How to Build a Planet (2013): Season 1, Episode 1 - Creating an Earth - full transcript
The Earth.
Third rock from the Sun.
And it's unique.
It has life.
So how do you make
a planet like ours?
I'm going to open up
the cosmic tool box
and work it out.
We're going to build a planet,
up there.
At the top of this
impossibly high tower.
It gives us the perfect platform
to make something really big.
Up here, we can do in seconds
what it takes nature millions
or billions of years to do.
We are going to build our planet
brick by brick.
But to do that,
I'm going to need help.
And I'll find it in the
most unlikely places.
Right now,
I am effectively weightless.
I'm on the ceiling.
I am on the ceiling.
Of course,
as with any construction work
there will be hiccups.
But out of these mistakes
will come real insights
into what makes our planet,
our solar system,
exactly right for
us and for life.
As an engineering challenge,
it doesn't get much bigger.
I love it here on this hill.
Feels like it was made
for bracing Sunday
walks with the family.
And indeed most
weekend mornings,
the place is full of
parents with their kids,
including me with mine,
sometimes.
And when I was on those same
family Sunday morning walks
as a kid myself,
I spent as much of
my time looking down
as I did up and around.
Rocks, stones,
the very stuff of the Earth.
They fascinated me.
And amongst my finds was
one I felt particularly important.
A rock the size of your fist.
A rich brown. Dimpled,
heavy, glinting,
somehow special.
It became one of my most
treasured childhood possessions.
I was convinced
it was a meteorite.
A rock that had
landed here from space.
Morning.
Like most treasured
childhood possessions,
it got lost or swapped,
probably wasn't even a
real meteorite anyway.
But it didn't matter
because it had done its job.
It sparked my interest in space,
the idea of "out there."
Like most kids, I suppose,
I believed that "out there"
would be full of
planets like the Earth,
each of them full of life,
even if it wasn't quite
the same as ours.
But as it turns out,
the planet we live on is very,
very special.
As far as we know, our Earth
is the only place in the
solar system with life.
To understand why,
we are going to
build our own planet.
At the top of that tower.
And to do that,
first we have to gather
up the basic raw materials,
all the big ingredients we
need to start making a planet.
All right, all right!
And here comes my delivery now.
Right on time.
Okay, so how much stuff do we
need to build a planet like the Earth?
I know that the entire Earth
weighs around 6 septillion kilograms,
that's a six followed
by 24 zeros.
But let's be sensible here,
I've ordered the main
planetary raw materials
and in the right proportions
but I've had to scale
the delivery down.
A bit.
Now,
you'd think that our living Earth
would be made up of
countless different things.
But actually,
it's constructed almost entirely
out of just four
basic ingredients.
So that's what my
convoy has delivered.
On these trucks,
girders, iron girders.
Like most big
construction projects,
we are going to
need a lot of iron.
Ah, we need this.
Oxygen.
And over here,
Sand.
That's rich in silicon.
Magnesium,
like you find in alloy wheels.
The convoy has
brought the elements
in exactly the same
proportion as we'd find on Earth.
So,
there are 15 trucks laden with magnesium
because 15% of our planet
is made from magnesium.
There are 16 trucks
for the 16% that's silicon,
30 trucks carrying oxygen,
and a column of 32
trucks with iron girders,
because almost a third of
our planet is made of iron.
It is incredible to think
that just these four elements
make up 93% of our planet.
The rest is elemental seasoning.
And here's Billy Bob with some
of the remaining ingredients.
Which are tiny.
Hydrogen,
aluminium,
a pinch of salt,
calcium.
The question now is
how does all of this
turn into a planet?
To find out, I need to take
these basic planetary elements
and stick them in a blender.
And I'm going to do that
at the top of our tower,
where there's a sky full of room
to break down my ingredients.
The thing is,
our planet didn't just pop into existence.
It started out as a swirling
cloud of elemental dust,
floating in the
great void of space.
So that's how I am going to have to start,
as well.
In case you're wondering,
yes, I am.
Scared of heights, that is.
High... Really high.
Four-and-a-half
billion years ago,
before the Earth began to form,
this dust and gas
was all there was.
So,
how do we get from this cloud of dust
to a planet like the Earth?
We need something
to bind it all together,
a sort of cosmic Super Glue.
Now,
you might think that'd be gravity. Right?
Wrong.
The best way to find out what
this super-strong planetary glue is
is to discover its power
in the weightless
environment of space.
It's why I've come
to this Air Force base,
where astronauts are trained.
I'll be honest,
I am pretty thrilled right now
because I'm about to boldly go
where quite a few
have gone before.
I'm not actually
going into space.
There were budgetary
issues with that.
But never mind,
because we have come up with
the very next best
thing for our purposes.
Where I'm headed is over there.
This plane offers
thrill-seekers something unique.
It can cancel out
the Earth's gravity.
For me, it means I can
recreate the conditions in which
that elemental dust
began to make a planet.
- Hi, how are you doing?
- Richard, hey.
Good to see you. Welcome aboard.
- Ready for a unique experience?
- I'm ready.
I don't know, I've never tried it,
obviously. Let's see.
On today's flight,
my chaperone is Dan Durda.
Thank you.
An expert on space dust.
All right, Richard. I think...
Which seat are you here?
I'm 2F. I'm just...
In the context,
having this conversation is hilarious.
I... I should imagine
all astronauts do this.
The flight attendant
service on the space flights is
- not quite up to par, though.
- I was wondering about that.
Do they have, like,
a trolley with all the space food on it?
I've got a window seat
but there is no window.
- That's on purpose.
- I don't doubt it.
A lack of windows
isn't the only strange
thing about this plane.
It's also got a padded interior,
sort of like a flying asylum.
That's because,
within 15 minutes,
we are going to
experience weightlessness.
And those
zero-gravity conditions
will allow Dan to show me
a fascinating experiment.
Inside this Perspex box
is the next step to
building a planet.
We're going to simulate
the way the planets formed
in the very earliest
days of the solar system.
Instead of microscopic
dust particles,
I've got coffee.
Ordinary coffee.
So in this little box,
we're going to see exhibited
what it was that
brought stuff together?
- Absolutely.
- So this is what kick-starts the whole process?
Big things have
small beginnings.
So it all starts with a coffee?
- It all starts with coffee.
- Just like my day.
- It all starts with a coffee.
- Even the solar system starts with coffee.
As it turns out. We shall see.
Right,
switch the gravity off, then.
That's right!
It doesn't work, it's broken.
The plane is now
climbing to 34,000 feet.
Once there, it'll throttle back
down to Earth in a steep arc,
perfectly judged so that inside,
we're falling at the same
rate as the plane drops.
The result,
a few moments of weightlessness.
Oh, yeah!
Oh, I swam, I did swim.
Oh, that's peculiar.
- Oh, look at that! Beautiful.
- Oh, we got it!
Look at! See,
that's what I was trying to show you.
Unfortunately, I'm upside down.
- I can't... It's over there.
- Here we go.
Hang on, it's...
You come here to do these
experiments all the time.
Right, I'm going to watch but
I'm going to do it upside-down.
Why are you better
at this than I am?
I'm really struggling. I'm...
Gravity... And there it is.
What are we looking
for? We're now weightless.
That's how our planet started.
So these clumps,
what's bringing them together?
Electrostatic forces.
Electrostatic's clumping
this coffee together.
So this is the effect,
this is what starts it all off.
It's hard to concentrate
when I'm floating.
That's not gravity
causing that clumping.
- I'm on the roof!
- That's electrostatics.
