85 Faits Essentiels sur l'Espace pour Votre Voyage Interstellaire

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Transcript

00:00:00 Once they have exploded, the stars are not supposed to come back to life.

00:00:07 But some stars have somehow survived the great explosion of supernovas.

00:00:12 These zombie stars are rather rare.

00:00:15 Scientists have found a very large one called LP40365.

00:00:20 It is a partially consumed white dwarf.

00:00:23 A white dwarf is a star that has burned all its hydrogen,

00:00:26 which was previously its nuclear fuel.

00:00:29 In this case, the final explosion was perhaps not powerful enough to destroy the star,

00:00:34 which explains why some of the matter survived.

00:00:37 Another of these zombie stars is an old white dwarf,

00:00:40 or a residue of an explosion that engulfed so much matter

00:00:44 from another star that, surprisingly, it exploded again.

00:00:48 If you go to the moon one day and see fresh footprints,

00:00:51 it doesn't mean there's someone else with you.

00:00:54 Footprints or other similar marks can stay there for a million years.

00:00:59 Because the moon has no atmosphere,

00:01:01 there is no wind that could slowly erase these footprints.

00:01:05 In space, you would be strong enough to weld two pieces of metal together with your own hands.

00:01:11 OK, it has nothing to do with strength.

00:01:13 You just have to press them together and that's it.

00:01:16 The oxygen in our atmosphere forms a thin layer on the surface of the metal that acts like a barrier.

00:01:22 That's why this impossible force field on Earth is perfectly plausible in space.

00:01:28 Besides, if you go there one day, don't take your suit off the spaceship.

00:01:33 The air in your lungs would spread, as would the oxygen in your whole body,

00:01:39 and you would swell like a balloon.

00:01:41 Good news, the skin is elastic enough to prevent you from exploding.

00:01:46 A light consolation.

00:01:48 If you watch a moving movie in space and start crying, your tears won't flow.

00:01:54 They will accumulate around your eyeballs,

00:01:57 your eyes will become too dry and you will feel like they are burning.

00:02:01 All the liquid on the surface of your body will evaporate, including saliva on your tongue.

00:02:06 Speaking of burning, you can't make a fire in space because it feeds on oxygen,

00:02:11 and since there is no oxygen in space,

00:02:13 if a fire breaks out in a sink, you just have to shut down the ventilation system.

00:02:18 It would be more complicated if smoke was produced,

00:02:21 and some materials would melt in conditions of reduced gravity.

00:02:25 Ordinary foam extinguishers, which we use on Earth, are useless here,

00:02:30 because they disparately release the foam.

00:02:33 Researchers are developing an extinguisher that would put out fires using sound waves.

00:02:40 The higher the sound intensity, the more it can put out big flames,

00:02:44 but astronauts may go deaf if the frequency is too high.

00:02:49 A black hole is not a hungry monster that wanders around,

00:02:52 and to the gravity of which nothing can escape.

00:02:55 When something approaches the point of no return, which we also call the horizon of events,

00:03:00 it disappears without ever coming back.

00:03:03 But according to quantum physics, nothing can really be reduced to nothing.

00:03:07 It is therefore a paradox.

00:03:10 It was Stephen Hawking who thought that black holes did not really have a horizon of events.

00:03:14 Perhaps they have apparent horizons that imprison things for a certain time,

00:03:19 and that the trapped energy ends up escaping in a different form.

00:03:24 When an object enters a black hole, it changes shape and stretches like a spaghetti.

00:03:29 This happens because the gravitational form tries to pull an object in one direction

00:03:34 while compressing it in another.

00:03:37 Another paradox.

00:03:39 Besides, a black hole as big as an atom has the mass of a huge mountain.

00:03:43 There is one in the center of the Milky Way called Sagittarius A.

00:03:47 It has a mass equivalent to a billion suns.

00:03:50 But fortunately, it is very far from us.

00:03:53 More than 23,000 of the biggest space debris than a baseball bat

00:03:57 float above our planet, moving at more than 28,000 km per hour.

00:04:02 And there are about 500,000 of them, the size of a ball.

00:04:06 Space debris is generally debris composed of natural particles

00:04:10 called meteorites and artificial particles,

00:04:14 like the ones we make on Earth.

00:04:17 Meteorites orbit the Sun,

00:04:21 while most of the debris of human origin orbit the Earth.

00:04:26 We have launched about 9,000 spacecrafts around the world,

00:04:30 satellites or rockets.

00:04:32 Even the smallest pieces can damage a spacecraft with such high speeds.

