Last Day On Earth Documentary 2017
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Last Day On Earth Documentary 2017

August 12, 2019


an immense cosmic Boulder rockets in from deep space on a direct collision course with earth when it hits it unleashes a global catastrophe this is not science fiction it happened 65 million years ago and much of life on Earth including the dinosaurs died today many scientists believe that this is not a one-time event at what wiped out the dinosaurs could happen again and we could be next Oh another impact accrue you bet it’s going to happen again the earth is sitting out there woody bull’s eye on it what are these mysterious invaders where did it come from and if one threatens the earth again will we be able stop it in time [Music] we think of commas as some of the heavens more spectacular pieces of eye candy and most are benign orbiting harmlessly around the Sun but some will inevitably collide with another body like earth at speeds of 25,000 miles an hour even a small cosmic Raider can wreak enormous havoc but a larger object over a mile or more in diameter could cause devastation on a global scale when impact by a comet will kill so many people and can produce such long-term changes in the environment that it can be a complete catastrophe for all of humanity scientists now believe a single blast from space helped wipe out the dinosaurs 65 million years ago a comet or asteroid about 6 miles across slammed into Mexico’s Yucatan Peninsula it dug a crater nearly 50 miles wide 20 miles deep less than a second Annelise explosion more powerful than all the world’s nuclear weapons combined the force of the shockwaves triggered earthquakes worldwide and sent tsunamis surging across the oceans a mammoth dirt cloud erupted miles into the sky engulfed in the globe and blocking out the Sun for years the dinosaurs slowly perished and they were not alone more than half of the Earth’s species were also wiped out in our solar system there are two kinds of cosmic bullets capable of devastation on a planetary scale asteroids and comets asteroids are essentially tiny planets dense boulders rock and metal left over from the formation of our solar system 4.6 billion years ago most are bunched between Mars and Jupiter and in orbit called the asteroid belt comets on the other hand are far more mysterious [Music] though also formed at the birth of our solar system they are made up of rock nice many like Halley’s Comet orbit the Sun in predictable paths unpredictable schedules [Music] but there are countless others we know nothing about they come hurtling out of the ether at unimaginable speeds of up to 100,000 miles per hour [Music] for scientist peering into space they look like lumps of charcoal on a black canvas invisible until they’re practically upon us only near the Sun do comets become easier to detect these icy bodies shed gas and dust as the Sun warms them when light hits the debris they blaze into view and can be seen for millions of miles but by that time if one is headed for us it may be too late to do anything to stop it to date more than 1,000 comets have been identified every year we spot perhaps the hundred comments we’ve never seen before entering the inner solar system each new arrival increases the odds that one will eventually strike the earth [Music] the earth is in a cosmic shooting gallery we get hit by pieces of comets and asteroids of all sides and the big ones certainly pose a very real threat it’s only a matter of time before the comet is in the same place as the earth giant pock marks all over our planet testified to past assaults and these collisions may be more frequent than we like to think the latest big one happened a little more than a century ago in 1908 of massive explosion rocks Tunguska and Russia’s remote region of Siberia eyewitnesses described a flying star with a fiery tail the sky opened and a fire righter than the Sun poured out whether an asteroid or a comet it collided with the Earth’s dense atmosphere at such a high rate of speed the friction caused it to explode in midair it blew up five miles above the surface of the earth creating this huge explosion and lit up the atmosphere for days you can actually read in Europe at night the Tunguska blast as we now call it was bigger and more powerful than the eruption of Mount st. Helens it left no tell-tale crater but it did flatten the forest and millions of trees over hundreds of square miles an area bigger than that of Washington DC if that would have happened over a metropolitan area it would have just wiped out the population for thousands of square kilometers around the impact site to astronomers Tunguska was a near-miss a relatively minor impact it a major impact from a comet would have devastating effects imagine the following scenario scientists have spotted a two-mile wide comet on a collision course with earth it’s too late to stop it the first thing you’ll know is the sky lights up in the ground shakes brilliant meteors streak across the sky as the giant Comets debris strikes the Earth’s atmosphere forests catch fire ignited by the superheated air when the comet hits a blast kicks up millions of tons of fiery rock and dirt the airborne debris blankets the planet blocks out the Sun day turns to permanent night bringing freezing temperatures and year-round winter it takes more than a year for the dust to settle and sunlight to filter through the clouds what does the earth starts to warm quickly elevated levels of gases created by the fires turn the planet into a sweltering greenhouse millions of species of living things that survived the earlier cold cannot take the heat they die it takes thousands of years for life on Earth to recover how great are the odds a comet will strike the earth what another impact occur you bet is going to happen again the earth is sitting out there with a bull’s-eye on it the chances of a major impact in our lifetimes maybe Slam perhaps on the order of one and 100,000 but astronomers the world over are working fervently to understand these strangers in our midst struggling to learn what comets are and where they come from mankind’s ultimate survival may depend on our ability to stop one before it strikes Donald Yeomans studied comets for NASA’s Jet Propulsion Laboratory they’re so big that they’ve got a lot of mass and its mass and velocity that’s important when they hit if we could track comments in advance and plot their orbits we’d likely have many years of warning if the orbit severe toward us it may seem like a tall order to scan the vast sea of space for that one pinprick that could spell disaster but that’s exactly what astronomers are doing in 1992 the US government launched an aggressive program to analyze the threat comets and asteroids posed to earth it’s called the Spaceguard survey today scientists all over the world are involved in the painstaking process they point their telescopes at a single region of the sky and take periodic snapshots bend them line up the images looking for anything that moves from frame to frame we are looking first for the larger asteroids and comets the ones mile or so in diameter