How did I get on the roof?
And now I'm on the floor.
Now gravity is coming back
into play... And it's all gone.
- And it doesn't work.
- That's why we're weightless,
to see phenomena that
we can't normally see
when gravity's turned on.
So what's happening here?
These coffee grains,
like that first cosmic dust,
rub together as they float.
This means individual grains
get either negatively
or positively charged.
And this static charge
means they stick together
just like the fledgling
particles of the Earth
four and a half
billion years ago.
This is as near as
we're going to get
to being out there with
those particles without gravity.
How cool is that?
Oh!
- Congratulations!
- Thank you for that.
I enjoyed it, thank you.
I need you to
know that I did that
only because it was the
best way of demonstrating
an essential principle
in building a planet
and not because I
had any fun at all.
It was... Yeah,
it's quite boring.
I loved that!
So,
around our planet-building tower,
we've bound together
those first clumps of dust
without gravity present.
But there is a problem.
Electrostatic forces
are very strong
but are only effective
over tiny distances.
Beyond a certain point,
about the size of gravel,
the dust stops growing.
So our planet-building
plans have ground to a halt
with nothing to show
beyond bigger bits of dust.
We need another force
to somehow grow them more.
I think it's time to introduce
a little gravity to the situation.
How, then, does gravity take
those bigger bits of dust and gravel,
and turn them into rocks
or even an entire planet?
At a concealed
underground laboratory,
I'm told there's a secret device
that will help me
find the answer.
Until 2001,
this was a gold mine.
Now, it's at the cutting
edge of scientific research.
My goal lies nearly a kilometre
and a half straight down.
I'm going deeper underground
than I've ever been before.
You know in disaster movies,
when things go wrong
in things like giant lifts
going a mile underground
the short guy never lasts very long,
does he?
Just thinking that out loud.
More and more
rock flashing past.
Still plunging.
Still,
plunging is better than plummeting.
At the bottom of this
shaft is an instrument
that's part of a global
gravity research experiment.
Apparently,
it's going to help us understand
how gravity can grow
a planet from gravel.
In the tunnels of these,
the Sanford Labs,
scientists are unravelling
the workings of the universe.
I might not look it,
but I feel a bit like James Bond
summoned to the underground lair
of an international
super-baddie.
And here is what
I've come to see.
Meet Dr Gnome.
Now the good doctor here is
no common or garden gnome.
He is a precision
instrument of science.
He's special because he
has a super tough coating
that means he can't be
chipped or damaged easily.
So you would think
that wherever he went,
he remained exactly the same.
Looks the same.
Same expression,
slightly puzzled.
Well, scientists have taken
Dr Gnome all over the world.
And wherever he's been,
he's been weighed with
high precision scales.
And it's his weight
that helps explain
how gravity can turn
gravel into a planet.
It's my job now to
weigh him down here,
a mile beneath the surface,
in laboratory conditions.
So let's zero the machine,
pop him on.
And as you can see,
the doctor tipping the scales
at 330.95 grams.
In the interest of thoroughness,
he has been weighed in a number
of other locations down here.
And in all of them,
we got the same reading.
A kilometre and a
half under the surface,
he weighs 330.95 grams.
And now we must travel
back up to the surface
where we shall
finish this experiment.
Right then, Doctor, you just
sit there. I'll do all the walking.
The doctor has
to travel first class.
It's vitally important that he
isn't damaged on the way up,
or picks up any dirt that
might interfere with readings.
Okay, Doctor,
time to weigh you up here,
on the surface.
Zero the machine,
let it calm down.
And here we go.
Look at that!
You are six hundredths
of a gram heavier up here
than you were down there.
I honestly didn't expect that.
But just to be sure,
he needs to be weighed
in some other places.
And sure enough,
331.01 grams.
The doctor is showing
a consistent weight gain
of six hundredths of a gram
up here on the surface,
compared to when he was down below.
Doctor! Have you
been secretly snacking?
I can assure you that Dr Gnome
hasn't grown on the way up.
His weight gain can be explained
by Earth's gravity.
Gravity is the universal force
that attracts one
thing to another.
When we measure
something's weight,
we are actually measuring
the Earth's gravitational pull.
So why has the
doctor's weight changed?
Well,
it's largely to do with differences
in the amount of rock underfoot.
Up here on the surface,
there's a good mile more rock
beneath me and Dr Gnome
than there is in
the lab down there,
meaning more planetary
bulk pulling down on us,
making for a heavier
Dr Gnome up here
than down there.
Nothing's changed
about the gnome.
What's changed is gravity.
Our experiment shows that
the more massive something is,
the stronger its
gravitational pull.
So in space,
around 4.5 billion years ago,
when there were no planets,
just those elemental clumps,
any difference in the
size of those clumps
would have mattered,
because of gravity.
If we add gravity to our
orbiting swarm of dust,
we start to see the larger
bits attracting the smaller bits.
Because they are bigger,
they have a stronger
gravitational pull.
The bigger they are,
the bigger they get.
They start to become rocks.
And the larger rocks
draw in the smaller ones.
In space,
a rock just a kilometre wide
can grow to a near
Earth-sized planet
in just a few million years.
Around our tower,
we can do it in seconds.
And we're seeing
something really promising.
The exciting thing is that
even though that process
began 4.5 billion years ago,
on Earth, it hasn't finished.
Because if you
know where to look,
you can see where gravity is
still shaping our planet today.
Out in Arizona's Badlands,
there is breath-taking evidence
of how gravity is still
building the Earth.
This is the Barringer Crater.
When this vast crater
was first discovered,
many believed it to
be an extinct volcano.
But in fact,
it was created by a meteorite.
This 1.2 kilometer-wide hole
is an impact crater.
And it's given scientists
like Matt Genge
a unique insight into
how planets are built.
- Matt, how are you?
- Hello, mate.
Sorry about the dust. Wow!
This crater is the scar
left by an incredibly
violent impact.
If you look at the crater wall,
you can see the strata,
- beds of rock, running across the crater.
- Yes.
There's this nice
red layer of rocks.
Above and below,
there's some lighter coloured rocks
and they're actually
the same band of rocks.
That layer has been folded
over the red layer, red layers,
like the cheese in a sandwich.
But they've been folded over
all the way round the crater,
like they've been thrown
outwards and have collapsed back.
How big was it? 'Cause
it's a really big crater.
We think the object itself was
probably only about 30 metres in size,
so a couple of double-decker
buses back-to-back.
- And it made a hole that big?
- It made a hole that big.
Why?
Simply because of
how fast it was moving.
So by the time it fell
towards the Earth,
it gets faster and faster
as it falls towards the Earth,
hits the ground maybe
at 26,000 miles per hour.
And the energy,
the kinetic energy
associated with that speed
is so huge,
it's around two megatonnes,
that it blew all that
material outwards.
The rocks actually flowed
like water out of the crater.
So this whole... All this
area has been affected?
It's not just the big hole,
then.
- It's everything around...
- Absolutely, yeah.
In fact, if you were here
before the crater was formed,
you'd have had all that
rock on top of your head,
so you wouldn't
have been very happy.
No, that would have been bad.
The meteorite was
just 30 metres wide
but the shockwave of its
impact would have been enough
to obliterate a brick
wall 60 kilometres away.
The Barringer Crater is evidence
of how gravity builds a planet.
Because every meteorite
that plummets to the ground
is drawn in by the
Earth's gravitational pull.
So when did all this happen,
then? How old is that?
So the crater itself is
about 50,000 years old.
