Original subtitles

In 1973, nine astronauts were sent to live and

work in the world's first space station, SkyLab.

Their mission was to observe the Sun, free from the Earth's

distorting atmosphere.

The astronauts witnessed what no human beings had ever

seen before: a sun more powerful than anyone

could have imagined.

To our ancestors, the sky was an unfathomable mystery.

At night, it was brimming with pinpoints of light: stars.

Then there was the Sun.

Its arrival in the morning caused those stars to vanish,

and miraculously brought warmth and light.

It was seen as the giver of life, the first god.

This is the story of mankind's struggle to see behind

the glare, and glimpse the truth about the Sun,

how we came to understand the scope of its power,

and its role in the Universe.

In February, 1998, the Caribbean island of Guadelupe

prepared for a rare celestial event.

For a few brief minutes, day would become night during a

total eclipse of the Sun.

This was Francisco Diego's tenth eclipse.

As a young boy in Mexico, he was deeply affected by the

first one he saw.

It started a lifelong fascination with the Sun.

The Sun was perceived as the immaculate, gold disc,

perfect, it was perfection, it was a religious belief,

because everything was perfect in the sky, and the Sun was

the most perfect circle in the sky, with no blemishes,

no structure, just a perfect, flat disc, golden disc.

And it was the Sun god for many, many religions

in the world.

The Sun remained a symbol of perfection until

a 17th century Florentine called Galileo first pointed a

telescope at the sky and found that that idea might

just be wrong.

What Galileo did was apply the telescope for the first

time, and discover that the Sun was not perfect.

That the Sun have sunspots, and that was a major revolution

in philosophy and of course, in science.

Over several weeks, Galileo watched the

sunspots move across the surface of the Sun, and realized

that it was spinning.

Galileo's discovery completely changed ideas about the Sun.

But although he spent the rest of his life studying it,

he never saw anything more.

The blinding light of the Sun made further scientific

observation very difficult.

But there were moments, provided the scientists chose them

carefully, when it was possible to cheat

the Sun's dazzling rays.

Roughly three times every decade, somewhere in the world,

the Moon passes directly in front of the Sun.

It offers a rare and special opportunity.

If the Sun was this big, the Earth would be a little ball

of about three or four millimeters in diameter, and the Moon

is even smaller than that.

The Moon is only a quarter of the size of the Earth,

so the Moon is four hundred times smaller than the Sun.

But the fantastic coincidence is that the Sun is 400 times

farther away than the Moon from us.

So we see both of them, by coincidence, more or less

the same size.

One minute!

For four hours, Francisco watched the Moon

creep into position.

No theatres!

He'd come halfway around the world to watch

just four minutes of total eclipse.

But even if you are in the right place at the right time,

there's never any guarantee of success.

In the end, Francisco got just a few moments to glimpse

the hidden Sun.

We lost it.

No corona.

Then, to his huge disappointment,

he was thwarted as the clouds rolled in

to wreck his eclipse.

Douglas Gough is a leading solar scientist.

To see his first total eclipse, he traveled to Indonesia.

The Indonesian government had declared it to be illegal

to watch the eclipse, at least for the Indonesians.

They had either to watch it on television,

or to go to the mosque and pray for the dragon to spit

the Sun out again.

Which is what they believed was taking place.

I was standing at the end of a road on my own,

and a little boy came up to me, had be watching me.

About three years old.

And I gave him some dark film,

to look at the Sun through,

and then an old man of about 70, who turned out to be

the head of the village, came too, and the three of us

saw this fantastic eclipse.

A total eclipse reveals the Sun's corona,

an outer layer normally lost in the glare.

A very eerie feeling, and almost total silence;

the birds stopped singing.

And the only thing we could hear in the distance was the

chanting from the mosques.

This is what early astronomers traveled

the world to see.

Within the corona were what looked like burning clouds.

It seemed that the surface of the Sun was smothered in a

turbulent, raging atmosphere.

Well, you realize, when you see these things

moving, that the Sun is active.

It's not just a quiet, passive ball of gas, but it's

churning away; interesting things are happening.

Seeing anything for the first time is exciting.

That's why explorers on Earth would explore parts of the

Earth where no man had been before.

There's very little left of the Earth now to do that,

so we go elsewhere in the Universe.

