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00:03it is a catastrophe of cosmic proportions an asteroid the size of the
00:10city smashes into earth the dinosaurs and 75 percent of all life on earth are
00:21doomed and it happens in just 24 hours perhaps one of the most important days in
00:31the history of earth now through a set of high octane experiments science attempts
00:40to deconstruct what happened second by second minute by minute on the last day
01:04of the dinosaurs
01:05it's a beautiful day in the late cretaceous era 65 million years ago here in what is
01:13now Colorado dinosaurs rule
01:23they dominate every continent as they have for more than 100 million years
01:33but they're not alone small mammals our own ancestors keep a low profile
01:44and the oceans are teeming with life
01:53all this is about to change
02:06an asteroid is approaching earth at 64 000 kilometers per hour
02:13this is no ordinary rock 10 kilometers across six miles about the same size as washington dc
02:28when it touches the ocean surface its top will still be at 30 000 feet
02:35nearly the cruising altitude of a 747 jet
02:40and it weighs roughly a trillion tons
02:49fate has set the clocks in motion
02:51there is no escape from what will happen in the next 24 hours
02:56the planet will never be the same again
03:01impact
03:06this single moment triggers a chain of events like no other in the history of earth
03:15scientists have called it the kt event
03:18the apocalypse of the dinosaurs
03:23but no one knows for sure exactly how it all happened
03:33what exactly killed the dinosaurs
03:37the debris the shock the heat or something else
03:44and how is it possible that some animals survived
03:51to understand the forces unleashed in the seconds after impact
03:56we'll need a big bang of our own
04:02in the new mexico desert a team is about to do just that
04:06so this whole platform will go down
04:08with a 2300 kilogram bomb
04:10okay i see so they have to dig out
04:12planetary scientist dan dirta is here to study the violent release of energy
04:17and use it as a small scale model for the kt event
04:28what forces are released in the milliseconds after impact
04:35how do they move
04:37and what makes them so deadly
04:41this is a really unique opportunity to uh to gather some data and then and to actually just watch and
04:47witness
04:48uh the energy of an event like this
04:51for durda this is the first time he'll be able to observe an explosion of this size
04:56it will give him the unique opportunity to gather data
04:59to stand in for the explosive power of the asteroid
05:03the team turns to ammonium nitrate and fuel oil
05:06triggered by c4 a plastic explosive
05:12the 30-second countdown begins
05:31in the bunker the team braces for impact
05:34so
05:37charging
05:37speedy
05:38stand by for count
05:40five
05:41four
05:42three
05:43two
05:44one
05:50oh man awesome
05:55oh
05:55look at the debris
05:58oh
05:59beautiful
05:59ejecta falling
06:01oh
06:01that's a crater
06:03good job guys
06:03outstanding
06:05it was a beautiful explosion
06:06um
06:07very much equivalent to what
06:08i you know i feel like i've now seen an impact
06:10uh
06:10you know forming an impact crater
06:12uh the closest i'll ever come into my life i'm sure
06:14um
06:15beautiful detonation
06:16gorgeous ejecta curtain
06:19high-speed cameras show dirta what can't be seen with the naked eye
06:26the forces produced by a sudden release of energy
06:31like an asteroid impact
06:34an initial flash
06:37explosive material is vaporized
06:40converted from a solid to a gas
06:45within milliseconds a radiating shockwave is visible
06:50traveling ten times faster than the speed of sound
06:54it precedes the physical debris ejected from ground zero
07:02it generates a sonic boom
07:04strong enough to blow out eardrums and damage lung tissues for hundreds of meters
07:11yet the sound is nothing compared to the shockwave itself
07:18in less than six milliseconds the blast wave travels some 24 meters
07:25here this wall of compressed air is so strong it can kill a human being
07:36if this model is accurate and we imagine how forces on the scale of the asteroid impact were released
07:43then 65 million years ago
07:47massive shockwaves also blasted out in all directions
07:51according to scientists at some 19 kilometers per second
08:12the shockwave's blast force is so strong that any creature within 160 kilometers is likely dead within the first 10
08:21seconds
08:25instantaneously shattered by the force
08:27long before any debris reaches them
08:34there's only one man-made explosion that comes close to modeling an asteroid impact
08:42an atomic bomb
08:54though at a hundred million megatons the kt asteroid impact still dwarfs any nuke
09:03if the usa and russia exploded all of their nuclear weapons at once
09:08the blast that killed the dinosaurs would still be 10 000 times more powerful
