Fifty thousand years ago,
a space rock
slammed into Earth
and made a big boom.
This meteorite was only
about 50 m (160 ft) wide,
but it weighed
a whopping 300,000 tons.
When it smashed
down into the ground,
it flattened everything
in the vicinity.
It left a crater so lunar-like
that astronauts trained there
before landing on the Moon.
Yeah,
this is Meteor Crater in Arizona.
And there’ve been many impacts
like this one in the long
history of Earth.
If this meteorite were to slam into
New York today,
it would destroy most of the city.
The impact would leave a crater
1.3 km (0.8 mi) wide.
But the fireball would spread
further.
Everything within 1.7 km (1.1 mi)
of the impact zone
would burn.
Even on the outskirts
of New York City,
the windows would shatter
and many people would perish.
It would take years to recover
from this disaster.
But this is nowhere
close to the size
of some of the largest
asteroid impacts Earth has seen.
Some of them were so gigantic
that if they smashed into us today,
they would cause our extinction.
Most of these asteroids crashed
when Earth was very young.
Well, at least in planetary years.
Some 2.2 billion years ago,
a pretty big asteroid
made its way down to Earth,
where Australia is now.
It left the oldest
confirmed crater on our planet.
Yarrabubba Crater doesn't
look like much today.
But when it made its fatal landing,
it shook the planet quite a lot.
Yarrabubba scarred the continent
with a crater 70 km (44 mi) wide.
It wiped out everything in its way
with a massive shockwave.
Scientists even think it helped
end the ice age
that Earth was going through
by creating so much vapor
that it changed the climate.
Now, imagine this giant
landing on Earth today.
If it hit Australia again
and left a 70 km (44 mi) crater there,
the fireball would spread for
130 km (80 mi) in all directions.
If it set a course for New York,
it would decimate the entire city.
Even on the outskirts,
everything would be on fire,
and you'd get third-degree burns.
But things could get so much worse
if an asteroid even
larger than that hit us.
Like the one that crashed
into Earth 1.8 billion years ago.
This giant comet
punctured the ground
and shattered the rock.
It left a crater 130 km (81 mi) wide
where Canada is today.
We call this crater Sudbury Basin,
and it's one of the largest
asteroid impacts
Earth has seen in its history.
1.8 billion years ago was a violent
time for our planet.
The atmosphere was changing
and continents were on the move,
shaking and rupturing the land
on their way.
Massive asteroid
collisions were part
of a regular day back then.
Now, if this comet hit us today,
it would be a total
doomsday scenario.
Yeah,
if the Sudbury Basin impactor
landed on New York City today,
there wouldn't be a New York City.
It would feel like being caught
in an earthquake
that measured an 11
on the Richter scale.
Everything would be shaking
from this immense
and loud shockwave.
And everything 300 km (186 mi)
from the impact would instantly ignite.
This is what the impact
would look like
if it landed in France.
Yeah, there's no chance
you're surviving this.
And we haven't even got
to the biggest impact yet.
It's time for
the dinosaur-wiping asteroid.
65 million years ago,
an asteroid at least
10 km (6.2 mi) wide
smashed into Earth,
where Mexico is now,
and violently ended
the era of giant reptiles.
Now, imagine that
same impact today.
And, well,
yeah,
it would be incredibly violent.
The asteroid would leave
a crater 180 km (112 mi) wide.
And the fireball?
The fireball would burn everything
in a 450 km (280 mi) radius.
If this asteroid hit New York,
its effects would spread
as far as Canada.
And the impact would be
so painfully loud
that it would deafen you.
You wouldn't just hear it.
You'd feel violent vibrations
in your entire body.
And if this big space rock
doubled down on Mexico,
well, much of the country
would see the same fate
the region saw
when the dinosaurs died.
Enormous shockwaves
would cause widespread
destruction hundreds of kilometers
beyond the impact site.
And just like 65 million years ago,
the impact would cause
a massive tsunami.
OK, it's bad.
Really bad.
But let's finally
get to our number one
largest impact in history.
Cue the Vredefort asteroid.
The largest,
almost the oldest
and the most terrifying space
event on our planet's record.
Two billion years ago,
a gigantic asteroid
slammed into where
South Africa is today.
It obliterated everything.
It likely
changed the Earth's climate.
And it most definitely killed
whatever lived here
before the dinosaurs.
This same impact
today would bring enormous
death and destruction.
This deadly space rock
would obliterate everything
for hundreds of kilometers.
The crater from the impactor
would be as wide as 300 km (186 mi).
And the fireball would spread
for 750 km (466 mi)
in all directions.
Intense shockwaves would rush
across the continent.
Add to this tsunamis,
earthquakes and wildfires,
and this would be
a horrifying disaster.
Nothing in the area
could survive this.
But what's worse
is that the disaster
wouldn't end there.
All the debris, dust and gases
from the impact
would block the sunlight
and pollute the atmosphere.
We'd be like the dinosaurs
during their last days.
Temperatures would plummet.
The sudden climate change
would cause
a massive extinction event.
Earth would become
a pretty barren place.
And humanity
might not be able
to come back from this.
Maybe it's best to nuke an asteroid
like this
before it ever reaches Earth.
But that's a story
for another WHAT IF.