BRIAN COX: Our universe
is a place of infinite variety.
Two trillion galaxies.
Billions and billions of stars.
And countless planets.
Worlds beyond imagination.
The universe is so vast,
so incomprehensible, so terrifying,
that I think it's quite natural
for us to choose
to live out our lives
completely oblivious to it.
Perhaps that's why there's a sense
of relief that rises with the dawn.
The brightening sky hides the stars
and the questions that they pose.
After all,
they are the biggest questions.
How did the universe come to be?
Why are we here?
And how will it all end?
We have to face those questions
if we're ever to acquire
a truly deep understanding of ourselves.
You see, astronomy challenges us.
From one perspective,
we're just grains of sand adrift
in an infinite and indifferent ocean.
But from another perspective, we are
nature's most magnificent creation.
Collections of atoms that can think
and wonder about the universe
and choose to explore it.
INDISTINCT VOICES: Five, four,
three, two, one.
We have lift-off. All systems go.
(THEME MUSIC PLAYING)
COX: In our quest for answers,
we're venturing ever further from home,
far beyond the planets...
and out to the stars.
Our spacecraft are sending back
a stream of extraordinary revelations.
Visions of alien worlds...
with the ingredients to create life.
We've seen galaxies collide,
black holes devouring star systems.
And we may have glimpsed
the origin of the cosmos itself.
With every new observation,
with every new piece of knowledge,
there is the opportunity to acquire
a deeper understanding.
And, as we answer
question after question
we get ever closer to being able to tell
what is surely
the greatest story ever told.
MAN OVER RADIO:
NASA's Parker Solar Probe,
a daring mission to shed light
on the mysteries of our closest star.
EUGENE PARKER: This is a journey
into never-never land you might say.
COX: NASA's Parker Solar Probe is
the first spacecraft to touch a star.
(EXPLOSIONS)
It's designed to fly
through the Sun's atmosphere,
braving temperatures
no spacecraft has ever endured.
The Parker Solar Probe is
allowing us to know our star
as we've never known it before.
And it's also helping us
to tell the story of all the stars.
Our Sun is from a long line of stars
dating back to the dawn of time.
From fierce blue giants
which first lit up the universe,
to later generations,
whose deaths enriched the cosmos
with precious elements,
the building blocks of our solar system,
and allowed our Sun to create the thing
which brings meaning to the cosmos.
Life.
You and me.
We have
a strange relationship with the stars,
somewhere between awe and indifference.
I think we take our star,
the Sun, for granted,
partly because of its predictability.
Every day it rises in the east
and sets in the west,
without any help or reverence from us.
But many ancient cultures deified
the Sun.
They treated it as a God,
and the Sun gods were creators
and destroyers of worlds.
So which is it?
Well, I think that the modern story
of the stars as told by science,
which is indisputably an epic story
stretching back over billion years
to the origin of the universe,
places them firmly
in the realm of the gods.
If we want to understand
where these gods came from...
we have to go back...
to a time before the stars.
In the beginning the universe was dark.
But it was not empty.
Something was lurking in the void,
stretching out tendrils.
The cosmic web grew
to become a vast structure,
criss-crossing the entire universe.
It was formed by interlocking filaments
of dark matter,
and it was at the places
where these filaments met,
the intersections,
that the first stars,
our Sun's earliest ancestors, were born.
The cosmic web is
the scaffolding of the universe,
the vast and intricate structure
that spans the void.
The web is made
primarily out of dark matter,
a mysterious substance
that dominates the universe,
although we don't know what it is.
It's one of the great mysteries
in modern physics.
It's probably some kind of particle
that interacts very weakly with itself
and with light.
If it doesn't interact with light,
we can't see it, which is
why it's called dark matter.
But it does influence the universe
through its gravity.
It was in the dark heart
of the cosmic web
that gravity began to sculpt
the early universe,
drawing together
the two simplest elements,
hydrogen and helium.
The raw material
for the very first stars.