But we actually know
that meteorites like this
have been falling on Earth
throughout the Earth's history,
for the last 4.5 billion years.
In fact, in the past,
they were much more frequent.
So back when the
Earth was forming,
that bombardment was continual.
There was probably one
of them every few minutes.
These were the objects
that were making the Earth.
Billions of years later,
meteorite fragments that
survived the initial impact
offer a glimpse into
the earliest moments
of a planet's formation.
This is rather a
special meteorite.
It fell in Mexico
in 1969
and it's called Allende.
We give meteorites names.
And what's special
about this meteorite
is it's perhaps the
oldest material on Earth.
So it's around 4.5
billion years old.
So that right there
is the oldest thing on Earth?
Yeah.
Wow.
Can I hold it?
- Er, no. - Okay.
But you can touch it,
if you like.
Just touch the
oldest thing on Earth.
Oh, come on.
Wow.
It is kind of a
goose-bump moment
because of the significance
of a little piece of rock that,
well, frankly,
I'd walk straight past.
Well,
most people probably would.
But although they're quite rare,
you can find them everywhere.
They fall all over the world.
But not always quite
as spectacularly as here.
- Yeah, you'd notice that.
- You'd certainly notice.
But to imagine that some of us
are walking past lumps of rock
that contain all the elements
you need to build a planet.
You know,
you've got the magnesium and the silicon
and the iron and the oxygen.
It's just incredible that
this is how we started
and they're just scattered
all over the world.
If you or I were to find
an actual meteorite,
and who knows, we might,
it's, I don't know,
almost a haunting thought
to consider that what
you had in your hand
might be 4.5 billion years old
and one of the fundamental
building blocks of our planet,
our world,
of our existence.
But the meteorite that you found
might not have landed
billions of years ago.
It might have landed the
day before you found it.
And that's quite exciting.
They're still arriving. The
process is still going on.
It's just that they're
late gate-crashers
to some giant planetary party.
Astonishingly, today,
40,000 tonnes worth of meteorites
fall to Earth every year,
the equivalent of
30,000 transit vans
dropping out of the sky,
mostly arriving as dust.
But very occasionally,
as something much bigger.
Early in 2013,
a meteorite fell near the
Russian town of Chelyabinsk
that was the
largest in a century.
Nearly 10,000 tonnes,
before breaking up.
But such spectacular
events are incredibly rare.
In fact, you're more likely
to die from falling out of bed
than from being
struck by a meteorite.
Back when the Earth was forming,
though,
huge meteorite
strikes were constant,
with tens of millions
hitting a year.
The thing is,
rather than destroying it,
the onslaught built our planet.
Starting 4.5 billion years ago,
it took just 100 million
years to reach almost full size.
So now we have a planet that's
roughly the same size as Earth
and the same shape.
But at the moment,
the surface of our planet
is a molten,
fiery vision of hell,
which is going to
be inconvenient.
For starters,
there's nothing to stand on.
No solid rock.
It's just a fiery,
molten sea of magma.
And there's no
way life could start
in this volcanic environment.
So how are we going to get
a solid surface for our planet?
Back on the desert floor,
Professor Jeff
Karson and his team
are setting up a
unique experiment.
They reckon they can show me
how to make land for our planet.
The first step in
their challenge,
recreating that
early molten Earth.
And that means constructing
what is basically a mobile volcano.
And now we're going to
see if we can make it erupt.
- All right, Richard? - Yeah.
Let's get the helmet on. Yeah.
I'm guessing what we've
got in here is not lunch, is it?
It isn't.
Whoa! That's really hot!
So what Bob is stirring there
isn't something that looks like lava.
- It's actual lava. - No, it is,
it is real lava, basaltic lava.
We just put in the ingredients,
just like a recipe,
and cook up this primordial,
primitive material
that makes up our Earth.
It's amazing and exhilarating
but also quite incredibly
hot up here. Can I get down?
It's very hot. And you can see,
we have to get it that hot so it
will flow in a very viscous form.
The recipe for lava
that Jeff's team are using
includes the essential
planetary ingredients,
iron, magnesium and silicon.
But before this
turns to solid land,
we need to make the lava flow.
The spout, here. Here it comes,
here it comes.
The temperatures reached
by this lava are extraordinary.
We know from using
our infrared camera,
where it's incandescent orange,
there,
it's about 1,100 degrees centigrade.
Where it starts to get dark grey,
like down at the toe here,
it's about 850 degrees centigrade,
now.
Wow!
And now it's coming out
here at 1,100 degrees again,
just like the temperature
that we're pouring in.
- So this is much hotter
than that stuff on top? It is.
Looking at what happens
here on a small scale
but with the same materials
and the same temperatures
and the same behaviours,
you can look back and work out
what happened on the early Earth.
Exactly. We're sort of replicating
those conditions of the early Earth,
in miniature.
Imagine the whole planet
covered with glowing,
incandescent orange lava
magma oceans.
That is intense.
You can see the
little wrinkles and folds
starting to form on the surface
as the surface cools
and a crust starts to form.
I can feel wrinkles and folds
forming on my face, watching.
So,
in order to create land from lava,
we need to cool it down
until it turns into a crust.
Simple.
But there's a
wrinkle in our plan.
On the early Earth,
the lava didn't cool in
the way you'd expect.
There was a reason the
surface stayed molten.
Jeff has a, well,
slightly unusual demonstration
of what that was.
Site up on the target.
Shooters, fire.
- We're going in there?
- Let's go have a look.
That was quite exhilarating,
I'll be honest.
Oh, God! I can't see the target.
What am I doing?
Okay, look here, Richard.
Here's where
all the bullets hit.
Feel how hot it is there, still.
It is, yes. Yes,
there's definite heat in there.
- Ow, they're really... You
could think of these as...
Each one of these like a tiny
meteorite that struck the Earth
and transferred its kinetic
energy to heat energy,
keeping the planet warm.
I think I see where
you're going with this,
'cause I did wonder
for a moment.
So these are like meteors.
- Right.
- So, the planet was under bombardment at the time.
-Right.
-And those were going in like these and when they hit,
this is kinetic energy
converting into heat.
And what,
a meteorite hitting is enough,
- is going to make it hot?
- It is.
It keeps it hot and
that's one of the reasons
your planet's not cooling down.
And these meteorites
are a lot bigger.
The meteorites are much bigger
than our little bullets, of course,
and they're travelling
about 10 times as fast.
I'd love to get a better idea,
a better sense of that moment
when that energy is
converted from kinetic into heat.
But to do that,
they'd have to shoot through my hand
and that's going to hurt, so...
Well,
we have a safer way to do that.
A thermal infrared camera's been
filming the entire experiment here
and we can show you
the images created by that.
- In here? - Yeah.
So, this is a thermal camera
looking at what we've just seen.
- Right. - There's the plate.
Hot areas are
going to show up red
and little cooler areas will
show up in a bluer, cooler colour
as each one of these
bullets strikes the metal.
And there they go, look!
I mean, it's really pronounced.
Look at the pieces being blasted off,
there.
Watching them go in like that,
I can imagine they
were meteorites.
Exactly,
much bigger and 10 times faster.
And this effect is
one of the reasons
why my Planet Earth won't set.
- That's right.
- Remains molten.
So, to stand a chance of creating
a solid surface for our planet,
we need to stop this constant
barrage of meteors and asteroids.
On the actual Earth,
this bombardment petered
out around four billion years ago.
On the planet we're building,
it can be done in a jiffy.
And reducing the impacts from
space helps the surface to cool,
so that lava turns to rock.
Perfect!
