Original subtitles

The earth is over 4.5 billion years old.

Its history is shaped by disaster...

after disaster.

Asteroid and comet collisions,

flares from the Sun.

Mass extinctions,

supernova explosions,

cosmic ray bombardment.

You name it, we've experienced it.

It's kind of a miracle we're here at all.

These violent events could be why Earth has life

We tend to thin of disaster as a bad thing,

but out of chaos can come possibility.

When we destroy something,

we can also create something new.

Earth has walked the line between survival..

And destruction.

It's tipping that fine balance of luck

between a good disaster and a bad disaster.

Could catastrophe and chaos be the essential ingredient

for life?

2021.

Scientists investigate something mysterious

buried deep inside the earth

It's a long hidden clue to our violent past.

Deep down

1,800 miles below the surface of the earth,

our core is surrounded by fluid rock,

but inside that,

600 miles high

and thousands of miles across

are two denser regions,

and they kind of cup the core of our planet like two hands.

One of them is, you know, half the size of Australia, for crying out loud.

So, I mean, they're big lumps down there.

There's no reason they should be there.

It's a mystery to us.

To solve this mystery,

scientists need to examine the rocks

buried over 1,000 miles beneath the surface.

We don't really know what these two big rocks are made of,

sitting there on the core.

However, we've been able to sample them.

How in the world is that possible?

Well, these blobs are actual feeding mantle plumes

that are rising up through the mantle.

So, volcanoes in Iceland and Samoa, for instance,

will dredge up some of these lumps of rock from the mantle.

It's a precious chance for us to sample some of that deep rock

that we'd normally not get a chance to see.

These rocks are old.

Very old.

It turns out that the samples in the lav

that we think came from these blobs of rock in the mantle

are 4.5 billion years old.

That is as old as the age of the earth.

So, they tell us something about, you know,

how the internal structure of our planet was, uh, arranged

in the earliest days of the formation of our planet,

so getting samples from that time is very, very important.

The age of the rocks may be a clue to their origin.

They date back to a time of monstrous cosmic mayhem.

4.5 billion years ago,

the solar system was still a pretty wild place.

We're approaching the end of the formation of planets.

Earth would still be growing.

Back then, you wouldn't necessarily recognize the earth.

In fact, you wouldn't recognize the earth at all.

For example, no moon.

The earth did not have a moon when it first formed.

The young earth orbits the S with other infant planets.

One of them is an object scientists call Theia...

and it's on a collision course with our home.

The Theia collision would ha been a spectacular event.

It would've been one of the coolest things

you could possibly witness

in the origin of the solar system,

certainly the biggest event in the history of the earth.

The Theia event is

something that completely reshaped the earth.

The planet that the earth was before the Theia event

is gone forever.

The impact melts rock

and throws out over a billio billion tons of debris.

During this incredible collision,

these two planets were literally broken apart

and combined into one big planet.

Huge chunks of Theia stayed together

as the now molten earth began to form anew.

Now, we can kind of paint a picture

of where these big lumps of rock might have come from.

They're very old.

They're, in fact, the same age as that large impact event.

They could be pieces of Thei

The giant slabs of Theia sink down into our planet...

and lie undiscovered for billions of years.

Earth reforms from the ruin of both planets.

Now, you might think that a collision like this is just devastating,

there's no upside at all,

but there's some things that came out of this collision

that may have led to the possibility of life.

When these two planets combined,

parts of Theia's iron core merged with Earth's.

So, that means that Earth collected a much bigger core

than it might have possessed on its own.

This is good news for us

because the core is the source of the magnetic field

that protects us.

Liquid metal flowing around in the outer core

generates Earth's magnetic field...

a protective shield from the Sun.

The Sun can actual output billions of tons

of high-energy protons and electrons in a single burp.

That, eventually, would hav stripped away our atmosphere

If it weren't for that active core

and that magnetic field,

we would look like Mars,

just sort of a bare and barren desert.

Thanks to Theia's extra iron,

Earth's molten outer core is large...

so it cools slowly,

staying molten,

and keeps on generating a strong magnetic shield.

