Original subtitles

NASA's Parker Solar Probe.

A daring mission to shed light on the mysteries of our closest star.

This is a journey into Never Never Land, you might say.

NASA's Parker Solar Probe is the first spacecraft to touch a star.

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 enrich 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 13 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, you can't see it.

That's 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 of gas 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 the 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 for 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 100,000 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.

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 of gravity.

Consuming more and more hydrogen fuel to maintain their precarious equilibrium.

For most of its life, the 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 26 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, of salvage, if you like, from its

destruction, it distributes those newly minted

heavy chemical elements out into the universe.

Imagine we could journey 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 explosion.

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 of gas and dust.

Nurseries, where new generations of stars were born.

And not just 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 of generations 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 of gas and dust.

The dust slowly clumped together,

forming clusters the size of pebbles.

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 fought for their lives.

Some 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.

Some sort of debris, if you like.

It's 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 planets.

The biggest 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 civilization.

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 19th century.

And it comes from the science of thermodynamics.

In the 19th century, people were interested in the efficiency of steam engines.

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 prophecy 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, and 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.

I mean, there's a part of that photosynthetic machinery, everything you

see here, every plant on the planet, called Photosystem II.

It's comprised of 46,630 atoms, all working together in an intricate machine.

Very, very complex.

Efficient.

It took billions of years 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've 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 200 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 be jealous 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.

A big bang 13.8 billion years ago.

After 100 million years or so the first stars formed.

On this scale one centimeter is about 20 million years.

After 4 billion years the peak rate of star formation occurred.

The maximum number of new stars were born.

After 9 billion years our sun was born.

And today we stand 13.8 billion years ago.

About half way through the lifetime of our sun.

Now in about 5 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 10 trillion years.

On this scale that's about 5000 meters 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't just disappear of course.

They'll be here for eons 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 are still here today.

also witness the end.

They're the longest lived stars in the universe.

Red dwarfs.

Trappist-1 is one of these ancients.

It's already more than 7 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.

Like the sun, Trappist-1 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-1.

The other side frozen.

Permanently exposed to the cold void of space.

If you could stand on the surface of one of these ancient worlds.

As the eons passed,

you could watch the future of the cosmos slowly unfold.

And one day, five billion years from now,

you will

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.

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-1 will linger on long after the death of our sun.

We

will never know the name of the last star.

But we know

that it It 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 will illuminate the universe and create its most intricate structures.

And one day they will all be gone.

I mean 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.

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.

There was a moment when we were putting the spacecraft together that I just took a

moment and looked at the spacecraft and realized this is going into a star and to

realize how special it was to be able to have worked on this and that humanity

decided this was something we wanted to do.

Minus 30.

Status check.

Go Delta.

Go PSP.

Minus 15.

Launch night.

I was sick to my stomach.

Five, four, three, two, one, zero.

Liftoff of the mighty Delta IV heavy rocket with NASA's Parker Solar Probe.

There we go.

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.

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.

Twenty-five seconds into flight.

Chamber pressures continue to look good on all three boosters.

Then realizing that this was all okay as it slowly made its way up into the sky.

Now 50 seconds into flight.

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 94 percent of the way from the Earth to the sun

to actually experience the solar corona, the sun's atmosphere.

I think that closest approach, it'll be about eight solar

radii from the sun, which is just mind-blowingly close.

So we were expecting things to be very hot, over 2,500

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.

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 6,000 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.

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's just begun its mission, really, and it's already really started to

truly transform our understanding for how the sun works.