We now have a planet we can
stand on without being burnt.
But there is something
pretty important missing.
If we're going to have
life on this planet of ours,
we are going to need water.
Incredibly,
some water has been with us
from the very
birth of our planet,
trapped in dust and rock,
and then locked inside of the Earth.
Volcanic activity released
this water as steam,
forming rain clouds that
then filled the first oceans.
A lot more water
arrived from space,
because asteroids and comets
actually carried ice inside them,
adding to our
already wet planet.
So, we've got water.
We've also got land.
But it doesn't look right.
All that volcanic activity hasn't just
pumped steam into the atmosphere,
it's produced a toxic
cocktail of gasses.
This isn't a planet for us yet.
So, how do we clean up
this poisonous atmosphere?
Well, the answer lies with the
oldest living thing on the planet.
On these rocks, there's a thin
film of bacteria called a stromatolite.
These ones today
are in Australia,
but three billion years
ago they were everywhere.
They live on sunlight,
and carbon dioxide in water,
and as a waste product,
they release oxygen.
For more than a billion years,
these bacteria pumped the stuff out,
until the air was right for
the evolution of complex life,
including us.
To build our planet, we started
with truckloads of raw materials.
And we mixed them together
into a cosmic cloud of dust.
We got it to stick together
with static electricity.
And then, we added gravity.
We bulked the planet up.
Then we stopped the onslaught
to cool it down, and make land.
And then we sourced water
and a breathable atmosphere.
But hang on. This isn't right.
There's something seriously
amiss with our planet.
This is definitely not how
things should be looking.
It's a bad case of the wobbles.
A wobble this big,
even slowed down over millions of years,
would be catastrophic.
Without stability,
seasonal changes are extreme,
ice ages are frequent,
and the surface is scoured
by hurricane-force winds.
It's no good. Our planet has
conditions completely hostile to life.
But don't worry,
because to stabilise things,
we don't actually
have to look too far.
The solution is a moon.
To find out how a moon
can stop a planet's wobble,
I've come to NASA in Texas,
where the answer is
kept in a bomb-proof vault,
wrapped in foil.
And if that isn't enough,
this entire facility demands
OCD levels of hygiene.
One man who knows a lot about
this object is Harrison Schmitt.
And that's because
he found it on the moon.
Four decades ago,
Harrison was an astronaut.
December 6th, 1972.
Dr Harrison Schmitt,
better known as Jack.
He would be the first geologist
to set foot on an alien world.
We have commit and
we have lift off at 2:13.
I'm going to meet Harrison,
after a final zap in the NASA microwave.
- Harrison. - Hey.
- Hello. - Welcome.
I so wanted to shake
your hand but it's in there.
A little bit later maybe.
It's great to meet you,
and what have you've got in here?
We have one of the
Apollo 17 samples.
It's one collected near the
lunar module Challenger.
And it is a...
Really quite a
unique type of rock.
That rock formed about
3.8 billion years ago.
That's with a "b".
So it's extremely old, it's part of a
mass of magma that partially filled
the valley of Taurus-Littrow,
where we landed on Apollo 17.
So let's just get this into context
because, for mere mortals like me
to understand, you are standing
there as the only geologist ever
- to have walked on the moon?
- That's correct.
And therefore,
when you saw these rocks on the moon,
they would have meant more to you anyway
because of your training and knowledge.
I hope so.
Your brain must have
been just screaming!
You were looking at that rock.
Well, you can't believe
where this geologic setting was.
It's a valley deeper than the
Grand Canyon of the Colorado
here in the United States.
It is, er...
The mountains on either
side are 6,000 and 7,000 feet
above the valley floor.
This was off the valley floor.
It's the moon that saves the
real Earth from the disastrous
climatic effects of wobbling.
But how exactly the
moon keeps us stable
is tied into its
mysterious origins.
Until the Apollo programme,
we had no real idea of
how the Earth got its moon.
Finding out was an important
goal for Harrison Schmitt,
when his Apollo 17 module touched
down on December 11th, 1972.
Fuel is good,
stand by for touchdown.
Stand by, down at two.
Fuel's good. Ten feet.
That's contact!
Harrison had just three days
to collect as many lunar
samples as possible.
Late in the mission,
things got a little tense.
Harrison had just half
an hour of oxygen left
and he was getting a bit
carried away with his work.
I've got to dig a trench,
Houston.
Fantastic, sports fans!
It's trench time!
They got to leave
at a certain time,
regardless of what they got.
There isn't enough time, Tony, to do it,
no matter which way we want to do it.
We need more time.
You better make it clear to
Parker that we've got to pull out.
We'd like you to
leave immediately.
Okay.
By golly, this time goes fast!
We're on our way, Houston.
Once Harrison and NASA
were able to examine the rocks,
they began to understand fully
just how the moon had formed,
and the massive
stabilising effect it brought.
What the scientists discovered
was an extraordinary connection.
It seems this moon rock was
made of pretty much the same stuff
as Earth rock.
The oxygen isotope ratios
in the rocks are identical
to those ratios that
we have here on Earth
and it tells you that the Earth
and the moon formed in, basically,
almost identically the same
part of the solar system.
And this information that
you brought back has helped
people narrow down the theories
as to how the moon came to be,
where it is and like it is.
No question about that.
The primary hypothesis
right now is giant impact.
Soon after the Earth formed,
another planet-sized
rock crashed into it.
The impact threw
huge chunks into orbit.
And these clumped
together to make the moon.
When first formed, it was much,
much closer than it is now.
One of the primary reasons
that we still are here on this planet
is that the Earth is a stable planet
and it's been stabilised by the moon.
With the moon there,
there's a gravitational stabilisation
that occurs that keeps the Earth's
wobble down to an absolute minimum
and that makes a
big difference for us,
because if you wanted to have major climate
change on Earth, introduce a wobble.
It doesn't mean that
life wouldn't be here
but it would be a very
difficult and different kind
of life that we would
have to deal with,
with this wobble,
over fairly long periods of time.
So, let's see what happens to
our planet when we add a moon.
Our planet and its new
moon are two dancers,
locked in a
gravitational embrace,
steadying themselves as
they swirl round and round.
Having a moon has
one other vital effect.
Tiny variations in its gravitational
pull on our planet's oceans
have given it tides,
and that's more important
than you might think.
Without the tides, early life on
Earth may never have left the sea,
because the tides created
damp strips along the coast
that tempted life onto land.
And the actual positioning
of the moon is crucial.
Ever since its formation,
it's been drifting away from the Earth.
But when it was closer,
it generated immense tides.
If we had them today, every few hours,
New York and London
would disappear under
tens of metres of water.
And if the moon was further away,
the planet's spin would slow
and the days would be longer.
But put it at just the right distance,
which in reality
is about 239,000 miles,
and we have the stability we need.
So, there it is,
the perfect planetary relationship.
After trial and error,
I have built my planet and its moon,
and got them working just right.
In reality,
this whole process took 4.5 billion years.
The sheer scale of it all is
understandably mind-blowing,
especially when you realise that
with just one element out of place,
nothing works, and life stops.
So what holds the
Earth and moon in place?
They need a sun to orbit around,
and other planets to
make our solar system,
all of which is just a tiny
part of a Milky Way galaxy
with 300 billion stars.
And that galaxy is just one
amongst half a trillion other galaxies.
So, to keep it all working,
we're going to have to build a universe.
And to build a universe,
I'm going to need a lot of help.
Oh, this is really difficult!
Oh, my God, it's beautiful!
- Do I look faintly ridiculous?