00:04:37 Galaxies, planets, comets, asteroids, stars,

00:04:42 celestial bodies are things that we can actually see in space.

00:04:46 But they represent less than 5% of the total universe.

00:04:50 Black matter, one of the greatest mysteries of space,

00:04:53 is the name we use to designate all the mass of the universe

00:04:57 that is still invisible to us.

00:04:59 It could make up 25% of the universe.

00:05:02 Black energy makes up the rest of the 70% of the universe.

00:05:07 Scientists don't know much about it,

00:05:11 but they think that black energy could be the cause of the growing expansion of the universe,

00:05:17 while black matter slows it down.

00:05:20 Black matter does not interact with us or with itself.

00:05:23 If that were the case, we would find galaxies of black matter,

00:05:27 planets of black matter, or other objects of this type.

00:05:31 Astronomers have found the biggest hole we have ever seen in the universe.

00:05:38 It is a giant void that extends over a billion light years.

00:05:42 One of the team members was bored and wanted to see how things were going in the direction of the cold point.

00:05:49 It is an anomaly in the map of the Cosmological Diffuse Background, or FDC.

00:05:54 It is a faint light that falls on our planet from different directions and fills the universe.

00:06:00 It has been passing through space for nearly 14 billion years,

00:06:03 like the remanence that occurred after the Big Bang.

00:06:07 But instead of the FDC, they realized that there was a huge area,

00:06:11 much colder than what they expected.

00:06:14 The team tried to find radio signals, but in vain.

00:06:18 This means that there are no galaxies, no cosmic hamas,

00:06:21 and because of this cold, there is no black matter or any other matter.

00:06:26 So the giant void is just a void, and the researchers think it could be made up of black energy.

00:06:33 Light can still pass through it, and it is not the only empty area in space, but it is the largest known.

00:06:40 The area around a star is habitable when it is neither too cold nor too hot

00:06:45 to find liquid water on surrounding planets.

00:06:49 Let's imagine that our planet is where Pluto is.

00:06:53 Being too far from the Sun, our oceans and our atmosphere would be frozen.

00:06:57 But if the Earth were in the place of Mercury,

00:07:00 we would be too close to the Sun and the water on our planet would evaporate.

00:07:04 Such a habitable area is called the "golden loop" area.

00:07:08 This is where the planets potentially able to live on their surface are located.

00:07:14 But Europe, one of Jupiter's moons, breaks this rule.

00:07:18 It is outside the habitable zone, but it is still warm enough.

00:07:22 Not directly thanks to the Sun, but thanks to Jupiter and its moons,

00:07:26 which pump their energy in the direction of Europe.

00:07:29 The latter changes shape when it revolves around Jupiter,

00:07:33 a bit like the tides that rise and fall on our planet.

00:07:37 Water on Earth changes shape in response to the force of lunar tides.

00:07:41 When this happens with a solid object, it creates a tension in the latter,

00:07:47 thus pumping energy towards it.

00:07:50 It's like playing tennis.

00:07:52 Every time you hit the ball, it deforms and warms up.

00:07:56 The surface of Europe is frozen, but there are cracks in the ice.

00:08:00 You can see cracks in this ice where there are cracks.

00:08:03 Then these pieces of ice move and freeze again.

00:08:07 You would see something similar if you could fly over the Arctic Ocean in winter.

00:08:12 Huge layers of ice break and freeze again.

00:08:16 So Europe cannot be completely frozen.

00:08:19 Scientists think there could be a liquid ocean under its frozen surface.

00:08:25 Europe is not the only moon concerned.

00:08:28 Another moon, Jupiter, Io, is also warm because of this same force,

00:08:34 but it also contains volcanoes that are constantly erupting.

00:08:38 The Sun is therefore not the only one to warm up space bodies and provide them with energy.

00:08:43 Many experts agree that the Universe could reach its end

00:08:48 within 3 to 22 billion years.

00:08:50 It is constantly expanding,

00:08:53 which means it has formed from a compact state.

00:08:56 If it has a beginning, it will probably also have an end.

00:09:00 A popular theory claims that its expansion will slow down

00:09:04 and that gravity will take over and make it shrink,

00:09:08 leading to the most complete chaos.

00:09:11 Galaxies, stars, planets and celestial bodies will collide

00:09:16 and destroy each other.

00:09:18 It's like a reversed Big Bang,

00:09:21 except this time everything will be compressed.

00:09:24 Well, on this happy note,

00:09:27 I wish you all to see life on the fun side.

00:09:31 Many people would like to fly in space.

