All language subtitles for 33EA2C2DD7EEA2259BF8B19108CF1FAA_eng

John Goodricke was a man
who was permitted only the

briefest glimpse of the stars.

And yet, it could be said
that he made one of the

greatest discoveries of all.

He had been left completely
deaf by a childhood illness.

And maybe that's why
he looked so carefully.

On a clear summer night in 1784,

he went outside to see if
a particular star was still

doing something
that mystified him.

Something that no other
astronomer had ever reported before.

Goodricke couldn't
believe his own eyes.

The star, called Beta Lyrae,

changed regularly in brightness
over a very brief period of time.

Only days.

What could possibly
make a star do that?

Even more surprising,
Goodricke found that he could

predict its variations
with high accuracy.

What could cause such a
change in a star's brightness?

None of the scenarios that
came to mind explained the

evidence before him.

And then, he thought
of another possibility.

Suppose there was
something orbiting Beta Lyrae

that eclipsed the star
on a regular basis.

But what could it be?

"A world perhaps?"

How about a trillion?

When John Goodricke's
discovery came to the attention

of the prestigious British
Royal Society in 1786,

he was immediately
made a member.

Word of this honor
never reached him,

days later he was
dead of pneumonia.

He was only 21.

It would be 150 years
before another astronomer

would solve Goodricke's mystery.

And in the process,
change our cosmos forever.

Even as a child, Gerard
Peter Kuiper could

see farther than anyone else.

He saw stars too distant
and too faint for others

to find without a telescope.

This was in the Netherlands
more than a century ago.

Back then, the son of
a poor tailor could not

hope to become an astronomer.

But the boy would
not be stopped.

Back then, astronomers thought
that the cosmos consisted of

only a handful of planets,
those of our own solar system.

The great multitude of other
stars were just barren points

of light that had never
given birth to worlds.

We on Earth could
still feel special.

Our star system,
the scientists told us,

was the rarest of all, one
blessed by worlds and moons.

Kuiper yearned to know
how our Sun and its planets

came to be.

And made his way to
the University of Leiden,

where he quickly
distinguished himself.

He was invited to join the
dynamic astronomical community

in the United States, but
Kuiper had rough edges,

he was argumentative
and easily drawn into conflict

with his colleagues.

The prospect of directing a
remote observatory far away

from the capitals of
scientific culture must have

appealed to him.

And besides, you could
see the stars better there

than just about anywhere else.

Kuiper was given an appointment
at the McDonald Observatory,

situated in a corner
of West Texas.

At the turn of the century, it
had been discovered that half

the visible stars were
really gravitational pairs.

Most binary stars
are like twins,

forming from the same
womb of gas and dust.

Others come of age separately
and become gravitationally

involved with each other
later in their development.

And the other half remain
single throughout their lives.

Kuiper chose to concentrate
on the binary stars.

He wondered if they could
shed light on the way that the

planets in our solar system
formed and came to be

gravitationally
bound to our Sun.

Bright ascension.
18 hours, 50 minutes.

Declination plus 33 degrees.

2175 minutes.

Mm-hmm.

Kuiper looked at the
very same star that

had baffled John
Goodricke 150 years before,

but Kuiper was looking at it
with a much bigger telescope.

And Kuiper was armed with
an awesome power that didn't

exist in Goodricke's
time, spectroscopy.

Spectroscopy is a way
to dissect the light of any

single star to find its
particular atomic and

molecular composition.

Kuiper looked at the
spectrum of the light produced

by Beta Lyrae and saw
that, as with all stars,

there was plenty of
hydrogen and helium,

but there was also
iron sodium and silicon.

So far, no surprises there.

Now, here comes the twist.

Bright lines?

Where were those
bright lines coming from?

At that time, no astronomer
understood why bright lines

would appear in the
spectrum of a star.

Kuiper leapt to the
conclusion that the two stars

were so close that they
were exchanging matter,

super-hot gases that would
produce such a signature.