and eventually we’ll extend it to the smaller ones scientists have discovered nearly 4,000 comments in our solar system with roughly 40 new ones in 2016 new comets are being discovered every year we may never be able to locate every threat there could be millions of comets and asteroids that measure 300 feet or so the length of a sports field [Music] still telescopes our first line of defense against what could be a major disaster for a planet if you don’t look you won’t know anything’s coming we would be taken by surprise just as much as the dinosaurs if you do carry out a survey then you hope that you can have warning but it’s one or the other either you have years or decades of warning or you’re taken completely by surprise there’s nothing in between there’s three things that are important you have to find them early you have to find them early and you have to find them early suppose we do detect a comet headed for Earth then what can we do scientists have just started to come up with solutions one of the leading ideas smash a rocket to it to slow it or knock it off course that’s harder than it may seem in 2005 scientists were ready to test their theories about how a comet would react when it was hit by crashing a rocket into one it was called deep impact it began here at NASA’s vertical gun range in Mountain View California where it was the job of dr. Pete Schultz and his team to figure out what the comet would do when it was hit this particular instrument allows us to fire a small sphere about a quarter-inch at speeds that are maybe six or seven times the speed of a rifle bullet this whole assembly rotates up to an elevation where the gun is basically three stories high this allows us to send a projectile through different openings in the chamber so that we can impact a flat surface at different angles scientists believe comics vary in their makeup so Schultz and his team built several different models and hit each with a shot from their ultra high speed gun the first scenario is what happens to be impact into something looks like lunar dust the second one is what happens if we impacted the fluff and the third one is what happens if we impact into a fluff cover with an organic layer as we go down and look at the evolution of this crater we find at the very end after it’s finished we can still see the crater here but in these two cases when we’re using fluff we can see the crater it’s completely masked the fluff completely absorbed the projectile a frustrating result for scientists hoping to get a look inside and there was another possibility shelfs had to consider what if the entire comet is extremely fragile and porous he searched for substance for that simulation the comet maybe sorta like a football may have been very low-density what do we do to try to simulate that the best thing probably is a complex organic what would that be cotton candy we’ve got our comet made of cotton candy turn off the lights and let’s get out of here the projectile soars right through the comet of the force shatters ooh oh my god there’s no more common that’s for sure what a mess but this is not good news a shattered comet can be even more dangerous than an intact one the pieces remain on the same course turning one projectile into many of what does that mean for our planet if we’re in the way in 2005 the team at NASA had completed their tests and we’re ready to take the plunge they would try to drive an eight hundred twenty pound impactor into a comet to find out what’s inside Deep Impact principal investigator dr. Michael Ahern so here we have the model of both Deep Impact spacecraft many people think it was only one spacecraft that’s really – January 12th 2005 after six years of study and preparation Deep Impact is ready for liftoff three two one we have ignition and liftoff of a Delta 2 rocket carrying the spacecraft’s destination is a four mile wide comet named Tempel 1 discovered in 1867 it’s well known to astronomers it orbits the Sun every five and a half years and has lost much of its gas and ice people would argue that you should preserve the Comets for posterity but doing a violin study on one that is just typical of a whole class seemed to us to be the right choice for science Deep Impact takes five months to reach temple one’s orbit on July 2nd 2005 it turns and points its cameras at the comet five hundred thousand miles away then it releases its impactor if all goes well the collision will blow a hole in temple one about six hundred feet across five stories deep about the size of the Roman Colosseum but it might destroy the comet by breaking it apart like cotton tent experiment [Music] back on earth hundreds of scientists hold their breath we lost signal and we had to stand there and wait around so everybody was trying to be go keep busy and not feel anxious but just before impact the signal returns the half-mile-wide comet at nasa’s eight hundred and twenty pound craft have collided at twenty-three thousand miles an hour the explosion is equal to nearly five tons of tnt and completely vaporizes the impactor and kicks up far more dust than anyone expects the amount of dust is a telltale clue to the comet’s makeup temple1 at least on the surface contains far less ice than scientists expected this is the first data we’ve ever had so in that sense it’s revolutionary analysis of the dust showed molecules containing carbon organic material so it’s plausible that comets could have brought such material to earth early in its history scientists hope to learn something else from deep impact clues about how to stop a comet from colliding with earth some thought deep impact might not temple1 into a slightly different orbit but the comet has continued on exactly the same path as before it was a secondary objective of the Deep Impact mission to come up with a plan to mitigate an impact if we had to did we figure out what it would take to move a comet out of an orbit that was intersecting the earth we didn’t figure out enough one plan calls for detonating a nuclear warhead near the comment to nudge it onto a different path a controversial proposal because of the unknown consequences of releasing radiation in space others have called for drilling into the nucleus and setting off a blast inside but as we’ve seen this has the danger of turning one deadly projectile into many the pieces could continue on the same orbit and like the blast from a shotgun wreak destruction over a wider area some have proposed less violent yet equally intriguing solutions they suggest putting lasers on the moon where the Earth’s atmosphere would not deflect them the lasers could bore into a comet and melt its icy blue we might even hit a spacecraft to a comet and tow it out of their way whatever the solution all ideas remain on the drawing board if a comet is on a collision course we may not be able to do anything even if we could tell tomorrow that something is headed our way we don’t necessarily have the means right now to protect ourselves but one day you might just look to the heavens and find a comet with our number on it edit our way you

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