Original subtitles

[crickets]

[owl hoot]

TYSON: 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?

[theme music plays].

♪ ♪

♪ ♪

TYSON: 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.

KUIPER: Bright ascension. 18 hours, 50 minutes.

Declination plus 33 degrees.

2175 minutes.

ASSISTANT: Mm-hmm.

TYSON: 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 intimate stellar

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.

♪ ♪

♪ ♪

TYSON: 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.

[ticking]

[street sounds]

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

filled with predictions,

that is now in the US Library of Congress.

♪ ♪

MAN [over PA]: 3, 2, 1, 0. All engine running.

Liftoff, we have a liftoff!

TYSON: 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.

TYSON: 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.

[counting down from ten in Russian].

[counting down from ten in Russian].

TYSON: 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.

[Sputnik radio signal]

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.

TYSON: 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.

TYSON: 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.

♪ ♪

♪ ♪

[animal call]

[waves and wind]

[distant animal calls]

[waves and wind]

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.

[finger snap]

[finger snap]

Captioned by Cotter Captioning Services.