Hydrogen gas clings
to the filaments of the web,
attracted there
by the gravitational pull
of the dark matter.
And where those filaments cross,
the gas can become dense enough
to collapse under its own gravity
to form great clusters of galaxies,
each filled with billions of stars.
The universe was
approaching a turning point.
Hydrogen and helium poured
into the regions
where the filaments crossed,
gathering into ever denser clouds.
Gravity asserted its grip,
and the clouds ofgas began to collapse,
becoming denser and denser.
And in the densest regions,
the gas became so hot...
that nuclear fusion reactions began.
And out of maelstrom,
the first gods emerged,
and there was light.
The stars illuminate the universe,
but that is the least interesting thing
that they do.
The thing that makes
the universe interesting,
that brings meaning to the universe is
that, life. You and me.
And life is just chemistry.
And chemistry requires
complex chemical elements.
The only thing that existed
in the universe before the stars
was hydrogen and helium.
Life requires carbon
and oxygen and iron.
All those things were made
in a process called nuclear fusion
in the cores of stars,
or even the heavier elements,
like gold, in the collisions of stars.
So, without the stars,
the universe would be uninteresting.
It would be meaningless.
It would be just an infinite box of gas.
The first stars were monsters.
Hundreds of times as massive as our Sun.
They burnt with such ferocity
that they shone blue,
with surface temperatures
in excess of , degrees.
They were the largest stars ever
to have lived.
Violent and volatile giants.
A star is essentially a balancing act.
The force of gravity is
constantly trying to collapse it,
and that pushes its ingredients,
primarily hydrogen, single protons,
closer and closer together.
Now, when those protons
get close enough together,
another of the fundamental forces
of nature,
the strong nuclear force, takes over,
and it can stick the protons together.
That releases energy which creates
a pressure which holds the star up.
Now the more massive the star,
the stronger the inward pull of gravity
and the more energy has to be released
to maintain the balance,
and so the faster
the ingredients are used up.
These giant stars were
in a struggle for survival,
fighting the relentless pull ofgravity,
consuming more and more hydrogen fuel
to maintain
their precarious equilibrium.
For most of its life,
a star burns hydrogen,
the simplest chemical element
with one proton in its nucleus,
into helium with two protons.
Now, when it runs out
of hydrogen in the core,
the core starts to collapse and heat up,
and the star responds by building
ever more complex elements.
So it makes carbon with six protons
and oxygen with eight protons,
releasing more
and more energy as it goes.
But when the star has
assembled iron in its core,
with protons in its nucleus,
no more energy can be released.
The star loses
its battle against gravity.
It collapses
and in a final moment of creation,
salvaged if you like,
from its destruction,
it distributes those newly minted
heavy chemical elements
out into the universe.
Imagine we couldjourney back in time
and watch the first star live out
its brief luminous life.
After only a million years
the star used up all of its fuel.
The core collapsed.
The star imploded.
And then rebounded...
in a colossal expl*si*n.
A supernova.
In death, the first stars began
to transform the cosmos,
enriching the ocean
of hydrogen and helium
which filled the universe
with heavy elements...
to build new generations
of more complex stars.
Over time,
these elements gathered together,
creating rich clouds ofgas and dust.
Nurseries where new generations
of stars were born.
And notjust stars,
but families of stars.
The first galaxies.
And around this time,
some of the earliest star systems
formed in our own galaxy, the Milky Way.
A new age of complexity was
dawning in the universe.
Now, there were stars
of different sizes,
and different colours.
And crucially new bodies had appeared.
Planets.
Places where the rich chemical elements
built by previous generations of stars
could finally find a home.
Countless billions of stars
have come and gone
since those first giants
illuminated the darkness.
Each enriching the universe
with the material
out of which the next generation formed.
Blue stars and white stars,
single stars, double stars,
even triple star systems orbiting
around each other.
The conditions were now right
for those stars to drive the universe
into a new and profound age
of complexity.
