Life on Earth is so delicate
that it has been close to disappearing several times.
But who, or what, could've been responsible for it?
We live in a very hostile planet
that wanders an even more dangerous Universe.
What if all life we know
is at risk of disappearing?
"THE GREAT EXTINCTION"
On October 19th, 2017, astronomer Robert Weryk
observes the sky with a powerful telescope and is astonished.
What he witnesses is something never seen before by science.
An object with such a weird shape
that it looks like a probe from another planet.
In fact, its features are so different
that science needs a new category to describe it.
The Oumuamua is not a comet nor an asteroid,
but the first interstellar object to ever be cataloged,
because it comes from outside of our Solar System.
Besides its odd shape,
another impressive thing is its speed.
It's faster than any celestial body
ever detected in the Solar System.
Traveling at an impressive 315,000 kilometers per hour,
the Oumuamua dangerously approaches the Earth.
But on October 14th, 2018,
the object passes very close to our planet
and continues its silent journey
to other corners of the Universe.
We were super lucky. It was a close call.
Our friend was really close to Earth.
But what does the future hold for us?
Could something more dangerous lead our species to extinction?
A NETFLIX ORIGINAL SERIES
Castanhari! It's the end of the world!
The FDA closed Kléber's!
-There's nowhere to eat lunch! -Grea--
I mean, that sucks. But you'll find a better diner.
Impossible. Kléber's was special.
The only cheap menu around here.
Don't be dramatic, man. You make it sound like an asteroid
will fall on Earth and end mankind.
Asteroids are nothing compared to Kléber's closing.
So you're not worried at all about asteroids?
Doesn't a bunch of stuff fall on Earth? Meteors, Superman, even Goku himself.
A small rock falling today wouldn't make my day worse.
But asteroids are a real problem.
What if I told you life on Earth almost ended due to them?
Oh. The dinosaurs, right?
-Yeah. -But they'd disappear anyway.
Their families were starting to vanish
due to lack of food, even before the asteroid hit.
Correct. Your studies are paying off.
Actually, I watched four seasons of Dinosaurs.
But we can't dismiss asteroids. In fact, dinosaur extinction showed us
that Earth suffered a huge impact back then.
Since most of them died 65 million years ago,
scientists suspected that some devastating event
could have caused it.
The answer began to appear when geologists found in Mexico
rocks containing a great amount of iridium,
a metal that's really common in comets and asteroids.
Castanhari, these rocks revealed some very important information.
Something had collided with Earth in that region
around the same time most dinosaurs became extinct.
So, scientists found out that that enormous area
was actually a huge crater over 180 kilometers of diameter.
The Chicxulub crater proves that, 65 million years ago,
Earth was hit by a huge asteroid
with a diameter of approximately ten kilometers.
The impact had the power of ten billion atomic bombs,
like the ones used to bomb
the Japanese cities of Hiroshima and Nagasaki
by the end of World War II.
Of course thousands of animals and plants died immediately,
but the problem was, the destruction didn't stop there.
The impact threw tons of dust into the atmosphere,
blocking the sunlight.
For 30 years,
temperatures on the surface dropped down to -20 ºC,
creating a long nuclear winter.
This devastated our ecosystem.
Without sunlight, plants started dying.
Herbivore dinosaurs didn't have anything to eat
and also died.
As a consequence, carnivores had no food
and faced the same end.
But a few dinosaurs refused to die.
All the existing birds today
descend from the dinosaurs that were able to survive and adapt
to this new world,
giving origin to hundreds of new species.
SÃO PAULO IMIGRANTES ECO PARK
The meteorite's impact was so devastating to Earth
that 75% of all its species were extinct.
However, as amazing as it seems, it wasn't the first time
a catastrophe almost destroyed our planet.
Life on Earth was close to being completely annihilated
at least five times.
It's not always an asteroid that causes such destruction.
Our planet has ways of doing that itself.
That's what happened 250 million years ago,
when Earth was still formed by a single supercontinent:
Pangaea.
PANGAEA SUPERCONTINENT
It all started in a way that no one could imagine:
because of the emergence of trees.
For a long time,
all the vegetation in the world was at most one meter high.
But the appearance of a molecule called lignin
increased the plants' flexibility and resistance,
so they started to grow.
That was the origin of all existing trees today.
Do you remember photosynthesis?
A plant uses carbon dioxide and solar energy
and releases oxygen.
When it dies, it's decomposed by microorganisms
that reintroduce carbon dioxide in the environment,
creating balance in the atmosphere.
But since lignin was a new molecule on Earth,
no fungus or bacteria had the means to digest it.
And termites, well...
Unfortunately, they didn't exist yet.
So, trees didn't decompose,
and the carbon dioxide released in the process
didn't return to the environment.
Since a plant releases way more oxygen than it consumes,
the gas's presence in the atmosphere
was twice the amount of today's.
2 TIMES MORE OXYGEN
The ones who benefited from that large amount of oxygen
were the insects.
They got ridiculously big back then.
