Warp Factor 55 The Sky at Night

Good evening. The Sky At Night is now 55 years old.

And in celebration, we're going to take you on a journey

to the edge of the known universe,

and perhaps even beyond,

assuming, of course, that there is a beyond.

With me are the two Chrises - Chris Lintott and Chris North.

Chris, something about the speed of light itself.

Absolutely, because if we're going to explore this vast

universe of ours, we'd better go as fast as we possibly can.

We know, thanks to Einstein,

that the fastest thing in the universe is light itself.

-And Einstein has always been right.

-That's right.

So, as far as we know, this is the fundamental cosmic speed limit.

Nothing can travel faster than light.

And light travels at about 186,000 miles every second, which is a lot.

It's so fast that it was actually rather difficult for most

-of the last few hundred years to try and measure that speed.

-Indeed.

And so this ridiculous speed, 186,000 miles per second, which incidentally,

I like to think of, it's about a foot every billionth of a second.

-Ha!

-So, a foot per nanosecond,

which makes it slightly more comprehensible, I think.

But it's this speed that we have to attain

if we're to get anywhere in the universe.

Light reaches us from the sun in about 8.6 minutes.

And from the moon in just over a second.

That means that once we look beyond the Earth and the moon,

our view of the universe is bound to be very out of date.

Absolutely, and that can cause some problems.

Yes, logistically, when operating space probes

and Mars Rovers elsewhere in the Solar System,

they have a problem that the signal from Earth that we might want

to send to Mars, to a Rover, takes somewhere between five and 20

minutes to get to Mars, depending on where it is in its orbit.

The response from the Rover, which might say, "Yes,

"I've moved that meteor you wanted me to move,"

also takes between five and 20 minutes to get back to Earth.

So if someone sends an instruction for the Opportunity Rover,

for example, to drive just to the edge of that cliff,

they can send that instruction,

but it might be more than half an hour before they find out whether it

did it, or whether it ran off the edge of the cliff, or anything.

Logistically, that can cause problems.

You can't drive the Mars Rovers with a joystick in real time,

as fun as that would be.

The nearest star beyond the sun is over four light years away.

Absolutely, Patrick,

but we should explore the rest of the Solar System first,

-don't you think?

-Yes, we should indeed.

I've got this torch here, I've turned it on, with a beam of light.

That beam of light is going to go through the Solar System and beyond.

And Pete and Paul have been in my garden

and they're going to go along with this beam of light.

So, Patrick has sent out a beam of light from Farthings.

Now that is heading out through space at the amazing speed

of 186,000 miles every second.

It is, and we are going to chart

its journey through the known universe.

-So let's first start off here on the planet Earth.

-OK.

We'll be Intergalactic Lollipop Men! There's the Earth.

As it's the 55th anniversary,

let's go out to a position which is 55 light hours out.

So what we're going to do is use Patrick's garden

to introduce a sense of scale.

This garden gets used for an awful lot.

I don't think it's ever been used to represent the universe before!

No, it hasn't. Let's mark the position of 55 light hours here.

That indicates the position in the Solar System where light,

travelling at 186,000 miles per second,

would have reached after 55 hours.

Let's put in the rest of the Solar System. I have here Pluto.

-Why don't you be Pluto? Can you catch?

-OK, yeah.

-Catch!

I'll be the planet Saturn.

The planet Saturn is a mere eight inches away from the Earth.

In actual terms, it is about 1.5 light hours.

Of course, we have the lovely Cassini spacecraft out there doing

wonderful things. So, if I send out a transmission to Cassini,

it takes 1.5 hours to get to it.

Right. And anything that Cassini sends back to the Earth

also takes an hour and half.

That's right. It's a very slow conversation!

-Now, you've got the planet Pluto there.

-I have.

And Pluto would sit

about a metre away from the Earth.

So that's the sort of scale out to Pluto.

Of course, that isn't the end of it, is it?

-There's more beyond that.

-There is.

There's a little man-made object.

Do you remember Voyager 1?

I've got a little prop here for it.

-Have you drawn those?

-I have,

for the lack of anything else.

Voyager 1, launched in the late '70s,

went out into space and surveyed the planets.