Because of that collision,

the extra iron, the extra heat,

we've stayed active.

We have a magnetic field.

We are protected,

and, in fact, that's why we're here talking about it.

The catastrophic impact helped life in other ways.

The Theia event was absolutely huge,

and not an impact like a 100-mile asteroid making a big crater in the desert,

but a planet hitting a planet,

causing a huge disk of debris spread out from the earth,

out of which formed the Moon

After the collision,

the earth tilts on its side

and spins incredibly fast.

A day only lasts a few hours

The earth itself rotates slightly on its side,

and, if left to its own devices,

would, in fact, experience unpredictable, chaotic wobbling.

The fact that the Moon is there

stabilizes the earth,

stabilizes our climate.

The Moon's gravitational pull on our oceans

creates tides and slows down the earth's spin...

creating a world primed for life.

We actually owe quite a bit to the Moon and Theia,

its progenitor,

for making Earth a hospitable planet for life.

A giant collision 4.5 billion years ago

sounds like a catastrophe,

but it was probably the best thing to happen to the earth.

Theia, I would shake your ha

because we have a lot to owe you.

We also owe the science of chance

because we lucked out

with a one in a million impact.

If the impact from Theia had been a little bit harder,

the earth may not have recovered as well as it did,

and we may not be here to talk about it right now.

If it had been a little bit less forceful,

then the impact of it may no have made the changes

that we think were needed for us to be here now.

We got lucky.

Most planets don't get to survive a collision like that

and get a bonus moon out of the deal.

Earth's huge collision with Theia

was not our planet's first brush with danger.

An earlier explosive event

could have stopped the solar system

from sparking into life...

and the earth from formin

Supernovas are one of the universe's most destructive events...

releasing, in one second.

As much energy as our sun will

in its entire lifetime.

But rather than wipe us out

supernovas may have kick-started the solar syste

4.6 billion years ago,

the solar system's not even really the solar system.

It's the precursor of the solar system.

So, what we ha was a cloud of gas and dust collapsing in on itself,

forming the Sun in the cente

a big, flat disk around it

out of which all the planets were forming.

There are all kind of vast clouds of dust and g floating around the Galaxy.

What actually causes them to start collapsing

and forming new stars?

Well, you have to give that cloud a push.

Scientists think this push could be a stellar blast...

a supernova.

Supernova are some of the most powerfu events in the universe.

One explosion can light up brighter than a galaxy.

So, not only do they eject elements and material,

they also eject a lot of light and energy.

A supernova explosion sends a shock wave

racing out into space at 18,000 miles per second.

The shock wave from a nearby supernova

compresses material together

until it begins to collapse under its own gravity.

Was this how our solar system started?

So far, it's been really difficult to find, uh, evidence

that there was some supernova,

or point to something that happened

that really kick-started the solar system.

The ancient supernova blast faded away a long time ago.

Imagine a crime scen

Now, imagine waiting 4.6 billion years

after the crime is committed,

and looking at it and going,

"There's... There's nothing here.

What are we doing?"

Uh, that's kinda what we're trying to do here.

Researchers from the University of Minnesota

tried to solve this ancient crime...

by studying asteroids that fell to Earth as meteorites.

Asteroids are critical for understanding the early solar system,

and this is because they have frozen in place all the conditions

that existed in that very early solar nebula,

right at 4.5 billion years ago.

The asteroids contain information

about the time leading up to the birth of the Sun and the solar system.

When a massive star ends its life as a supernova,

it undergoes what we call nucleogenesis.

In fact, we call it explosive nucleogenesis.

Literally, the explosion is generating new types of nuclei,

new elements, heavier elements.

Well, it turns out the types of elements it makes

depends on the star that blew up.

The Minnesota tea ran computer simulations

to investigate which elements form

when a star up to 12 times the mass of the Sun explodes

Then, they compared the results

with analysis of elements found in asteroids

dating back to the birth of the solar system.

They match.

So, the remains of this supernova was actual under our noses all along

in the elements that have been in our solar system for ages.

