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
They witnessed what no human being had seen before -
a sun more powerful than they could ever imagine
To our ancestors, the sky was a patchwork of puzzles
At night it was brimming with pinpoints of light - stars
Then there was the sun
Whose arrival banished the stars and brought warmth and light
It was hailed 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,
and how we came to understand
its power and its role in the universe
In February 1998,
the Caribbean island of Guadeloupe geared itself up 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 boy, he was deeply affected by his first
It started a lifelong fascination with the sun
The sun was perceived as an immaculate
gold disc, perfect
It was a religious belief,
Everything was perfect in the sky
The sun was the most perfect circle,
with no blemishes, no structure
A perfect, flat, golden disc.
It was the sun god for many religions
The sun remained a symbol of perfection
until a seventeenth century Florentine called Galileo
first pointed a telescope at the sky -
and instantly recorded the first scientific milestone
Galileo apply the telescope for the first time
and discover the sun was not perfect.,
It had sunspots,
That was a major revolution in philosophy and science
Galileo watched the sunspots
move across the sun's surface...
and realised that it was spinning
It was the first of many secrets sunspots would reveal.
Galileo's insight heightened speculation
about the true nature of our Sun
But for the two centuries,
astronomers were frustrated by its blinding disc.
What were sunsports?
What other landscapes existed on the Sun's surface?
What was the source of its power?
There were moments, scientists realised,
when the Sun offers a rare and special opportunity
Roughly six times every decade,
somewhere around the world
The sun passes directly behind the moon
If the sun's this big,
Earth's a little ball of 3-4mm in diameter
And the Moon is even smaller.
It's a quarter of the Earth,
400 times smaller than the sun.
The fantastic coincidence
Is that the sun is 400 times further away
Than the Moon from us,
So we see both more or less the same size.
One minute!
For 4 hours,
Francisco watched the Moon creep into position.
No filters!
He came halfway round the world
For just four minutes of totality.
But where the sun is concerned,
dedication has never been any guarantee of success
'We lost it... we lost it... shit.'
Francisco got just a few moments to glimpse the hidden sun
We lost it.
No corona.
Like many astronomers before him, Francisco was thwarted
as the clouds rolled in to spoil the party
Douglas Gough is a leading solar scientist
To see his first total eclipse, he had travelled to Indonesia
The Government had declared it illegal to watch the eclipse,
at least for the Indonesians
They had to watch it on television
or go to the mosque and pray the dragon would spit the sun out
They believed that was happening.
I was standing on a road,
and a little boy came up to me
I gave him a dark film, to look at the sun
An old man of seventy, the head of the village, came too,
and the three of us saw a fantastic eclipse
A total eclipse reveals the sun's corona
an outer layer normally lost in the glare
An eerie feeling, and almost total silence
The only thing we heard was the chanting from the mosques.
This is what early astronomers travelled the world to see
Within the corona were seemingly burning clouds
The surface looked smothered
in a complex, raging atmosphere
You realise, seeing these things,
the sun's active, not a passive ball of gas.
It's churning away. Interesting things are happening
Discovering new things is exciting
That's why explorers explored places no man had been before
On Earth, there's little left, so we go into Universe
Seeing the sun, peeling off a layer of mist,
of lack of understanding, and seeing how something works
is an amazing experience
The rarity of a clear eclipse
gave scientists few chances to study these prominences
In the nineteenth century, Father Angelo Secchi,
the Vatican's chief astronomer,
caused a revolution in the way we looked at light
From an observatory above his church
he pioneered a new branch of science - Spectroscopy
His spectroscope split sunlight into its constituent colours,
then magnified the light in one region
It was possible to see the sun's edge
without relying on an eclipse
Spectrocopy revealed a solar surface
of astonishing complexity
You were no longer dazzled by the sunlight
You could see the things
you can see at the edge of the sun during an eclipse.