In trying to understand
what he had seen that night,

Kuiper discovered and
named the most interstellar

relationship in the cosmos.

Stars that are physically
locked in everlasting oneness,

bound together by
gravity and a bridge of fire

made of star stuff.

A bridge eight
million miles long,

connecting two stars,

one three times more
massive than our Sun,

the other 13
times greater still.

A contact binary star system.

Why aren't they round
like our own star?

They are so closed
to one another,

tidal forces of gravity pull
them together and stretch them

into flaming teardrops.

The Beta Lyrae system is
about 1,000 light-years from earth.

The largest telescopes of the
mid-20th century were just not

powerful enough to resolve
them as individual stars.

You needed that new
power of spectroscopy

to disentangle them.

Kuiper imagined how the
formation of the contact

binary star system
could have happened.

He deduced that they were
formed when a vast cloud of

gas and dust become so dense
that gravitational whirlpools formed.

In thinking about
these contact binaries,

Kuiper couldn't help but
wonder if any of these stellar

courtships ever
failed to catch on fire.

Kuiper asked
himself, was our world,

our Moon and all the planets
of our solar system nothing

more than a failed
binary star system?

And if that's how our
solar system was created,

had the same thing happened around
other stars throughout the cosmos?

Gerard Kuiper had
a special power,

he could see farther
than anyone else.

He was the first to envision
the universe we now live in.

Not a barren vastness
meagerly dotted by childless stars,

but one overflowing
with possible worlds,

countless planets and moons.

In 1949, Kuiper astonished
the world by declaring that

our solar system was
not so special after all,

that every other star had
its own family of worlds.

A world perhaps?

But science wasn't
ready for that universe,

it wasn't even ready to take
its first baby steps off the planet.

Why not?

Science was carved
up into little kingdoms,

the various scientific
disciplines and scientists of

one discipline didn't collaborate
with anyone from another.

But this had to change for
us to venture beyond Earth.

It all came to a head in a
feud between Kuiper and

another great scientist.

Like two stars of a
contact binary system,

they could not disengage.

But despite their
loathing for each other,

they managed to create a
new kind of science and they

pioneered the Space Age,

mentoring its greatest
visionary and voice.

Sometimes, the cosmos
just barges right in

and breaks down
your door, like tonight.

What's going on here?

Our planet is passing through
the epic remnants of a comet,

a debris field
millions of miles long.

That's why it looks like
it's raining stars tonight.

But they're not stars at all,

just bits of rock and ice
burning up in Earth's atmosphere.

It's called a meteor shower.

And this one happens at
the same time every year.

Why?

Because it takes a year
for Earth to orbit the Sun and

return to that same
place where the comets

streaked by so long ago.

That's what a year is.

This could be a piece
of that comet or possibly

a fragment of an asteroid.

It came from another world,

a leftover from the
creation of our solar system.

But how to understand it?

Well, back in
Gerard Kuiper's time,

during the middle
of the 20th century,

it depended on what kind
of a scientist you were.

The geologists would bring
their hammers and break this

sucker apart and look at its
dust under a microscope to

study its crystalline structure.

It was their way of finding
out which missing piece in

this puzzle of Earth the
meteorite could provide.

The chemists were searching
for the same answers,

but they would drop it in
acid to see if it could be

transformed from one
compound into another,

torturing it to see
if it would give up

its secrets about nature.

The physicists would want
to see it at its most naked.

Stripped down to its mass,
its density, its hardness.

Its resistance to heat.

The biologist wouldn't
even stop to pick it up.

Back then, they would've
walked right by it because

they didn't think there was
any chance that a meteorite

from space had
anything to do with them.

Life could only be from
one place, right here, Earth.

And you want to know
the craziest thing?

Back then,

the astronomers would've
walked right by it, too.

Their sights were focused
on the distance and we can't

really blame them.

What was happening
in astronomy back then?