- Yes!
I'll be honest.
I'm faintly nervous.
Third rock from the Sun.
And it's unique.
It has life.
So how do you make
a planet like ours?
I'm going to open up
the cosmic tool box
and work it out.
We're going to build a planet,
up there.
At the top of this
impossibly high tower.
It gives us the perfect platform
to make something really big.
Up here, we can do in seconds
what it takes nature millions
or billions of years to do.
We are going to build our planet
brick by brick.
But to do that,
I'm going to need help.
And I'll find it in the
most unlikely places.
Right now,
I am effectively weightless.
I'm on the ceiling.
I am on the ceiling.
Of course,
as with any construction work
there will be hiccups.
But out of these mistakes
will come real insights
into what makes our planet,
our solar system,
exactly right for
us and for life.
As an engineering challenge,
it doesn't get much bigger.
I love it here on this hill.
Feels like it was made
for bracing Sunday
walks with the family.
And indeed most
weekend mornings,
the place is full of
parents with their kids,
including me with mine,
sometimes.
And when I was on those same
family Sunday morning walks
as a kid myself,
I spent as much of
my time looking down
as I did up and around.
Rocks, stones,
the very stuff of the Earth.
They fascinated me.
And amongst my finds was
one I felt particularly important.
A rock the size of your fist.
A rich brown. Dimpled,
heavy, glinting,
somehow special.
It became one of my most
treasured childhood possessions.
I was convinced
it was a meteorite.
A rock that had
landed here from space.
Morning.
Like most treasured
childhood possessions,
it got lost or swapped,
probably wasn't even a
real meteorite anyway.
But it didn't matter
because it had done its job.
It sparked my interest in space,
the idea of "out there."
Like most kids, I suppose,
I believed that "out there"
would be full of
planets like the Earth,
each of them full of life,
even if it wasn't quite
the same as ours.
But as it turns out,
the planet we live on is very,
very special.
As far as we know, our Earth
is the only place in the
solar system with life.
To understand why,
we are going to
build our own planet.
At the top of that tower.
And to do that,
first we have to gather
up the basic raw materials,
all the big ingredients we
need to start making a planet.
All right, all right!
And here comes my delivery now.
Right on time.
Okay, so how much stuff do we
need to build a planet like the Earth?
I know that the entire Earth
weighs around 6 septillion kilograms,
that's a six followed
by 24 zeros.
But let's be sensible here,
I've ordered the main
planetary raw materials
and in the right proportions
but I've had to scale
the delivery down.
A bit.
Now,
you'd think that our living Earth
would be made up of
countless different things.
But actually,
it's constructed almost entirely
out of just four
basic ingredients.
So that's what my
convoy has delivered.
On these trucks,
girders, iron girders.
Like most big
construction projects,
we are going to
need a lot of iron.
Ah, we need this.
Oxygen.
And over here,
Sand.
That's rich in silicon.
Magnesium,
like you find in alloy wheels.
The convoy has
brought the elements
in exactly the same
proportion as we'd find on Earth.
So,
there are 15 trucks laden with magnesium
because 15% of our planet
is made from magnesium.
There are 16 trucks
for the 16% that's silicon,
30 trucks carrying oxygen,
and a column of 32
trucks with iron girders,
because almost a third of
our planet is made of iron.
It is incredible to think
that just these four elements
make up 93% of our planet.
The rest is elemental seasoning.
And here's Billy Bob with some
of the remaining ingredients.
Which are tiny.
Hydrogen,
aluminium,
a pinch of salt,
calcium.
The question now is
how does all of this
turn into a planet?
To find out, I need to take
these basic planetary elements
and stick them in a blender.
And I'm going to do that
at the top of our tower,
where there's a sky full of room
to break down my ingredients.
The thing is,
our planet didn't just pop into existence.
It started out as a swirling
cloud of elemental dust,
floating in the
great void of space.
So that's how I am going to have to start,
as well.
In case you're wondering,
yes, I am.
Scared of heights, that is.
High... Really high.
Four-and-a-half
billion years ago,
before the Earth began to form,
this dust and gas
was all there was.
So,
how do we get from this cloud of dust
to a planet like the Earth?
We need something
to bind it all together,
a sort of cosmic Super Glue.
Now,
you might think that'd be gravity. Right?
Wrong.
The best way to find out what
this super-strong planetary glue is
is to discover its power
in the weightless
environment of space.
It's why I've come
to this Air Force base,
where astronauts are trained.
I'll be honest,
I am pretty thrilled right now
because I'm about to boldly go
where quite a few
have gone before.
I'm not actually
going into space.
There were budgetary
issues with that.
But never mind,
because we have come up with
the very next best
thing for our purposes.
Where I'm headed is over there.
This plane offers
thrill-seekers something unique.
It can cancel out
the Earth's gravity.
For me, it means I can
recreate the conditions in which
that elemental dust
began to make a planet.
- Hi, how are you doing?
- Richard, hey.
Good to see you. Welcome aboard.
- Ready for a unique experience?
- I'm ready.
I don't know, I've never tried it,
obviously. Let's see.
On today's flight,
my chaperone is Dan Durda.
Thank you.
An expert on space dust.
All right, Richard. I think...
Which seat are you here?
I'm 2F. I'm just...
In the context,
having this conversation is hilarious.
I... I should imagine
all astronauts do this.
The flight attendant
service on the space flights is
- not quite up to par, though.
- I was wondering about that.
Do they have, like,
a trolley with all the space food on it?
I've got a window seat
but there is no window.
- That's on purpose.
- I don't doubt it.
A lack of windows
isn't the only strange
thing about this plane.
It's also got a padded interior,
sort of like a flying asylum.
That's because,
within 15 minutes,
we are going to
experience weightlessness.
And those
zero-gravity conditions
will allow Dan to show me
a fascinating experiment.
Inside this Perspex box
is the next step to
building a planet.
We're going to simulate
the way the planets formed
in the very earliest
days of the solar system.
Instead of microscopic
dust particles,
I've got coffee.
Ordinary coffee.
So in this little box,
we're going to see exhibited
what it was that
brought stuff together?
- Absolutely.
- So this is what kick-starts the whole process?
Big things have
small beginnings.
So it all starts with a coffee?
- It all starts with coffee.
- Just like my day.
- It all starts with a coffee.
- Even the solar system starts with coffee.
As it turns out. We shall see.
Right,
switch the gravity off, then.
That's right!
It doesn't work, it's broken.
The plane is now
climbing to 34,000 feet.
Once there, it'll throttle back
down to Earth in a steep arc,
perfectly judged so that inside,
we're falling at the same
rate as the plane drops.
The result,
a few moments of weightlessness.
Oh, yeah!
Oh, I swam, I did swim.
Oh, that's peculiar.
- Oh, look at that! Beautiful.
- Oh, we got it!
Look at! See,
that's what I was trying to show you.
Unfortunately, I'm upside down.
- I can't... It's over there.
- Here we go.
Hang on, it's...
You come here to do these
experiments all the time.
Right, I'm going to watch but
I'm going to do it upside-down.
Why are you better
at this than I am?
I'm really struggling. I'm...
Gravity... And there it is.
What are we looking
for? We're now weightless.
That's how our planet started.
So these clumps,
what's bringing them together?
Electrostatic forces.
Electrostatic's clumping
this coffee together.
So this is the effect,
this is what starts it all off.
It's hard to concentrate
when I'm floating.
That's not gravity
causing that clumping.
- I'm on the roof!
- That's electrostatics.
How did I get on the roof?
And now I'm on the floor.