And perhaps in the earth as well.

The earth has lots of rocks that's made of, uh, silicon.

That's only produced in supernova explosions,

and the very core of our earth,

the thing that keeps us alive,

that's iron, nickel.

Again, you only get that in supernova explosions.

In February 2021

scientists shed light on the supernova explosions

that helped seed our solar system

and provided the materials to build our planet.

The research examined fragments

blasted off the giant space rock, Vesta...

4.5 billion years ago,

and later landed on Earth.

These asteroid fragments contain the fingerprints

of not one,

but at least two supernova explosions.

Our solar system was seeded, was enriched, by at least two separate supernova explosions.

That's incredibly lucky

because that is what delivers the ingredients necessary for life.

Scientists believ that these two supernovas

may have enriched different parts

of the infant solar system.

One provided the materials

that helped form the outer gas planets.

The other supernova seeded the inner solar system

with elements that built the rocky planets,

including the earth.

Once again, our fate came down to pure chance.

A series of extraordinarily violent supernova blasts

gave the solar system the kick-start it needed

and the elements to build the planets

without destroying our future home.

It's a fine line between being too close to a supernova,

which will just shred your pre-stellar cloud...

and not too far away that you don't get any of the good stuff.

Supernova play both creation stories

and destruction stories.

They play both roles.

We lucked out.

This chapter of the story ends well.

The solar system gets the ingredients it needs to build planets.

Earth forms in a good location,

close to its star.

The future looks bright,

but then,

the biggest bombardment in history

smashes into the earth.

From the moment our planet formed...

we've been under fire.

2021.

A fireball streaks across the night sky in Europe.

2018.

A 1,500-ton meteor explodes over the Bering Sea

with 10 times the energy of an atomic bomb.

2013.

An asteroid explodes over Russia,

injuring over 1,000 people.

The earth is hit by quite a few asteroids every day.

You see them as shooting stars,

meteors in the sky.

These events are violent and destructive

but these space invaders also brought something every living planet needs:

volatiles.

When we say volatiles,

what we mean are elements that are really light

and easily moved around.

Often, they're gases,

so that's oxygen, and water, and carbon dioxide,

and just all those light elements

that are really important building blocks for life.

These elements ar abundant on our planet today

but were not when it first formed.

From observing other solar systems forming all around us in space,

we know that planets as close to their stars as we are to the Sun,

when they form, they're very hot and dry.

There's probably some littl bit of water around there,

but really not very much.

So, what this means

is any volatiles will basically be boiled away.

If you have a molten surface,

anything like water is gonna get boiled away.

Young Earth was a dry planet,

devoid of all the precious volatiles needed for life.

These materials must have been delivered to Earth after its formation.

We think volatiles arrived in the early days of the solar system...

when the giant planets, including Jupiter,

moved around...

and stirred up the conten of the solar system.

As Jupiter moves,

its gravity is pulling on all the objects in there

basically speeding them up,

and there's a little bit of chaos there in the first place,

but now, Jupiter is basically supercharging it.

Jupiter's path sends countless asteroids and comets

on a collision course with the earth.

It would have been utterly chaotic.

This is a rain of large objects

onto all of the inner planets,

but these objects that came screaming into Earth were gigantic.

Four billion years ago,

a storm of giant asteroids and comets

hits the earth.

Some are tens of miles wide

They bring the volatiles

that help fill the earth's oceans

and build its atmosphere...

but cosmic deliveries can both give

and take.

The importance of impacts for atmosphere

could go either way.

You could have a... A really big,

really powerful impact...

that blows away the atmosphere

of a small, fledgling planet

or you could have a bunch of small impacts of water-rich asteroids

that are simply contributing water, and volatiles,

and new chemicals to the surface

that might help the atmosphe that's already there.

When you think about an object coming to Earth,

is it gonna land on Earth,

and if it does land,

is it gonna be a... An erosive event,

where material is lost from the earth,

or is it gonna be an accretion event,

where the earth gains material?

Well, the devil's in the details.

Details like the size of the impactor.