Big ideas about things far
beyond our solar system,

Einstein's theory of relativity,

with its vision of riding a
light beam across the cosmos

and Edwin Hubble's discovery
that the universe was expanding,

that distant galaxies were
flying away from one another.

That's what raised goosebumps,
not looking at a dumb rock

lying in your own backyard.

Studying the planets, moons,
comets and meteors of our own

tiny solar system
seemed like little league.

Until Kuiper dared to
venture into territories

off-limits to astronomy.

Night after night, he
would stay up here...

A virtuoso playing the
45-ton instrument like a violin.

Searching the solar
system for clues to its origin.

A mystery that he alone
recognized was insoluble

without the cooperative enterprise
of all the scientific disciplines.

But the scientists didn't
know they needed one another.

There wasn't a single
university department where

scientists of multiple disciplines
could study planetary astronomy.

So here, in the
middle of nowhere,

in a corner of West Texas,
Kuiper conducted his one-man

exploration of the solar system.

He looked at Titan,
one of Saturn's moons,

and discovered that
it had an atmosphere,

it was thick with methane.

A point of light in the sky had
suddenly become a real place.

Kuiper used the spectroscope
to probe the acrid clouds in

the upper atmosphere of Jupiter
to see what they were made of,

their chemical and
atomic structures.

And when he looked
at the red planet, Mars,

he found carbon dioxide in its
atmosphere and he wondered,

"Am I looking at my
planet's future or its past?"

But to some people, Kuiper was
doing nothing more than trespassing.

Butting into chemical
matters where an astronomer

had no business.

Harold Urey was a chemist.

Like Gerard Kuiper,

he also had to fight
his way into science.

Urey's family was
poor like Kuiper's.

So he took a job teaching
grammar school in a

mining camp in Montana.

The parents of one of
his students urged him to

find a way to get to college.

Harold Urey took that
advice all the way to a

Nobel Prize in chemistry.

By 1949, he was riding high,

a distinguished professor
at the University of Chicago.

Then, and now,

one of the world's
great capitals of science.

But when Urey read
his morning paper,

something began
to curdle inside him,

a rising resentment.

First, a pang at a fellow
scientist's heightened celebrity.

Well, that was normal.

Then he got to the part
about the origin of the planets.

He was offended that an
astronomer was making

pronouncements about the
chemical nature of the solar system.

That was his turf.

Scientists are human.

We're primates.

We carry the same evolutionary
baggage as everyone else.

Kuiper and Urey were
two alpha males who chose

scientific argument as
their weapon of combat.

And the two men fought
over a single hostage,

a young student.

When Carl Sagan was a kid,

he lived here, in a small
apartment in Brooklyn.

In the mid-1940s,
he made this drawing,

filled with predictions,

that is now in the US
Library of Congress.

3, 2, 1, 0. All engine running.

Liftoff, we have a liftoff!

In an era where life here
was in the last seconds

of its four billion
captivity on Earth,

he dreamed of going to the
planets and even to the stars.

But he didn't want to
just go in his imagination,

he wanted to really go.

He wanted to know what
those worlds were really like.

And he knew that the only way to
do that was to become a scientist.

The boy would come under the
wings of the two warring giants.

As much as they
hated each other,

he loved them both.

Together, the three of them
would tear down the walls

between the scientists.

And the boy would tear
down the tallest wall,

the one between science
and everyone else.

Do something for me.

I need you to pretend that
we live in a time before any

spacecraft or human
had ever left Earth,

no one had ever seen
our world from space.

The most extravagant fantasies
of the greatest artists were

no match for what was coming.

This is how one of them imagined
Earth must look from space.

And then, in one
instant on a single day,

everything changed.

This is how Mother Earth
looked when she was naked,

before nearly 5,000 satellites
were in orbit around her,

before anyone had ever
counted backwards from ten.

On October 4, 1957,

the Soviet Union became
the first nation to dip its

toe into the shallows
of the cosmic ocean.