The world on double the oxygen became a sort of heaven to them.
With air to spare, those invertebrates could grow way bigger.
Imagine walking in a forest
and seeing a bee bigger than a tennis ball.
But what matters to us are the trees.
Since they didn't decompose when they died,
more and more trunks accumulated on the planet's surface.
This process kept happening for millions of years
and ended up transforming several regions of the planet
into enormous firewood deposits.
FIREWOOD DEPOSITS
In a world full of firewood,
all it takes is a little spark to make everything burn.
And that spark came from a series of mass eruptions
that occurred precisely in the greatest firewood deposit
at the time.
The volcanic lava started burning all the firewood,
which led to a gigantic fire.
Let's not forget that the atmosphere had double the oxygen,
which facilitated combustion.
This was the missing ingredient for an environmental disaster.
The fire cast a large amount of smoke into the atmosphere,
creating a sulfurous acid fog that blocked the sunlight.
Temperatures dropped below freezing everywhere.
When the eruptions subsided,
the acid fog descended to the ground,
and sunlight heated the Earth's surface again.
But that created a new problem.
The fire left the atmosphere with a carbon dioxide concentration
that was higher than normal.
It caused a super greenhouse effect that increased the temperatures even more.
It was so hot that the ocean waters also started getting warmer.
Large amounts of methane that were frozen
at the bottom of the ocean melted and escaped into the atmosphere.
This increased the greenhouse effect, making the planet even hotter
and exposed to solar radiation.
The situation only got worse.
While many terrestrial animals and plants died,
marine life was suffering even more tragic consequences.
Aquatic plants were the first ones to die,
reducing the volume of oxygen in the water.
And the situation got worse
when the seawater stopped moving.
Oceanic currents occur due to a difference in temperature
between the surface and the bottom of the ocean.
With water getting hotter, the oceans became still.
So, the oxygen from the air stopped mixing with water,
which made it impossible for the fish that were still alive
to be able to breathe.
Still waters also made way for the increase of bacterial colonies
that loved that environment.
They began to multiply,
causing even more deaths on the continents,
as these small creatures produced hydrogen sulfide,
an extremely toxic and corrosive gas.
When this gas reached the surface,
animals and plants that had survived the heat
were poisoned.
And Earth did all that on its own?
I told you a little space rock wouldn't be a problem.
Maybe "on its own" isn't the best way to put it.
While Earth was dealing with all these problems,
the cosmos gifted us with another asteroid.
Do you know where it landed?
Right in the middle of Brazil.
The Araguainha crater has a diameter of 40,000 meters.
It's so big, it accommodates an entire town.
An asteroid over one kilometer in diameter
hit the planet at that area at a speed of about 54,000 km/h.
Since the world was formed by Pangaea, everything was different.
This region was a huge sea of shallow waters,
and the impact caused earthquakes and tsunamis
that spread over almost 500 kilometers.
All existing life there was completely affected.
So what happened wasn't just one destructive event,
but a series of interconnected catastrophes.
Briggs.
Let's recap.
A huge fire caused a greenhouse effect
that transformed the planet into an oven.
The oceans got warmer,
which destroyed the ozone layer and stopped the seawater from moving,
increasing the amount of bacteria
that produce a super poisonous gas.
This chain reaction caused so much destruction
that was later named "The Great Extinction."
It made 95% of marine species and 70% of terrestrial species disappear.
Wow.
So, 165% of species... disappeared?
Adalberto.
That's not how percentage works.
But if it's any consolation, the sum result was correct.
Briggs, there's no point in cheering me up.
I still need time to get over Kléber's being closed.
I remember how Jamal enjoyed licking the fat
from the hamburger, you know?
Stop it, Betinho. There's always a way, man.
Yeah, for asteroids there is.
I saw in a movie that, even if the asteroid is in space,
you can go... And it explodes.
Exploding an asteroid would only make it worse, dude.
It would shatter into a thousand pieces.
There are more efficient methods to overcome that threat.
If it's still far away from Earth,
we can alter its course without spending too much energy.
But as it gets closer to our planet,
it gets more difficult,
because the higher the angle needed to diverge it,
the more energy we'd need.
ENERGY
One way to change its course
is sending over a probe that would enter the asteroid's orbit.
The probe would be attracted by its gravity,
and from time to time, it would have to turn on its retrorockets
to push away and not crash into the space rock.
The energy from the propellers would push the asteroid,
diverging it from its course.
Another alternative would be painting part of it black.
The painted area would absorb the sunlight more intensely,
which would increase pressure only on that side of the rock,
making it change its course.
Imagine the amount of paint we'd use for that.
But we have a much more serious problem
than a space object hitting Earth.
Many scientists say a great extinction
is happening right now.
It has nothing to do with asteroids or oceans not moving.
Because we are the Great Extinction.
WE ARE THE GREAT EXTINCTION
Mankind has been interfering too much with the planet
and many animal species have paid the price for it.
The Pinta island tortoise is among them.
Despite being able to live for almost 200 years,
they didn't survive the arrival of man to the islands.