Soon astronomers were studying the body of the Sun
The sunspots were Earth-sized tears in the surface,
Like windows on a mysterious interior
The surface itself bubbled before their eyes
Soon they were cataloguing the chemicals in the Sun
Dark bands in its spectrum meant hydrogen,
calcium, iron
Astronomers discovered an alien element, unknown on Earth
They named it after Helios the Greek Sun God - 'helium'
When Secchi turned his spectroscope to the stars
he made his most profound discovery
He recognised the pattern immediately
Their chemistry was identical to the Sun
One great mystery of the heavens was resolved
Our sun was a star
The sun was a star, and one realised
It belonged to the family of stars
Scientifically that's fantastic,
As we want to know what the universe is like.
By studying the sun, we study a typical star
In the '40s we got out first inkling
of how deadly a typical star can be
As the first rocket rose to the fringes of space
They were scorched with radiation.
Our atmosphere lets heat and light through.
But shields us from X-rays, gamma rays
and ultra-violet light from the sun
Soon a man was to brave this deadly radiation
and come face to face with a star,
Alexei Leonov
'Three, two, one, zero.'
In 1973, a solar laboratory
was sent to study the sun directly from space.
But the sun didn't give up its secrets lightly.
When Skylab was launched, it had a heat shield,
that was to open up after it got into orbit,
sixty seconds into flight,
that heat shield popped open.
It's still in the air stream,
so the air stream tore the heat shield off,
and unlocked both solar wings
Conrad had been on the Moon when he became crew leader on Skylab
Their new home was no longer protected by an atmosphere,
and temperatures started to soar
They had to find a way of shielding the station
from the sun's excesses
We got this temporary heat shield rig
which we could rig from inside through an air lock.
We could push like an umbrella pole,
and mylar sheets popped open like an umbrella,
Then we could pull it to where it was offset a few inches
It did make the temperature go down immediately
As the temperatures dropped the crew went into the Observatory
They had to get used to life in a weightless environment
At first, nausea prevented all but the most hardy from eating
That problem quickly passed. Soon space didn't seem so bad
Then, with no distorting atmosphere to blur their sights,
the most extensive period of solar observation began
The Skylab flight was very dear to my heart
I know a lot don't understand that
It means more to me than going to the moon,
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 had before in great quantities
When I switch to the two positions called h-alpha,
these words stand for hydrogen-alpha
called that because the light here
comes from light from hydrogen atoms in the sun's atmosphere...
Viewing the sun in the same wavelengths of light
used by Secchi a hundred years earlier,
the astronauts saw incredible details on the sun's surface
...wavelengths radiated by the hydrogen atoms,
We can see Sunspots, networks, filaments,
all of these things in great detail
We all took a four-hour turn at the solar telescope panel
Now, I've always related
It's like playing three eighty-eight keyboard pianos
at the same time
It was a very complicated set of switching and everything
It was very very intense
You'd work hard to make sure the sequences read the right way
Things would come up in real time, like solar flare,
so we had to be prepared to catch that also
Solar flares are planet-sized eruptions of boiling gas,
prominences that break free of the sun
They been seen from earth but not in such detail and quantity
Somebody was running it and would call us to take a look
That happened frequently,
when something unusual came up that we could witness,
we'd call the other guys up to take a peek
In nine months,
successive Skylab crews took more than one hundred and sixty thousand images,
revealing hitherto unknown aspects of the sun
The most spectacular discoveries
were the coronal mass ejections
outbursts of material on a scale that dwarfs solar flares
These were the best views yet of the angry sun
But what causes these convulsions?
The answer lies in an invisible side to our sun,
and once again, sunspots were the key to its discovery
Long before the space age,
the summit of the San Gabriel mountains
was the closest an American could get to space
In 1903, George Ellery Hale,
the son of an engineer, had a dream
He'd build the world's most advanced solar observatory
High above the town of Pasadena
Sallie Baliunas is an astrophysicist
at the Mount Wilson observatory
Hale was my personal hero
He was a great scientist and had instinct about engineering,
so he could successfully build the world's largest telescopes.