It launched Sputnik 1,

a simple radio transmitter that
circled Earth every 96 minutes.

All over the planet,
people came outside to find

this new light in the
sky, a man-made moon.

Nothing could stop
us from achieving our

most daring dreams.

Think of it, something we made
was a new light in the night sky.

Something like a star.

As this was happening,

the boy was
becoming a scientist,

and this new knowledge
moved him as nothing before had.

All he could think was that
he wanted to share it with

everyone on Earth,

but that kind of thing was
frowned upon by scientists,

they saw themselves as
being members of an elite club.

In 1950, when Carl Sagan
was just a high school student,

he wrote a paper that earned
him an invitation to work in

the lab of H.J. Muller,

who had won the Nobel Prize
for his discovery that radiation

causes mutations in genes.

By the time Carl got to
the University of Chicago,

he was beginning to
make a name for himself,

and Harold Urey
chose to mentor him.

Urey, the chemist,

was now doing the thing that
he had resented Kuiper for,

trespassing on the turf of
another scientific discipline.

This time it was biology.

Urey and his team wanted
to know how life could have

originated from lifeless matter.

Working with
another student of his,

Stanley Miller, Urey designed
an experiment to simulate the

chemical conditions of the
atmosphere on the early Earth.

They wanted to see whether
those basic chemicals could

have led to amino acids,
the building blocks of life.

Could lightning have provided the
spark that awakened matter into life?

"And if it could
happen here on Earth,

where else could it have
happened?" Carl wondered.

When he wrote a paper
speculating on that possibility,

Urey responded harshly.

He scolded his apprentice for
venturing beyond his expertise.

But still, Carl loved Urey
because he knew that this

toughness would make
him a better scientist.

In the summer, Carl
traveled to the enemy camp,

to McDonald Observatory,

to observe Mars
with Gerard Kuiper,

the only planetary
astronomer on Earth.

That year, Mars was in a
favorable opposition to Earth.

The two worlds would be the
closest they'd been in 30 years.

But the weather
didn't cooperate,

not in Texas, but on Mars.

A global windblown dust
storm there prevented Kuiper

and Sagan from
seeing anything new.

Instead, they spent those
summer nights talking

of many things.

The older man taught
the young scientist the

most efficient ways to
test his bold new ideas.

They fantasized about what
those possible worlds circling

other stars might be like.

These two fearless scientific
imaginations ventured

throughout the
galaxy all that summer.

The gates to the wonderworld
were swinging open for Carl.

And all of this was
happening as we were reaching

beyond the planet
for the very first time.

Soviet Union's Sputnik
scared the hell out of

the United States.

The Cold War was a contest
between dueling ideologies

about property and freedom.

When the Russians
got there first,

it seemed to reflect
badly on our world view.

And if they could send an
object into orbit above our heads,

we could no longer
protect our skies.

Suddenly, there was
a new delivery system

for nuclear weapons.

Nowhere on Earth could
be safeguarded against

espionage or attack.

We needed a space
program of our own.

The National Aeronautics
and Space Administration was

founded a year
after Sputnik in 1958.

Science was at last ready
to see Earth as Kuiper

had been seeing it
for years, as a planet.

What a concept.

It may seem obvious to us
now, but in a time of fanatical,

fight to the death nationalism,
it was a thunderbolt.

But Kuiper's feud
with Urey still raged,

even as they both took
leadership roles in the

fledgling space program.

Carl continued ferrying
between their warring labs.

The enmity between the two
men was emotionally so corrosive

that he said at the time he,

"Felt like the child of
divorced parents and he was

the only bridge
left between them."

Urey fought for NASA
to go to the Moon.

Among his reasons was
a desire to know, at last,

how the solar system formed.

Kuiper predicted what it
would be like when we got there.

That when we stepped down on
the lunar surface for the first time,

it would feel like
walking on crunchy snow.