09:17the energy released would be like exploding a one megaton warhead
09:21every five square kilometers across the planet
09:36Durda's blast in the desert has begun to give us insight into the forces of such a massive explosion
09:47but it reveals nothing about the ballistics of the collision
09:53what role did the trajectory of an asteroid the size of mount everest
09:59play in what happened in the seconds and minutes after impact
10:08in palo alto california the kt asteroid is about to strike again
10:15this massive gun at the nasa ames hypervelocity impact lab
10:20will allow astro geologist peter schultz
10:23to safely observe the dynamics of the impact on a miniature scale
10:32this is kind of a special gun it's different from a large rifle
10:36a rifle can only get up to about 700 meters per second
10:39it's just not fast enough so this is a much faster gun
10:44in just minutes this gun will use a combination of hydrogen gas and gunpowder
10:50to accelerate this tiny glass pellet
10:54quadrillions of times smaller than the rock that killed the dinosaurs
10:58the miniature asteroid will make impact at over 22,500 kilometers per hour
11:04the difference between this and large-scale impact
11:07something the scale of chichu is really dramatic
11:11on the other hand you get clues you just have to slow down the sequencing
11:16to understand what really happened
11:20for that they'll use a grid of high-tech cameras that can record up to a million frames a second
11:30inside the impact chamber is the target
11:35the sand will stand in for ground zero 65 million years ago
11:44its exact location a mystery for years
11:47scientists now believe that the impact site is centered on the edge of Mexico's Yucatan Peninsula
11:54in a place called Chicxulub
11:58Schultz has studied the shape and structure of the features in the region
12:02and believes that the asteroid came in from the southeast at around 30 degrees
12:10it's a critical detail
12:13the angle determines the trajectory of the debris in the seconds after the asteroid's impact
12:24ok, lunar
12:27ok, are we all set?
12:29yeah
12:30ok
12:30the exposures are critical
12:34the lighting has just gotta be perfect
12:37one's gonna get wiped out
12:38the other one's gonna be good
12:4120 seconds to impact
12:563...2...1
12:58oh!
12:59now that triggered
13:00pull that up
13:01I'm gonna quick take a quick look at this
13:03wow
13:05wow
13:06wow
13:06Schultz sees what he's been hoping for
13:09gorgeous
13:10that is all hot stuff
13:13sweet
13:14look at this stuff
13:15that is just hot
13:16just zooming out downrange
13:19good going
13:21yeah, it's amazing how much power there is
13:24in this initial stuff
13:28the action in the chamber is only visible in slow motion
13:34even slowed way down
13:36the projectile moves too fast to be seen
13:40yet its effect is dramatic
13:44a bright flash ignites in less than a thousandth of a second
13:49signaling the release of energy and heat
13:52as parts of the projectile and the target are vaporized
13:57it's a burst of plasma
14:00supercharged ionized gas
14:03as hot as 5,000 degrees kelvin
14:08if you imagine scaling that up to the gargantuan proportions of the asteroid
14:14the plasma burst would be so strong
14:17it could potentially blind dinosaurs
14:20far from ground zero
14:24the asteroid
14:25a trillion tons of rock
14:27transforming into gas in less than a second
14:31it's so hot
14:33it takes rock and turns it into vapor
14:36extremely hot gas
14:38up to temperatures of 4,000 to 5,000 K
14:43it's nearly the temperature of the sun
14:46so it just simply vaporizes the surface
14:49and now I have all that molten material
14:51and even more gas being released
14:56at Chicxulub the surface is a shallow stretch of ocean
15:00perhaps a hundred meters deep
15:04if the observations from these experiments are valid
15:07then in just one one-hundredth of a second
15:10billions of gallons of water vaporize into towering geysers of scalding steam
15:19yet the models show something else
15:21the shallow 30 degree impact trajectory
15:24hurls a curling plume directly forward
15:28this form is called the rooster tail
15:31if the models are correct
15:33this leading burst of superheated water vapor
15:36and vaporized rock
15:38hurdles through the sky
15:39at more than 65,000 kilometers per hour
15:44it spells death
15:46for almost everything in its path
15:51more importantly
15:52if Peter Schultz is right
15:54and the asteroid came in from the southeast
15:57then it could tell us
15:59what creatures are about to be obliterated next
16:03North America would have been in its crosshairs
16:06all that debris
16:08the really high speed
16:09very hot debris
16:10would have been heading right toward
16:12our place that is North America
16:15within another 60 seconds
16:17the rooster tail tears across the Gulf of Mexico
16:20some 965 kilometers
16:23as it makes landfall
16:25it scorches everything in its path
16:28but this is just a taste