Our Sun was formed from the ashes
ofgenerations of ancestors.
Just one small star in a galaxy
of billions of brilliant gods.
For the first million years of its life,
the Sun was virtually alone,
wreathed in clouds ofgas and dust.
The dust slowly clumped together...
forming clusters the size ofpebbles.
Then, boulders.
And finally...
planets.
But the planets were lifeless rocks.
Only the Sun had the power
to turn them into worlds.
Some were too far away from the Sun.
Ice giants,
frozen, seemingly into infertility.
Others formed too close to the Sun,
seared by a relentless light.
They became scorched desert worlds.
But there was a planet
in the Sun's family
that, quite by chance, formed
neither too close nor too far away.
An Arcadia, where our star could
breathe life into dust.
The planets are just the leftovers
from the formation of stars.
Debris, if you like.
They're just little specks orbiting
around those magnificent flames.
But the planets are also
the places in the universe
where gravity has concentrated
the heavy elements built
by previous generations of stars.
And that makes the planets the canvas
on which the stars can create.
"The canvas on which the stars can
create." What do I mean by that?
Well, just look around.
Everywhere you look on Earth
there is complexity.
Not only mountains and rivers,
but living things, animals and plants,
human beings, human civilisation,
the most complex thing we know of
anywhere in the universe.
So, you have to ask yourself
how can it be
that such complexity can emerge
completely naturally in the universe?
Well, the answer, in fact, was
known in the th century
and it comes from the science
of thermodynamics.
In the th century,
people were interested
in the efficiency of steam engines,
and steam engines are, after all,
the machines that powered the factories
that allowed people to build
increasingly complex things.
And it turns out that the only thing
that matters for a steam engine,
the thing
that determines its efficiency,
the thing that allows it
to do work and build things
is the temperature difference
between the fire,
the furnace
at the heart of the steam engine,
and the cold environment surrounding it.
In the universe, the stars are
hot spots in a cold sky.
We are sitting, in a very real sense,
inside a giant steam engine,
powered by the furnace of the Sun.
And it's in that sense
that the stars are the creators
of complexity in the universe.
But creating complexity is a subtle art.
You need an engine, in this case a star,
that's not too wild and flashy.
A star which is
consistent enough for long enough
to kindle the sparks of life,
and allow those sparks
to flicker and flourish.
The most important property of a star,
if it's to nurture a civilisation...
is magnificent dependability.
No one knows exactly
how life on Earth emerged.
But what we do know is
that at some point
primitive cells living in the ocean
began using the Sun's energy
to power life-giving chemical reactions.
These cells formed a bridge
between Earth and Sun.
Delicate engines
which harness the fires of our star,
using sunlight to turn
carbon dioxide and water into food.
This process, known as photosynthesis,
unleashed the Sun's creative power,
and drove the evolution of complexity.
From primitive bacteria,
to plants and trees...
and ultimately, to you and me.
You know, photosynthesis is a process
that's very easy to describe in words.
The plants take energy from the Sun,
then use it to react carbon dioxide
and water together
to make sugars
and a waste product, oxygen.
Really easy to say.
Very difficult to do.
There's a part
of that photosynthetic machinery
in everything you see here.
Every plant on the planet has
got Photosystem II.
It's comprised of , atoms
all working together
in an intricate machine.
Very efficient.
It took billions ofyears of evolution.
Then we eat the plants,
or we eat something
that's eaten the plants
and we do the reverse reaction.
We take those sugars and we breathe in
that waste product, oxygen.
React them together,
release a bit of energy,
a bit of the stored sunlight
if you like,
and we use that energy to maintain
our structure, to grow, to live.
Trillions of stars have existed
since the universe began.
But ours has nurtured
that most miraculous thing,
life.
And that makes the Sun
a truly remarkable star.
That is the only star
we know of anywhere
where there are collections of atoms
in orbit around it, you and me,
that have named it The Sun. Our Sun.