Seeing the Sun, peeling off a layer of mist,

a lack of understanding, and suddenly seeing how something

works is an amazing experience when you see this

for the first time.

For more than 200 years, scientists had only

fleeting chances to study these unique views of the Sun.

Then, in the middle of the 19th century, father Angelo

Secchi, the Vatican's chief astronomer, found himself

at the forefront of a revolution in how we looked at light.

Through an observatory above his church in Rome,

he pioneered the use of a new branch of science called

spectroscopy.

Secchi's spectroscope split sunlight into its different

colors, then magnified the light from just one region.

What the discovered at the edge of the Sun was a revelation.

Spectroscopy revealed a complexity that would have

astonished Galileo.

What had happened is that you were no longer dazzled

by most of the light from the Sun;

you could see something else.

You could see the kinds of things that you can see at the

edge of the Sun during an eclipse when you're no longer

dazzled by the light from the Sun.

Astronomers could now study not just the

edges, but the body of the Sun.

Galileo's sunspots were revealed as Earth-sized tears

in the surface, like windows on a mysterious interior.

The surface itself bubbled before their eyes.

Soon, they were able to identify the chemicals that made up

the Sun.

Dark bands in its spectrum revealed the presence

of hydrogen, calcium, iron, and astronomers discovered

an alien element, completely unknown on Earth.

They named it after Helios, the Greek Sun god: Helium.

In 1862, Father Secchi turned his spectroscope to the night

sky to see what stars were made of.

He recognized the pattern of chemicals immediately.

They were all but identical to the Sun.

One of the great mysteries of the heavens had been resolved.

Our Sun was a star.

The religious implications of Secchi's discovery were

profound, but what troubled the church was a huge step

forward for astronomers.

The Sun was one of those stars, and so now, for the first

time, one realized that the Sun was a member of the family

of stars, but from a scientific point of view, that's

fantastic, because we want to know what most of the Universe

is like, and so, by studying the Sun, we can study

a typical star.

By the late 1940s, rockets were going beyond

the Earth's atmosphere.

Scientists discovered that the fringes of space were

scorched with radiation.

It seemed that while our atmosphere allowed heat and light

to pass through, it was shielding us from x-rays, gamma

rays, and ultraviolet light that had to be coming

from the Sun.

Alexei Leonov was the first man to brave this dangerous

radiation and come face to face with a star.

Then, in 1973, the first solar space laboratory was

launched, but the project almost ended in disaster.

When SkyLab was launched, it had a heat shield wrapped

around it that was to open up after it got into orbit,

and what happened was 60 seconds into the flight,

that heat shield popped open, and of course, it's still

in the air stream, and so the air stream tore the heat

shield off, and when it did that,

it unlocked both solar wings.

Commander Pete Conrad had already walked

on the Moon when he was chosen to lead the first crew

on SkyLab.

But their new home was no longer protected by an atmosphere,

and inside, temperatures started to soar.

Their first job was to find some way of shielding

the damaged station from the worst of the Sun's rays.

Right away, on day one, we went in and got this temporary

heat shield rigged, which we were able to rig from inside.

We were able to put it out through one of the air locks.

We were able to push, just like an umbrella, a pole

and mylar sheets that then popped open like an umbrella,

and then we were able to pull it back into where it was

just offset by just a few inches off the side, and it did

take care of the heating problem.

Temperature began to go down immediately.

As the temperatures finally dropped

to safe levels, the crew made their way

into the observatory.

Their next task was to get to grips with life in a

weightless environment.

Initially, nausea prevented all but the toughest from

eating, but the problem soon passed, and within a few days,

space didn't seem such a bad place after all.

And then, with no distorting atmosphere to blur their

sights, the most comprehensive solar observation

in history began.

The SkyLab flight is very near and dear to my heart.

I know a lot of people don't understand that it probably

means more to me than going to the Moon, and of course,

part of that was being able to run the solar telescope

and know that we were bringing back a tremendous amount

of information that nobody ever had before

in any great quantities.

And to begin with, when I switch to the new position

called H-Album, these words stand for hydrogen album,

and they are called hydrogen because the light that we see

comes from light radiated by hydrogen atoms

in the Sun's atmosphere.