One study suggests

that asteroids between 60 fe and 3,300 feet wide

add more to the atmosphere than they take away.

And speed at the point of impact also matters.

Asteroids are orbiting the sun.

And when they fall towards the sun, they are gaining speed,

they're gaining velocity.

Imagine dropping a coin into one of those spiral wells.

As the coin gets closer and closer to the middle,

it spins up faster and faste

The closer an asteroid gets to the sun

the stronger the sun's gravitational pull...

and the faster the asteroid travels.

So proximity to your star

is a vital factor in how intense any impacts will be.

It's possibl that the Earth

is the right distance from its host star

so that when an impact happens,

the energy isn't insanely high.

It's just the right amount that it's the right speed to make everything work.

Supernovas seed the solar system

with the elements to build the planets.

Asteroids and comets delive volatile chemicals to the surface of the Earth

Together they create a habitable environment.

So we need those impacts to happen to have life on Earth.

Disasters create a planet primed for life.

But it appears that even mor mayhem and chaos

are needed to trigger life itself.

An asteroid tear through the solar system,

hurdling through space at 40,000 miles an hour.

It's destination,

Earth.

Will this space rock inflic unimaginable damage...

or will it bring the spark of life?

This idea of a spark of life,

we've all kinda seen it

in the Frankenstein movies, right? "It's alive!"

This comes from legend, from myth, from history

that there's some sort of a spark that differentiates

cold inanimate matter from living stuff.

And in some sense it's kind of true.

On Earth, we thin this spark may have arrived

over 4 billion years ago.

The Hadean Eon was the time from the Earth's formation

about 4.6 billion years ago

to about 4 billion years ago.

It's named after literally Hades.

So the conditions on Earth were literally hellish.

It was hot and soupy, a lot of water vapor around

high pressure atmosphere, very intense heat.

You wouldn't survive.

The planet would literally kill you back then.

It's shocking. And I mean, really shocking

that the evidence of first life that we have on Earth

dates to the Hadean Eon.

This was a terrible place,

molten and poisonous and awful.

And yet life somehow arose in all of that mess.

June 2020,

Japanese scientists simulat the conditions

of this hellish planet...

and then try to recreate the spark of life.

So what the scientists were trying to do was mimic those conditions

and see what would happen.

If you smash a meteorite into the ocean back then,

could it produce sort of the same chemicals

that we see life using today?

They use a mix of carbon dioxide, nitrogen water, and iron

to replicate the Hadean environment.

Firing a mini meteor at 2,000 miles an hour into this chemical soup

triggers a reaction between the basic organic elements..

Creating amino acids.

We call amino acids the building blocks of life.

Really they're the building blocks of proteins.

And life needs proteins to exist.

But that's why they're so important.

Without amino acids, there's no proteins,

without proteins, no life as we know it.

The experiment proves

that meteorite impacts can help build the components for life.

But for these building block to come together

and create life,

we need more.

It's like making a cake.

You can put together the oil, and the flour, and the butter, and the sugar,

but if you don't put it in an oven,

you're not gonna end up with a cake.

You're gonna end up with something else.

We thought that the violence of asteroid impacts

prevented life from forming

Now, we think they could be an essential ingredient.

If the asteroid impact is big enough and fast enoug

it can punch right through the crust.

Then you're getting geothermal heat,

heat the bubbles up from the mantle.

And it is certainly possibl to get an asteroid impact that big.

Large meteorite impacts can create hydrothermal vent

which some scientists believ were the cradles of life.

They provide warm, wet environments

and bring up chemicals from deep inside the Earth's crust...

the perfect place for life to begin.

As bad as those conditions seem to us,

to the molecules that are beginning to combin and do their thing,

that was a wonderful place to be.

That could actually be that the conditions

that are best for early life

might actually be those just after an impact.

So you have sort of this petri dish environment

in which life could really thrive.

These vents might be similar

to those we see in the oceans today.

These hydrothermal vents provide little window

into what the conditions on the primordial Earth would've been like.

And the sort of chemistry

that goes on in those hydrothermal fluids

seems to be the right kind of chemistry for creating life.