That, even travelling at the speed

it is, is little more

than a third of the distance away.

OK, so a third of the distance

-from the Earth to our 55 light hour marker.

-That's right.

The furthest man-made object.

And just look at that, Pete.

That's incredible.

The small bit of Solar System,

the furthest man-made object,

but look how much distance

there is still to go.

So that is actually the edge of

the Solar System there,

where Voyager is?

What have we got in this space beyond the Solar System?

There's not really a tremendous amount, apart from the odd comet,

-which you might find. I have a comet in my pocket.

-Do you?

-We can put that there.

-Must be uncomfortable!

This is a picture of a comet with a tail, of course.

Now, out this far, the influence of the sun would be pretty weak.

So any comet out here probably wouldn't have a tail

or anything around it like that.

It's only when it gets into the inner part of the Solar System

that all those effects take over.

-That takes us back to the very first Sky At Night.

-It does.

The very first one was accompanied by

Comet Arend-Roland,

which has now been flung out of the Solar System and will never return.

But to go out further,

so we're going out into the stars,

we have to look at scales which are much, much larger than this.

We do. We have to up from light hours to light years.

Our light beam is now travelling beyond 55 light hours

and we're going to 55 light years.

Let's find out what's out there.

We've gone out now to 55 light years.

So, let's pause to see what we've found on the way.

Well, we've already passed about 200 of the naked-eye stars,

the ones we can see from Earth without telescope or binoculars.

And those are the stars that are cheating, really,

that appear bright in our sky, because they're not intrinsically

brilliant, they're not particularly luminous, but they're close

and so they appear bright. We've left them behind us.

Interestingly, we've passed a couple of thousand stars now,

and 80 of those we now know have planets.

So we may well have passed other worlds like the Earth

and other solar systems like our own.

Given that this is out here at 55 light years,

we are just receiving the first transmission of The Sky At Night.

If there is life on any of those thousands of stars that we've passed,

they'll be enjoying your programmes.

-They'll now know all about us.

-Absolutely.

I'm sure they're entering your competitions and writing in

and sending in their observations as we speak.

One of the fascinating things about going so far out

is that we've gone 55 light years,

we've only passed a couple of thousand stars.

It sounds like a lot, but if you look at the distance

between the stars, it's actually immense compared to the size

of the stars themselves.

So if we scaled the sun down to a millimetre across,

that's about the size of a pinhead, and we put it in the middle of London,

outside the Houses of Parliament, on top of Big Ben or something,

the next nearest star on that scale would be where the M25 is,

25 miles away, that kind of distance.

They are incredibly far apart, given their size.

So what this tells us is that in terms of stars,

space is pretty empty.

There's a bit of gas and dust there as well.

We've explored 55 light years, it's time to move on.

Pete and Paul can show us where we're going next.

So, Paul, as we represent our light beam journey across space

with our garden scale model, I've got the Earth here,

I've got a marker indicating a position 55 light hours out from Earth,

and you're indicating the position 55 light years from Earth.

That's right. But we want to step up to the next level, which is 5,500.

And I've got a marker to indicate that one here.

Once more, we've become galactic lollipop men.

Let's compress space and set the model up.

-So, I'm going to bring the 55 light years back down here.

-OK.

And I'll mark the position here,

which represents where the light beam would have got

if it had been travelling at light speed for 5,500 hundred years.

So, I'm going to remove the 55 light hours

and here becomes the distance to 55 light years.

I'll tell you what, Paul, the view from here is mighty fine.

-Yes, that's most of the stars we can see in the sky.

-That's right.

Every individual star we can see in the night sky

sits in a sphere around the Earth,

which has approximately got a radius of 5,500 light years.

Well, as we've set up the scale model, Pete,

-let's put in some of our favourite night sky objects.

-OK.

Here we have the Earth, 55 light years.

All the little bystars go in this little bit.

So, we have Syrius.

-That's the brightest star in the night sky.

-Right.

8.5 light years.

-So, let's plonk that there.

-OK.

-Vega.

-OK.

-Lovely star, blue star in the Summer Triangle.

We'll plonk that there.