Viewing the Sun with the same wavelengths

of light used by Secchi more than 100 years earlier,

the SkyLab astronauts saw incredible details

on the Sun's surface.

For example we can see sunspots, we can see network,

we can see filaments, all these things on the Sun,

in great detail.

Each one of us took a four-hour turn at the solar

telescope panel.

Now, I've always related that to playing three 88-keyboard

pianos at the same time.

It was a very complicated set of switching and everything.

It was very involved and very intense, and you'd work

real hard during that time frame, making sure those

sequences ran the right way.

And then things would come up in real time, like a solar

flare all of a sudden.

So we had to be prepared to catch that, also.

Solar flares are planet-sized eruptions

of boiling gas that somehow break free of the Sun.

They had been seen from Earth, but never in such

extraordinary detail.

If somebody else was running it, they might call us,

and we could go up and take a look also.

So that happened quite frequently, when something really

unusual came up that we could witness, we would call

the other guys up, let them come take a peek.

In nine months, successive SkyLab crews

took more than 160,000 images, revealing aspects of the Sun

that had never been known before.

The most spectacular discoveries were the coronal mass

ejections, outbursts of material on a scale

that dwarfed solar flares.

These were the best views yet of the turbulent Sun.

But why were the coronal mass ejections so much more

powerful than the solar flares?

The key lay with Galileo's sunspots.

Before the dawn of the space age, the summit of the

San Gabriel mountains was as close as it was possible

for an American to get to space.

In 1903, George Ellery Hale, the son of a wealthy engineer,

had a dream.

He would indulge his passion for astronomy by building

the world's most advanced solar observatory high above

the town of Pasadena.

Sallie Baliunas is an astrophysicist

at the Mount Wilson Observatory.

Hale is my personal hero.

He was not only a great scientist, he had instinct

about engineering, so he could build the largest telescopes

in the world so successfully, he raised a lot of money

to do these projects, something scientists always have to

do, and as he often said himself, he made no small plans.

The route to the top of Mt. Wilson wasn't easy.

This road wasn't built until 1936, so all the

tons of concrete and steel had to be brought up by backpack,

or by mule train, on a very steep seven mile trail

up the side of the mountain.

The pack horses had to make over 60 trips

to transport the telescope alone.

But Hale soon had an observatory that was the envy

of the world.

Hale's first challenge was to understand the Sun's oldest

known feature: sunspots.

Hale built a spectrograph, which is beneath this table.

75 feet below is a grating that disperses the light

of the Sun into its energy components.

The grating would look like this.

And would break up the sunlight into its different colors,

and buried in this spectrum are the absorption lines

of the gases of the Sun.

With his unique spectrograph, Hale set about,

analyzing the surface of the Sun.

He was able to take photographs of sunspots, in more detail

than anyone had ever achieved before.

But it was during a study of the chemical absorption lines

of the Sun's surface that Hale made a profound discovery.

When he looked at the quieter part of the Sun,

he saw ordinary looking absorption lines, and then,

as the sunspot rolled into the slit, the lines began

to broaden a little bit, and then split.

As Hale saw the lines split apart,

he instantly recognized the phenomenon.

Voila.

Magnetic fields.

He could see it.

June, 1908.

In that instant, Hale had unraveled

one of the Sun's greatest mysteries.

Sunspots were caused by magnetic distortion.

These distortions are some 4,000 times greater than the

Earth's magnetic field.

They hold back the gases rising up, cooling the surface

by 2,000 degrees, and causing the dark spots.

So a sunspot, on the surface,

is nothing more than a twisted and kinked magnetic field,

looped out of the surface.

This magnetogram shows how the surface

of the Sun is speckled with positive and negative lines

of magnetic force.

These field lines channel the Sun's storms;

eruptions of plasma, which explode outwards for thousands

of kilometers, before being dragged back

into its boiling surface.

Coronal mass ejections and prominences,

everything we see on the surface of the Sun,

all the dynamical features, are all magnetic in nature.

In one of the coldest places on Earth,

some 15 years before Hale started his investigation

into the sun, a scientist in Norway had drawn his own

extraordinary conclusions about the Sun's magnetism.

In a land where scientists cannot see the Sun for months

on end, he was convinced that you could still feel its

presence in one of the most beautiful natural phenomena

on Earth.