He raised a lot of money to do these projects,
As he often said, he made no small plans
The route to the top of Mount 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 mule train on a very steep seven-mile trail
The packhorses made sixty trips to transport the telescope alone,
but Hale soon had an observatory that was the envy of the world
His first challenge was to understand the sunspots.
Hale built a spectrograph
which is here beneath this table
Seventy-five 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 the sunlight into its different colours,
In this spectrum are the absorption lines of the gases
With his unique spectrograph,
Hale started analysing the sun's surface
He could take photographs of sunspots
in more detail than anyone had before
During a routine study
of the chemical absorption lines of the sun's surface,
he made a breakthough.
Looking at the quieter part of the sun,
he saw ordinary-looking absorption lines
Then as the sunspot rolled into the slit,
the lines began to broaden and split
Hale saw the lines split apart, and recognised the phenomenon.
Voila, magnetic fields He could see it, June 1908
Hale had unravelled one of the sun's greatest mysteries
Sunspots were caused by magnetic distortion
These distortions are four thousand times greater
than the earth's magnetic field
They suppress the upward surge of gases,
cooling the surface by two thousand degrees
and causing the dark spots
A sunspot on the surface
is just a twisted and kinked magnetic field
looped out of the surface
This magnetogram shows how the surface is speckled
with positive and negative lines of magnetic force
These tortured field lines channel the sun's storms -
eruptions of plasma, exploding outwards
for thousands of kilometres
before being dragged back into its boiling surface
Coronal mass ejections, prominences,
All features on the sun's surface are magnetic in nature
In one of the coldest places on earth,
fifteen years before Hale started his investigation into the sun,
a Norwegian scientist had drawn his own conclusions
about the sun's magnetism
In a land where you can't see the sun for months,
he was convinced you could feel its presence
in one of the most beautiful phenomena on earth
It may be strange to see why we are here,
far to the north, in the darkness, dealing with the sun,
but here you see the aurora, the northern lights
I really like to see the aurora
It's beautiful in many colours
you don't see anywhere else.
It really lights up the dark days here in wintertime
Earlier, it was thought the northern lights
was the souls of dead soldiers fighting
Norway is one of the best places to study auroras
Truls Hansen monitors the radioactivity
high in the earth's atmosphere
This area of research goes back over a century
A hundred years ago, Norway's most famous scientist
dedicated his life to the study of atmospheric disturbances
His name was Doctor Christian Birkeland
Birkeland was brilliant, but a bit mad,
You might see that from his book
It contains ont only theories about particles and the aurora,
but a lot of ideas
Some right, most wrong
One of them was Terrela, which we see clearly here
A vacuum chamber with a small globe
pretending the earth inside it
We can also see Birkeland controlling this experiment
This experiment artificially created the Northern lights,
To protect his brain from radiation, he always wore a fez
Birkeland's theories about the origin of auroras
Stemmed from years of dedicated study
Auroral activity is particularly energetic
After a period of solar activity
Birkeland wanted to find a mechanism to link the two
These are the old magnetometers,
which have been operating for more than 100 years,
They're still used here and there
Birkeland used very similar instruments
Here's a recording of the magnetic field
taken with this instrument
It starts quiet around noon,
and then, here in the evening,
you get a magnetic storm
which you see clearly here,
During this period you have a large and very bright aurora
This is the Birkeland Terella experiment
He built several but this is the biggest one
and the last one, I suppose, being made in 1913
It's a large vacuum chamber with a model of the earth inside
Birkeland's thought the magnetic storms with the Northern lights
were caused by electrically-charged particles
buffeting the earth's magnetic field
He believed these particles come from the sun,
but his ideas were never taken up
In 1917, Birkeland committed suicide
In fact, evidence of the extraordinary reach of the sun
had been visiting our skies for millennia
The dusty comet tails always pointed away from the sun.