And in the constellation of Orion, of course, Betelgeuse.

-"The armpit of the central one," its name means.

-Oh, lovely.

You've just ruined it now.

We're going to put that around about the 700 light-year mark.

-OK.

-About there.

I have a representation for the Pleiades open cluster,

that beautiful cluster known as the Seven Sisters.

That's about 420 light years out.

So that would be about...

-there?

-Yeah.

-OK.

So you realise that 5,500 light years is an incredibly long way away

from the Earth, but you can still see individual stars out that far.

If we go right to the very boundary,

we find a star which is known as

Mu Cepehei, or Herschel's Garnet Star.

-A lovely deep red star.

-It's a very deep red star.

That sits roughly in this position here.

Isn't that remarkable?

From the Earth out to 5,500 light years,

the naked eye can see one little star.

-That's amazing, isn't it?

-That is remarkable.

We are now leaving 5,500 light years behind

and we are on our way to 5.5 million.

But first, we've reached a crossroads.

We have a decision to make now. What do you think, Chris?

The decision is a tricky one,

because we could keep going through the Milky Way.

We'd hit the centre of the galaxy in about 25,000 light years' time.

It's an interesting place, very dense stars, black hole in the centre.

You now, I want to get a view that we've never had before.

I want to head up out of the disk of our galaxy

and look back on the Milky Way,

the island universe that has been our home.

-See it as it really is.

-Exactly.

And the interesting thing is, it doesn't take that long for us

to leave the disk of the galaxy.

The disk is only a few thousand light years thick.

As we rise up above it, we'll see first the little spur of a spiral arm

that the sun lives in. You'd like to think we're in an important place,

but we're not in the middle,

not even in one of the impressive spiral arms.

We are in a little side arm, the suburbs of the galaxy.

As we head out, the first thing we encounter

as we get hundreds of thousands of light years away from the Milky Way

are some smaller galaxies.

-Oh, yes, dwarves.

-Yeah, so the Milky Way is by no means alone.

Surrounding it are a whole host of much, much smaller galaxies.

The largest of these smaller galaxies,

we call the Large Magellanic Cloud.

The second largest is called the Small Magellanic Cloud.

They are imaginatively named.

As we moved outwards and we carry on going,

we'll see more of these dwarves.

Eventually, we'll get far enough out

to start seeing some bigger galaxies.

If we get to 2.5 million light years away, we encounter

the brightest galaxy in our naked-eye sky,

the Andromeda Galaxy.

There is a third one, and that's the Triangulum Galaxy.

These three, along with a couple of dozen smaller galaxies,

make up a local group.

We said earlier on that stars are very, very far apart

compared with their sizes,

and so stars almost never collide.

Galaxies are much, much closer together

compared to their own sizes,

so we do sometimes see them collide.

But they are much, much closer

together than the stars are compared to their own sizes.

They are indeed.

So let's go back now to Pete and Paul in my garden

to show us the scale of the local group.

Let's get the cosmic wanderers to map out our journey

from 5,500 light years to 5.5 million.

-We have a model here of our own galaxy.

-Look, The Sky At Night plate.

This is a wonderful model. Made by Chris North, actually.

He did a very good job here.

We've got the core of the galaxy represented here

and then the spiral arms coming off, like so.

And we have little companions around the galactic core.

We have globular clusters.

That's right, these are little, sort of, condensations of stars

in a halo around our galaxy.

All gravitationally bound. M13 in Hercules is a good example.

They sort of hover around the galactic core, like this.

They do, but the globular clusters...

M13 is a good one you've mentioned.

That's an amazing object.

You can see that from the UK through a telescope.

It is beautiful thing to look at.

It contains anywhere up to an estimated million stars

in a sphere which is 145 light years across.

-Quite impressive.

-Very impressive.

They look like glowing spiders' nests to me.

I've never seen that, but OK.

-We have companions to our own galaxy too.

-We do.

-Our own galaxy is, what, about 100,000 light years across?

-Yeah.

So, next to our own galaxy,

we have two companion galaxies. In fact, there are a lot of

companion galaxies,

but these are two of the most prominent.

The large and small Magellanic clouds.

Right, visible from the Southern Hemisphere.