It may be strange to see why we are out here, far to

the North, on top of a snowy roof, in the darkness,

when you're dealing with the Sun.

But here, you see the Aurora, the Northern Lights.

I really like to see the Aurora of a dark sky.

It's a beautiful sight, and many strange colors,

which you do not see in any other place.

It really lights up this dark days that we have here

in the North, in Wintertime.

Earlier, it was often thought the Northern Lights were

the souls of dead soldiers fighting.

Norway is one of the best places in the world

to study Auroras.

Truls Hansen monitors the radioactivity high in the

Earth's atmosphere.

It's an area of research that goes back over a century.

100 years ago, Norway's most famous scientist dedicated

his life to the study of these strange atmospheric

disturbances; his name was Dr. Kristian Birkeland.

Birkeland was certainly brilliant, but all the little

bit mad, and you might see that from his book here, really.

This book you will find not only the theories

about particles and Aurora, but you will find a lot

of ideas; some of them were right, most of them are wrong.

And one of them was in his terella, which we see clearly

here, was a vacuum chamber with a small globe pretending

the Earth inside it.

And we can also see Birkeland himself on the side here,

controlling the experiment.

Birkeland's most celebrated experiment

artificially created the Northern Lights, and to protect

his brain from radiation, bizarrely, he always wore a fez.

Odd as he may have appeared, Birkeland's theories about the

origin of Auroras stemmed from years of dedicated study.

The Northern Lights were known to be particularly energetic

following a period of solar activity.

Birkeland wanted to try and find a mechanism

that linked the two.

These are the old magnetometers, which we are operate...

Have been operating here for more than hundred years,

and are still used some places around the world.

And Birkeland, he used very similar instruments.

We have here a recording of the magnetic field during

one day, taken with this instrument.

It starts rather quiet around noon, and then here,

in the evening, we get a sort of attack, and we get

a magnetic storm, which you see very clearly here,

and during this period, we also have a large Aurora,

very bright Aurora.

What we see here is the so-called Birkeland terella

experiment, he built several of this kind, but this is the

biggest one, and the last one I suppose, being made in 1913.

It's really a large vacuum chamber,

with a model of the Earth inside.

Birkeland's hunch was that the magnetic storms

which accompanied the Northern Lights were caused

by a stream of electrically charged particles buffeting

the Earth's magnetic field.

He believed that these particles had to be coming

from the Sun.

But other scientists never followed up his ideas.

In 1917, Birkeland committed suicide.

In fact, evidence for the extraordinary power of the Sun

had been visible to humans for thousands of years.

Chinese astronomers noted that the tails of comets

always pointed directly away from sunlight.

It was assumed that the trail of dust was being pushed

away by the gentle pressure of the Sun.

But in 1947, a German physicist, Ludwig Biermann,

calculated that something far more substantial than sunlight

had to be pushing the tails of comets.

He called it "solar corpuscular radiation," but his idea

was widely rejected by scientists.

Despite the general derision, a physicist from Chicago

called Eugene Parker believed there might be something

in Biermann's argument.

I had a particularly good chance to talk with him

when he was visiting Chicago.

He pointed out that if it isn't the sunlight,

there is only one other possibility, and that is the

solar corpuscular radiation, the emission of particles

from the Sun, that interacts with the tail and blows

it away from the Sun.

His revelations about the comet tails really got to me,

and I realized he had a fundamental point.

The eminent physicist Sydney Chapman

was particularly eager to attack Biermann.

He pointed out that the volume of the Sun was 330,000 times

greater than the earth, and that no particle, however small,

could escape its enormous gravitational pull.

Dismissing Biermann's ideas about solar wind, Chapman

was interested in researching a quite different area:

examining how the Sun's corona worked.

He suggested that the corona, though still firmly bound

to the Sun, stretched much further than could be seen

during the solar eclipse.

Eugene Parker met Sydney Chapman at an observatory

in Boulder, Colorado.

Coming home from Boulder, I was thinking about what I

had learned from Chapman: this very basic idea that the

corona extends out through the Solar System, filling

everything, and then I realized that Chapman and Biermann

were mutually exclusive, that is, the solar corpuscular

radiation that seems to effect the comet tails cannot

penetrate through a static corona.

