All language subtitles for How the Universe Works - 2X05 Extreme Orbits - Clockwork and Creation

Space -- a maelstrom
of chaos and violence.

Stars gobbling up other stars.

Black holes eating up
entire star systems.

Galaxies colliding
with other galaxies.

The Universe
is a hostile place.

You are blowing up a star.

There's no way to describe
that kind of energy.

The hidden mechanism
controlling these phenomenon --

orbits.

If you understand
all possible orbits,

you understand the dynamics
driving the Universe.

Orbits hold everything
together and tear it all apart.

Extreme orbits mean
colliding galaxies,

collapsing dust clouds,
the very creation of life,

as well as destruction.

Extreme orbits --

Masters of life and death
in our Universe.

This is our solar system.

8 planets, more than 150 moons,

billions of space rocks,
dust, and gas

all orbit a single star

in a giant whirling disk
10 billion miles across.

It's been this way
for 4 billion years.

Everything moves around
in an orderly fashion,

serene and stable.

But our solar system is unusual.

Elsewhere in our Universe,
orbits are nothing like this.

They're unstable, chaotic,
even destructive.

Even in the nearby Universe,

we see incredibly violent
examples of orbits --

giant planets that hurtle in
toward their stars.

We see shock waves
of thousands of degrees

perpetuate
through the atmosphere.

There are planets that dip

right over the surfaces
of other stars,

huge stars orbiting each other,
multiple orbital systems,

where there's just chaos,

and entire objects can be kicked
out of the system.

Stars gobbling up other stars.

Black holes eating up
entire star systems.

Galaxies colliding
with other galaxies.

That's the norm.

Earth is an oasis
of water and warmth.

Life flourishes because
of how we orbit the Sun.

Earth's orbit
is almost circular.

We stay about the same distance
from the Sun all year round.

The temperature here
is relatively constant.

And Earth's orbit
has been stable

for the past
4 1/2 billion years.

Without this stability,
we would not exist.

To create DNA out of the oceans
takes hundreds of millions,

perhaps even a billion years.

And for that stability,
you need circular orbits.

And so without the stability
of the solar system

and the Earth's orbit,
there's no life on Earth.

We owe everything
to Earth's orbit.

We get a gentle ride.

In an otherwise
violent Universe,

we've hit the orbital jackpot.

Yet, chaos is never far away.

Even within our solar system,

there are extreme
and violent orbits,

where life could never survive.

Mercury --
the closest rock to the Sun

and the smallest planet
in the solar system.

Its orbit stretches
into an oval shape.

At its furthest point,

Mercury is 43 million miles
from the Sun.

But at its closest point,
it's just 28 million.

This close in, it's hot.

800 degrees Fahrenheit,
hotter than a baker's oven.

Also, because there's very
little atmosphere on Mercury,

you'd choke.

And because
there's no air to speak of,

the blood in your body
would boil

and it would burst your skin.

You would literally explode
on the surface of Mercury.

But the temperature
can also fall

to 300 degrees below zero,

three times colder than
the coldest place on Earth.

Mercury has the most extreme
temperature variations

of any planet
in the solar system.

But it's also proof
that orbits don't just loop.

With each revolution around
the Sun, Mercury's path shifts.

Over thousands of years, the
planet follows a daisy pattern.

At the other end
of the solar system,

there's Pluto,
4 billion miles from the Sun.

The further away an object is,
the slower its orbit.

Pluto takes 248 years
to complete a single loop.

And Pluto is an anomaly.

Its stretched orbit

is on a completely different
plane from the major planets,

and it creates
an amazing spectacle.

During most of its orbit,

Pluto is a frozen block of ice
and rock.

But as it gets closer
to the Sun, summer begins.

When Pluto warms up, the frozen
ices on the surface of Pluto --

these are water ices,
carbon dioxide,

even some carbon monoxide, maybe
methane ices -- they evaporate.

And you get a fog,
and the fog gets thicker.

And then you get thick clouds,

and, suddenly, you have an
actual atmosphere around Pluto

that wasn't there before.

This atmosphere

is thickest when Pluto
is closest to the Sun.