We can represent them in this rough position down here.

-So let's put the galaxy plate down here.

-And the Magellanic clouds.

-The two clouds, yes.

-Let's go see what's in the neighbourhood.

Let's go and meet the neighbours.

-And look at this!

-Another plate!

-This is the Andromeda Galaxy.

So, we are 2.5 million light years from Earth.

-This galaxy is much larger than ours, isn't it?

-It is.

This is quite an easy thing to see in the night sky

if you've got clear skies. Actually, if we look at that...

If you have that galaxy face-on like that, the Andromeda Galaxy

is tilted over a bit, so you see it as an elongated smudge.

We have these little satellite galaxies - NGC205

and M32 that accompany it.

If you look at them through a telescope,

a small telescope, it'll show those satellite galaxies quite closely.

-You need a wide field to see it.

-You do.

-What do we have here?

-This is a bit further.

This is just over three million

light years away. This is

the Triangulum Spiral, Messier 33.

This is a lovely galaxy,

although it is very difficult to see with the naked eye.

Where we had that one slightly tilted over, this one is face-on to us.

We see it like that.

And because of that, its light is spread out over a big area of sky.

It is. It is three degrees, which is six lunar diameters.

In the sky, it's not too far from the Andromeda Galaxy.

It's in the neighbouring constellation of Triangulum.

This is about three million light years away from Earth.

It is, so all these galaxies here,

and including some others, are what are known as the local group.

They're a group of galaxies

which are all gravitationally bound together.

-A family of galaxies, if you like.

-A family of galaxies.

This is all our local family and neighbourhood.

Right, the local galactic neighbourhood.

But the galaxies are all moving through space together.

To find out where they're going, we're going to have to go

a little bit further than our 5.5 million light-year marker.

Our journey continues to the edges of the known universe.

Well, I'm travelling with my beam,

starting from my garden in Sussex.

We've travelled 5.5 million light years, and that's quite a distance.

Well, Chris, where next?

Everything we've talked about, after all, isn't static, it's in motion.

The Earth is going round the sun,

the sun is going round the centre of the Milky Way Galaxy.

The Milky Way itself is moving to create those cosmic collisions,

those interactions with Andromeda

and M33, the Triangulum Galaxy that we talked about.

But from out here, all this way out, we can see that the local group

itself is moving, and it's being pulled

by the gravitational attraction of our nearby city of galaxies,

what we call the Virgo Cluster - a vast collection of many,

many galaxies, most of them more massive than our own.

One of the interesting things that can happen,

you get these enormous clusters of galaxies that they themselves

start colliding. You get clusters reaching clusters.

If you go even further out, instead of talking about hundreds

of millions of light years, we talk about billions of light years,

thousands of millions of light years.

Then you really start to see the honeycomb structure.

And you see the galaxies are arranged not just in walls,

but in a huge sort of arrangement of...

-Filaments.

-Yeah.

-Leaving huge voids.

-Yes.

There are areas where there are very, very few galaxies.

What would it be like to be in a galaxy there?

Very lonely, I think.

You'd have fewer astronomers to study the universe

cos you'd think you were in a special place.

If you were one of those few galaxies floating in the voids.

But you can see those void galaxies tend to be younger, so they're only

just forming now, cos they haven't had this long history of interaction.

And most of the action takes place in the filaments

and in these giant clusters where the filaments cross.

There is this very dynamic picture of galaxy formation.

Because by coming out to something like 5.5 billion light years,

I guess is the next natural stop, coming all this way out,

although we're seeing a huge scale, of course,

we're seeing processes that have happened

right across the 13.7 billion years of cosmic history.

So we can talk about these filaments colliding, galaxy clusters forming.

Don't you think the Milky Way looks insignificant

when you see a map of the universe like this?

Oh, it's very... It means nothing at all.

One more parochial note,

cos we should finish this tale of where we're moving.

We got as far as the local group heading towards the Virgo Cluster,

so you might want to know - what's pulling Virgo and the Virgo cluster?

And we've given a name to the thing. We call it the Great Attractor.

The Great Attractor.