You get interactions that block this.

And, on the other hand, I could not see that either one

of them was wrong.

Parker worked at the apparent contradiction

in the two theories, and found that they were both right.

I wrote down the equations of motion and integrated them

and found there was one and only one solution that fitted

the condition of strongly bound at the Sun and zero

pressure in infinity, and that was the solution providing

the supersonic solar wind.

Immediately declared that it was false and published

papers purportedly showing alternatives, and gave lectures

decrying the idea, and a lot of my friends were sympathetic,

they said, "Oh, well, it was a great idea, but you know,

"great ideas often fall flat on their face."

And my reaction, of course, was, "Well, we'll see what

"falls flat on its face."

Parker had to wait five years for his theory

to be vindicated.

In 1962, the Mariner II probe to Venus provided the evidence

showing that Parker just had to be right.

The world's first interplanetary probe signaled back

that space is awash with the solar wind, exceeding even

Eugene Parker's estimates.

The JPL plasma detector simply showed there was a wind

of anywhere from 300 to 800 kilometers per second,

and the wind was always there and it never ceased,

and that was it.

I refused to argue with anybody after that.

Modern space telescopes revealed

the complexity of Parker's solar wind.

From the Sun's equator, a constant stream of particles

evaporates into space.

Occasionally, violent gusts break free of the Sun's

gravitational and magnetic forces.

These are the flares and coronal mass ejections

first witnessed by SkyLab.

These electrically charged hurricanes are ferocious

and brutal, and the planets lie in their firing line.

Mercury, the closest planet to the Sun, bears the full

brunt of the solar wind.

Any atmosphere this moonlight world may once have had

has long been blown away, leaving its surface bathed

in deadly radiation.

Mars is larger than Mercury, and four times further from

the Sun, and yet, even here, it is thought that the solar

wind has stripped away up to a third

of its original atmosphere.

Venus, our nearest neighbor, has an atmosphere many times

thicker than the Earth, but probes have discovered its

clouds are also being eroded by solar wind,

creating a comet-like tail that stretches back to the orbit

of the Earth.

But what of our own atmosphere?

The Earth's magnetic field stretches far into space,

and fights a constant battle with the Sun to deflect

the solar wind and protect our atmosphere from erosion.

As the solar wind and the Earth's magnetic field is

steadily battling against it's other magnet field,

is being compressed by the solar wind, and as this pressure

increases and sends the particles along the magnetic fields,

and down to the polar areas of the Earth, and we see the

most light as Aurora in the upper atmosphere.

It's clear that we live in a region dominated by the

solar wind, which extends far out into space, far beyond

the outer planets.

The next question is how far out into space does the solar

wind extend, as is spreads out, going farther and farther

from the Sun?

To try and measure the solar wind, scientists

relied on space probes.

From as far away as Jupiter, these recorded massive

radio emissions.

The noise was being generated by a battle between Jupiter's

magnetic field and the solar wind.

As the spacecraft Voyager visited all the outer planets,

it picked up the same telltale signature of solar wind

buffeting magnetic fields.

When it left Neptune, it was still accompanied

by the solar wind.

Three years beyond Pluto, it detected a mysterious burst

of radio energy.

The signals were picked up at the tracking station at

Goldstone, California, where Don Gurnett had been keeping

in touch with Voyager.

Well, my primary interest these days is to follow the

solar wind as it expands out from the Sun.

We know that it has to be stopped someplace by the

interstellar gas, and this boundary we call the heliopause.

The radio burst picked up by Voyager

was completely unexpected.

There were no giant planets within three billion kilometers.

We did not, at first, really know for sure the origin

of this thing, and we thought it might be coming from

a planet such as Jupiter or Saturn.

It also occurred to us that it may be coming from

much farther away from the Sun.

In the end, their search led them back to the

heart of the Solar System.

We noticed that there was a series of extremely powerful

coronal mass ejections some 400 days before the radio burst.

Checking through Voyager's log,

Gurnett found that it had been overtaken by the outburst

after 100 days.

Ten months later, the solar gust reached some kind

of magnetic boundary.

Was this the heliopause, the outer limit of the solar wind?

