00:0066 million years ago, dinosaurs disappeared from the surface of the earth,
00:08except for those who evolved to become birds.
00:11In an instant, the planet went from the era of dinosaurs to that of mammals.
00:15Scientists designate these periods by specific terms, the Cretaceous and the Paleogene.
00:21This cataclysmic event, on the other hand, is called the K-Pg extinction.
00:27Imagine this dramatic moment in terrestrial history,
00:30which happened in a blink of an eye.
00:32An asteroid of a colossal size, comparable to that of Mount Everest,
00:36and moving at a dizzying speed, hit the earth.
00:40It crashed into the region that we know today as the crater of Chicxulub,
00:44located in the south of Mexico.
00:48The impact was titanic, and everything that was nearby was instantly vaporized,
00:53releasing a colossal energy.
00:55It is one of the most powerful explosions that the planet has experienced in several billion years.
01:00Nothing survived on board the impact point.
01:03While the immediate effects were diminishing,
01:05the earth's surface was subject to violent upheavals.
01:08The ground began to tremble, causing earthquakes of incredible intensity.
01:12The continents themselves seemed to bounce under the impact.
01:16Then, the ocean floor agitated, generating a tsunami.
01:20The ocean floor agitated, generating a tsunami of exceptional magnitude,
01:25whose waves penetrated deeply into the lands around the Gulf of Mexico.
01:30The debris projected into the atmosphere began to fall back on the ground, like a burning rain.
01:35Even if you were away from the most imposing fragments that collapsed in Mexico,
01:40smaller pieces, but heated to white, were still floating in the air.
01:43This heated the atmosphere so much that forest fires were declared all over the globe.
01:50Dinosaurs that lived far from the impact zone first noticed a slight tremor.
01:55Very quickly, the sky darkened, plunging the planet into an artificial night in broad daylight.
02:01Temperatures dropped drastically, and this night lasted for several weeks.
02:08Little by little, a sandstorm began to cover the entire planet.
02:12Harmful substances, such as carbon dioxide and particles from the ocean floor,
02:17dispersed in the atmosphere, disturbing the temperature once again,
02:22with extreme variations in heat and cold.
02:26Nature suffered.
02:28Forest fires, the absence of sunlight and toxic gases in the atmosphere
02:32caused immense difficulties to herbivorous dinosaurs, which began to disappear.
02:37Carnivores took advantage of this to feast, but it didn't last long.
02:41Quickly, the entire food chain collapsed.
02:44It was at this moment that, according to estimates,
02:47between 50 and 80% of the species of dinosaurs disappeared permanently.
02:52What is even more striking is that this figure only reflects the diversity of species.
02:57If we consider the number of individuals who perished, the balance is even heavier.
03:02Interesting fact.
03:03If the asteroid had hit the Earth 30 seconds earlier or later,
03:07it would have landed in the Atlantic or the Pacific rather than offshore the Mexican coasts.
03:12In this scenario, it is possible that some species of dinosaurs did not come
03:16and could survive to this day.
03:18However, the impact occurred with a force equivalent to 10 billion times that of the Hiroshima bomb.
03:27The main survivors were N'Daar, our mammal ancestors.
03:30Small creatures, similar to muse spiders,
03:33with very fast energy systems,
03:36adaptable food regimes,
03:38and talent to hide.
03:40These first mammals mainly managed to survive thanks to their small size
03:44and required very little food resources.
03:47We are incredibly lucky that these mammals survived this chaos.
03:51They probably didn't understand what was going on around them,
03:54but they must have perceived the nauseating smell,
03:56the gigantic corpses,
03:58the acid rain,
03:59and the volcanic eruptions.
04:01Knowing now how devastating this event was,
04:04let's ask ourselves the question.
04:05Could we, as modern humans,
04:07survive to a catastrophe of this magnitude?
04:10The answer is complex.
04:12Research on another asteroid impact,
04:15which occurred about 790,000 years ago,
04:18suggests that this would be possible,
04:20although it is not an easy war.
04:25During this event,
04:26a massive asteroid hit the Earth again.
04:29Like the one in Chicxulub,
04:31it projected debris into the atmosphere,
04:33covering about a tenth of the Earth's surface.
04:36Scientists discovered fragments of this impact,
04:39including vitrified rocks called tektites.
04:42By analyzing them,
04:43they discovered a rare mineral,
04:45reddite,
04:46which only forms under pressure and extreme temperatures.
04:50After studying these clues,
04:52researchers hypothesized that the impact occurred in Southeast Asia,
04:56probably near Thailand.
04:58Curiously,
04:59the exact crater remains undiscovered.
05:01Nevertheless,
05:02what matters is that the collision did indeed take place,
05:05and that our ancestors lived during this tumultuous time.