But as the planet
heads back into deep space,

the temperature plummets
to 400 degrees below zero.

It begins to snow flakes
of frozen nitrogen and methane.

As winter comes,

these gases slowly begin
to freeze out of the atmosphere.

They may rain down
in a snow-like way,

but, gradually, they accumulate

sort of a glassy,
semitransparent layer,

a frozen atmosphere
on the surface of Pluto.

After a bitter winter,
Pluto drifts closer to the Sun,

and the 248-year cycle
begins again.

Extreme changes like these
remind us how lucky we are

that earth's orbit is stable
and benign.

But it's a delicate balance.

The smallest change
could kill us all.

If Earth's orbit were closer
to the Sun,

we would be like
our closest neighbor, Venus.

Venus is a pretty good example

of what might happen
to the Earth

if our orbit shifted a little
bit in from where we are now.

Venus has this hugely
thick atmosphere

that traps all of the heat,

and the surface is close
to 900 degrees.

If we moved even just
a little bit closer to the Sun,

we would become more like Venus.

Oceans would boil away.

Our planet would become
a desert.

Life would be destroyed.

A small shift
in the opposite direction,

and instead of boiling,
we'd freeze.

You would have snowball Earth,

the Earth completely encased
in ice.

And that's only by moving
the Earth

a fraction of its distance
from the Sun.

The polar ice caps would expand.

Oceans would freeze.

A permanent ice age would begin.

The smallest shift
in Earth's orbit,

and we'd die by fire or ice.

Orbits allow life to flourish.

But they can also cause chaos.

Orbits are even capable
of destroying entire stars.

Our planet's orbit
makes life possible.

But most orbits are violent.

Space is a cosmic freeway.
Nothing stands still.

Everything moves
around everything else,

thanks to a single force --
gravity.

Gravity is the universal force
of attraction

that spreads throughout
the Universe itself.

It's the force
that holds stars together.

It's the force that binds
the solar system together.

All objects have gravity,

so all objects
attract each other.

The more mass an object has,
the stronger its attraction.

That's why falling apples
are pulled toward Earth.

In our solar system,
the biggest object is the Sun.

It's 700 times more massive than
all the planets put together.

The titanic force
of the Sun's gravity

pulls all the planets inward.

But something stops them
from falling in.

The planets
are in constant motion.

They fly through space
at incredible speed --

not directly toward the sun
but sideways,

creating a tug-of-war

between the Sun's gravity
and the planets' speed.

When the two balance out,
the planet loops around the Sun.

We call this an orbit.

An orbit is simply the motion,

the path of an object around
another object due to gravity.

So you can have circular orbits.
You can have elliptical orbits.

Even if I were to take a ball
and throw it in the air

and catch it, very briefly,

that ball is an orbit around
the center of the Earth.

It's just motion
affected by gravity.

Imagine what would happen

if the Sun had no gravity.

The planets' speed would
shoot them out into space.

On the other hand,
if the planets stopped moving,

gravity would pull them
into the Sun.

All orbits are a balance
between gravity and motion.

We like to think the Universe
runs like clockwork,

everything neat and orderly,

the planets moving
in cosmic harmony.

But that's wrong.

Orbits can be wild
and unpredictable.

And the more objects there are,

the more unpredictable
their orbits become.

Things can get complicated when
you have more than two objects

all trying to orbit
around each other.

Then an orbit can actually loop
between one object and another.

Speeds can get faster
and slower.

An orbit doesn't have to be
just one regular path.

The Universe's creativity

defies the imagination.

Travel out beyond Pluto,
halfway to the nearest star,

and you find these --
comets, chunks of ice and rock.

They float in vast clouds,

frozen remnants from the dawn
of our solar system.

Every so often,
one falls towards the Sun.

They can start
a trillion miles out

and fall right above the surface
of the Sun.

So when they're really far away,
they're hardly moving at all.

When they're whipping
past the Sun,

they're moving really,
really fast.

And so, these can be some
of the most extreme orbits

in the solar system.

They can be so elongated,
they're almost a straight line.

Comets travel at
up to a million miles an hour.

They're cosmic missiles
guided by gravity and speed.