Once again, Earth got lucky.

Impacts that could've destroyed everything...

may have helped spark life into existence.

I once hear this quote from Confucious..

That creation is quiet but destruction is loud.

Well, these impacts

were both destructive, but they also may have been creators.

Earth leaves behi the Hadean age.

The planet calms, and life takes hold.

But disaster is our constant companion

as we prepare to face a stor of deadly cosmic bullets.

The universe is a dangerous place for lif

There are asteroid impacts..

Black holes...

and exploding stars.

But public enemy No. 1

cosmic rays...

lethal energic particles born in violent events.

Cosmic rays are incredibly small

but travel so fast, near the speed of light,

but they can tear through our DNA and damage I

Your full of DNA.

If that DNA gets broken apart, guess what happens?

That could lead to cancer and death.

At first glance, these cosmic rays are the worst things for life.

They're terrible.

Despite their frighting rap sheet,

cosmic rays may have played a crucial roll in the evolution of life.

2020,

scientists at New York and Stanford universities

investigate biological molecules that have a twin...

mirror image versions called chiral molecules.

The concept of chirality in chemistry

is when you have two molecules, two chemicals,

that are physically the same

They're made of exactly the same things,

but their structure is different.

And they're not just different,

they're reflections of each other.

It's literally called handedness

because look here's my right hand

with my thumb over here and my fingers over here,

here's my left hand with my thumb over here and my fingers over here.

I can't wear a left glove on my right hand.

There's nothing I can do to make these guys the same.

And it turns out this is true not just for hands,

but also for large number of simple organic compounds,

things like amino acids or sugars,

which are the building blocks of all life on Earth.

Billions of years ago, early life may have had

both left- and right-handed DNA and RNA.

But life chose to use mostly right-handed molecule

The reason may have been cosmic rays.

When cosmic rays hit Earth's atmosphere...

they degrade into even smaller subatomic particles

called muons.

Most muons spin in one direction.

So we have these little muons, which are very energetic,

and they're spinning a certain way.

And when they hit a molecule they interact with it.

They can disrupt it. They can change it.

Some scientists believe these spinning muons

interact more readily with right-handed DNA and RNA...

triggering mutations.

Some mutations are beneficia but they have to get a chanc

So if you have right-handed molecules and left-handed molecules,

and they're both being hit by muons,

the one that's hit more gets more chances to have a beneficial mutation.

Cosmic rays may have given right-handed life

an evolutionary advantage.

Left-handed life could not compete.

It's like throwing dice.

If you're trying to get double sixes,

and the left hand only gets to throw ten times,

and the right hand gets to throw 100 times,

more likely to get double sixes

with the right hand than the left hand.

But the dice don't always land in our favor.

359 million years ago, Earth's luck ran out.

And cosmic rays may have lived up to their reputation

as the baddest particle on the block.

Earth's oceans were teeming with marine lif

And by this period as well,

plants had started to colonize onto the contents and landmasses,

attracting animal life, insects, millipedes.

And it's in this environmen

the Earth experienced one of the greatest mass extensions

in the history of life.

Something killed off 97% of all vertebrae species.

We call this wipeout the end Devonian extinction

One possible explanation, a supernova.

When some dying stars explod they fire out cosmic rays.

This radiation bombards the upper atmospher of the Earth

and drives the chemistry of nitrogen, turning into nitrogen dioxide,

a gas which itself then reacts with the ozone layer

and destroys it.

Without the protective ozone layer,

ultra violet radiation from the sun bombards Earth

Radiation rains down for thousands of years...

damaging the DNA of plants and animals.

Many species die out.

The end Devonian mass extinction mostly effected marine life

This is where we see the greatest percentage of deaths.

The oceans once populated by fish the size of school buses...

now host fish no bigger than a sardine.

These smaller fish reproduce quickly.

In the challenging environment,

they adapt and diversify faster than larger species.

Mass extinction is not only wipe the slate clean

and provide other animals and other life forms an opportunity,

it creates a sort of chaoti and complex environment

that drives natural selectio and evolution.