00:09:36 The weightlessness, the unbearable view of the Earth on one side,

00:09:40 and the incredibly scary black area on the other.

00:09:43 Yes, all of this is great,

00:09:45 but don't forget that this trip can turn into a nightmare.

00:09:49 Lack of oxygen, floating in space and staying in a space ship for a long time

00:09:53 without knowing when you can go home.

00:09:56 That's what happened to an astronaut.

00:09:58 His stay in space is one of the longest in the world.

00:10:02 Sergey Krikalev, 33, a space engineer,

00:10:06 spent 311 days in weightlessness in the Mir space station.

00:10:10 But that's not the most interesting part of this story.

00:10:13 Sergey's long journey began on May 18, 1991.

00:10:18 That day, he boarded a transport ship

00:10:21 and went into space to the Mir space station.

00:10:24 On May 20, the docking process at the station took place.

00:10:28 There, with another engineer, Sergey fulfilled his duties in space.

00:10:33 They went outside several times,

00:10:35 made repairs, took care of the station,

00:10:38 and conducted scientific experiments.

00:10:40 When you have company and a lot of work,

00:10:43 living in space is not that difficult.

00:10:45 But things went south the day Sergey was supposed to go home.

00:10:50 According to the plan, the mission should have lasted 5 months.

00:10:53 A new astronaut was supposed to replace the old ones.

00:10:56 The transport ship finally docked at the station.

00:10:59 But on October 10, only one astronaut came back to Earth.

00:11:03 Sergey stayed alone in the Mir station.

00:11:06 He continued to work as the only flight engineer on the crew.

00:11:10 The station could not stay alone.

00:11:12 They had to send someone to replace him.

00:11:14 He was not ready for such a long stay in space.

00:11:17 He had not trained for it, but he had no choice.

00:11:20 He could not leave the station like that.

00:11:22 A month had passed.

00:11:24 The crew informed Sergey that he would return home soon,

00:11:27 but something happened that no one expected.

00:11:30 On December 25, 1991, the USSR collapsed.

00:11:35 They contacted Sergey and told him that he could not return to his country,

00:11:39 since the country that had promised to bring him home no longer existed.

00:11:43 Indeed, during this time, a great crisis had broken out in Russia.

00:11:48 The return of the cosmonaut was impossible,

00:11:50 because no one had the money to do it.

00:11:52 Imagine Sergey's situation.

00:11:54 You are hundreds of kilometers from home, in the dark space,

00:11:58 completely alone, and you have no idea how many days you have left to spend there.

00:12:03 The days passed slowly.

00:12:05 The weeks, then the month, passed.

00:12:07 It would have been much easier if being in space was not dangerous to your health.

00:12:12 But in weightlessness conditions, the human body suffers serious damage.

00:12:16 First, there is a weakening of the muscles.

00:12:19 The body does not receive the necessary load it needs,

00:12:22 and the muscles are constantly in a state of relaxation,

00:12:25 which leads to a dystrophy.

00:12:27 Certainly, astronauts do a series of exercises every day,

00:12:30 but this is not enough to keep the body in shape.

00:12:33 In addition to the muscles, the bones begin to weaken, and the person becomes weak.

00:12:37 Even after six months of this kind of life,

00:12:39 every astronaut needs a lot of time to regain his previous form after his return home.

00:12:44 In addition, there is a lot of radiation in space, which is dangerous for people.

00:12:49 It comes from several sources at once.

00:12:51 The main radiation comes from the sun.

00:12:53 On Earth, we are protected from this radiation thanks to the magnetic fields of the planet.

00:12:58 Almost all the radiation accumulates in the high atmosphere and does not reach us.

00:13:02 This accumulation of radiation in the atmosphere is harmful for astronauts.

00:13:07 But the worst radiation is that of the galaxy.

00:13:10 It comes from stars and distant galaxies and has a powerful effect on all living things.

00:13:15 Radiation causes many unfavorable conditions and destroys the body at the cellular level.

00:13:21 Today, all space ships and the ISS are equipped with shields and coatings that reflect radiation.

00:13:28 But this still does not provide 100% protection.

00:13:31 In space, the astronaut's immune system changes.

00:13:34 There is no condition in which the immune system could improve.

00:13:39 Apparently, the absence of many bacteria and microbes is not abnormal.

00:13:43 But the defense of the body weakens.

00:13:45 The person becomes more vulnerable to microbes that can be brought by another astronaut.

00:13:50 There are also serious food restrictions.

00:13:53 The food in the tubes does not contain as many useful vitamins as in natural products.