Which sound like a terrible sci-fi movie, but the reason

we don't know much about the Great Attractor is that it's in a place

that's awkward for us to see from Earth.

If you remember, if you go back, we made that decision to come

out of the plane of our galaxy, to go up above the Milky Way.

Yes, we did.

But within the plane, the Great Attractor is hidden in

-what we call rather wonderfully the Zone Of Avoidance.

-Yes.

The part of the sky that we can't really look into the distance in

because it's blocked by the nearby galaxies.

So there's something down there, probably a very large cluster

or a place where a couple of these filaments cross

is this Great Attractor, this cluster to end all clusters

that is attracting something even as large as Virgo.

It would be very easy to get lost on this scale,

so we should probably take a brief pause

and look at something we'll be doing in a second

of our special episodes to celebrate the 55th anniversary

of The Sky At Night. It's called a Moore Marathon -

things you would actually see in the night sky.

And it's something you came up with in the 1960s, Patrick,

and we've managed to find some old Sky At Night footage.

Long, long ago.

Good evening.

So our first Sky At Night went out just over five years ago

and we have been told we can have more programmes,

which is just as well, because 1962 is going to be a busy year.

We've had a Russian and now an American, John Glenn,

in space, and the young President of America, John F Kennedy,

says he wants to land a man on the surface of the moon.

The Russians want to do the same and get there first.

It's really rather like a race.

There are, of course, a great many things to observe in the night sky

and people are frequently asking me, "Patrick, what shall I look at?"

It is for this reason I've come up with something new -

a Moore Marathon, full of objects observable in the night sky

throughout April, and I've chosen 55.

Seems like a good, symmetrical number to me.

Don't worry if you don't have a telescope,

a great many of these objects are visible with the naked eye,

although you may need to find a dark side.

So number one should be my old favourite object, the moon.

This is my moon globe here.

Visible is the missing section, the side normally turned away from us.

The Russians sent their Lunik 3 probe here to take a look.

Finally putting paid to that story

that the moon is made of green cheese.

For my April Moore Marathon,

I've included a great many constellations,

such as Cassiopeia at number four

and the Pleiades at number 14.

Should be visible with the naked eye,

but once again, by 2012, you might need to visit a dark side.

Then, we reach our binocular objects.

I recommend a good pair of binoculars.

These once belonged to a German U-boat commander.

I picked those up during my time in the RAF.

And this takes us to our telescope objects.

And so, let's go outside to my telescopes.

My dear friend Arthur C Clarke has some futuristic ideas about

a space station with people on board orbiting around the planet Earth.

So, I've included that at number 15.

I'm calling it the International

Space Station because we will all

have to work together internationally

if we are to explore space.

Now, this is my wonderful brass three-inch telescope

I received as a boy.

And the rings of Saturn look quite superb in it.

So, at number 39 in the Moore Marathon, the rings of Saturn.

I've been mapping the moon recently and I picked out some

fascinating objects for you to observe, visible even with a small scope.

Number 45 is the Alpine Valley, and at 46, the crater Clavius.

Quite, quite spectacular.

Mars, as you know, a great favourite of mine,

and in at 49, Syrtis Major on Mars.

There is still some debate as to whether or not this is vegetation

and we won't know for sure until a spacecraft is sent there.

And that won't be for quite some time yet.

So, back to mapping the moon.

Someone from the National Aeronautic and Space Administration

has been on the telephone.

As I was saying, they want to land a man on the moon

and need some advice as to where to go.

I shall recommend the Mare Tranquillitatis.

It's hard to think that one day, there will be cities on the moon.

I wonder!

Patrick has set us the challenge of seeing 55 objects in the April sky.

If you go to our website at...

..you can find out how to take part.

And next month, we'll report how everyone got on.

Now, to return to our fantastical journey on a beam of light.

We travelled from 5.5 million light years

all the way to 5.5 billion.

And Pete and Paul are going to try and set out

this truly cosmic scale.

So, our light beam travelling from Patrick sent it off from the Earth,

it's now gone past the 5.5 million light years and, look,

-5.5 billion is the next target.

-And that's a huge distance.

In fact, it's absolutely vast. So, what are we going to find out here?