Now gravity is coming back
into play... And it's all gone.
- And it doesn't work.
- That's why we're weightless,
to see phenomena that
we can't normally see
when gravity's turned on.
So what's happening here?
These coffee grains,
like that first cosmic dust,
rub together as they float.
This means individual grains
get either negatively
or positively charged.
And this static charge
means they stick together
just like the fledgling
particles of the Earth
four and a half
billion years ago.
This is as near as
we're going to get
to being out there with
those particles without gravity.
How cool is that?
Oh!
- Congratulations!
- Thank you for that.
I enjoyed it, thank you.
I need you to
know that I did that
only because it was the
best way of demonstrating
an essential principle
in building a planet
and not because I
had any fun at all.
It was... Yeah,
it's quite boring.
I loved that!
So,
around our planet-building tower,
we've bound together
those first clumps of dust
without gravity present.
But there is a problem.
Electrostatic forces
are very strong
but are only effective
over tiny distances.
Beyond a certain point,
about the size of gravel,
the dust stops growing.
So our planet-building
plans have ground to a halt
with nothing to show
beyond bigger bits of dust.
We need another force
to somehow grow them more.
I think it's time to introduce
a little gravity to the situation.
How, then, does gravity take
those bigger bits of dust and gravel,
and turn them into rocks
or even an entire planet?
At a concealed
underground laboratory,
I'm told there's a secret device
that will help me
find the answer.
Until 2001,
this was a gold mine.
Now, it's at the cutting
edge of scientific research.
My goal lies nearly a kilometre
and a half straight down.
I'm going deeper underground
than I've ever been before.
You know in disaster movies,
when things go wrong
in things like giant lifts
going a mile underground
the short guy never lasts very long,
does he?
Just thinking that out loud.
More and more
rock flashing past.
Still plunging.
Still,
plunging is better than plummeting.
At the bottom of this
shaft is an instrument
that's part of a global
gravity research experiment.
Apparently,
it's going to help us understand
how gravity can grow
a planet from gravel.
In the tunnels of these,
the Sanford Labs,
scientists are unravelling
the workings of the universe.
I might not look it,
but I feel a bit like James Bond
summoned to the underground lair
of an international
super-baddie.
And here is what
I've come to see.
Meet Dr Gnome.
Now the good doctor here is
no common or garden gnome.
He is a precision
instrument of science.
He's special because he
has a super tough coating
that means he can't be
chipped or damaged easily.
So you would think
that wherever he went,
he remained exactly the same.
Looks the same.
Same expression,
slightly puzzled.
Well, scientists have taken
Dr Gnome all over the world.
And wherever he's been,
he's been weighed with
high precision scales.
And it's his weight
that helps explain
how gravity can turn
gravel into a planet.
It's my job now to
weigh him down here,
a mile beneath the surface,
in laboratory conditions.
So let's zero the machine,
pop him on.
And as you can see,
the doctor tipping the scales
at 330.95 grams.
In the interest of thoroughness,
he has been weighed in a number
of other locations down here.
And in all of them,
we got the same reading.
A kilometre and a
half under the surface,
he weighs 330.95 grams.
And now we must travel
back up to the surface
where we shall
finish this experiment.
Right then, Doctor, you just
sit there. I'll do all the walking.
The doctor has
to travel first class.
It's vitally important that he
isn't damaged on the way up,
or picks up any dirt that
might interfere with readings.
Okay, Doctor,
time to weigh you up here,
on the surface.
Zero the machine,
let it calm down.
And here we go.
Look at that!
You are six hundredths
of a gram heavier up here
than you were down there.
I honestly didn't expect that.
But just to be sure,
he needs to be weighed
in some other places.
And sure enough,
331.01 grams.
The doctor is showing
a consistent weight gain
of six hundredths of a gram
up here on the surface,
compared to when he was down below.
Doctor! Have you
been secretly snacking?
I can assure you that Dr Gnome
hasn't grown on the way up.
His weight gain can be explained
by Earth's gravity.
Gravity is the universal force
that attracts one
thing to another.
When we measure
something's weight,
we are actually measuring
the Earth's gravitational pull.
So why has the
doctor's weight changed?
Well,
it's largely to do with differences
in the amount of rock underfoot.
Up here on the surface,
there's a good mile more rock
beneath me and Dr Gnome
than there is in
the lab down there,
meaning more planetary
bulk pulling down on us,
making for a heavier
Dr Gnome up here
than down there.
Nothing's changed
about the gnome.
What's changed is gravity.
Our experiment shows that
the more massive something is,
the stronger its
gravitational pull.
So in space,
around 4.5 billion years ago,
when there were no planets,
just those elemental clumps,
any difference in the
size of those clumps
would have mattered,
because of gravity.
If we add gravity to our
orbiting swarm of dust,
we start to see the larger
bits attracting the smaller bits.
Because they are bigger,
they have a stronger
gravitational pull.
The bigger they are,
the bigger they get.
They start to become rocks.
And the larger rocks
draw in the smaller ones.
In space,
a rock just a kilometre wide
can grow to a near
Earth-sized planet
in just a few million years.
Around our tower,
we can do it in seconds.
And we're seeing
something really promising.
The exciting thing is that
even though that process
began 4.5 billion years ago,
on Earth, it hasn't finished.
Because if you
know where to look,
you can see where gravity is
still shaping our planet today.
Out in Arizona's Badlands,
there is breath-taking evidence
of how gravity is still
building the Earth.
This is the Barringer Crater.
When this vast crater
was first discovered,
many believed it to
be an extinct volcano.
But in fact,
it was created by a meteorite.
This 1.2 kilometer-wide hole
is an impact crater.
And it's given scientists
like Matt Genge
a unique insight into
how planets are built.
- Matt, how are you?
- Hello, mate.
Sorry about the dust. Wow!
This crater is the scar
left by an incredibly
violent impact.
If you look at the crater wall,
you can see the strata,
- beds of rock, running across the crater.
- Yes.
There's this nice
red layer of rocks.
Above and below,
there's some lighter coloured rocks
and they're actually
the same band of rocks.
That layer has been folded
over the red layer, red layers,
like the cheese in a sandwich.
But they've been folded over
all the way round the crater,
like they've been thrown
outwards and have collapsed back.
How big was it? 'Cause
it's a really big crater.
We think the object itself was
probably only about 30 metres in size,
so a couple of double-decker
buses back-to-back.
- And it made a hole that big?
- It made a hole that big.
Why?
Simply because of
how fast it was moving.
So by the time it fell
towards the Earth,
it gets faster and faster
as it falls towards the Earth,
hits the ground maybe
at 26,000 miles per hour.
And the energy,
the kinetic energy
associated with that speed
is so huge,
it's around two megatonnes,
that it blew all that
material outwards.
The rocks actually flowed
like water out of the crater.
So this whole... All this
area has been affected?
It's not just the big hole,
then.
- It's everything around...
- Absolutely, yeah.
In fact, if you were here
before the crater was formed,
you'd have had all that
rock on top of your head,
so you wouldn't
have been very happy.
No, that would have been bad.
The meteorite was
just 30 metres wide
but the shockwave of its
impact would have been enough
to obliterate a brick
wall 60 kilometres away.
The Barringer Crater is evidence
of how gravity builds a planet.
Because every meteorite
that plummets to the ground
is drawn in by the
Earth's gravitational pull.
So when did all this happen,
then? How old is that?
So the crater itself is
about 50,000 years old.
But we actually know
that meteorites like this
have been falling on Earth
throughout the Earth's history,
for the last 4.5 billion years.
