00:00 Living on our beautiful planet may seem safe,
00:03 but only until you start thinking about everything that lurks in the corners of the street
00:08 or in the vast darkness of the cosmos.
00:11 Let's see what could lead to the end of planet Earth.
00:14 Each new potential threat is more terrifying than the previous one.
00:18 I warned you.
00:20 First of all, let's talk about hypercyclones.
00:23 This natural disaster can become really extreme.
00:27 A hypercyclone is a theoretical hurricane of unequal power.
00:31 It would occur if the ocean was overheated due to climate change.
00:36 A massive volcanic eruption could also be the cause.
00:40 In any case, the hurricane created, unlike the usual hurricanes,
00:44 would extend well beyond the low stratosphere.
00:47 The speed of such a storm would reach 800 km/h.
00:51 The pressure inside the hypercyclone would be very low
00:55 and consequently, it would last longer than a normal hurricane.
00:58 It could even last for weeks.
01:00 But the worst, it would damage or even destroy part of the ozone layer
01:05 and the hole resulting from it would be the size of the entire North American continent.
01:10 Then, there are super destructive tornadoes.
01:13 A tornado is a column of air in violent rotation.
01:16 It usually spreads from a storm and is in contact with the ground.
01:21 Inside a storm cloud, hot and humid air rises and cool air falls with rain or hail.
01:28 These conditions can cause the appearance of air currents in rotation inside the cloud.
01:33 It is interesting to note that these air currents are first horizontal,
01:37 but at some point, they can become vertical again and start to descend,
01:41 thus transforming into tornadoes.
01:43 Some tornadoes are narrow whirlwinds like ropes.
01:47 Others are large funnels.
01:50 Tornadoes are classified by the improved scale of Fujita.
01:53 A weak tornado usually lasts a few minutes and does not move at more than 160 km/h.
01:59 The next level is a strong tornado.
02:02 These whirlwinds can last about 20 minutes and their winds can reach 320 km/h.
02:08 Finally, violent tornadoes can last more than an hour and move at a speed between 320 and 480 km/h.
02:18 On average, a thousand tornadoes occur each year in the United States.
02:23 There is even a region called "Tornado Alley",
02:26 an area that extends over a dozen states in the Midwest.
02:29 But tornadoes can occur in any state.
02:32 One of the most destructive natural disasters was the tornado of the three states in the United States.
02:38 It lasted an endless time and traveled 354 km through Missouri, Illinois and Indiana.
02:46 The average trajectory of a tornado usually does not exceed 8 km.
02:50 But what would happen if one day a much larger and much more powerful tornado
02:55 than all the ones we have known so far crossed countries and continents?
03:00 It would devastate everything in its path.
03:03 And what about supercellular storms?
03:06 It is the least common type of storm, but the most dangerous.
03:09 It is likely to cause violent meteorological phenomena,
03:13 destructive winds, very large hail and even powerful tornadoes.
03:17 What makes supercellular storms unique is the presence of a deep and persistent ascending current called mesocyclone.
03:25 Supercellular storms can last hours and cause considerable damage.
03:30 The impact of an asteroid could also end any form of life on Earth.
03:35 If one of these space vagabonds was big enough,
03:39 it could cause widespread devastation.
03:42 As was the case with the 13 km wide asteroid that appeared 66 million years ago.
03:47 It is said that it destroyed three quarters of the planet's plant and animal species, including dinosaurs.
03:54 Depending on the size of the asteroid and its approach speed,
03:58 the impact could cause large-scale fires, tsunamis and create an "eternal winter".
04:04 This occurs when the debris ejected into the atmosphere blocks the sunlight and disturbs the global climate.
04:11 Fortunately, thanks to our technology, we would probably notice an asteroid of this size
04:17 approaching our planet long before the collision, and we would have enough time to get rid of it.
04:23 It may be our own sun that will put an end to our world.