The Moon is a silent world
because it has no atmosphere

to carry sound waves.

But Neil Armstrong later said
that he felt Kuiper's crunchy

snow when he stepped
down onto the surface for the

very first time.

Some of the things the
wanderers left behind.

Thanks to Urey and Kuiper,

Carl Sagan was part
of this great adventure.

He was living his most
extravagant childhood fantasies.

He briefed the Apollo
astronauts before they left

for the Moon.

And he was there when
scientists first met to

evaluate the information
gained from the dawn

of space exploration.

For the first time ever,
the biologist, the geologist,

the astronomers,

the physicists, the
chemists were all talking

to one another.

Actually, mostly shouting.

The young Carl Sagan
stood up at one of their

joint scientific
meetings and said,

"Hey, guys, we're the first generation
of scientists to receive these riches.

We're in this together."

He set a tone for planetary
science that still holds today.

He edited the first modern
interdisciplinary journal for

researchers studying
the world of the cosmos,

Icarus, which
continues to this day.

And he did something else.

He started a lifelong campaign
to bring the revelations of

science to everyone, and
he was one of a handful of

scientists who made the
search for possible worlds,

for extra-terrestrial life and
for intelligence respectable

scientific pursuits.

We've only been hunting for
new worlds for a few decades,

but we've already discovered
many thousands of them.

We think some of them
are hospitable to life and at

least a dozen of
them are earth-like.

What will they be like?

Come with me.

Carl Sagan wanted
to liberate a scientific

imagination from the single
example of life that we know,

Earth life.

He envisioned what the
life of another very different

world would be like.

Sagan collaborated with fellow
astrophysicist Ed Salpeter in

the design of plausible
ecological systems for life in

the roiling clouds of Jupiter.

The challenge was to
imagine such life-forms without

violating the laws of
physics, chemistry or biology.

Is life so tenacious that it could even
make a home in this storm of hydrogen,

helium, water,
ammonia and methane?

There's no accessible
solid surface.

It's just this thick cloudy
atmosphere in which organic

molecules are falling
like manna from heaven,

like the products of Harold Urey and Stanley
Miller's laboratory experiment on life's origin.

However, this environment
poses a problem for life.

The atmosphere is turbulent
and deep down it's very hot.

An organism must be careful
that it's not carried downward

to the hell below.

One way to make a living
under these conditions is to

reproduce before
you sink and get fried.

Your only hope is that
convection will carry some of

your offspring to the
higher and cooler layers

of the atmosphere.

Such organisms
could be very small.

Sagan and Salpeter
call them "sinkers."

But you could
also be a "floater,"

a vast hydrogen blimp pumping helium
and heavier gases out of your interior and

retaining only the
lightest gas, hydrogen.

Sagan and Salpeter reasoned
that like a hot air balloon

you'd stay buoyant by
keeping your interior warm using

energy acquired
from the foods you eat.

A floater must eat organic
molecules or make its own food

from sunlight and air,
as plants do on Earth.

The bigger a floater is,
the more efficient it will be,

up to a point.

Floaters would be immense,
several kilometers across,

enormously larger than the
greatest whale that ever was,

beings the size of cities.

The floaters may propel
themselves through the

planetary atmosphere
with gusts of gas,

like a ramjet or a rocket.

Sagan and Salpeter imagined
them arranged in great lazy

herds for as far as
the eye could see.

The patterns on their skin
are adaptive camouflage,

implying that they
have problems, too,

because there's at least one other
ecological niche in such an environment...

Hunters.

Hunters are fast, maneuverable.

Hunters eat the floaters,

both for their organic
molecules and for their

store of pure hydrogen.

There cannot be very many hunters
because if they consume all the floaters,

the hunters
themselves will parish.

When scientists of the
21st century tested Sagan's

imaginary life-forms
against what they knew of life,

they realized that the
concept of a habitable zone

had to be expanded.