In fact, in the past,
they were much more frequent.
So back when the
Earth was forming,
that bombardment was continual.
There was probably one
of them every few minutes.
These were the objects
that were making the Earth.
Billions of years later,
meteorite fragments that
survived the initial impact
offer a glimpse into
the earliest moments
of a planet's formation.
This is rather a
special meteorite.
It fell in Mexico
in 1969
and it's called Allende.
We give meteorites names.
And what's special
about this meteorite
is it's perhaps the
oldest material on Earth.
So it's around 4.5
billion years old.
So that right there
is the oldest thing on Earth?
Yeah.
Wow.
Can I hold it?
- Er, no. - Okay.
But you can touch it,
if you like.
Just touch the
oldest thing on Earth.
Oh, come on.
Wow.
It is kind of a
goose-bump moment
because of the significance
of a little piece of rock that,
well, frankly,
I'd walk straight past.
Well,
most people probably would.
But although they're quite rare,
you can find them everywhere.
They fall all over the world.
But not always quite
as spectacularly as here.
- Yeah, you'd notice that.
- You'd certainly notice.
But to imagine that some of us
are walking past lumps of rock
that contain all the elements
you need to build a planet.
You know,
you've got the magnesium and the silicon
and the iron and the oxygen.
It's just incredible that
this is how we started
and they're just scattered
all over the world.
If you or I were to find
an actual meteorite,
and who knows, we might,
it's, I don't know,
almost a haunting thought
to consider that what
you had in your hand
might be 4.5 billion years old
and one of the fundamental
building blocks of our planet,
our world,
of our existence.
But the meteorite that you found
might not have landed
billions of years ago.
It might have landed the
day before you found it.
And that's quite exciting.
They're still arriving. The
process is still going on.
It's just that they're
late gate-crashers
to some giant planetary party.
Astonishingly, today,
40,000 tonnes worth of meteorites
fall to Earth every year,
the equivalent of
30,000 transit vans
dropping out of the sky,
mostly arriving as dust.
But very occasionally,
as something much bigger.
Early in 2013,
a meteorite fell near the
Russian town of Chelyabinsk
that was the
largest in a century.
Nearly 10,000 tonnes,
before breaking up.
But such spectacular
events are incredibly rare.
In fact, you're more likely
to die from falling out of bed
than from being
struck by a meteorite.
Back when the Earth was forming,
though,
huge meteorite
strikes were constant,
with tens of millions
hitting a year.
The thing is,
rather than destroying it,
the onslaught built our planet.
Starting 4.5 billion years ago,
it took just 100 million
years to reach almost full size.
So now we have a planet that's
roughly the same size as Earth
and the same shape.
But at the moment,
the surface of our planet
is a molten,
fiery vision of hell,
which is going to
be inconvenient.
For starters,
there's nothing to stand on.
No solid rock.
It's just a fiery,
molten sea of magma.
And there's no
way life could start
in this volcanic environment.
So how are we going to get
a solid surface for our planet?
Back on the desert floor,
Professor Jeff
Karson and his team
are setting up a
unique experiment.
They reckon they can show me
how to make land for our planet.
The first step in
their challenge,
recreating that
early molten Earth.
And that means constructing
what is basically a mobile volcano.
And now we're going to
see if we can make it erupt.
- All right, Richard? - Yeah.
Let's get the helmet on. Yeah.
I'm guessing what we've
got in here is not lunch, is it?
It isn't.
Whoa! That's really hot!
So what Bob is stirring there
isn't something that looks like lava.
- It's actual lava. - No, it is,
it is real lava, basaltic lava.
We just put in the ingredients,
just like a recipe,
and cook up this primordial,
primitive material
that makes up our Earth.
It's amazing and exhilarating
but also quite incredibly
hot up here. Can I get down?
It's very hot. And you can see,
we have to get it that hot so it
will flow in a very viscous form.
The recipe for lava
that Jeff's team are using
includes the essential
planetary ingredients,
iron, magnesium and silicon.
But before this
turns to solid land,
we need to make the lava flow.
The spout, here. Here it comes,
here it comes.
The temperatures reached
by this lava are extraordinary.
We know from using
our infrared camera,
where it's incandescent orange,
there,
it's about 1,100 degrees centigrade.
Where it starts to get dark grey,
like down at the toe here,
it's about 850 degrees centigrade,
now.
Wow!
And now it's coming out
here at 1,100 degrees again,
just like the temperature
that we're pouring in.
- So this is much hotter
than that stuff on top? It is.
Looking at what happens
here on a small scale
but with the same materials
and the same temperatures
and the same behaviours,
you can look back and work out
what happened on the early Earth.
Exactly. We're sort of replicating
those conditions of the early Earth,
in miniature.
Imagine the whole planet
covered with glowing,
incandescent orange lava
magma oceans.
That is intense.
You can see the
little wrinkles and folds
starting to form on the surface
as the surface cools
and a crust starts to form.
I can feel wrinkles and folds
forming on my face, watching.
So,
in order to create land from lava,
we need to cool it down
until it turns into a crust.
Simple.
But there's a
wrinkle in our plan.
On the early Earth,
the lava didn't cool in
the way you'd expect.
There was a reason the
surface stayed molten.
Jeff has a, well,
slightly unusual demonstration
of what that was.
Site up on the target.
Shooters, fire.
- We're going in there?
- Let's go have a look.
That was quite exhilarating,
I'll be honest.
Oh, God! I can't see the target.
What am I doing?
Okay, look here, Richard.
Here's where
all the bullets hit.
Feel how hot it is there, still.
It is, yes. Yes,
there's definite heat in there.
- Ow, they're really... You
could think of these as...
Each one of these like a tiny
meteorite that struck the Earth
and transferred its kinetic
energy to heat energy,
keeping the planet warm.
I think I see where
you're going with this,
'cause I did wonder
for a moment.
So these are like meteors.
- Right.
- So, the planet was under bombardment at the time.
-Right.
-And those were going in like these and when they hit,
this is kinetic energy
converting into heat.
And what,
a meteorite hitting is enough,
- is going to make it hot?
- It is.
It keeps it hot and
that's one of the reasons
your planet's not cooling down.
And these meteorites
are a lot bigger.
The meteorites are much bigger
than our little bullets, of course,
and they're travelling
about 10 times as fast.
I'd love to get a better idea,
a better sense of that moment
when that energy is
converted from kinetic into heat.
But to do that,
they'd have to shoot through my hand
and that's going to hurt, so...
Well,
we have a safer way to do that.
A thermal infrared camera's been
filming the entire experiment here
and we can show you
the images created by that.
- In here? - Yeah.
So, this is a thermal camera
looking at what we've just seen.
- Right. - There's the plate.
Hot areas are
going to show up red
and little cooler areas will
show up in a bluer, cooler colour
as each one of these
bullets strikes the metal.
And there they go, look!
I mean, it's really pronounced.
Look at the pieces being blasted off,
there.
Watching them go in like that,
I can imagine they
were meteorites.
Exactly,
much bigger and 10 times faster.
And this effect is
one of the reasons
why my Planet Earth won't set.
- That's right.
- Remains molten.
So, to stand a chance of creating
a solid surface for our planet,
we need to stop this constant
barrage of meteors and asteroids.
On the actual Earth,
this bombardment petered
out around four billion years ago.
On the planet we're building,
it can be done in a jiffy.
And reducing the impacts from
space helps the surface to cool,
so that lava turns to rock.
Perfect!
We now have a planet we can
stand on without being burnt.