If a supernova was to blame for this extinction event,

scientists believe that the culprit was 65 light years away.

Any closer and Earth's luck would've run out completely

It seems the existence of life

is always balanced on a knife edge.

When an exploding star goes off a little bit too close to us...

and we are all destroyed

So there's this wonderful balance

between just violent enough and too violent.

And we have been lucky enough to dance on that edge for 4.5 billion years.

This mass extinction reset life on Earth

and paved the way for four-legged creatures,

our distant ancestors.

Cataclysmic events go hand in hand

with human evolution.

Some knocked us back

and others like the event 66 million years ago

gave us a push forward.

66 million years ago

a massive asteroid crashes into the Earth.

It triggers a huge extinction event.

Without it humans may have never evolved.

At this time in Earth's history,

we had these enormous plants and gigantic insects

that actually would be incredibly terrifying if we saw them today.

Pterosaurs sa through the air.

Huge marine reptiles dominat the oceans.

And the T. rex is the king of the world.

Then a glowing object appear in the sky.

I'm sitting on the beach

what was then gonna be the Yucatan of Mexico

enjoying a drink with a, you know, a little umbrella,

but up there in the sky all of sudden

approaching me at 40,000 miles an hour

is Mount Everest glowing thousands of times more intensity than the sun...

and it's just seconds away from dropping on my head.

A 6 mile wide asteroid...

slams into the Earth.

The impact throws trillions of tons of rock and dust into the ai

The rocks heat up as they fall back to Earth..

Setting the planet on fir

That beach holiday suddenly turns into absolute nightmare.

The impact also throws up soot,

chocking the atmosphere.

Now, the skies are blotted out by all these materials,

so the sun is no longer shining brightly on the surface.

Plants need sunlight to photosynthesize

Without this vital energy source,

many species die out.

With their food source gone

plant eating dinosaurs starv to death,

followed by their predators

It was a huge disruption to all of life on Earth.

The dinosaurs have been around for 160 million years at this point.

That's astronomical amount of time.

And in one event, they're gone.

Again the dice ro is in our favor.

Most dinosaurs become extinc

paving the way for the evolution of mammals...

leading eventually to humans.

Without the asteroid impact we wouldn't be here.

As a furry primate on this planet, I kinda like the K-Pg impact, right?

I'm here because of it.

We all are.

Some plants benefited from the asteroid strike.

To learn out plants changed after the impact,

Smithsonian scientist examined thousands of tropical plant fossils

from the time of the die off

This disaster opened the way for new types of plants to develop.

It transforme the plant kingdom...

producing a richer and more diverse global ecosystem.

Before the asteroid strike,

conifers and ferns dominate the tropical forests of South America.

But afterwards, falling ash from the impact

enriched the soil.

And fast growing flowering plants took over.

The impact was very hard to recover fro

but it actually opened the opportunity

for a greater diversity of plant life,

which ultimately has benefited us as humans

because it has allowed us to have more food sources.

This new world order eventually gave rise

to the modern Amazon Rainforest,

home to 10% of all species on Earth.

It really destroyed and rema our entire environment.

The world grew back, of course it did, here we are,

but it changed everything.

And another age may be just around the corne

We should absolutely expect

that at some point in the future,

and I'm not saying you should lose sleep over it,

but at some point there will be another mass extinction.

Maybe that will be the end our days.

It's intriguing question is

what might come after humans on planet Earth?

Catastrophe may b the universe's recipe for li

throughout the cosmos...

one that every planet must follow.

Looking at our own history,

life thrives on catastrophes

We need these disasters for evolution to work.

So, hopefully, and I hate saying this, I know how it sounds,

hopefully, these other plane have had terrible disasters as well.

Think abo the word disaster.

It means bad star.

It means that something has gone wrong,

something that's dangerous.

We are children of disasters

There's no way you get us without planets colliding...

without asteroids and comets streaming through the atmosphere...

without even stars exploding and supernovas.

You are a child of that violence.

That's part of the environment that we grew up in in a cosmic way.

And I think that is tremendously beautiful.