Comets show us how
destructive orbits can be.

Many plunge into the Sun...

...or crash into planets.

If a comet were
to hit the Earth,

perhaps 5, 6 miles across...

Watch out.
It would be a planet-buster.

It would be an object

sufficient to wipe out all life
as we know it on the planet.

But most comets miss.

They fly in from deep space

and out again
on million-year orbits.

But move beyond
our solar system,

and orbits become
even more violent.

Death spirals rip apart
entire planets...

...shred stars, and even
tear holes in space.

The Universe
is unimaginably big,

so there should be other
Earth-like worlds out there.

Scientists looking
for habitable planets

thought they would find orbits
just like ours.

They were wrong.

Now we're on HD 154088.

They were wrong.

Now we're on HD 154088.

And there it is.
Looks good.

We have discovered
hundreds of planets

outside our solar system, but
they're not like Earth at all.

These are strange, alien worlds
with unfamiliar orbits.

What we're finding
among extra-solar planets

is an incredible diversity of
these orbital shapes and sizes.

Some of the orbits are extremely
tight around their host star,

the planet going around
in just hours or days.

So we're seeing interactions
and shapes and sizes of orbits

that are like nothing
we ever imagined.

Some worlds are so hostile,

life as we know it
would be impossible.

This is WASP-18b.

It's a hot Jupiter,

a class of huge planets
that closely orbit their stars.

WASP-18b is 50 times closer to
its star than we are to the Sun.

It's so close, it orbits
in less than one day.

If you had said, "What's
the weirdest, least-likely orbit

you could possibly imagine?"

I would have said,
"take something like Jupiter

and plop it down right next to
a star, 5 million miles away."

And it turns out,
I would be totally wrong.

That is an extremely
common thing

that we see in the Universe.

In fact, most of the planets

that we're discovering
around other stars

appear to be in orbits
like that.

This cosmic duel

produces incredibly powerful
physical effects.

WASP-18b burns at 4,000 degrees.

Thermal hurricanes
blast across its surface.

And both star and planet

are distorted by vast
gravitational forces,

the same forces that cause
the tides on Earth.

Everybody is familiar
with the idea of tides.

In the course of a day,

the level of the oceans
get higher and then lower.

Well, that's from the influence
of the Sun and the Moon,

from the influence of orbits,
things that are going around us

or that we're going around.

If you bring things
closer together,

tides become more extreme.

Planets can actually get pulled
into different shapes.

WASP-18b was formed
in a cold region of space

far away from its star.

Over millions of years,

it spiraled
into its present position.

It's locked
in a gravitational battle

that can only end one way.

Less than a million years
from now,

it will be consumed by fire.

The key conclusion
you have to draw is --

when you see the Universe today,
it won't be that way tomorrow

and it won't be that way
the week or the millennium

or a billion years later
because of gravity.

Our search
for Earth-like planets

reveals a destructive Universe,

from the deadly missile-like
orbits of comets

to the searing paths
of hot Jupiters.

There are even planets

that don't seem to orbit
anything at all.

Scientists have recently
detected tiny fluctuations

in the light from distant stars.

The only explanation?

A massive object
between us and them.

These rogue planets
don't orbit a parent star.

They are planetary orphans,
all alone in space.

Planets, by definition,
go around stars,

so, boy, were we shocked
to find rogue planets.

Rogue planets are
a contradiction in terms --

planets without a mother star.

Scientists think

every rogue planet
did once orbit a star

until gravity hurled them away.

New solar systems
are chaotic places.

Planets tug on each other
and dramatically change course.

Some planets even spiral out
to wander the galaxy alone.

The presence of rogue planets

shows us that gravity is not
just this attractive force

which binds the solar system
together.

It can also fling entire planets
into outer space.

A recent sky survey suggests

our galaxy contains more
rogue planets than stars.

We've discovered orbits we
didn't even know were possible.

Gravity and motion keep our
Universe in constant turmoil.

Vast orbiting suns
cannibalize each other.

Violent vortexes
distort space itself.

And powerful forces flick a star
like a spinning top.

Gravity causes chaos
on an epic scale...

...hurling planets
to their destruction

or firing them off into space.