It moved into the cloud
tops of gas giants and

the subsurface
oceans of ice worlds,

and places we've yet to imagine.

Of all those worlds,
of all those stars,

one must have been first.

Come with me to the
oldest world we know.

We're in a globular cluster,

a densely packed ball of
a million stars, called M4,

on the outskirts of
the Milky Way galaxy.

When pulsars, rapidly
rotating neutron stars,

were first discovered,
scientists wondered if they

were a sign of intelligent
life because of the regularity

of their radio signals.

Once upon a time, this
star was a blue supergiant,

but after a few million
years, it ran out of fuel,

went supernova, then collapsed
into this ball of neutrons,

no larger than a small town.

It's nearby companion,
a white dwarf star,

another burnt-out
stellar corpse,

orbits only a few
million miles away.

That's not why we've come here.

We've come in search of the
oldest known planet in the cosmos.

The cosmos was
young when this star,

a white dwarf, was born,
12.7 billion years ago.

The star was single then,
long before it was captured

by the pulsar that
gave birth to a world.

That world is out
here somewhere,

taking 100 Earth years to
orbit these two shrunken stars.

The fact that it exists bodes
well for those who dream of

virtually infinite
possible worlds.

If it formed less than a billion
years after the cosmos itself,

then stars started
fostering planets soon after

the beginning of time.

Nurturing worlds
is what stars do.

And what will the fate of
this oldest of planets be?

Sorry to say, it's a lonely one.

Sometime in the
next billion years,

the two stars will be
gravitationally ambushed by a third.

A red dwarf star will come
barreling into their vicinity.

It's gravity will send this
ancient world careening out of

its system and into the
lonely dark between the stars.

A rogue planet doomed to
wander a never-ending oblivion.

But there are also homes
away from home that call to us,

illuminated in warmth
not by one star,

but three.

I want to take
you to Gliese 667,

a triple-star system
with six worlds,

three of them enough like earth to
hold the promise of life as we know it.

Stars A and B are both a
little smaller than our Sun.

This pair of orange
dwarfs orbit each other.

Star C orbits them
both, it's a red dwarf.

They're the most common
kind of star in the galaxy.

As many as 80% of all
the stars in the cosmos may

be red dwarfs.

They consume their
hydrogen fuel slowly,

so they last longer.

More massive
stars, like blue giants,

maintain such high pressures
that they burn out quickly.

This outermost world of
the Gliese 667 system is

four times the size of
earth, but it's too far from

its stars to have liquid
water on its surface.

That doesn't mean it's lifeless.

We don't yet know enough
about life to say what

might be going on
beneath its frozen shell.

We haven't yet reached
the habitable zone of

this star system.

Getting closer,
but not there yet,

this even larger
world is impressive,

but still just outside that
region considered to be

hospitable to life and to the
human scientific imagination.

Now, this is more like it.

The kind of atmosphere
that promises life is here.

This isn't the stuff
of distant worlds,

this little guy is
one of our own.

All the other life-forms we've just
seen were actually homegrown,

right here on Earth.

We haven't even begun
to get to know all the

living things on
this tiny world.

Think of all the possibilities,

the different kinds of
life there must have been,

and are, and will
be in the cosmos.

Thanks to Gerard Kuiper,

Harold Urey and so
many other scientists,

we now know that it takes just a
few million years for stars to evolve,

and planets and moons to
coalesce out of gas and dust.

In other words, a solar system.

It's a long period of gestation,

but far from rare.

In our own galaxy, it happens
about once every month.

In the observable universe,

which we now think
contains as many as

a trillion galaxies,
containing some

200 million trillion stars,

a cosmos of 200
million trillion stars,

1,000 solar systems may be
forming every single second.

That's 1,000 new solar
systems right there.

1,000 new solar systems.

1,000 new solar systems.

1,000 new solar systems.

1,000 new solar systems.

1,000 new solar systems.

1,000 new solar systems.