We worshipped it, deified it
since the dawn of history.
In fact, it's been argued
that the Sun lies at the foundation
of all religion, and there may be
some truth in that.
In fact, I think
there is a deep truth in that
because we all owe our existence,
this brief time we have
in the universe to that star.
In fact, in a deeper sense
to all the stars.
We don't need to invent
imaginary gods to explain the universe.
We can replace them with the real thing.
Everyone we love.
Everything we value.
Our supreme accomplishments
as a civilisation...
were created and crafted...
by stars.
There are over billion stars
in our galaxy.
And there are two trillion galaxies
in the observable universe.
We're living in the age of stars.
An era of light and life in the cosmos.
From our fleeting human perspective,
stars seem eternal.
But even gods are not immortal.
Where there is light,
there is darkness.
Stars are creators,
but they can bejealous guardians
of their creations.
Many smaller stars don't die
in spectacular explosions.
Instead, they slowly fade away.
They hang on
to the precious elements they made,
becoming fossil stars.
And as more fossils litter the universe,
more life giving elements
remain locked away,
starving the cosmos
of the material needed to make
new generations of stars.
The age of stars may seem infinite,
but it had a beginning,
and it will also have an end.
Imagine a timeline of the universe
and imagine that this is
the origin of the universe,
the big bang . billion years ago.
After million years or so,
the first stars formed.
On this scale, one centimetre is
about million years.
After four billion years the peak rate
of star formation occurred.
The maximum number
of new stars were born.
After nine billion years,
our sun was born.
And, today, we stand
. billion years later,
about halfway through
the lifetime of our sun.
Now, in about five billion years' time,
our sun will die
but new stars will be born,
and many of the older stars
in the universe,
the smaller stars, will
continue to shine.
In fact, we think that the last star
will cease to shine,
the universe will go dark,
in around ten trillion years.
On this scale,
that's about metres away
from the big bang.
But that's not the end of the universe.
As far as we know, the universe will
continue expanding forever.
And so, the age of starlight is
the briefest moment of time
in the infinite history of the universe.
The age of darkness will go on
and on and on.
Stars won'tjust disappear, of course.
They'll be here for aeons to come.
But, over time,
the universe will grow darker,
colder and emptier.
There are stars around today
that existed close to the beginning
of the age of stars.
And some of them will
also witness the end.
They're the longest-lived stars
in the universe.
Red Dwarfs.
Trappist- is one of these ancients.
It's already more than
seven billion years old.
Almost twice as old as our sun.
But only around a tenth of the size,
and less than one percent as bright.
It's a cool star.
Slow burning.
And that is the secret of its longevity.
Because they burn slowly,
Red Dwarfs live for a very long time,
far longer than any other star.
Like the sun, Trappist- has
its own planets.
Seven rocky worlds,
each roughly the size of Earth.
Some may have atmospheres,
and even oceans.
But there the similarity ends,
because these are strange worlds.
Every one of these planets
is locked in its orbit,
one side facing Trappist- ,
the other side frozen,
permanently exposed
to the cold void of space.
Ifyou could stand on the surface
of one of these ancient worlds,
as the aeons passed,
you could watch the future
of the cosmos slowly unfold.
And, one day,
five billion years from now,
you'd see our sun flicker
and fade away forever.
The death of our sun will
probably go unremarked.
I doubt that we'll be around to see it.
Maybe some alien astronomer,
on a world far away
across the milky way, will see it
through the end of their telescope
but I don't think
they'll give it a second thought.
I mean, we've seen hundreds of stars die
and we don't give them a second thought.
But, I think the death of our sun will
matter here, locally,
in this little corner of the galaxy,
because it will mark the end
of a glorious time
in the history of our galaxy,
where meaning,
where science and literature
and art and poetry
and music existed here.
And that does matter.
Why does meaning have to be eternal?
It's the fragility of our lives
that makes them valuable.
I think the wonderful thing is
that our star has
taken the laws of nature,
here on this planet,
and crafted such
a magnificent expression of them.