04:29 Our star is a gigantic ball of gas in fusion, in constant evolution.
04:34 From time to time, it spits energy bubbles, solar eruptions.
04:39 They often go hand in hand with what we call coronal mass ejections.
04:44 These are giant ionized gas bubbles that can reach incredible speeds.
04:49 The most powerful volcanic eruptions are not the same as solar eruptions,
04:54 which release 10 million times more energy.
04:57 In a few minutes, a solar eruption can emit billions of tons of charged particles.
05:02 Solar eruptions are also extremely hot, with temperatures reaching several million degrees.
05:08 Astronomers think that these solar radiation explosions occur when the magnetic field of the sun deforms in certain regions.
05:16 At some point, all the reflected energy is released.
05:20 The star emits light and particles, mainly electrons and protons.
05:25 Most solar eruptions last a few minutes, but some last hours.
05:30 Scientists classify solar eruptions according to their luminosity in x-rays.
05:37 You probably won't notice the smallest eruptions if you don't have special equipment.
05:42 Medium solar eruptions cause short-circuits in the pole, but nothing serious.
05:47 Class X eruptions should worry you.
05:50 They cause the strongest and most durable solar storms.
05:54 If you could see gamma rays, you would see flashes of extreme luminosity.
05:59 They occur every day, eclipse everything around you, then disappear again.
06:04 They are called gamma bursts.
06:07 Only one of them could destroy the Earth's atmosphere.
06:10 The flare that could destroy our planet would most likely be born in a distant galaxy,
06:14 during the fusion of two stars that are collapsing.
06:17 It would be immensely powerful and superluminous.
06:20 Even a thousand years from now, it would shine as much as the sun.
06:25 The atmosphere of our planet would try to protect us, but this natural shield would be quickly destroyed.
06:31 This radiation would be so powerful that it would literally burn the atmosphere.
06:35 Its nitrogen oxides would destroy the ozone layer.
06:38 Without this layer, the ultraviolet rays from the sun would hit the surface of the Earth with full force.
06:44 They would destroy the entire tiny plankton of the ocean.
06:47 However, this plankton produces 50 to 70% of all the oxygen on the planet.
06:52 Their disappearance would therefore lead to a serious oxygen shortage,
06:55 which would lead to the disappearance of life on the planet.
06:58 Finally, the heat and ultraviolet light from the sun would turn the planet into a huge ball of rock.
07:05 What if we fell into a black hole?
07:08 You may know that a black hole is a region of space where gravity is so strong that even light cannot escape.
07:13 Luckily, the closest black hole to us is 1,500 light years away.
07:18 So we didn't really worry about it until we learned about the existence of black holes.
07:25 Then, things started to get really scary.
07:28 If such a black hole entered our solar system, the Earth would be doomed.
07:32 We would have no chance against this monster of space.
07:35 In 2020, 13 black holes were spotted not far from our planet.
07:40 But "not very far" in terms of space means about 1 billion light years.
07:45 So we have a little time left.
07:47 The possibility of such a disaster is very, very low.
07:51 One day, a wandering planet could push the Earth out of the habitable zone and place it on an extreme orbit, further away from the sun.
07:59 The climate of the planet would then begin to get colder and colder.
08:03 Remember that the further our planet is away from the sun, the less gravitational attraction of the star on our planet.
08:10 In the end, our beautiful Earth would move too far from its main source of light and heat.
08:16 It would turn into a piece of lifeless rock, covered with a thick layer of ice.
08:22 Or the sun could expand and turn into a red giant.
08:27 If this happened, the entire habitable zone of the solar system would be modified.
08:32 The disaster would begin when our star would run out of hydrogen.
08:36 This would trigger a chain reaction that would eventually lead to warming and the densification of the heart of the sun.
08:43 As a result, our beautiful star would become much larger than it is now.
08:48 During this transformation, it would swallow Venus, Mercury and Earth.
08:53 [MUSIC PLAYING]
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