But there is something
pretty important missing.
If we're going to have
life on this planet of ours,
we are going to need water.
Incredibly,
some water has been with us
from the very
birth of our planet,
trapped in dust and rock,
and then locked inside of the Earth.
Volcanic activity released
this water as steam,
forming rain clouds that
then filled the first oceans.
A lot more water
arrived from space,
because asteroids and comets
actually carried ice inside them,
adding to our
already wet planet.
So, we've got water.
We've also got land.
But it doesn't look right.
All that volcanic activity hasn't just
pumped steam into the atmosphere,
it's produced a toxic
cocktail of gasses.
This isn't a planet for us yet.
So, how do we clean up
this poisonous atmosphere?
Well, the answer lies with the
oldest living thing on the planet.
On these rocks, there's a thin
film of bacteria called a stromatolite.
These ones today
are in Australia,
but three billion years
ago they were everywhere.
They live on sunlight,
and carbon dioxide in water,
and as a waste product,
they release oxygen.
For more than a billion years,
these bacteria pumped the stuff out,
until the air was right for
the evolution of complex life,
including us.
To build our planet, we started
with truckloads of raw materials.
And we mixed them together
into a cosmic cloud of dust.
We got it to stick together
with static electricity.
And then, we added gravity.
We bulked the planet up.
Then we stopped the onslaught
to cool it down, and make land.
And then we sourced water
and a breathable atmosphere.
But hang on. This isn't right.
There's something seriously
amiss with our planet.
This is definitely not how
things should be looking.
It's a bad case of the wobbles.
A wobble this big,
even slowed down over millions of years,
would be catastrophic.
Without stability,
seasonal changes are extreme,
ice ages are frequent,
and the surface is scoured
by hurricane-force winds.
It's no good. Our planet has
conditions completely hostile to life.
But don't worry,
because to stabilise things,
we don't actually
have to look too far.
The solution is a moon.
To find out how a moon
can stop a planet's wobble,
I've come to NASA in Texas,
where the answer is
kept in a bomb-proof vault,
wrapped in foil.
And if that isn't enough,
this entire facility demands
OCD levels of hygiene.
One man who knows a lot about
this object is Harrison Schmitt.
And that's because
he found it on the moon.
Four decades ago,
Harrison was an astronaut.
December 6th, 1972.
Dr Harrison Schmitt,
better known as Jack.
He would be the first geologist
to set foot on an alien world.
We have commit and
we have lift off at 2:13.
I'm going to meet Harrison,
after a final zap in the NASA microwave.
- Harrison. - Hey.
- Hello. - Welcome.
I so wanted to shake
your hand but it's in there.
A little bit later maybe.
It's great to meet you,
and what have you've got in here?
We have one of the
Apollo 17 samples.
It's one collected near the
lunar module Challenger.
And it is a...
Really quite a
unique type of rock.
That rock formed about
3.8 billion years ago.
That's with a "b".
So it's extremely old, it's part of a
mass of magma that partially filled
the valley of Taurus-Littrow,
where we landed on Apollo 17.
So let's just get this into context
because, for mere mortals like me
to understand, you are standing
there as the only geologist ever
- to have walked on the moon?
- That's correct.
And therefore,
when you saw these rocks on the moon,
they would have meant more to you anyway
because of your training and knowledge.
I hope so.
Your brain must have
been just screaming!
You were looking at that rock.
Well, you can't believe
where this geologic setting was.
It's a valley deeper than the
Grand Canyon of the Colorado
here in the United States.
It is, er...
The mountains on either
side are 6,000 and 7,000 feet
above the valley floor.
This was off the valley floor.
It's the moon that saves the
real Earth from the disastrous
climatic effects of wobbling.
But how exactly the
moon keeps us stable
is tied into its
mysterious origins.
Until the Apollo programme,
we had no real idea of
how the Earth got its moon.
Finding out was an important
goal for Harrison Schmitt,
when his Apollo 17 module touched
down on December 11th, 1972.
Fuel is good,
stand by for touchdown.
Stand by, down at two.
Fuel's good. Ten feet.
That's contact!
Harrison had just three days
to collect as many lunar
samples as possible.
Late in the mission,
things got a little tense.
Harrison had just half
an hour of oxygen left
and he was getting a bit
carried away with his work.
I've got to dig a trench,
Houston.
Fantastic, sports fans!
It's trench time!
They got to leave
at a certain time,
regardless of what they got.
There isn't enough time, Tony, to do it,
no matter which way we want to do it.
We need more time.
You better make it clear to
Parker that we've got to pull out.
We'd like you to
leave immediately.
Okay.
By golly, this time goes fast!
We're on our way, Houston.
Once Harrison and NASA
were able to examine the rocks,
they began to understand fully
just how the moon had formed,
and the massive
stabilising effect it brought.
What the scientists discovered
was an extraordinary connection.
It seems this moon rock was
made of pretty much the same stuff
as Earth rock.
The oxygen isotope ratios
in the rocks are identical
to those ratios that
we have here on Earth
and it tells you that the Earth
and the moon formed in, basically,
almost identically the same
part of the solar system.
And this information that
you brought back has helped
people narrow down the theories
as to how the moon came to be,
where it is and like it is.
No question about that.
The primary hypothesis
right now is giant impact.
Soon after the Earth formed,
another planet-sized
rock crashed into it.
The impact threw
huge chunks into orbit.
And these clumped
together to make the moon.
When first formed, it was much,
much closer than it is now.
One of the primary reasons
that we still are here on this planet
is that the Earth is a stable planet
and it's been stabilised by the moon.
With the moon there,
there's a gravitational stabilisation
that occurs that keeps the Earth's
wobble down to an absolute minimum
and that makes a
big difference for us,
because if you wanted to have major climate
change on Earth, introduce a wobble.
It doesn't mean that
life wouldn't be here
but it would be a very
difficult and different kind
of life that we would
have to deal with,
with this wobble,
over fairly long periods of time.
So, let's see what happens to
our planet when we add a moon.
Our planet and its new
moon are two dancers,
locked in a
gravitational embrace,
steadying themselves as
they swirl round and round.
Having a moon has
one other vital effect.
Tiny variations in its gravitational
pull on our planet's oceans
have given it tides,
and that's more important
than you might think.
Without the tides, early life on
Earth may never have left the sea,
because the tides created
damp strips along the coast
that tempted life onto land.
And the actual positioning
of the moon is crucial.
Ever since its formation,
it's been drifting away from the Earth.
But when it was closer,
it generated immense tides.
If we had them today, every few hours,
New York and London
would disappear under
tens of metres of water.
And if the moon was further away,
the planet's spin would slow
and the days would be longer.
But put it at just the right distance,
which in reality
is about 239,000 miles,
and we have the stability we need.
So, there it is,
the perfect planetary relationship.
After trial and error,
I have built my planet and its moon,
and got them working just right.
In reality,
this whole process took 4.5 billion years.
The sheer scale of it all is
understandably mind-blowing,
especially when you realise that
with just one element out of place,
nothing works, and life stops.
So what holds the
Earth and moon in place?
They need a sun to orbit around,
and other planets to
make our solar system,
all of which is just a tiny
part of a Milky Way galaxy
with 300 billion stars.
And that galaxy is just one
amongst half a trillion other galaxies.
So, to keep it all working,
we're going to have to build a universe.
And to build a universe,
I'm going to need a lot of help.
Oh, this is really difficult!
Oh, my God, it's beautiful!
- Do I look faintly ridiculous?
- Yes!
I'll be honest.
I'm faintly nervous.