It was assumed that sunlight alone was the cause
But in 1947, a German physicist Ludwig Bierman
Calculated that something far more substantial
had to be pushing the comet tails
He called it solar corpuscular radiation,
and his idea was rejected immediately
Despite the general derision, physicist Eugene Parker
was unable to dismiss Bierman's argument
I had a chance to talk to him in Chicago
He said if it isn't the sunlight,
there it must be the solar corpuscular radiation,
the emission of particles from the sun
that blow the tail away from the sun
His revelations made me see he had a fundamental point
The physicist Sidney Chapman was very eager to attack Bierman
He said the sun was 330,000 times more massive than earth,
and that no particle, however small,
could escape its enormous gravitational pull
Regardless of his scorn for the solar wind,
Chapman was developing his own idea
for how the sun was reaching out to the earth
He suggested the Corona,
though firmly bound to the sun,
stretched much farther than is seen during an eclipse
Eugene Parker met Sidney Chapman in Boulder, Colorado
I was thinking about what I had learned from Chapman,
that the corona extends out through the solar system
I realised that Chapman and Bierman were mutually exclusive
The solar corpuscular radiation that affect the comet tails
Can't penetrate through a static corona, interactions block this,
But I could not see that either one of them was wrong
Parker worked at the apparent contradiction in the theories
and found that they both were right
I integrated the equations of motion.
I found only one solution that fitted the condition
of strong rebound at the sun and zero pressure in infinity,
That was the solution providing the supersonic solar wind
Parker's solar wind was more complex than Bierman's version
He calculated that the corona did have enough thermal energy
to escape its gravity and stream off at 500km a second
But when he went public, Parker himself was ridiculed.
The referees for my papers were anonymous,
I was assured they were experts
They declared the ideas were absurd
Others declared it was false
and published papers showing alternatives
and gave lectures decrying the idea,
My friends said, "It was a great idea,"
"but great ideas often fall on their face."
My reaction was, "We'll see what falls on its face."
Parker waited five years for his theory to be vindicated
In 1962, the Mariner 2 Probed to Venus carried particle detectors
Designed to discover how empty space was
The world's first interplanetary probe signalled back that space
is awash with a solar wind exceeding Parker's estimates
The JPL plasma detector
Showed there was a wind
of anywhere from 300 to 800km per second
The wind was always there and it never ceased,
I refused to argue with anybody after that
Modern telescopes have revealed the complexity
of Parker's solar wind
From the sun's equator particles constant evaporates into space
Occasionally, gusts broke free
of the sun's gravitational and magnetic forces
These are the flares and coronal mass ejections seen by Skylab
These electrically-charged hurricanes
are ferocious and relentless,
The planets lie in their firing line
Mercury, closest to the sun,
bears the brunt of the solar wind
Any atmosphere this world may have had has been blown away,
leaving its surface bathed in deadly radiation
Mars is four times further from the sun than Mercury,
yet it's thought the solar wind has stripped
a third of its original atmosphere,
leaving a veil one hundred times thinner than ours
Venus, our nearest neighbour,
has an atmosphere a hundred times thicker than ours.
Modern probes discovered a comet-like tail
That stretches back to the Earth's orbit.
The clouds on Venus are also being eroded by the solar wind.
And what of our own atmosphere?
Earth has a magnetic field that stretches far out into space
It deflects the solar wind and protects our atmosphere
A force-field fighting a constant battle with the sun
The solar wind and the earth's magnetic field battle together.
The magnetic field is being compressed by the solar wind,
As this pressure increases
and sends the particles through along the magnetic fields
down to the Earth's polar areas
We see them as aurora in the upper atmosphere
We live in a region dominated by the solar wind,
which extends far out into space,
The next question is how far out into space it extends,
as it spreads out farther from the sun.
What is the full extent of the sun?