But the cosmic roller coaster
gets even more extreme.

Orbits become so violent,
they rip chunks out of stars.

This is HM Cancri,

a binary star system
16,000 light-years from Earth.

They're white dwarfs --
small but incredibly dense.

One teaspoon of white-dwarf
matter can weigh 5 tons.

The stars are just
50,000 miles apart,

five times closer than we are
to the Moon.

They orbit at more than
a million miles an hour.

We have two white dwarves
an infinitesimal distance apart,

rotating around each other
in 5 1/2 minutes.

This is a world's record for
an astronomical body in space.

The forces are immense.

Gravity rips superheated gas
out of one star

and slams it into the other.

Scientists believe
this orbit is so violent,

it warps the fabric of space
itself.

In the process, the stars lose
energy, falling even closer.

Eventually, they'll collide...

...creating a supernova.

A supernova is one
of the most violent,

energetic events
in the Universe today.

You are blowing up a star.

There's no way to describe
that kind of energy.

Some supernovae
are so powerful,

they are second only
to the Big Bang itself

for energy and sheer power.

They are so magnificent,

they can outshine an entire
galaxy of 200 billion stars.

Supernovas can create

one of the weirdest objects
in the Universe...

a pulsar.

Pulsars are intensely
magnetic stars.

They fire out beams
of electromagnetic radiation

that sweep across space.

There are few things
in the Universe

more dramatic than a pulsar.

Imagine a ball
about 10 miles across

rotating hundreds of times
a second

with a density
that's almost unimaginable.

1 cubic centimeter
of this material

would have as much mass
as Mount Everest.

You would feel a gravity that is
millions, millions of times

what you're feeling sitting
on the surface of the Earth.

You wouldn't just be
crushed flat by this.

You would be crushed
into a paste

that is only a few atoms thick.

Anything that orbits
a pulsar too closely

risks being torn to shreds.

This is the black widow pulsar.

It rips through our galaxy
at 600,000 miles an hour.

The shock wave is so vast,

our telescopes can't detect it
5,000 light-years away.

Traveling alongside it,

a brown dwarf bigger than
a planet, smaller than a star.

The pair are locked
in an orbital dance of death.

The black widow, in some sense,
is like a vampire,

sucking the lifeblood
from this brown dwarf star,

eating away at its hydrogen
and helium fuel.

Radiation blasts the
brown dwarf's gases into space.

A pulsar just 10 miles wide

is destroying an object
bigger than Jupiter.

Eventually, the brown dwarf
will evaporate.

A single pulsar has immense
destructive power.

But two pulsars together

can change the shape
of the Universe.

This is the only known
double-pulsar system

in our galaxy.

Orbiting at 700,000 miles
an hour,

their speed and mass
make them spin chaotically.

It's incredible to think

of the enormous forces,
gravitationally,

that these two stars exert
on each other,

causing the whole geometry,
the architecture of the system

to change and spin around
like a top on the table.

The gravity
of the heavier pulsar

makes the smaller one
wobble erratically.

It whips around so violently

that the whole star almost tips
over, just like a spinning top.

It can't last forever.

85 million years from now,
the two pulsars will merge

to form a vast
gravitational abyss...

...the Universe's ultimate
monster -- a black hole.

A black hole --

the most extreme object
in the Universe.

At its center, the laws
of physics break down.

Time comes to an end.

Gravity is infinite.

A black hole is a bottomless pit
of gravity

caused by the death of a star.

There is nothing in the Universe
more mysterious

than how black holes work.

If you want to talk about

extreme orbits
and extreme gravity,

you're talking black holes.

That is at the top of the list.

Nothing has stronger gravity
than a black hole.

It is the mass of something
like the Sun or more

compressed down into a ball

that's only a couple of miles
across.

50 years ago,

black holes were dismissed
as science fiction,

but not anymore.

Now we see them
at the center of galaxies,

wandering through outer space.

Black holes, we now know,

are central to the evolution
of the Universe.

We now think there may
be 100 million black holes

in our galaxy alone.

An encounter with any of them
leads to oblivion.

This is one of the largest and
hottest stars in the Universe.

