even in his youth,

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he started to read books on astronomy,

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read books on optics.

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He'd been teaching himself a little bit of Greek.

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He taught himself Italian and Latin,

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partly because of his music interests as well.

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-So much self-taught.

-Incredible, yes. Very tenacious.

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But it was really when he came to Bath

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that it really started to take off.

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This is how the night sky would have looked on March 13th 1781.

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In the constellation of Gemini, there was an object, which other

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eminent astronomers such as Flamsteed and even Galileo had overlooked.

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Herschel immediately knew that this was something special.

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He wasn't actually looking for a planet.

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He'd only just moved back into the house.

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They'd been in a previous property.

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In fact, rather unusually, he was on his own.

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-Because Caroline normally observed with him.

-Absolutely.

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He set the telescope up here in the garden

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doing the systematic review of the heavens and there trained it on

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the constellation of Gemini and that's where he made the discovery.

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-And that brand-new world needed to be named.

-It did indeed.

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-For a long time, people wanted to call it Herschel.

-Yes.

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He wanted to name it after his patron, King George III.

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In a lot of the old texts,

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you can find it listed as Georgium sidus for George's star.

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That's right.

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Herschel, of course, was no fool.

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Patronage in those days was immensely important.

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The other link, of course, is that King George III,

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part of the Hanoverian Empire.

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Herschel was from Hanover.

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So, as part of the patronage,

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the King created a brand-new post for him.

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He had to leave his life here in Bath

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so he could be at the beck and call of the King and the Royal Family

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to be able to go and show them the wonders of the heavens.

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It's remarkable, over the two or three years

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immediately following the discovery, all the eminent people

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from around the world and Europe, who would come and pay homage

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and their respects and want to look through a Herschelian telescope.

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The planet was eventually named Uranus,

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which in Greek mythology is the father of Saturn.

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It's in our night sky at the moment

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in the constellation of Pisces, the fishes.

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It took some time to find it,

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but I made this drawing of it the other night.

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Herschel discovered this strange world over 200 years ago.

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It changed his life for ever and guaranteed him

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a place in astronomical history.

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The Herschel Museum, well worth a visit if you are in Bath.

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Herschel always makes me think of you,

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because he was a musician and an astronomer as well.

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You've played some of Herschel's music?

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I'm a very amateur musician. I've never had a lesson in my life.

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But I borrowed some of Herschel's music once

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and played it live on the piano.

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Was it any good?

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-His music is!

-I wasn't asking about your piano playing!

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I got through it.

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GENTLE PIANO MUSIC

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We've come a long way now,

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so let's go even further out of the solar system

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and come to the Kuiper Belt,

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from which the best-known member is of course Pluto.

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Pluto is a very similar object to Triton,

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in that, it has, over the surface,

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ices of things like nitrogen and carbon monoxide,

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that over the course of Pluto's extremely long orbit around the sun,

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will sublimate off to form a kind of atmosphere.

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When it was discovered, by my old friend Clyde Tombaugh,

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it was thought to be at least the size of Mars, probably larger,

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and therefore of planetary status.

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So we regarded it as a planet

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and it has been demoted.

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It's been demoted, that's true,

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but I'm not sure it's particularly because

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Pluto's smaller than we thought -

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though it is, it's smaller than Mercury.

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-But it's more that we've found lots of other things this size.

-It's not the only one.

-No.

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So we have the choice of having eight planets,

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as we do, from Mercury out to Neptune,

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or many, many, many planets.

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And we call those the Kuiper Belt -

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Pluto and Pluto-like objects on one part of it.

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Of course, the most exciting thing about Pluto

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is that's there's a spacecraft on the way, New Horizons,

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which was planned - not that it matters -

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but it was planned while Pluto was still a planet,

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and a big part of their pitch

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-was this was the last planet that we haven't seen.

-Quite.

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But where's New Horizons got to now? It's a few years away yet.

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So it's still on its way to Pluto,

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it's going to get there in July of 2015

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and it's just got past the orbit of Uranus.

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That doesn't mean it visited Uranus,

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but it's on its way to do a slingshot by Pluto.

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And after Pluto,

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it's going to go on to look at another Kuiper Belt object.

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-Which hasn't been discovered yet.

-No.

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It's something that we're still looking for at the moment.

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Pluto is the brightest member of the Kuiper Belt,

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it's certainly nothing more than that.

0:17:440:17:47

Recently there was a big conference in France about these things

0:17:470:17:51

and Dr Chris North went there

0:17:510:17:54

and brings us back news from the Kuiper Belt.

0:17:540:17:57

This year's annual gathering of planetary scientists in Nantes

0:17:570:18:01

was the largest for many years.

0:18:010:18:03

For space scientists,

0:18:030:18:05

it's a great place to talk about missions to the planets,

0:18:050:18:07

and for the astronomers,

0:18:070:18:09

a platform to launch their new ideas.

