How the Universe Works - Eleventh Season

This show is fictitious.

There is not actually an asteroid

headed to New York City today,

but this is based on simulations of such an event.

We run simulations of fictional asteroid strike

to prepare for the worst-case scenario.

November 4, 2029.

We face a countdown to catastrophe.

A giant asteroid hurtles towards Earth.

It's heading straight for

the eastern seaboard of the United States.

The space rock could wipe out an entire city

and cause widespread devastation.

Can Earth survive?

New York City, November 4, 2029.

The deserted metropolis waited for the asteroid to strike.

A giant space rock entered the atmosphere,

heading straight for the eastern seaboard of the USA.

As it comes through the atmosphere,

we would see something as bright as the sun getting

brighter and brighter and brighter.

At speeds of maybe 20 kilometers per second or so.

That's something like 18 times faster than

the speed of a bullet coming out of a rifle.

This asteroid was headed towards

the most populous city in America,

and when it impacts, it would deliver

more energy than 1,000 Hiroshima nuclear bombs.

It would level some of the most expensive real estate

in the world in seconds.

There would be a crater where Central Park used to be.

I actually don't even like thinking about this,

of how horrible it would be.

This is beyond the worst disaster

the world has... Would have ever faced.

There's nothing in our history that would have

done this much damage so quickly and so devastatingly.

The story of the asteroid

and the Earth's fight back

started seven years ago, here in Arizona.

September 2022,

the Catalina Sky Survey.

Guardian of heavens Greg Leonard drives

to Mount Lemmon Observatory near Tucson.

He's on the hunt for asteroids and comets.

We are the watchers of the skies for the planet.

We literally represent the first line of defense

against potentially incoming asteroids,

and I want to emphasize the words planetary defense.

This is not in the benefit for one nation.

This is for the entire planet.

Greg takes a series of images

over a 20-minute period.

Stars don't move in the photos,

but asteroids and comets do.

A-ha.

We can see four points of light

tracking across the background of the stationary stars.

This one is moving very quickly across the sky.

So this tells me

this is a real near-Earth asteroid candidate.

It's one of over 27,000 near-Earth asteroids,

or NEAs for short, discovered by the early 2020s.

The huge gravity of Jupiter can rip space rocks

from their home in the asteroid belt.

Some race outwards, away from the sun.

NEAs head inwards, occasionally towards Earth.

We didn't know it back in September of 2022,

but these were our first images

of a deadly incoming asteroid.

It's relatively close to Earth's neighborhood.

We don't know exactly how far it is yet,

but it's close enough where its motion across the sky

appears rapid.

The discovery of an NEA set a series

of planet protection protocols in motion.

Step one, enlist a global team of experts

to investigate the asteroid's orbit.

We have some of the brightest minds,

some of the best telescopes,

some of the biggest supercomputers

working to protect Earth,

collaborating across language barriers,

across international borders to protect humanity.

This international planetary defense team

was tasked with discovering if the distant object

would become a serious threat to Earth.

Their first job...

Determine if the NEA's orbit would intersect with our own.

Orbits are a little like roads, right?

You've got a path that something follows,

and they can intersect, you can have a crossroads.

Now, typically, if only one object is there,

that's not a big deal,

but if you have two objects approaching that intersection

at the same time, they could collide,

and that's the danger from asteroids.

The team of scientists

track the asteroid for four months.

Over time, you can build up observations.

You can gradually narrow down the possible number of orbits,

then determine whether there's any chance of a future impact,

but if the asteroid is orbiting the sun,

the Earth is orbiting the sun, and there's this dance going on.

Sometimes the asteroid is near the Earth,

and we can observe it, it's bright.

Other times the asteroid is

on the other side of the sun.

We can't observe it at all.

We were lucky.

The asteroid was visible throughout the fall of 2022.

However, our observations of the space rock's orbit

showed a very real possibility

that it would slam into Earth in just seven years.

Astronomers gave the incoming asteroid

a suitably appropriate name, Apep.

Apep was the Egyptian god of chaos,

so that's a fairly good name for an asteroid

that could hit the Earth

because that's exactly what would happen.

You'd have chaos, destruction, and death.

A catalog of devastation to be unleashed on Earth.

But just how bad would the impact be?

January 2023.

Asteroid Apep was on a collision course with Earth.

Step two in our planetary defense...

Know your enemy and build up a picture of the asteroid.

Apep was 1,800 feet wide,

five times the length of a football field.

Its huge size bumps it up into a new category of asteroids.

Apep was what we refer to as

a PHA, a potentially hazardous asteroid.

We're talking about something

that is a third of a mile across.

This is enormous.

An 1,800-foot-wide asteroid is about 112 million metric tons.

That's over 300 times the weight of the Empire State Building.

Computer simulations of the impact

of an asteroid that massive hitting a city

revealed extraordinary levels of destruction.

An 1,800-foot-diameter asteroid,

that would create a crater

that's 3 or 4 miles across, 1,600 feet deep.

It would have a radiation blast wave that

would set things on fire for about 20 miles,

but no sooner would things be lit on fire,

there would be a 500-mile-an-hour wind

radiating out,

leveling buildings, knocking down trees,

destroying highways.

100 miles away, you'd still feel a magnitude seven earthquake.

It's not easy to say what is going to kill you first.

It's probably going to be simply the flash of energy.

There's so much heat from this thing that you can be vaporized.

If you somehow survived that,

then there's going to be the blast wave that will

pulverize anything in its path.

To build an accurate simulation,

the scientists used more than size and mass.

They also studied its composition

and the speed of its orbit.

You need to know what an asteroid is made of,

the speed of that asteroid,

how large it is in order to understand,

will it make it through Earth's atmosphere,

and what might the impact effects be?

Asteroids vary in composition and structure.

Some are loose collections of small rocks,

others rocky and compact.

The most dangerous are metallic.

A metal asteroid can be five times as dense

as some of the lower density asteroids,

and so for the same speeds on the same orbits

they pack way more punch when it comes to an impact.

If you want to see exactly

what a metallic asteroid can do,

go no farther than Barringer Crater in Arizona.

Now that crater is about a mile across,

and the meteor that made it was only about 150 feet across.

Arizona, 50,000 years ago.

The last major asteroid strike on present day North America,

a tiny metallic space rock

hits the ground at 25,000 miles an hour,

releasing energy equivalent to 2.5 million tons of TNT.

Scale that up to the size of 1,800-foot Apep,

and it would create a blast wave the size of Delaware.

If Apep were a metal asteroid, it would tear through

the atmosphere like a cosmic bullet.

In a modern city, without warning,

it could kill a lot of people.

But although they're very dangerous,

they're also very rare.

More common are rubble piles,

loose collections of small rocks held together by gravity.

Rubble pile is kind of the perfect name for them,

but you can think of them as like a literally

a pile of stuff out of a dump truck in your driveway,

but if you take that and you put that in space,

they don't have much gravity but they have enough to stay

bound to each other,