around 66 million years ago.

The sun has set and you're minding your own business,

just lumbering around an area that will eventually

be called Austin, Texas, when something glowing in the sky

catches your eye.

You're not too concerned, but you keep an eye

on that weird glowing star for a couple of hours anyway.

The thing is, that star keeps getting brighter,

but it doesn't seem to be moving, so you forget about it.

Then out of nowhere, around 60 hours later,

you feel the thunderous boom of a supersonic shock wave.

That thing you hoped might be a routine shooting star

is actually an asteroid around 6 miles wide--

6 miles wide.

Before you can even think "what the hell was that?"

the thing you thought was a star 60 hours ago plunges

18 miles into the Earth, and you die immediately.

Today we're going to do a step by step

breakdown of the asteroid that wiped out the dinosaurs.

But before we get started, now is a great time

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Leave a comment and let us know what you think about this video

or tell us what weird phenomenon or person

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Now, onto the disastrous event which some scientists say

nearly demolished Earth before it even really had a chance

to make it as a planet.

The Chicxulub asteroid slammed onto the coast of Mexico

and killed just about everything on Earth.

The first thing Earth felt before the Chicxulub asteroid

struck was its violent shock wave.

Because the air in front of the asteroid

was compressed and unbelievably hot,

it blasted a hole through the Earth's atmosphere,

causing the mother of all shock waves.

Naturally, ground zero absorbed the asteroid shock wave first

with a sudden spike in air pressure, which

ruptured lungs and other internal organs of every living

creature within a 1500 mile radius.

But that wasn't even the worst of it.

Not long after you, the leaf-eating Alamosaurus

died from the pulverizing shock wave,

the 6-mile wide asteroid plunged onto the shore of what we now

refer to as the Yucatan Peninsula, which is

about 200 miles west of Cancun.

Immediately after the asteroid-- which, by the way,

vaporized upon impact--

smashed into the rim of the Gulf of Mexico,

the Earth rebounded from the impact

and the peak of its crust briefly

rose higher than Mount Everest before it broke apart and fell

back to sea level.

The energy produced from the impact of the explosion

was equivalent to 100 trillion tons of TNT,

roughly 7 billion times as powerful

as the Hiroshima atomic bomb.

But the blast didn't look like the kind

of atomic explosion you're familiar with-- you know,

the all too-familiar mushroom cloud.

Instead, the impact looked more like a rooster tail made up

of molten material.

A lot of the molten debris was several times hotter

than the surface of the sun, and it set fire to everything

within 1,000 miles.

What molten debris?

Good question.

Once the asteroid hit Earth, the force

kicked back 25 trillion metric tons of rock ash

and shot debris into the Earth's atmosphere.

An inverted cone of liquefied molten rock

shot up into the sky.

The heat turned the molten rock into little red hot beads

of glass.

Scientists call them tektites, and after they

reached the peak of their trajectory,

they began falling back down to Earth

at 100 to 200 miles per hour.

Jan Smit, a retired professor of sedimentary geology

from Vrije Universiteit in the Netherlands,

who is considered the world expert on tektites,

studied the North Dakota fossil site

and says the fish got it the worst from the tektites

found there.

"Paddlefish swim through the water

with their mouths open, gaping, and in this net,

they catch tiny particles, food particles,

in their gill rakers, and then they swallow, like a whale

shark or a baleen whale.

They also caught tektites.

That by itself is an amazing fact.

That means that the first direct victims of the impact

are these accumulations of fishes."

Smit also noted that the buried body

of a Triceratops and a duck-billed hadrosaur

proves beyond a doubt that dinosaurs were still

alive at the time of impact.

It's theorized that it rained the very same tektites

for nearly an hour, and set everything that

came in contact with on fire.

While the tektites were busy setting fire to the Earth,

the heaving ocean turned into a towering tsunami

tearing up coastlines, sometimes peeling up

hundreds of feet of rock, pushing debris inland,

and then sucking it back out into deep water.

Less than 10 minutes after impact,

a 30-foot wave pounced on what we now

know as fossil site North Dakota, nicknamed Tanis

after the lost ancient Egyptian city.

The wave threw thousands of fish onto a sandbar,

trapping them as the water receded.

They struggled to breathe, but their gills

were clogged with tektites, essentially suffocating them.

Approximately 20 minutes after the asteroid's impact,

a second wave reached North Dakota's fossil site,

burying the beached fish under a pile of gravel, sand, and dirt.

The massive disruption created a fossilized graveyard.

The fossils show fish topped on top of each other

with scorched tree trunks, insects, part of a Triceratops,

and mammals.