It's 20 times more massive than
our Sun and 10 times hotter.

Stars like this never live long,

but this one is locked
in a diabolic waltz,

trapped in the grip
of a black hole.

The gravity here is so powerful,

the star orbits at
half a million miles an hour.

The black hole sucks
the star's outer layers

into a vast, swirling disk,

a disk so hot
it blasts out X-rays

a million times more powerful
than our Sun.

This configuration --

a star orbiting around
a black hole --

is extreme and it's unstable.

First of all, the black hole

is eating away at the atmosphere
of its companion star,

but the star itself is unstable.

It will one day undergo
a supernova

and perhaps leave a black hole
in its wake.

And then it will have
two black holes

rotating around each other,

one of the rarest sights
in the Universe.

Eventually,
these black holes will merge

to create a new, larger monster,

and the cycle of destruction
will continue.

But this black hole is small.

Other black holes take violence
to a whole new level.

In 2011, astronomers witnessed

one of the biggest explosions
ever recorded,

a flash of radiation brighter
than 100 billion suns --

a gamma-ray burst.

It was a spectacular event.

The burst came from
a supermassive black hole

at the center
of a distant galaxy.

It had been dormant,

but something had shocked it
back to life.

If you pass by
the event horizon,

an imaginary sphere
surrounding the black hole,

that's the point of no return.

It's like the ultimate
roach motel --

everything checks in,
nothing checks out.

Several stars
were orbiting the black hole

at a safe distance.

Then one of them got too close.

The sleeping giant
suddenly awoke.

Immense gravitational forces

stretched the star
to its breaking point

until, finally,
it was torn apart.

Debris swirled around
the black hole,

heated to millions of degrees.

Two giant jets of gamma rays

blasted into space
at the speed of light.

A black hole has torn
a star apart,

swallowed up half
of the material of the star,

and ejected the other half
in an event

that is among the most violent
things we have ever seen

in the history of astronomy.

The event was so violent,

we saw it from Earth,
3 billion light-years away.

Black holes can suck in planets
and rip apart stars.

But gravity doesn't always
pull things in.

Any high-school student knows
that gravity sucks.

It pulls. It never pushes.

But it's actually
more complicated.

That's true when you
just have two objects.

But the minute you have
more than two objects,

strange things can happen,

and gravity can actually
push you away.

You can get very close
to a body,

but if you come in
at just the right angle

and just the right speed,
instead of colliding together,

one object can slingshot
the other one away.

Recently,
scientists discovered stars

hurtling away from our galaxy
at incredible speed.

Normal stars don't do this.

So what could accelerate
a star to hypervelocity?

The answer was a surprise.

You can only eject stars at
these very, very high velocity,

so close to 700, 800,
1,000 kilometers a second.

You could only eject these

with interactions
with a supermassive black hole.

Each hypervelocity
star was originally

one of a pair of stars orbiting
a supermassive black hole.

When they got too close,
gravity pulled them apart.

The black hole catapulted

one star out of the galaxy
at 2 million miles an hour.

Eventually, the other was
sucked in and destroyed.

The interesting thing here is

that you can get a complete
redistribution of stars,

so you have stars that are
in the center of the galaxy,

and, suddenly, they're ejected
out into intergalactic space.

And it's out here,
in deep space,

that orbits are
at their most powerful,

smashing entire galaxies
together

to create the structure
of the Universe itself.

Across the Universe,

extreme gravity
is a force of destruction.

The orbits of planets and stars

can be chaotic,
unpredictable, and violent.

But on a truly cosmic scale,

gravity is no longer
just a destroyer.

It also creates new worlds.

These are galaxies --
giant spinning clusters

of stars, gas, and dust
100,000 light-years across.

Galaxies orbit each other

in the same way
planets orbit stars.

Gravity pulls them together.

Their speed keeps them apart.

But, ultimately,
gravity always wins.

Entire galaxies smash together.

One of the most spectacular
events in the Universe

is when galaxies collide.

You're talking about hundreds
of billions of stars

100,000 light-years across,

two of these things slamming
into each other.

Collisions
between orbiting galaxies

take place
over millions of years.