16:31of what the asteroid has in store for the planet
16:36twenty seconds have passed
16:38since a colossal asteroid has pounded into the planet
16:44creatures within hundreds of kilometers of ground zero
16:47annihilated by a massive blast wave
16:50and scorched by temperatures as hot as the surface of the sun
16:57the force of the impact is excavating a giant crater in the sea floor
17:02propelling vaporized rock and debris into the sky
17:08in the NASA gun test
17:10the entire process is over in a tenth of a second
17:15in New Mexico
17:16debris from the crater rains down for more than 10 seconds
17:22as we scale up the timeline to the dimensions of the actual asteroid impact
17:27it becomes a matter of minutes
17:32it's an explosion unparalleled in history
17:37but time has eroded its effects
17:39and hidden the clues
17:44to get an understanding of what might have happened
17:47in these cataclysmic minutes after impact
17:50we need to look at a fresh crater
17:54okay let's see what we got
17:56Dan Derda is about to do just that
17:59oh look at that
18:01I see a beautiful rim on that crater
18:03it really looks like a miniature version of meteor crater
18:08from just a 2300 kilogram explosion
18:12debris is blown across the desert
18:17a killing field of boulders
18:20this is a perfect analog here on earth for real planetary craters
18:28we could be Apollo astronauts right now
18:30walking up to the rim of a crater on the moon
18:35Chicxulub would have been much more massive
18:37if we were to transpose feet for miles
18:40this crater here would be 50, 60, 70 feet across
18:44the Chicxulub crater would have been maybe 60, 70 miles across
18:51if we scale up the debris
18:53the dimensions of what rained out of the sky 65 million years ago
18:59become almost unimaginable
19:03the blocks that we see here laying around us
19:06wouldn't be blocks the size of my hand
19:07they'd be blocks the size of buildings
19:1365 million years ago
19:15over 400 cubic kilometers of fossilized coral
19:20limestone and granite
19:22enough to fill the Grand Canyon 38 times
19:27would have been raining down in giant chunks
19:30squashing out life up to 1500 kilometers away
19:4025 seconds after impact
19:42the ever-expanding killer shock waves
19:45moving at 19 kilometers per second
19:48are now nearly 500 kilometers from ground zero
19:53where will these forces of destruction stop?
19:57how far will the death zone reach?
20:0665 million years after impact
20:0824,140 kilometers from ground zero
20:14paleobotanist Kirk Johnson is hunting in Colorado
20:19for debris from the asteroid impact
20:22it's this real sleuthing
20:23it's talking about a needle in a haystack
20:25we're looking for a layer of rock
20:26that's a few centimeters thick
20:27in the surface of the earth
20:30which can be thousands of feet thick
20:35he struck pay dirt
20:39a black line in the layers of sediment
20:44a geological marker
20:46scientists call the KT boundary
20:49my fingers are now bracketing the KT boundary
20:52here it's a little bit more than an inch thick
20:54maybe two inches thick
20:55and the dust that's here between my fingers
20:59was blown here from Mexico one day
21:0266 million years ago
21:03but there's more
21:05clues to the reach of the destruction
21:10one of the KT boundary's most distinctive features
21:13is the presence of unusually high concentrations
21:17of the element iridium
21:19iridium is a platinum group metal
21:21that's very rare on the surface of the earth
21:23but it's relatively common in asteroids meteorites
21:27iridium is the signature of an asteroid impact
21:31in the early 1980s
21:33a group of scientists discovered iridium
21:36in large concentrations inside the KT boundary
21:40they concluded that this layer marked not only the end of the dinosaurs
21:45but also the impact of a huge asteroid
21:50iridium was the smoking gun of a global cataclysm
21:57Kirk Johnson's detective work has led to another big discovery
22:01according to new evidence he's unearthing
22:03the asteroid didn't crash into the earth
22:0665 million years ago
22:08new dating of the layer suggests that it may have happened slightly earlier
22:12these dates of the KT boundary are going to be right around 66 million years
22:16and we'll have dates that are precise and accurate to within 20,000 years
22:21so we'll be able to actually say within a 20,000 year window when this event happened
22:29and the phenomenal thing about this layer is that I can find it in Wyoming or North Dakota
22:34Saskatchewan or Alberta
22:35I can find it in New Zealand
22:37I can find it in Western India
22:38I can find it at the bottom of the Atlantic Ocean
22:40or the bottom of the Pacific Ocean
22:42this is a worldwide layer of rock
22:44the direct physical evidence of the asteroid that hit Mexico
22:48although most of the data is from North America
22:51the question remains
22:52how did the debris get to the other side of the globe?