00:13:58 Without vitamins, the body weakens even more.

00:14:01 And sometimes, astronauts have to go out into space, which is not easy.

00:14:06 A space suit is a huge and uncomfortable outfit.

00:14:10 It restricts your movements and exerts pressure on your body.

00:14:13 Space work can last up to several hours.

00:14:16 During this time, you sweat a lot.

00:14:19 One of the suit's filters can be broken,

00:14:22 and all the liquid released by the body can spread in the suit and reach your face.

00:14:27 You can have wet eyes.

00:14:28 The drops disturb your vision.

00:14:30 Thousands of dangers can befall an astronaut on a space mission.

00:14:35 Imagine that you are doing repairs and something is wrong.

00:14:38 The key to the wheel jumps out of the bolt and it flies away, for example.

00:14:42 You try to catch it and you move away without noticing the ship.

00:14:45 You catch the bolt, but your body is already flying away.

00:14:48 You have nothing to cling to.

00:14:51 But luckily, you have a safety rope.

00:14:54 But it can detach from your space suit because you have fixed it wrong.

00:14:58 As soon as the rope breaks, your body changes flight angle.

00:15:01 Now, you are not content to fly away. Your body turns at this moment.

00:15:06 The Earth and the black space are in front of you.

00:15:09 So you understand, there are really big risks.

00:15:12 But none of this happened to Sergei.

00:15:15 All astronauts spend many hours training to be ready to face any problem.

00:15:20 They acquire a good physical shape and lose it during the mission.

00:15:24 Add to all this the psychological factor.

00:15:27 Your body weakens, you can't breathe fresh air, you can't see your friends,

00:15:31 and you can't go home.

00:15:34 A small layer of walls separates you from the cold vacuum of space.

00:15:37 All this causes stress, which also weakens immunity and damages the nervous system.

00:15:43 Fortunately, astronauts also undergo serious psychological training.

00:15:47 They are able to keep their cool in the most stressful situations.

00:15:51 But when you are alone in space for more than six months

00:15:54 and you don't know when you will come back, you can become seriously nervous.

00:15:58 Fortunately, Sergei didn't panic.

00:16:01 He did his daily tasks, trained, and of course, got bored of his home.

00:16:06 A month later, he received the same answer.

00:16:09 "We can't get you back yet. The country is in a difficult situation."

00:16:13 He felt worse every day. His strength was leaving him.

00:16:17 He was not sure he could survive.

00:16:20 What was interesting was that the station had a capsule developed to return to Earth.

00:16:24 But Sergei didn't use it because no one would have made the station run.

00:16:29 Russia sold the station's posts to other countries.

00:16:32 They also hoped to sell Mir.

00:16:34 Sergei had to continue to run the station.

00:16:37 Sergei's mission lasted twice as long as planned.

00:16:41 As a result, he spent 10 months, or 311 days, in space and set a world record.

00:16:47 During this period, he went around the Earth about 5,000 times.

00:16:51 And finally, he received the long-awaited message. He was going home.

00:16:56 Germany had paid about $24 million for a ticket to the station.

00:17:01 They were going to replace the astronaut.

00:17:04 Krikalev got on the capsule and flew to Earth.

00:17:07 Many people were waiting for him to return here.

00:17:10 The cosmonaut landed and everyone rushed to help him.

00:17:13 He looked very thin, sweaty and exhausted.

00:17:17 Four men helped him get out of the capsule.

00:17:20 They helped him stand up, gave him a fur coat and brought him a bowl of broth.

00:17:25 One could imagine that such a flight would leave a mark on his life forever.

00:17:29 But the cosmonaut was in excellent mood.

00:17:32 Two years later, he returned to space and became the first Russian cosmonaut to fly on a NASA shuttle.

00:17:39 And two years later, he was one of the first to live on the ISS.

00:17:43 In 2005, he made his sixth and last flight.

00:17:47 He went to the ISS, where he spent about six months, after which he returned home on board the shuttle.

00:17:53 After this flight, he set a world record for the total duration of stay in space, or 803 days.

00:18:00 Only 10 years later, someone managed to break this record.

00:18:04 But that's another story.

00:18:07 It is said that somewhere, there is a pen that can work in gravity, at extreme temperatures and even underwater.

00:18:14 That this pen can write on almost all surfaces, even upside down, and this at temperatures that can reach 300 degrees.

00:18:23 It is also said that NASA has spent millions, if not billions of dollars and almost a decade, to develop such an object.

00:18:31 The problem with ballpoint pens in space is that they do not work in weighty conditions.