First of all, we have the Virgo-Coma Cluster,

about 50, 60 million light years out.

-So that's actually...

-Quite a pathetic distance.

-Right down there.

-OK.

Let's go out now to an even greater astronomical distance,

cos you've found a quasar that amateurs can image.

Well, these distances are absolutely vast

and when you're using amateur equipment, you can still see,

amazingly, things out at these incredibly vast distances.

Now, the other day, I took an image of what is called a quasar.

That is called 3C273, which is in Virgo.

Quasar comes from quasi-stellar object.

It's a contraction of those two words.

That basically means it looks a bit like a star, rather than a galaxy.

Isn't it remarkable that amateurs can get this far out

with just a telescope?

-It's quite remarkable.

-It is.

The light left that 2.4 billion years ago, which is incredible.

Let's leave our quasar behind

and head on out to 5.5 billion light years.

There really isn't much out here for the amateur, is there?

No, it starts to fall off, because the light is so dim from these

objects that amateur equipment has trouble picking it up,

so you're in the realm of the really large, professional telescopes.

Until you get out to this area here.

Yeah, and here, we have the edge of the observable universe.

Anything beyond this, its light can never reach the Earth,

it's completely cut off.

So we don't get any information back about what is beyond here.

I think the best way of describing this region here is to call it

the Great Unknown.

That's a very good name because we have no idea what is out here.

We've come as far as we can riding Patrick's beam of light

and we've reached the end of our journey.

In our final stages, we've passed stars,

nebulae and galaxies which looked rather familiar,

although from Earth, they are a very different sight.

It's taken us 5.5 billion years to get to this part of the universe.

If we sent Patrick's beam of light back to Earth,

its return journey would equally take billions of years.

And so when astronomers left back at home

look out to these distant realms,

they see things as they were when the light left.

They see a snapshot of the cosmic past.

In the Hubble Ultra Deep Field, we see a part of the universe

as it was when the light left, more than ten billion years ago.

And so the galaxies appear mere babies.

They're young, with lots of new stars being born.

But there is a boundary to how far back in time we can go,

how far we can see, and beyond it is quite simply the Great Unknown.

There is a limit and we don't think there's nothing beyond there.

In fact, we're pretty sure there is stuff beyond there.

There simply hasn't been enough time

for the light to travel from those most distant regions

to the Earth for us to see it.

And so you'd think that that limit was 13.7 billion light years away,

because the universe is 13.7 billion years old,

but in fact, in that time,

the universe has been expanding.

So the observable universe,

the stuff we can see, is actually at 45 billion light years across.

And in that volume,

we've got probably 100 billion galaxies with 100 billion stars.

But all of that is probably only a tiny fraction

of the whole universe.

And out in the Great Unknown,

beyond the limits of the observable universe, our theories tell us

that we think the universe could be infinite.

And if that's true, there will be infinitely many galaxies,

between them, infinitely many stars

and around them, infinitely many planets

with, on them, infinitely many Patrick Moores

celebrating the 55th anniversary of The Sky At Night.

I wonder. We're looking now into the Great Unknown.

So what do you think is out beyond the Great Unknown?

I have no idea, it's a fascinating thought.

-Shall we go and explore it?

-That's a good idea.

Do you think there will be a pub?

-There might be an infinite number of pubs.

-Your round...

So, the Great Unknown, that part of the universe

that is so distant that what exists there is not actually visible to us.

So I've always had a great fascination with what may be

discovered there.

And most reassuringly, by Jove, it's me.

Hello again, Patrick.

Hello, Patrick. What a surprise to find you here.

Yes, it's most reassuring. I couldn't resist having a look,

how have the 55th anniversary celebrations of The Sky At Night

been going?

Very well, Patrick.

We are celebrating our 55th anniversary of The Sky At Night

and next month, we're going to do a Moore Marathon.

Yes, I remember thinking of a Moore Marathon in 1962,

and I wish everyone great success with it in 2012.

And as for the Great Unknown,

what can exist there? A void? A vacuum?

Perhaps an infinity of universes? Well, one thing is for sure...

We just don't know.

No, we certainly don't.

So, from all of us here, until next time...

Goodnight.

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