22:56to answer that we have to go back to doomsday
23:0065 million years earlier
23:05time
23:06one minute since impact
23:08the collision has pounded an ever-growing hole into the earth's surface
23:13the experiments we've seen so far suggest that billions of gallons of seawater are propelled outward
23:21unleashing another killer force
23:24a mega tsunami
23:29most tsunamis are the result of undersea earthquakes
23:34a fault line shifts
23:36the sea floor suddenly rises
23:42billions of gallons above are displaced
23:45triggering waves as high as 9 to 12 meters
23:57but mega tsunamis are almost 10 times higher
24:00and aren't caused by an undersea earthquake
24:07up to 300 meters high they are produced by landslides
24:15and asteroid impacts
24:20events that result in huge water displacements
24:26according to a new computer model
24:29the Chicxulub asteroid impact
24:31sends a 90 meter wave in all directions across the ocean's surface
24:39according to the model
24:41that's just the beginning
24:48another 30 seconds later
24:50the gaping hole in mid-ocean more than 20 kilometers deep
24:55and 112 kilometers across
24:58becomes unstable
25:00the walls collapse
25:01and the crater grows wider
25:05within 90 seconds
25:07billions of gallons of seawater
25:09are pouring back into the crater
25:16the surging torrents refill it
25:20the cascades collide in the center
25:22to form a towering peak
25:24some 38 kilometers high
25:29as the clock ticks forward
25:31the water splashes back out again
25:33creating a second even more powerful tsunami
25:37perhaps 300 meters high
25:43a wave like that could potentially inundate the gulf coast
25:47over 300 kilometers inland
25:50drowning everything in its path
25:54but it's about to get worse
25:58time five minutes after impact
26:03the seismic waves set off by the asteroid race around the planet
26:09they circle the globe in less than an hour
26:12and trigger huge earthquakes
26:14one would have probably felt magnitude 10 or 11 or 12 earthquakes in the vicinity
26:19pretty devastating from that point of view
26:27a magnitude 12 is 3,000 times stronger than the worst quakes in recorded history
26:37that's powerful enough large sections of the continental shelf could collapse and trigger yet more tsunamis
26:50the disasters triggered by the impact are adding up
26:54mega tsunamis
26:56global earthquakes
26:58landslides
26:59but it will take more than this to wipe out the dinosaurs
27:0840 minutes after impact
27:11material from the crater and the remains of the asteroid
27:15thousands of cubic kilometers of ejecta
27:18are rocketing out through the stratosphere
27:23about 10 percent of that material moves so fast
27:27it reaches escape velocity and flies off into space never to be seen again
27:32but the remaining 90 percent are about to trigger a new catastrophe
27:39with every passing minute
27:41the debris fans out in all directions in a low earth orbit
27:47in less than an hour
27:49gravity begins to pull it back down
27:53through the atmosphere
27:54here the ejecta undergo yet another transformation
27:59the vaporized rock reforms
28:02and condenses into tiny droplets called tektites
28:08today these dark particles shaped like spheres or barbells
28:13can be found inside the kt boundary all around the planet
28:2065 million years ago they lit up the sky like a trillion shooting stars
28:27some believe that all this superheated material in the atmosphere
28:31creates a sudden thermal pulse
28:35temperatures in the thousands
28:39broiling everything on the surface
28:49large land animals including most dinosaurs would have been unable to escape the heat
28:56lungs are seared skin is scorched the dinosaurs are cooked
29:03within hours of the impact most dinosaur species are destined for extinction
29:12yet somehow not all animals succumb to the apocalyptic inferno
29:18life on earth does not come to an end
29:22how is that possible?