00:18:37 The ink cannot flow to the ball normally, since gravity does not affect it.

00:18:42 Instead, pressure is applied to the ink tank and the pens start to run away.

00:18:47 Until recently, NASA used paper pencils.

00:18:51 This being made of wood, it represented a risk of fire in most of the space ships of the time,

00:18:56 whose internal atmosphere was composed of 100 degrees of oxygen.

00:19:00 The need for a super pen was therefore obvious.

00:19:03 But whatever the rumors say, NASA did not create such a pen, nor did it spend a fortune on research.

00:19:10 Its development was sponsored by Paul C. Fischer, of the Fischer-Penn Company, based in Chicago.

00:19:15 More than a million dollars and nearly 10 years were needed to develop a pressurized ink cartridge.

00:19:21 It was supposed to allow space pens to work in zero gravity and in other extreme conditions.

00:19:27 In short, they got a pen that could be used at temperatures ranging from -35 degrees to 120 degrees.

00:19:34 Impressive, isn't it?

00:19:35 The pen was patented in 1966.

00:19:38 A year later, after conducting several in-depth tests, NASA started to equip astronauts with Apollo missions.

00:19:45 Surprisingly, the rumors that NASA spent a huge sum on developing space pens have been circulating for decades.

00:19:53 They have been denied many times, but they resurface again and again.

00:19:58 Many science fiction movies can make you think that everything that happens in space is accompanied by a kind of sound effect,

00:20:05 which is a totally false idea.

00:20:07 In space, no one hears you scream.

00:20:09 Do you know why?

00:20:11 Because there is no air in space.

00:20:13 It is an almost perfect vacuum that makes the movement of sound waves impossible.

00:20:17 They cannot reach your pens and make them vibrate to send the signals necessary to your brain.

00:20:23 But it's a good thing, especially for astronauts as they leave space.

00:20:27 Without the calm of space vacuum, they would be constantly submerged by the noise of solar storms.

00:20:33 Here is another well-received idea.

00:20:35 All comets have beautiful and long tails.

00:20:37 It's just a popular myth.

00:20:39 In reality, comets are very difficult to spot in space.

00:20:43 They usually spend a lot of time far from the stars.

00:20:46 But here, in the darkness of space, they remain rather inactive and completely frozen.

00:20:50 Comets have a tail that, when they approach a star,

00:20:53 it is at that moment that they begin to warm up.

00:20:56 This process leads them to develop a kind of cloud atmosphere,

00:20:59 called a coma, and a distinctive tail.

00:21:02 The tail always points to the opposite side of the star that influences the comet,

00:21:06 because it is pushed in the opposite direction by the radiation and solar winds.

00:21:10 That's why the tail can also be in front of the comet, and not afterwards.

00:21:15 Now let's look at what a light year is.

00:21:18 The very name of this notion can suggest that we are talking about time.

00:21:22 But in reality, light years are a unit of distance.

00:21:26 The definition of a light year by NASA is as follows.

00:21:29 The total distance that a beam of light travels in a straight line,

00:21:33 takes a year.

00:21:35 And since light travels at a speed of 300,000 km per second,

00:21:38 a light year is almost 9 billion km.

00:21:42 People often believe that we are experiencing zero gravity in space.

00:21:46 Hence the weightlessness that astronauts experience in the International Space Station.

00:21:50 But that's not entirely true.

00:21:52 Gravity is one of the most important forces in the universe.

00:21:56 Thanks to it, the Moon can rotate around the Earth,

00:21:59 and the Sun does not drift far from our galaxy, the Milky Way.

00:22:03 ISS astronauts do not experience zero gravity, but microgravity.

00:22:08 Gravity on the ISS is only 10% lower than gravity on Earth.

00:22:14 But astronauts are constantly free-falling.

00:22:17 The spacecraft, the people on board, and all the objects on board

00:22:20 constantly fall forward, not downwards, but around our planet,

00:22:24 following a specific orbit.

00:22:26 And since they all fall together, the crew and the objects inside seem to float.

00:22:30 This is why astronauts can move objects weighing hundreds of kilos at the tip of their fingers.

00:22:35 And even though microgravity is often called zero gravity,

00:22:39 they are actually two very different things.

00:22:42 You might think that the Sun is always on fire.

00:22:45 At least, that's what the photos show.

00:22:47 But in reality, our star is a giant gas ball.

00:22:51 Nuclear reactions that occur constantly in its core burn the Sun.

00:22:56 Every second, hundreds of millions of tons of hydrogen are transformed into almost as much helium.