The lucky dinosaurs died upon the impact of the asteroid.

The dinosaurs that lived had a rough couple of months.

Debris from both the asteroid's impact in the Western

Hemisphere and volcanic activity in the Eastern Hemisphere

blocked out the sun's light.

The plants that survived impact died from lack of light.

Without any vegetation, surviving herbivores

succumbed to starvation, and the carnivores quickly followed.

Scientists have hypothesized the mass extinction

eliminated 75% of all species and wiped out

99.9999% of all living organisms.

For many years after, the Earth was toxic.

Due to the asteroid's heat and impact,

many minerals vaporized and released dangerous gases

into the atmosphere, including greenhouse gases,

such as carbon dioxide, carbon monoxide, and methane.

One of the more immediately damaging effects,

however, was from sulfur.

Sulfur was introduced into the water cycle,

creating sulfuric acid and causing subsequent acid rain.

About 45 minutes after impact, a thunderous blast of wind

would tear through ground zero at 600 miles an hour,

blasting debris everywhere and leveling anything

that might still be standing.

The sound of the explosion would arrive

at the same time, around 105 decibels,

about as loud as if you were standing underneath the rotors

of a Huey helicopter.

For the first few hours, there would have

been close to total darkness.

But soon after that, the sky would begin to lighten.

For anyone or anything out of range

of the direct effects of the asteroid explosion,

one would be treated to the sight of dark skies

and a display of shooting stars created by the impact

debris raining back on Earth.

They wouldn't have looked quite like regular shooting stars

or meteors though.

Meteors burn up at higher speeds and get hotter.

These shooting stars would have been re-entering the atmosphere

at lower altitudes, traveling slower and emitting

infrared radiation.

The best guess is that the atmosphere would have

been some sort of red glow.

After the red glow, the sky would darken as ash

and debris swirling around the globe

created a creeping twilight.

During the following weeks, months, and maybe even years,

the skies were probably somewhere between twilight

and a very cloudy day.

Once the dust literally settled, one

of the more distinctive clues that the asteroid left

us was a thick layer of clay packed

with iridium, a metal rare on Earth but common

in asteroids and comets.

This layer is known as the K-T or K-Pg boundary,

marking the end of the Cretaceous Period,

and the beginning of the Tertiary Period, or Paleogene.

Walter Alvarez, the UC Berkeley professor

who, along with his father, Nobelist Luis Alvarez of UC

Berkeley, were the first to recognize

the significance of iridium that was

found in the same 66 million-year-old rock layers

around the world.

They proposed that a comet or asteroid impact

was responsible for both the iridium

at the K-T boundary and the mass extinction.

While most scientists agree that the effects of the Chicxulub

asteroid killed off the non-aerial dinosaurs,

some scientists still claim volcanic eruptions wiped them

out rather than the asteroid.

New evidence suggests both may have contributed

to the mass extinction.

While the Chicxulub asteroid smashed into Earth,

it triggered earthquakes with magnitudes as high

as 11 on the Richter scale, strong enough

to be felt on the opposite side of the globe.

The theory is that the asteroid's impact may have led

to volcanic eruptions in India.

Nearly 200,000 square miles of lava

spread across the region known as the Deccan Traps.

This would have released disruptive toxic gases

into the atmosphere and generated enough ash to block

out sunlight for years.

While most accounts focus on the crazy violence and destruction

from those first few minutes to days

after the impact of the Chicxulub asteroid,

it was the long-term environmental effects

that ultimately wiped out most dinosaurs and much of the rest

of the life on Earth.

The lack of sun caused by the dust cloud

meant photosynthesis would have been incredibly reduced.

The soot and ash would have taken months

to filter out of the atmosphere, and when it did,

the rain would have fallen as acidic mud.

Further massive fires would have produced huge amounts of toxins

that temporarily destroyed the planet's protective ozone

layer.

Then there was the carbon footprint of the impact itself,

which released an estimated 10,000 billion tons of carbon

dioxide, 100 billion tons of carbon monoxide,

and another 100 billion tons of methane in one fell swoop.

Scientists still debate many of the details, which

are derived from computer models and field studies of the debris

layer, knowledge of extinction rates,

fossils and microfossils, and many other clues.

But one thing just about every one of them agree on

is the fact that the Chicxulub asteroid landed just off

of Mexico and tore it up.

How do you think it all went down?

What would you do if NASA spotted

another 6-mile-wide asteroid hurtling towards Earth?

Share your thoughts in the comments below.

And while you're at it, check out some of these other videos

from our Weird History.