The first space probes ventured to Jupiter,
recorded massive radio emissions
The was the same battle
between Jupiter's magnetic field and the solar wind
As the spacecraft Voyager visited the outer planets,
it found the same signature of solar wind
buffeting magnetic fields
When it left Neptune, the solar wind was still there.
Where would it end?
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
My primary interest now is following the solar wind
as it expands out from the sun
It has to be stopped some place by the interstellar gas
This boundary we call the heliopause
The radio burst picked up by Voyager was totally unexpected
There were no giant planets within three billion kilometres
We didn't know the signal's origin.
We thought it was coming from Jupiter or Saturn
Or maybe it was coming from much further away from the sun
Their search led them back to the heart of the solar system
We noticed a series of very powerful coronal mass ejections
some four hundred days before the radio burst
Checking through Voyager's log,
Don found it had been overtaken by the outburst
after a hundred days
Three hundred days later, the solar gust reached a magnetic boundary
Was this the heliopause, the outer limit of the solar wind?
Our model is that this coronal mass ejection
Produced a plasma pulse coming out from the sun
That propagated for four hundred days
We detected it going by Voyager One and Two
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 the extent of the sun
Even the most distant planets,
when the sun's just a bright star,
bathe in its evaporating atmosphere
The planets are bound by our sun's gravity.
They were formed as a by-product of its creation
There's a more fundamental bond
Between the planets and the stars.
The very stuff of life is built inside them.
A star's core is the ultimate fusion reactor
Douglas Gough wants to see it in action
My goal is 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
help us to understand the physics of elementary matter
1995 saw the launch of a new era of solar exploration
A journey that may take us to the heart of the stars
The solar observatory Soho can view the sun in X-rays,
Ultra-violet and visible light
But Soho doesn't just look. It listens.
In 1975,
when Douglas Gough learned the sun's surface rippled like a pond,
he instantly saw a way to see into its core
I realised that this is a way of seeing inside the sun
You can't see inside the sun with light, it's opaque
But this was sound. You can hear inside it
By doing so, you could learn the structure of the sun inside,
I found that an amazing concept,
that you could get inside a star
The surface of the sun is heaving
Every six minutes the entire star breathes in and out
lts gaseous ocean swells and dips,
and a complex pattern of ripples shimmer across its surface
Clues to the turmoil within
The sun's like a chorus of instruments,
Playing, but not in tune
It's cacophonous, which gives
much information about the detailed interior
The sound waves move back and forth
and give tones, like a musical instrument
Soho has revealed new surface phenomena
After a solar flare, seismic quakes spread out
for thousands of kilometres But there is much more
We've learned about the sun's outside
from studying the sound waves from Soho
We've learned about the dynamics and the chemical composition
We want to do something similar in the core
Soho has started to strip away the sun's outer layers
Under its surface, it discovered rivers of plasma,
Super-heated gases that circle its pole
Looking like the jet stream on earth,
it seems the sun has weather too
But deep in the core is that remarkable chemical factory
The stars make all the matter that we are made of,
from hydrogen and helium, That's what we're made of
They're the factories that make material
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 of the universe
We believe the stars' physics are the same as on earth
This physics we must understand more carefully,
so we can work out what that implies
about the structure of the universe and how it evolves
In the beginning, the universe contained hydrogen and helium
For twelve billion years, stars have been transforming them
into more complex elements
Our sun is born from that process
Four and a half billion years ago,
a star on the fringes of our galaxy
ended its existence as a supernova
lts death throes sent the contents of its core into space
These heated grains of silicone, iron and many other elements
Careered into a cloud of gas, causing it to collapse
As the gas and dust mixture went to the cloud's centre,
they ignited a nuclear reaction and our sun burst into life
The remaining debris from the Supernova formed the planets
We are made of star dust, forged in the heart of the star
In the last four hundred years,
science has peeled back our sun's layers,
to reveal a star, one of the countless engines of creation
which made the planets, which made us
Our ancestors saw a perfect disc of light. A god
Science has revealed an entity more powerful
than they could ever have imagined