00:23:01 During this process, huge amounts of energy are released in the form of gamma rays.

00:23:06 Then, these rays turn into light.

00:23:09 In other words, the Sun actually emits a blinding light and an incredible heat.

00:23:14 But it's not really on fire, because there's no oxygen involved in the process.

00:23:18 A human can explode if he goes into space without a space suit.

00:23:22 Well, contrary to popular belief,

00:23:24 taking off a space suit during a spacewalk

00:23:28 won't be as dramatic as what we often see in movies.

00:23:32 The person will simply lose consciousness due to a lack of oxygen

00:23:36 after 15 seconds in space without a protective suit.

00:23:39 Before that happens, he will have to breathe as much air as possible,

00:23:43 otherwise this oxygen will damage his internal lungs.

00:23:47 Then, without the protection of the space suit, which acts like a mini space ship,

00:23:52 the pressure inside his body will drop.

00:23:55 This will cause even more serious problems.

00:23:57 And even if this person won't explode,

00:24:00 they won't have to stay outside for too long.

00:24:03 We often hear that black holes are gigantic and terrifying cosmic vacuum cleaners.

00:24:08 But in reality, black holes are more like a fly trap.

00:24:12 They're not constantly looking for things to suck.

00:24:15 Instead, they stay there, quite passively.

00:24:18 It's only when a star gets too close that a black hole takes action.

00:24:22 And even then, only the objects in space that cross a certain boundary get ripped apart.

00:24:27 If the Sun were suddenly replaced by a black hole, the Earth's orbit wouldn't change.

00:24:32 However, its temperature would be different.

00:24:35 Our planet wouldn't be affected by magnetic storms or solar winds.

00:24:40 Let's suppose that this black hole is the same mass as our star.

00:24:43 According to the laws of physics,

00:24:45 the Earth would have to get really close to be dragged into it.

00:24:49 The legend of the dark side of the Moon was demystified more than 50 years ago.

00:24:54 Yet, not everyone knows that this dark side is simply the part of the Earth's natural satellite

00:25:00 that is oriented on the opposite side.

00:25:02 It is by no means darker than the rest of the Moon.

00:25:05 And the Sun's light reaches the entire lunar surface equally.

00:25:10 If it seems darker, it's only because we can never see it from Earth.

00:25:14 This is the result of a phenomenon known as "synchronous rotation".

00:25:19 Over billions of years of space history,

00:25:21 the gravitational link between our planet and its natural satellite has changed their orbits.

00:25:27 Their speed of travel has also changed.

00:25:29 And since the Earth is much more voluminous than the Moon,

00:25:32 the satellite's rotation has been gradually slowed down,

00:25:36 until it has reached its equilibrium point.

00:25:39 And today, it takes the same time as the Moon to make a complete rotation on its axis

00:25:44 and to make a complete orbit around the Earth.

00:25:47 You may have heard people talk about Venus as the twin of the Earth.

00:25:51 It is true that these two planets are almost the same size.

00:25:54 They also have a similar mass and composition.

00:25:57 The gravity on the surface of Venus is equivalent to 91% of that of the Earth.

00:26:02 So if you weigh 45 kilos on our planet, you would weigh 40 on Venus.

00:26:07 And yet, to qualify these planets as twins is very exaggerated.

00:26:11 Venus's atmosphere is 100 times thicker than that of the Earth.

00:26:14 In addition, the temperatures on its surface are incredibly high, up to 455 degrees.

00:26:20 It's hot enough to melt lead or carbonize your pizza.

00:26:24 Venus does not have an ocean filled with liquid water or any form of life.

00:26:28 It also rotates in reverse compared to all the other planets in the solar system, including the Earth.

00:26:34 By the way, another myth claims that Mercury is the hottest planet in the solar system.

00:26:39 After all, it is the planet closest to the Sun.

00:26:41 But in reality, Venus is hotter.

00:26:44 Asteroids hit the Earth much more often than people tend to believe.

00:26:49 But the vast majority of these collisions are far from being the kind of cataclysmic event

00:26:53 capable of turning history upside down, causing, for example, a massive extinction.

00:26:58 Most of them go completely unnoticed.

00:27:01 Most of the asteroids that approach our planet are classified as geocruisers.

00:27:06 They are generally consumed in the Earth's atmosphere

00:27:09 before they have the slightest chance of destroying life on the planet's surface.

00:27:13 Not that they are big enough to do so.

00:27:16 And yet, about 40 to 80 tons of space debris falls on Earth every year.

00:27:21 Most of these debris are tiny asteroids, also called bolides.