0:18:090:18:11

This year, the icy, dark depths

0:18:110:18:14

of our solar system have caused a bit of a stir.

0:18:140:18:17

The Kuiper Belt stretches beyond Neptune

0:18:200:18:23

and has previously been dismissed as the dustbin of the solar system,

0:18:230:18:27

the leftovers of its formation.

0:18:270:18:29

Meg Schwamb has been raking through the rubbish,

0:18:300:18:33

to find clues about the Kuiper Belt and its formation.

0:18:330:18:35

We now know that there are lots of exotic objects out there.

0:18:380:18:42

They come in a range of sizes

0:18:420:18:44

and some, such as Pluto, even have moons.

0:18:440:18:47

While many formed in these icy outer depths,

0:18:470:18:51

others formed closer in

0:18:510:18:52

and were flung out there by the movement of the giant planets.

0:18:520:18:56

The Kuiper Belt really is

0:18:570:18:59

the icy remnants left over from planet formation.

0:18:590:19:01

You can think of it as the embryos and the failed planets

0:19:010:19:04

that didn't form into the terrestrial planets

0:19:040:19:07

or the cores of the giant planets

0:19:070:19:09

and have been scattered out, or may have formed out,

0:19:090:19:11

in orbits beyond Neptune.

0:19:110:19:13

And so Pluto is one of the well-known and largest of these objects

0:19:130:19:17

and there are now many Pluto-sized bodies known in this region,

0:19:170:19:21

as well as many hundreds of thousands of other smaller bodies

0:19:210:19:24

that orbit well beyond Neptune.

0:19:240:19:27

In 2007, Meg discovered an object nicknamed Snow White,

0:19:270:19:32

one of the largest Kuiper Belt objects

0:19:320:19:34

at around half the size of Pluto.

0:19:340:19:36

Despite its name, Snow White is actually red.

0:19:360:19:40

The colour is caused by a tarry gloop called tholins,

0:19:400:19:44

a term coined by Carl Sagan.

0:19:440:19:46

We think tholins are methane and other chemicals

0:19:460:19:50

broken down by weak sunlight over billions of years.

0:19:500:19:53

I don't think we've quite touched tholins in the outer solar system,

0:19:550:19:59

but we think that if you take these methane ices and nitrogen ices

0:19:590:20:04

and you keep radiating the methane,

0:20:040:20:06

you get a higher and higher order of hydrocarbons,

0:20:060:20:08

and so you get more gunk and tar.

0:20:080:20:10

And so, that's what we think it is

0:20:100:20:12

and we think it's reddened their surface.

0:20:120:20:14

And so it's sort of this red crust, or radiation crust,

0:20:140:20:18

sitting on the surface.

0:20:180:20:19

-It's goo.

-It's goo, it's sort of, yeah...

0:20:190:20:21

-It comes from the Greek word for muddy, I believe.

-Yes.

0:20:210:20:24

Kuiper Belt objects are the preserved remnants of our early solar system

0:20:240:20:28

and they tell us what is was like billions of years ago

0:20:280:20:31

when the planets were forming.

0:20:310:20:32

But studying it can be very frustrating,

0:20:320:20:35

as the objects are so small and so very far away.

0:20:350:20:38

Occasionally, however,

0:20:380:20:40

we get visitors from the outer limits - comets.

0:20:400:20:44

'Mike Ahern has led one of the most successful mission to not one,

0:20:470:20:51

'but two comets.

0:20:510:20:52

'In July 2005,'

0:20:520:20:55

part of the Deep Impact probe was smashed into Comet Tempel 1,

0:20:550:20:59

giving our first view of material from inside a comet.

0:20:590:21:02

Following this successful mission,

0:21:020:21:05

the Deep Impact spacecraft was re-routed

0:21:050:21:07

and in November 2010,

0:21:070:21:09

flew past Comet Hartley 2

0:21:090:21:11

where it saw a very different world.

0:21:110:21:13

Every comet we've visited

0:21:130:21:14

has been very different

0:21:140:21:16

from what we would have predicted from the previous one we visited.

0:21:160:21:21

So that's the reason for going to multiple ones -

0:21:210:21:23

to try to find a pattern.

0:21:230:21:25

One difference between Tempel 1 and Hartley 2,

0:21:250:21:28

the two that Deep Impact spacecraft visited,

0:21:280:21:30

is they're very different sizes

0:21:300:21:32

and very different activity for their size.

0:21:320:21:35

On Tempel 1 we saw differences in the outgassing

0:21:350:21:39

from different parts of the comet.

0:21:390:21:42

Now, does this mean different parts of the comet

0:21:420:21:44

came from different parts of the proto-planetary disc?

0:21:440:21:47

It was hard to tell...