29:3010 hours after a massive asteroid has smashed into the earth
29:38for thousands of kilometers it has unleashed destruction
29:42shattering blast waves, earthquakes, mega tsunamis
29:47for hours the planet has been broiled by superheated debris
29:57as this airborne shroud of ejecta now begins to cool
30:02the destruction continues
30:08dan derda has mapped a pattern of wildfires around the globe based on the location of the impact
30:15the amount of material thrown skyward
30:18and the likely trajectories of this heated debris
30:22if he's right then this is an inferno of global proportions
30:28and creatures that survived the destruction so far will soon be destroyed
30:37now the scientists at the fire lab in san antonio texas
30:41are finding clues to how some life may have survived the roasting temperatures
30:49the data from the temperature sensors in the model forest may hold the answer
30:59fifteen seconds after the heat blast begins
31:02the rush of heat raises surface temperatures to 816 degrees celsius
31:09thirteen centimeters underground inside one of the test burrows
31:13the temperature rose to just 41 degrees celsius
31:17twenty-five centimeters below the surface it was only 35 degrees celsius
31:23both survivable temperatures
31:27is this how some species survived?
31:31by burying themselves underground
31:37the results of the furnace test seems to lend credence and support to this idea
31:43that animals and plants that could shelter or already lived underground
31:47would likely have made it through okay
31:51if you think about life as a small mammal
31:53that there are lots of places that you could have been sheltering
31:57you don't have to be able to burrow yourself to be a burrow dweller
32:01and you don't even have to be a burrow dweller
32:04to be able to survive in holes underground
32:07there are lots of holes that are made by other things or by fallen trees
32:11or by overturned rocks, etc.
32:14other small animals could survive in the same way
32:18many reptiles and amphibians will burrow either to create a nest
32:23or to burrow down into the soil to hibernate or estivate
32:26sometimes the amount of soil between the animal and the surface
32:30could be a few inches or even a few feet below the surface
32:32so this layer of soil and air pockets and roots and stones
32:37would form a perfect barrier between the resting animal or nesting animal
32:42and the outside air
32:47animals that live in water also have better odds of surviving
32:53heat dissipates rapidly in water
33:02and even if the surface is hot
33:05it could remain cool down below
33:16it may be a living hell
33:19but soil and water are protecting some animals
33:23and the same defensive barriers could protect their young too
33:28not only do reptiles and amphibians have a lot of offspring at once
33:32but they also lay them in water and sometimes even beneath soil
33:37and what that soil layer can do and what the water can do for their eggs
33:41is protect it quite well from any sort of outside variation in temperature
33:49many primitive birds are thought to have been precocial
33:53their young don't need parental care
34:00a modern example of this is the malio
34:03a bird that incubates its eggs by burying them in soil
34:09when an egg hatches the young bird digs its way out
34:13fully feathered and ready for life on its own
34:17birds like the malio would be perfect candidates for survival
34:22after an asteroid impact
34:2518 hours after impact
34:29the fires continue to rage as they will for days to come
34:34consuming millions of square kilometers of vegetation
34:42smoke is lifting potentially billions of tons of soot into the atmosphere
34:52inside the KT boundaries some experts see tangible evidence of these fires
34:59vast amounts of soot
35:03it may take months for this material to fall back to earth
35:08in the meantime it blocks sunlight
35:12shrouding much of the planet in darkness
35:17darkness that will potentially trigger severe global cooling
35:23for perhaps six months large parts of the earth are chilled to near freezing
35:33a killing frost
35:38but many animals are able to wait out the cold and darkness by doing what animals do today during winter
35:49all reptiles and amphibians as well have one main key feature that benefits them tremendously and that's that their metabolism
35:57is extremely slow much slower than ours
35:59so they can get by with very little food and they can also lower the metabolism even further to go
36:05into a state of hibernation
36:06so you have entire populations and lifestyles of small mammals that live what's called a subnivian life which is that
36:14under the snow and they go on caring about being small mammals under snow in complete darkness
36:20the darkness and chill disrupt the food chain for survivors
36:30the darkness and chill disrupt the food chain for survivors
36:41terrestrial and marine ecosystems
36:45but there still might be plenty to eat
36:50there would have been just a phenomenal amount of barbecue around
36:54as long as the dinosaurs hadn't incinerated
36:57completely and they didn't mind well done meat