So our basic model is that this coronal mass ejection

produced a pulse of plasma that came out from the Sun

and propagated for 400 days; we detected it going by

Voyager I and Voyager II.

And that pulse of plasma eventually reached the heliopause

and caused the radio emission.

The radio burst places the heliopause

at four times the distance of Pluto.

This is how far the power of our Sun extends.

Even the most distant planets, where the Sun appears

as little more than a bright star,

bathe in its evaporating atmosphere.

The planets are bound by the gravity of our Sun.

They were formed as a byproduct of its creation.

On at least one of them, the Sun sustains life.

But our Sun, along with the billions of other stars,

has a more fundamental significance

for the planets.

And this lies at its very core.

The Sun's core is the ultimate nuclear reactor.

Douglas Gough wants to see it in action.

My ultimate goal is mainly to learn about the structure

of the core, because the nuclear physics is so interesting.

The nuclear reactions that change material that produce

new particles that leave the Sun, understanding that

helps us to understand the basic physics

of elementary matter.

1995 saw the launch of a new era of solar

exploration: the start of the journey that may yet take us

to the heart of the stars.

The solar observatory SOHO can view the Sun in x-rays,

ultraviolet, and visible light.

But SOHO carries an additional feature:

in 1975, when Douglas Gough learned that the Sun's surface

rippled like a pond, he instantly saw a way

to see into its core.

What I realized is that this is a way of seeing

inside the Sun.

You can't see inside the Sun with light,

because it's opaque.

But this was really sound.

You could hear inside the Sun.

And by hearing inside the Sun, you could learn what the

structure of the Sun is inside, and this was an amazing

concept for me, that you could actually get inside a star.

The surface of the Sun was heaving.

Every six minutes, the entire star breathes in and out.

Its gaseous ocean swells and dips, and a complex pattern

of ripples shimmers across its surface, providing clues

to the hidden world beneath.

The Sun is like a chorus of people, of instruments,

playing, but not in tune.

They're all very different.

It's cacophonous, which gives us lots of information about

the detailed interior.

The sound waves move back and forth inside the Sun,

and give tones, just like the tones of a musical instrument.

Already, SOHO has revealed new surface phenomena.

In the aftermath of a solar flare, seismic quakes spread

out for thousands of kilometers.

We've learned a great deal about the outside of the Sun

from studying the seismic waves from SOHO.

We've learned about the dynamics.

We've learned about the chemical composition.

Now we want to do something similar in the very core.

SOHO has stripped away the outer layers of the Sun.

Beneath the surface, it has discovered rivers of plasma,

superheated gases that circle its pole.

Looking like a jet stream on Earth,

it seems the Sun has weather, too.

But deep in the core is a remarkable chemical factory.

The stars generate stuff.

They make all the matter that you and I are made of,

from hydrogen and helium, but they make this heavy stuff

that we are made of.

They're the factories that make material.

So to understand the Universe, we need to study the stars.

Every star has a core, almost all stars are generating

nuclear energy, transmuting elements from one to another,

building up the heavy elements, the whole building blocks

of the Universe.

We believe the physics in those stars is the same as the

physics on Earth.

This physics we need to understand more carefully,

so that under extreme conditions we can work out what

that physics implies.

On a very large scale, what it implies about

the structure of the Universe,

and how the whole Universe evolves.

In the beginning, the Universe contained

just hydrogen and helium.

For 12 billion years, stars have been transforming these

simple gases into more complex elements.

Our Sun was born from that process.

Four and a half billion years ago, a massive star on the

fringes of our galaxy ended its existence as a supernova.

Its death throes sent the contents of its core spraying

outwards into space.

These superheated grains of silicon, iron, and many other

elements careered into a neighboring cloud of gas,

causing it to collapse.

As the mixture of gas and dust gravitated towards the center

of the cloud, they ignited a nuclear reaction, and our Sun

burst into life.

Around it, the remaining debris from the supernova combined

to form the planets.

We are made of stardust, forged in the heart of a star.

In the last 400 years, science has peeled back the blinding

layers of our Sun to reveal a star, one of the countless

engines of creation which made the planets,

and which made us.

Our ancestors saw a perfect disc of light; a god.

But modern science has revealed an entity for more complex

and powerful than those ancient humans could ever

have believed possible.