00:27:26 They are generally no more than 20 meters in diameter.

00:27:29 You might think that the Earth is massive,

00:27:32 but the Sun represents almost 99.9% of the mass of the entire solar system.

00:27:38 The rest of this mass is made up of planets and their satellites, asteroids, comets, gas and dust.

00:27:45 The Sun is located about 150 million kilometers from our planet,

00:27:49 but it keeps us warm every day.

00:27:51 Its temperature is about 5,500 degrees Celsius,

00:27:54 but the space around it is always as cold as ice.

00:27:58 To understand this, we must distinguish between heat and temperature.

00:28:02 Heat is the energy that is inside an object.

00:28:05 Temperature is what tells us whether the object is hot or cold.

00:28:10 When heat is transferred from this object, the temperature increases.

00:28:14 When the object loses heat, its temperature decreases.

00:28:18 Heat can be transferred in three different ways.

00:28:21 The Sun does it by radiation.

00:28:23 This means that it releases heat in the form of light.

00:28:26 Your body also releases heat in the form of infrared waves.

00:28:30 This is why thermal cameras can detect your presence in a room, even at night.

00:28:35 The hotter the object, the more heat it releases.

00:28:38 Temperature affects only matter.

00:28:40 Since space is mainly empty, it does not contain enough particles

00:28:44 for heat to be transferred in other ways than by radiation.

00:28:48 When heat from the Sun arrives on an object,

00:28:51 the atoms begin to absorb energy.

00:28:53 But heat cannot be transferred because there is no matter in space.

00:28:57 These rare atoms and molecules in space will absorb heat,

00:29:01 and they will simply remain that way, while the cold vacuum will remain cold.

00:29:06 There is a lot of matter in the Earth's atmosphere,

00:29:09 so the Sun's energy can be transferred easily.

00:29:12 But if you put an object out of the Earth's atmosphere in the sun,

00:29:16 it will end up being heated to 121 ° C,

00:29:20 because it is a matter made up of atoms and molecules.

00:29:24 The temperature in the vacuum is -270 ° C.

00:29:28 This means that depending on where you are,

00:29:31 space can either burn you or freeze you.

00:29:34 The Sun is not really yellow.

00:29:36 It emits light over a wide range of wavelengths.

00:29:40 We can determine its temperature and color by the peak of its spectrum.

00:29:44 For example, the colder stars will be red,

00:29:47 and the warmer stars will be blue.

00:29:50 Between the two, yellow, orange and white stars.

00:29:53 As for the Sun, the spectrum culminates at a wavelength

00:29:57 that we generally define as green.

00:29:59 But our eye sees it differently.

00:30:01 Thus, this nuance of green, combined with other spectrum wavelengths,

00:30:05 will appear white to the human eye.

00:30:08 We generally perceive the Sun as yellow,

00:30:11 because our atmosphere diffuses blue light more effectively than red.

00:30:15 During sunrise and sunset,

00:30:17 there is more red light in the Sun's spectrum,

00:30:20 which gives us sparkling colors.

00:30:22 Solar stains are visible parts of the Sun's surface

00:30:25 that are, on average, much colder than the Sun itself.

00:30:29 They overlap with parts with an increased magnetic field.

00:30:32 These parts do not allow the release of heat

00:30:35 to the visible surface of the Sun.

00:30:37 Thus, the rest of the Sun's surface is three times brighter than these solar stains.

00:30:42 This contrast makes them appear almost black.

00:30:45 If we could separate a solar stain from the Sun

00:30:48 and place it somewhere in the night sky,

00:30:50 it would be different, as bright as the Moon

00:30:53 when we see it from Earth.

00:30:55 All the planets in our solar system rotate in the same direction,

00:30:59 because they are formed from a single protoplanetary cloud,

00:31:02 with the exception of Uranus and Venus.

00:31:05 They probably underwent a strong impact

00:31:07 that made them rotate in the opposite direction.

00:31:10 But this is different with galaxies.

00:31:12 They are generally not formed from the same cloud of dust and particles.

00:31:16 In addition, they are not randomly distributed in space.

00:31:19 They are formed in the form of filaments,

00:31:22 dense and thin strands of black matter and galaxies,

00:31:25 with gaps between them.

00:31:27 Protogalaxies are connected by gravitational forces

00:31:30 in small areas of space.

00:31:32 This is probably due to the distribution of black matter in the universe.

00:31:37 The matter in the filaments moves in a "cork"

00:31:41 and goes to the densest area.

00:31:43 There could be a common direction in which galaxies tend to rotate,

00:31:47 but it is mainly random.