Gravity slowly
pulls them together.

And you get these two galaxies

that merge like two fluids
mixing together.

And you get long tidal tails
as they pass through each other,

but then gravity brings them
back together again.

And in the end,
you get a full-fledged,

more mature, larger galaxy
than you had originally.

On this intergalactic scale,

gravity and motion are
no longer destructive forces.

Now they trigger
the creation of life itself.

You would think
a galactic collision

would be incredibly destructive,

and in one sense, it is,

but in another sense,
it's a very creative force.

Colliding galaxies
smash vast gas clouds together.

Huge shock waves rip
through them, squeezing the gas.

Then something amazing
happens --

the birth of countless stars.

It's incredible to think
about two galaxies

that gravitationally attract
each other and collide.

What could be more destructive?

But, in fact, there is a power
of construction in such mergers,

because as two galaxies
come together,

the gases are compressed,
and sometimes,

the gases are compressed so much
that you get the birth of stars

and the associated planets
around those stars.

And so, in the titanic collision
between two galaxies,

you can get the birth of stars
and planets

and perhaps eventually
life on those planets.

Sometimes,
these collisions

trigger a chain reaction...

...two spiral galaxies
in mid-collision

creating stars and planets.

But this time,
there's a difference.

Some of these new stars

are massive, unstable,
and short-lived.

They explode.

Each explosion blasts out
new shock waves

and triggers the birth
of even more stars.

Astronomers call this
a starburst.

It's the ultimate example
of gravity's creative power.

A starburst galaxy is one

that is creating stars
at a much higher rate

than we usually see
in normal galaxies.

And so, it's amazing

that you can have such
a beautiful, creative process

coming out of something
so violent and destructive.

Gravity and motion,

the two forces that give birth
to every new star,

also weave together the fabric
of the Universe itself.

Our cosmos is not random.
It has structure.

The Universe is a vast
three-dimensional tapestry.

Each of these threads
and filaments

contains billions of galaxies.

It's the scaffolding that holds
everything together,

the cosmic web.

And we think about scaffolding
of a building,

it's just sitting there, static.

But, in fact, this scaffolding

is quite dynamic
and quite amazing

because all of the constituents

are moving around
at very high speeds,

crashing into one another --

galaxies, stars,
black holes, supernovae --

all in this tremendous
cosmic dance.

The cosmic web
is incomprehensibly vast.

Each thread is full of motion.

Galaxies form, orbit,
and collide,

countless billions
in a constant stream.

Every filament
is a galactic freeway

with an endless flow of traffic,
each point of light a galaxy.

It's rush hour 24/7, and
sometimes, there's gridlock.

Every billion light-years,

several filaments join
to form a knot.

Whole clusters collide to form

some of the largest structures
we know of -- superclusters.

This is one of them --
Abell 2744.

Five orbiting galaxy clusters
crashed together

in the single biggest
cosmic pile-up ever discovered.

Gradually, the five clusters
merged and fused

to form a single giant
supercluster

6 million light-years across.

The incredible power of orbits

can literally tie the universe
in knots.

Structures in the Universe have
evolved over billions of years

through their orbits and their
mutual gravitational attraction,

and they've built up into larger
and larger structures.

And it's all thanks to these
same attractive forces

that bring them together
but can also tear them apart.

Again and again,

we discover orbits
dominating the cosmos.

The atom is the basic unit
of chemistry.

In the same way,

the orbit is the basic unit
of the Universe itself.

If you understand
all possible orbits,

you understand the dynamics
driving the Universe.

Orbits have created a cosmos

full of richness and complexity.

Orbits are changeable.
They're chaotic.

Things that we never thought
were possible

are, in fact, possible.

From the smallest scale
to the largest scale,

it's the gravitational
interactions and collisions

that actually make our Universe
the beautiful place that it is.

And behind it all
is a curious paradox.

Extreme orbits mean variations,
collisions.

That seems very destructive.

But, also, extreme orbits
mean colliding galaxies,

collapsing dust clouds,
the very creation of life,

as well as destruction.

Orbits are the driving force

behind this never-ending cycle
of creation and destruction.

They're at the very heart
of how the Universe works.