0:21:470:21:48

-Because they're made of different stuff.

-Yeah.

0:21:480:21:51

But there could be still strong seasonal effects on Tempel 1.

0:21:510:21:54

Now, at Hartley 2, it's in this excited state rotation

0:21:540:21:57

where in addition to going around like this, it rolls.

0:21:570:22:00

So everything gets illuminated all the time

0:22:000:22:02

and there are no strong seasonal effects.

0:22:020:22:04

And we still see big differences

0:22:040:22:06

between the outgassing at the two ends,

0:22:060:22:08

which says that they really must have come,

0:22:080:22:10

in the early solar system, from different distances from the sun.

0:22:100:22:14

-So they are different?

-They really are different.

0:22:140:22:16

Comets, the archaeological remains of our early solar system,

0:22:170:22:20

will help us understand

0:22:200:22:22

how the planet Earth became such a unique world.

0:22:220:22:24

It's important, because, for one thing,

0:22:240:22:27

we think the comets bring all the water to Earth,

0:22:270:22:29

or at least some of us have thought that all along.

0:22:290:22:31

Is that just because Earth's the only planet we know with standing water...

0:22:310:22:36

-That's correct.

-..on its surface.

-Yes.

-And the early Earth,

0:22:360:22:39

-that should have all boiled off.

-Exactly.

0:22:390:22:41

-So where did it come from?

-So it has to have been brought in at a somewhat later stage -

0:22:410:22:45

-only half a billion years after the formation, but...

-A long time ago.

0:22:450:22:49

The Kuiper Belt is clearly not the dustbin of the solar system

0:22:510:22:54

and the exotic objects that live there are far more than just rubbish

0:22:540:22:58

thrown out during its formation.

0:22:580:23:00

Instead, each one is a fascinating world

0:23:000:23:04

and the more we find out about them,

0:23:040:23:06

the more we find out about our own origins.

0:23:060:23:09

Plenty of news this month

0:23:100:23:12

so we'll go now to Chris North and Chris Lintott.

0:23:120:23:15

A huge storm going on on Saturn.

0:23:150:23:19

A huge storm that's been going on for most of the last year.

0:23:190:23:22

It was discovered last December as this white spot,

0:23:220:23:26

which is the form storms on Saturn normally take,

0:23:260:23:28

but this one spread out until it covered quite a lot of the disc.

0:23:280:23:32

-Huge.

-You can see it in these new images that we just got from Cassini

0:23:320:23:35

that were taken over the last year.

0:23:350:23:37

Of course, the amateurs saw this as well.

0:23:370:23:39

Then they saw the storm fade over time

0:23:390:23:42

and it seemed like all was quiet on Saturn.

0:23:420:23:44

But if you talk to the professionals who can use

0:23:440:23:46

some really big telescopes and they can look in the infrared,

0:23:460:23:49

they see that actually what's happened is up in the top

0:23:490:23:52

of Saturn's atmosphere, in what would be the stratosphere,

0:23:520:23:56

there's still a lot going on.

0:23:560:23:58

The storm now covers about a quarter of the disc,

0:23:580:24:01

so all of the northern bit you can see on one side.

0:24:010:24:05

But as it emerges in January, we're going to see

0:24:050:24:07

some interesting things happening

0:24:070:24:10

where this storm was last year.

0:24:100:24:12

-I wonder what we'll see.

-We'll find out.

0:24:120:24:15

Coming into Jupiter and the second moon there, Europa,

0:24:150:24:19

interesting news?

0:24:190:24:20

Europa's this moon that's got the very weird terrain.

0:24:200:24:23

We call it chaotic terrain. It was terrain that the Voyager probes and Galileo saw

0:24:230:24:27

covered in cracks and fissures and all sorts.

0:24:270:24:31

-Map-maker's nightmare.

-Indeed. Map-maker's complete nightmare.

0:24:310:24:34

What we think is happening still is that that's cracked

0:24:340:24:37

and broken up by the motion of a sub-surface ocean.

0:24:370:24:42

We can compare that to stuff we see on the Earth.

0:24:420:24:45

Some of the features look like things we've seen in Antarctica,

0:24:450:24:49

with a sub-surface sea or lake that's not quite that deep.

0:24:490:24:52

I'm quite excited about this because

0:24:520:24:53

it's been my favourite idea for a mission anywhere in the solar system,

0:24:530:24:57

which is you land on Europa, melt your way through the surface

0:24:570:25:00

and you see something with teeth coming towards you.

0:25:000:25:03

The reason people care about this ocean is

0:25:030:25:07

it's an interesting place to think about life.

0:25:070:25:09

It could well be.

0:25:090:25:10

Life on Earth, we think, started in deep oceans

0:25:100:25:13

without much sunlight, so Europa's a fascinating world.

0:25:130:25:16

They all are. Of course, you can't get away from Mars.