05:09It is certain that this event did not happen unnoticed,
05:12even if they may not have fully grasped the extent of the situation.
05:16The debris of this collision would have led to significant climatic upheavals,
05:20and it is difficult to assess how this influenced human evolution.
05:25What we do know
05:26is that we managed to get through this ordeal.
05:30Currently,
05:31about 1,200 asteroids are listed on a potential threat list.
05:36Fortunately,
05:37we are not in immediate danger,
05:39because these asteroids are less than 1 km in diameter.
05:43The probability that a large asteroid,
05:46similar to that of Chicxulub,
05:48measuring between 5 and 15 km in diameter,
05:51will hit Earth,
05:52is extremely low.
05:53Such cataclysmic events
05:56occur once every 100 to 200 million years.
06:00In addition,
06:01the majority of asteroids are located between Mars and Jupiter,
06:04and pose no risk to our planet.
06:07However,
06:08there are thousands of small asteroids
06:10that could potentially collide with us.
06:13Most of them are so small
06:15that they consume themselves in the atmosphere without causing any damage.
06:18Some,
06:19larger ones,
06:20could damage buildings or cities,
06:22but would not pose a threat to life as a whole.
06:25But what would happen
06:27if a comet or a major asteroid hit Earth today?
06:30Such an impact could first of all change Earth's orbit.
06:34The initial energy released
06:36would cause a burning shock wave
06:38reaching 300 °C.
06:40A fire of such magnitude
06:42would burn vast regions of the Earth's surface
06:45and could have long-term consequences
06:48on the winter climate.
06:50The smoke of mega-fires,
06:52as well as dust and water vapor,
06:54would form a thick layer of clouds in the high atmosphere.
06:57As during the extinction of dinosaurs,
06:59this cover would reduce the sunlight,
07:02causing a drop in temperatures for decades.
07:05Most of the vegetation would perish in a few weeks.
07:09Large trees could survive for many years
07:12thanks to their sugar reserves
07:14and a slowed metabolism.
07:16In addition,
07:17life would be essentially reduced to microbes
07:20and the smallest creatures.
07:24To deal with this kind of situation,
07:27three strategies are conceivable for humanity.
07:30The most effective
07:31is to prevent the impact from happening in the first place.
07:34Scientists are already working
07:36to identify asteroids
07:38likely to cross the Earth's trajectory
07:41and are debating ways to defend themselves.
07:44One option is to use our most powerful weapons
07:47to fragment the asteroid into small pieces.
07:50These fragments could miss the Earth
07:52or disintegrate by entering our atmosphere,
07:55which would be effective for asteroids
07:57about 1 km in diameter.
07:59However, this method would not work
08:01for asteroids as massive as Chicxulub's.
08:04The amount of energy required to destroy them
08:07far exceeds our current arsenal.
08:09But if the asteroid is spotted early enough,
08:12a series of explosions could perhaps change its trajectory
08:15and avoid the disaster.
08:17According to researchers,
08:18asteroids over 40 km in diameter
08:21would be almost impossible to stop
08:23with our contemporary technology.
08:25Fortunately,
08:26the probability that such an asteroid hits the Earth
08:29is extremely low.
08:32If we cannot prevent the impact,
08:35the second strategy would be to take refuge underground
08:38by building large bunkers.
08:40Numerous endangered species
08:42living deep in the oceans
08:44have survived mass extinction
08:4666 million years ago.
08:48These underground habitats could thus protect us
08:50from the direct effects of the impact,
08:52such as explosions and fires,
08:54as well as winter.
08:56We could exploit the Earth's natural heat
08:58and live in protective domes
09:00built in stable continental regions
09:03or deep under the oceans.
09:05These shelters should be equipped with essential supplies
09:08such as food, medicine, fuel and water
09:11and perhaps even gene banks
09:13to preserve biodiversity.
09:15The third strategy,
09:16much less recommended,
09:18would be to do as in the film Don't Look Up.
09:20Ignore the problem until it is too late.
09:23A real solution would require
09:25the cooperation of governments and institutions
09:27from many countries to design,
09:29build and launch devices
09:31in space to prevent the impact.
09:33Succeeding in obtaining such cooperation
09:35would already be an exploit in itself.
09:37In any case,
09:38NASA takes very seriously
09:40the threat posed by asteroids.
09:42It has a complete plan
09:44including early detection,
09:46evaluation,
09:47deviation strategies,
09:49international collaboration,
09:51public communication
09:53and rescue plans to protect the Earth
09:55from these cosmic dangers.
09:56We can therefore hope that,
09:58if such an event occurs,
10:00logic and preparation will prevail.
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