37:00they would have been able to eat off carcasses for quite a long period of time
37:03you can imagine that some portion of them certainly would have starved to death
37:07but clearly there was enough to eat
37:08to have brought them forward and made them into our ancestors
37:1324 hours after impact
37:18what was once the lush world of the dinosaurs has been transformed into a wasteland
37:32the smoke from a world's worth of wildfires combined with ejecta and debris from the impact has poisoned the atmosphere
37:42the air is filled with chemicals similar to those produced by automobiles and power plants
37:49chlorine and bromine
37:52sulfuric and nitric acid
37:54they are capable of destroying the ozone layer
37:58and producing severe acid rain
38:03the impact also releases vast amounts of greenhouse gases like CO2 and methane
38:10it's enough to equal 3,000 years of modern fossil fuel burning
38:18the chill of impact winter is soon replaced by intense global warming
38:26it will take thousands of years for the climate to stabilize and the earth to be cleansed of toxic chemicals
38:38but for many survivors there are opportunities
38:44the loss of one life form makes room for others better adapted to the new conditions
38:51if you actually survived the first hour the first day the first year
38:57and there were enough individuals of your species left
39:00maybe 90% of your species when it was killed
39:03but if 10% survived your species was part of the survivor group
39:09and that group then wanted to repopulate the earth
39:12and what we see in the 10 million years that follows the KT boundary
39:17actually is the beginning of the evolution of our world
39:23a clean slate
39:29some scientists believe that as plant life re-emerges
39:33among the first to take root are ferns
39:42it may take thousands of years for forests to recover
39:48for CO2 levels to drop
39:51and for the atmosphere to be scrubbed clean
40:01within one million years after impact
40:05surviving reptiles and amphibians start to diversify
40:11as the few remaining species evolve into new forms
40:18mammals come into their own
40:22they thrive in the new post-apocalyptic world
40:27you could imagine that when they woke up
40:30in a sense after this cataclysm and photosynthesis had restarted
40:33the light had come back
40:35there would have been an opportunity
40:36for mammals to begin to exploit a whole variety of different niches
40:40that would not have been available to them beforehand
40:46many of these new mammals are the ancestors of creatures
40:50that are still with us today
40:55and even though the age of dinosaurs is over
40:58in its aftermath
41:00some of their closest relatives do just fine
41:06as for the Chichulub crater
41:08that massive wound in the earth fades quickly
41:12filled in by ocean sediments
41:16it finally disappears beneath the jungles
41:19beaches and shallow sea at the edge of the Yucatan Peninsula
41:25the asteroid that blasted out that crater
41:28replaced old life forms with new ones
41:31and helped create the world that we know today
41:35the biggest animals right before the boundary were the size of a delivery truck
41:39above the boundary we find crocodiles
41:42turtles and mammals
41:44no dinosaurs at all
41:45so what you see is
41:47before an ecosystem dominated by large animals
41:52immediately transits to an ecosystem dominated by tiny animals
41:55the biggest mammals left on the planet
41:57in fact the biggest terrestrial animals of any kind on the planet
42:01after the KT boundary were no bigger than the raccoon
42:03so it's a huge difference in the kind of animals we're walking on this landscape
42:08from the day before the KT boundary to the day after the KT boundary
42:11one of the most profound and abrupt changes in Earth's ecosystems
42:15this planet has ever seen
42:17that changing of the guard has happened before in Earth's history
42:22will it happen again?
42:26dozens of tons of debris hit Earth every single day
42:32most of it no bigger than a snowflake
42:36it burns up as it tears through the atmosphere
42:44space is full of objects on a collision course with Earth
42:49comets, meteors, asteroids
42:56NASA has identified and tracked some 2,000 objects
43:00that are a potential threat
43:07over the 4.6 billion year life of our planet
43:12countless collisions have occurred
43:23the Chicxulub event was not the first, or the last
43:27the Chicxulub event was not the first, or the last
43:32some scientists believe an asteroid wiped out the woolly mammoths in North America
43:37only some 10 to 14,000 years ago
43:54in 1908
43:56an asteroid 45 to 70 meters in diameter
44:00plunged into the atmosphere over Siberia
44:05the blast was so strong it leveled over 2,000 square kilometers of forest
44:14events like this happen once every few hundred years
44:22asteroid impacts like the one at Chicxulub
44:25occur only about once in a hundred million years
44:31with thousands of large asteroids out there
44:36it is inevitable
44:39that sooner or later
44:41one of them
44:43will hit the Earth
44:52DEMONICAL
44:53TITLE
44:57I don't know.
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