WEBVTT

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A killer asteroid streaking

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towards earth at 67,000 miles an hour

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[explosion and drums]

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Giant chimney like towers scorching hot

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rising from the bottom of the ocean floor

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[ music ]

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a young man epic sea voyage that shook
the foundation of the world.

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[explosions and Music]

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An expedition back through time into
the heart of human ancestry

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Of all the discoveries in the history 
of science

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Few have the power to compel...

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Or the potential for controversy,

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Than those concerning how life on earth 
began

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How species evolved

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Why some species survied

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And others become extinct

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[rumbling and panicked roars]

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These are the greatest discoveries 
in the origin in evolution of life

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[music climaxes]

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[Theme Music of piano and violin]

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[Bill Nye}
Life is a game of chance

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The odds of surviving or facing extinction 
are always changing

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Now some changes are gradual; 
the result of a slow process of nature

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Others, happen in a blink

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Like the one that caused the extinction
of the ancient Dinosaurs

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[Music]

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In 1980, a Geologist named Walter Alvarez

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was studying rock strata in mountains
North of Rome

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When he came across something curious.

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a thin ancient layer of clay

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(Scientist) So this clay layer here

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marks the boundary between two

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different geological periods. [music]

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(Bill Nye) The layer of clay marked what is

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known in geology as the KT boundary.

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A dramatic turning point in the history

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of the earth about 65 million years ago.

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When the ancient dinosaurs mysteriously vanished.

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For Alverez, here was the moment of discovery.

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analyzing samples from the KT boundary

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he found the clay contained

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extremely high levels of aridium.

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an element rarer on earth but abundant in space.

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When similar levels of aridium where found

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around the world Alverez began

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wonder what could have caused it to blanket the

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earth.

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The answer he concluded was the impact from an asteroid 
of gigantic proportions

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Over six miles across

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Taller than Mount Everest

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Moving at a speed of 67,000 
Miles an hour

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[Boom]

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Doctor Elisabetta Pierazzo is a research scientist
at the Planetary Science Institute


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In Tuson Arizona

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(Bill Nye)
So how much energy did this thing have?

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[Elisabetta]
an energy that is about a 
hundred million megatons


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of TNT

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This is about 10 times the worldwide

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nuclear arsenal at the peak of the Cold War

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[Bill Nye]
Ten times the worlds Nuclear Arsenal

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when it was really big

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[Elisabetta]
yes

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[Bill Nye]
All in one place?

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[Elisabetta]
all in one point released in...

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a second. So that was a humongous amount of
energy

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That was delivered to the Earth

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[dramatic music plays]

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[Bill Nye]
The devastation was colossal

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[Dinosaur screeches]

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A cloud of vaporized rock and debris
mushroomed into the air

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blocking the Sun

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scorching fireballs blasted across the face
of the Earth

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The air became chocked with poisonous gas
and soot

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nearly half of all life forms on earth

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perished in the Apocalypse

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including the ancient Dinosaurs

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The only piece of the puzzle missing
from Alvereze's story was proof of the asteroid

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if it was as big as he said it was

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then it must have left quite a crater

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finally Geologist found one that just happened
to be sixty five million years old

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the Chicsalu Crater

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an immense hole

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1,200 miles wide

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buried under a thick layer of sediment
at the bottom of the Gulf of Mexico


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off the coast of the Yucatan Peninsula

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[Elisabetta]
yes so, the complexity increases
with the magnitude

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of the impact event.

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Because the Chicsalu crater is under water

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this is a good place to get a sense of
what happened

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when the asteroid hit.

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this is meteor crater Arizona

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50,000 years ago...

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A meteorite about the size of a house

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streaked out the sky and slammed into the Earth

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it triggered an explosion greater than
twenty million tons of TNT

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And created this.

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A crater five hundred fifty feet deep

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and three quarters of a mile across

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room enough for twenty football fields

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and more than 2 million spectators

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[Bill Nye]
Impressive, isn't it?

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But remember, the asteroid that caused the
"KT" Event

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was the size of Mount Everest

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so to visualize the crater that it made
we need something a lot bigger

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Like the Grand Canyon!

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this is the South Rim.

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from here to the other side is 16 Miles.

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but even that's not big enough.

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the Asteroid that caused the "KT" Extinction

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blasted a Crater 8 times as large

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one hundred twenty five miles across

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from here to the gaming tables in Las Vegas

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And when the Asteroid hit it went deep as well

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It's a long climb from here to the bottom of the Canyon

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about a mile and a quarter.

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but according to Walter Alveraz, the Asteroid made a crater
that was a staggering 20 miles deep upon impact

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then quickly filled in.

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How do Scientist know all this?

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the Evidence has come from a variety of sources

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Seismec studies revealed the enormous ring like shape
of the Crater

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Thousands of core samples uncovered rocks


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with traces of having been altered by an high-impact
collision

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And computer modeling that calculated the explosion
it would have taken to create

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the Chicsalu Crater.

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But Walter Alvarez's discovery of what caused
the extinction of the ancient Dinosaurs

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is not without contraversy

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his Asteroid scenario is at the center of an ongoing debate.

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with opposing Scientist offering their own theories.

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One theory argues that intense volcanic eruptions
poisoned the Earth's atmosphere

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and killed the ancient Dinosaurs before
the "KT" Event ever occurred.