You and me,
and all this.
Stars like Trappist- will linger on
long after the death of our sun.
We will never know the name
of the last star.
But we know
that the last star to shine
will be a Red Dwarf.
The last star will slowly cool...
and fade away.
With its passing
the universe will become,
once again, a void,
without light,
or life,
or meaning.
The stars illuminate the universe
and create
its most intricate structures.
And, one day, they will all be gone.
The stars are gods,
but they're mortal gods.
And, when that time comes
and the last stars have faded,
and all possibility of life and meaning
in the universe has faded with them,
they will have left
the most profound legacy.
Because, for a moment
in the long history of the universe,
the stars illuminated the dark,
and allowed us to illuminate it, too.
RAMAN PRINJA: We want to study the sun
because it teaches us a lot about stars.
It teaches us a lot about all the other
millions and billions of stars
in our galaxy and beyond.
KELLY KORRECK: There was a moment,
when we were putting
the spacecraft together,
that I just took a moment
and looked at the spacecraft
and realised,
this is going into a star,
and to realise how special it was
to be able to have worked on this,
and that humanity decided this was
something we wanted to do.
- MALE : Minus .
- MALE : Status check.
- MALE : Pro delta.
- MALE : Go PSP.
MALE VOICE : Minus .
KORRECK: Launch night,
I was sick to my stomach.
MALE : Five, four, three, two,
one, zero.
- Lift-off of the mighty Delta IV...
- (CHEERING)
...Heavy Rocket
with NASA's Parker Solar Probe.
- There we go.
- (APPLAUSE)
DR CHEN: The spacecraft is the first
that NASA has named
after a living person,
because Eugene Parker is
really such, you know,
an eminent physicist in our field.
KORRECK: The Delta IV Heavy
is a very slow rocket
compared to the other launches
I've seen,
so I just saw fireballs,
and was very,
very frightened for a while.
MALE : Twenty-five seconds
into flight.
Temp and pressures continue to look good
on all three boosters.
Then realising that this was all okay
as it slowly made its way up
into the sky.
MALE : Now seconds into flight.
KORRECK: Parker Solar Probe is
so revolutionary
because it's the first time that we're
actually going in to touch the sun.
We're going % of the way
from the Earth to the sun
to actually experience the solar corona,
the sun's atmosphere.
I think, at closest approach,
it'll be about eight solar radii
from the Sun
which is just mind-blowingly close.
KORRECK: So, we were expecting
things to be very hot,
over , Fahrenheit,
but in a soup
of a million degree plasma.
That's a real challenge
for the spacecraft
to survive that environment.
So, in order to do that,
there's a very large heat shield
on the front of the spacecraft
which protects
the majority of the instruments
which are sat behind
on the spacecraft body.
KORRECK: What makes
Parker so great is the fact
that it has a set of instruments
that work together
in order to look in all directions
in order to solve those big mysteries
about the solar wind.
The solar corona has been mysterious
to us since we've known about it,
so it's a very strange thing.
The surface of the sun is
sort of , degrees
and then, above that, you have
this very thin atmosphere
that's a million degrees.
Super-hot.
And the way that's heated,
we know it has something to do
with magnetic fields
but we don't know exactly how it works.
That's where
the solar wind is generated.
We don't know quite exactly
how that works either.
KORRECK: Other things that have
come out of this are
coronal mass ejections.
When we originally did the proposal,
we were thinking that we would see five
in the entire seven-year mission,
if we were lucky.
We ended up seeing around
four to five in the first year.
So, there has been just a total switch
in terms of how active the sun is
or what we classify
as coronal mass ejections.
Maybe a little bit of both.
It is a joy to see
all the data coming back.
It's a joy to share it with others
and to see them be as curious
as I have been for the last decade.
So, Parker has just begun
its mission really,
and it's already really started
to truly transform our understanding
for how the sun works.
(END THEME PLAYING)