0:25:160:25:19

Always something new there and,

0:25:190:25:21

of course, this new probe Phobos-Grunt.

0:25:210:25:24

Yes, this was a Russian probe that was meant to go to Mars's moon, Phobos,

0:25:240:25:29

collect a sample, bring it back to Earth.

0:25:290:25:31

Unfortunately, it made it into orbit, it's been stuck there.

0:25:310:25:35

It's not sure what will happen, which is very sad.

0:25:350:25:39

The Russians have never had any success there.

0:25:390:25:41

It was incredibly ambitious. That would have been the first sample-return mission,

0:25:410:25:45

BUT we shouldn't forget there's good news for Mars this month as well,

0:25:450:25:49

which is that the American Curiosity rover is successfully on its way.

0:25:490:25:53

Lift off of the Atlas V with Curiosity.

0:25:530:25:57

We're going to find out a huge amount about Mars's past

0:25:570:26:01

and about whether there are the conditions for life there.

0:26:010:26:04

-So I'm really excited about Curiosity.

-So far, all goes well.

0:26:040:26:07

We have spacecraft separation.

0:26:070:26:09

APPLAUSE

0:26:090:26:11

One more news item.

0:26:110:26:13

We found a long-lost Sky At Night programme

0:26:130:26:15

on a recording machine and here it is.

0:26:150:26:18

I'm talking about moon bases tonight for two reasons.

0:26:230:26:25

First, because they are very topical

0:26:250:26:28

and we've just shown you one new design study.

0:26:280:26:31

But secondly because I am delighted to have with me

0:26:310:26:34

my old friend Arthur Clarke.

0:26:340:26:36

Arthur, you, of course,

0:26:360:26:38

were forecasting developments of this kind more than 20 years ago.

0:26:380:26:42

Thank you, Pat.

0:26:420:26:43

I'd like to begin with a flashback to the communication satellite

0:26:430:26:46

which you mentioned,

0:26:460:26:48

by showing this illustration which has some sentimental interest to me

0:26:480:26:53

because I displayed this on BBC TV about ten years ago.

0:26:530:26:57

This was undoubtedly the first time that anything

0:26:570:27:00

about communication satellites appeared on TV anywhere in the world.

0:27:000:27:04

So, this is a programme from 1963.

0:27:040:27:07

To put us in context, that was before Apollo.

0:27:070:27:10

Apollo was still in the planning.

0:27:100:27:12

We'd had people into space, but only a few probes whizzing past the moon.

0:27:120:27:17

Arthur C Clarke was predicting not only these communication satellites,

0:27:170:27:21

which were starting to become a reality back then,

0:27:210:27:25

but also was talking about bases on the moon, bases on Mars,

0:27:250:27:29

all incredibly exciting for what we might do

0:27:290:27:31

from then, in the next 20, 30 years.

0:27:310:27:34

I think a great deal has depended there upon

0:27:340:27:36

the question of the lunar atmosphere

0:27:360:27:38

because if the moon had proved to have anything of an atmosphere,

0:27:380:27:41

then the surface dome would have been the answer.

0:27:410:27:44

Do you think that this means that the lunar base

0:27:440:27:47

has got to go underground?

0:27:470:27:48

If it turns out that a meteor bombardment is a serious danger,

0:27:480:27:53

then, undoubtedly, we will have to put our bases underground.

0:27:530:27:56

But I rather hope that the necessity of a lunar underground movement

0:27:560:28:00

does not arise.

0:28:000:28:02

-I hope we can stay on the surface and look at the stars.

-So do I.

0:28:020:28:04

He and I were great friends.

0:28:040:28:06

This is one of the few recordings we made together

0:28:060:28:09

that's actually been preserved.

0:28:090:28:11

Yes, it's wonderful.

0:28:110:28:12

If you could have picked one Sky At Night out of those that were lost,

0:28:120:28:16

-this one would have been high on the list.

-I would agree.

0:28:160:28:18

You can see more clips

0:28:180:28:20

on the website, which is...

0:28:200:28:24

I'm going to watch it again and dream of Mars bases.

0:28:240:28:28

Thank you both very much indeed.

0:28:280:28:30

When I come back next month, we're going even further

0:28:300:28:33

and look at planets on other stars.

0:28:330:28:36

Until then, good night.

0:28:360:28:38

Subtitles by Red Bee Media Ltd

0:28:440:28:48

E-mail [email protected]

0:28:480:28:51

The outer limits of the solar system are a dark, cold and mysterious place, which only the Voyager spacecraft have visited. Sir Patrick Moore discusses the ice giants Uranus and Neptune, while Chris Lintott has an early Christmas treat - a lost episode of The Sky at Night from 1963 which has been returned to the BBC, in which Arthur C Clarke talks about his vision of bases on the moon and speculates when man will be on Mars.


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