The last one was found in 1971
and became known as Lonesome George.
Biologists tried to make him reproduce with a female tortoise,
but their efforts were in vain.
George died on June 24th, 2012,
ending these tortoises' history on the planet.
The Western black rhinoceros
also fell victim to human greed.
This species was poached to death due to their valuable ivory horns,
which in the illegal market can cost up to 65,000 dollars per kilo.
The species succumbed to the out-of-control poaching.
The result is evident:
the last member of the species was killed in 2011,
and the Western black rhinoceros disappeared from the planet forever.
Humans are responsible for the extinction of over 300 species.
And each one that disappears causes an ecological unbalance.
The alterations are mostly small,
but they do exist and they deeply affect the planet.
At least Earth isn't going crazy anymore, causing extinctions on its own.
Betinho, who said Earth isn't going crazy anymore?
Many factors responsible for the Great Extinctions are still around
and can affect the entire planet.
A supervolcano, for example,
is capable of causing a global catastrophe.
The last time one erupted was 70,000 years ago,
where today lies Lake Toba, in Sumatra.
It was the biggest eruption on Earth in the last 25 million years.
It lasted two weeks,
and the area around the volcano was covered with a layer of ash
that, in some places, reached nine meters high.
Needless to say
that most of the animals and plants in that region
weren't able to escape.
Even humans who roamed the planet around then
were at risk of disappearing.
I didn't know there were so many tragedies that could kill people.
Nuclear winter, volcanoes, fires,
Kléber's closing down...
And I'm only talking about the stuff on our planet.
The Universe has many things that can threaten life on Earth.
One of them is in our Sun. Did you know that?
Have you ever heard of solar winds?
It's very different from the refreshing breeze
we have on Earth.
At every second, no less than one million tons
of subatomic particles are launched from the Sun
directly into space in the form of a wind.
This wind creates a huge bubble that covers much of the Solar System,
and it's called heliosphere.
HELIOSPHERE
During periods of great Sun activity,
the radiation levels in this wind increase so much
that astronauts in the International Space Station
are forbidden from performing external activities.
The only thing protecting us is the Earth's magnetic field,
which works as a shield against these solar winds.
But we can't completely trust this shield,
since an inversion in the magnetic poles
could end up weakening it.
Worst case scenario, Earth would end up like Mars,
which lost its magnetic field,
and its atmosphere was ripped by solar winds.
The planet was very similar to Earth, but eventually died.
REAL IMAGES OF MARS
Solar winds are just one of the threats
outside of Earth.
The Universe is fascinating, but extremely dangerous.
All celestial bodies are at risk
of being destroyed without warning,
just for being in the wrong place at the wrong time.
That could happen, for example, due to a kilonova.
KILONOVA
The power of a kilonova
comes from collisions of neutron stars,
which are the most dense in the universe.
The amount of gamma ray explosions released in a kilonova
affects entire regions of the Universe,
destroying pretty much everything in its path.
But that's not the only thing I'm worried about, Briggs.
There's another bomb close to us,
just waiting for a chance to explode.
And it was famous astronomer Edmond Halley
who discovered this true space monster
that occupies an area
that's almost equal to the distance between the Earth and the Sun.
Its name is Eta Carinae.
Not so long ago, scientists believed
that it was one of the biggest stars in the Universe.
But that changed when Brazilian astronomer Augusto Damineli uncovered
one of the greatest secrets of the Milky Way.
Eta Carinae is actually a binary system
formed by stars Eta Carinae A and Eta Carinae B,
which are so close to each other
that they look like they're just a single star.
But for us, who live so close to this system,
there's an even scarier piece of information.
It's extremely unstable.
The intensity of Eta Carinae's light
has increased and decreased a lot since the 19th century,
and it hasn't followed an identifiable pattern.
This instability is extremely disturbing,
since it means the fuel from one of these stars
may end at any moment.
The day that happens, Eta Carinae will explode
into a supernova,
and its light will be equal to hundreds of billions of suns.
The explosion will be so gigantic
that nights in the South Hemisphere of our planet
will be lit up by Eta Carinae for several months.
Earth has suffered from five mass extinctions,
but life has continued to endure.
How long will our luck last?
It's ironic that, among all the dangers hidden in the vast Universe,
the very event responsible for creating our planet...
will destroy it.
In about five billion years, we'll lose our Sun.
The hydrogen in its core will be completely consumed
and the star will collapse.
The Sun will pretty much double its size,
becoming a red giant,
swallowing our poor planet
and extinguishing all life here.
After that, it will lose much of its mass,
moving into its final form:
a small white dwarf,
which will keep on shining for trillions of years.
The Helix Nebula, also known as The Eye of God,
gives us the opportunity to see the Sun's destiny.
Right in the middle of this thundering burst of colors,
there is a white dwarf
that was once very similar to our star.
That'll be the Sun in five billion years.
Will we still be here in five billion years?
Maybe mankind will disappear way before that,
becoming a small mark in the Universe's never-ending memory.