00:31:50 It is possible that one day we would set up a lunar elevator.

00:31:53 Yes, a cable anchored to the surface of the Moon.

00:31:56 It would extend over 400,000 km.

00:31:59 We could not attach it directly to our planet,

00:32:02 because the Earth and the Moon are both moving.

00:32:05 But we could keep it, high in the orbit of our planet.

00:32:09 Some researchers think that we could build such an elevator

00:32:13 for a few billion dollars.

00:32:15 The Moon has resources that we could certainly use.

00:32:18 A rare form of helium found there

00:32:21 could be useful in the fusion plants of our planet.

00:32:24 We could also take other rare elements

00:32:27 and use them in smartphones and the rest of electronics.

00:32:31 Thus, after about 53 ups and downs,

00:32:34 the elevator could be cushioned.

00:32:37 The cable would be as thick as a pencil,

00:32:40 but its weight would be about 40 tons.

00:32:42 It could even be made from the material we already have on Earth,

00:32:46 without having to invent anything.

00:32:48 It could even be a combination of two elevators.

00:32:52 A space ship would tow an elevator from the surface of our planet

00:32:56 to a space station.

00:32:58 Then it would be projected towards the Moon.

00:33:00 There would be another elevator to finally bring it down to the surface of the Moon.

00:33:05 The planets of our solar system have predictable and stable orbits,

00:33:09 but collisions of gas giants could occur at an early stage

00:33:13 when the planetary system was still in formation.

00:33:16 In the event of a frontal collision, two gas giants would fuse.

00:33:20 They would not end up losing their mass,

00:33:23 the materials of their gas envelopes,

00:33:25 or those of their solid nuclei.

00:33:27 A collision of this magnitude at a higher speed

00:33:30 would cause the loss of most of the gas in the envelope.

00:33:33 At a very high speed, boom!

00:33:35 The two planets would disappear.

00:33:37 It would be different if the collision was not frontal.

00:33:40 If the two nuclei could be completely avoided,

00:33:43 the gas giants would not fuse,

00:33:45 but they would lose part of their mass.

00:33:47 The gas giants could even change shape

00:33:50 because of such a collision.

00:33:52 Astronomers have discovered that there is a galaxy

00:33:55 that is very far away from us,

00:33:57 which looks like our Milky Way.

00:33:59 We see it today as it was

00:34:01 when the Universe was only 1.4 billion years old.

00:34:04 Today, it is 13.8 billion years old.

00:34:07 It took more than 12 billion years

00:34:10 for the light from this distant galaxy to reach our planet.

00:34:14 This galaxy is peaceful, stable, and surprisingly not chaotic,

00:34:19 unlike all the other galaxies

00:34:21 that were quite turbulent at the beginning.

00:34:24 To leave the Milky Way,

00:34:26 we would have to travel at about 25,000 light years

00:34:29 from the centre of the galaxy

00:34:31 or 500 light years vertically.

00:34:34 Our galaxy is a star disk

00:34:36 that extends over about 100,000 light years

00:34:39 and is 1,000 light years thick.

00:34:42 The Sun, its central star,

00:34:44 is halfway from the centre of the galaxy

00:34:47 and near the centre of the disk in the vertical direction.

00:34:51 Leaving the galaxy, we would have to go further than its edge

00:34:55 to get away from the halo surrounding the Milky Way,

00:34:58 old stars, diffuse gas, and globular amas.

00:35:01 If you wanted to go even further

00:35:03 to see the Milky Way in its entirety,

00:35:05 you would have to travel 48,000 light years vertically.

00:35:08 At present, we don't even have a telescope

00:35:11 that we could send there.

00:35:13 There are central stars that swallow up planets.

00:35:16 Our solar system is stable,

00:35:18 unlike many other planetary systems,

00:35:20 so we are not afraid that the Earth or another planet

00:35:23 will change its orbit and head towards the Sun.

00:35:26 But at least a quarter of other planetary systems

00:35:29 with stars orbiting similar to our Sun

00:35:31 have a rather chaotic past.

00:35:33 In some of them, planets were moving

00:35:35 and their unpredictable migration

00:35:37 may have disrupted the trajectories of some other planets

00:35:40 or even pushed them out of their orbit.

00:35:43 This means that some planets

00:35:45 probably fell into the central star.

00:35:47 When this happens,

00:35:49 the planet dissolves in the outer layer of the star,

00:35:52 which means that it is swallowed up.

00:35:55 You fall directly into the black hole

00:35:59 and prepare for a sad end.

00:36:01 Well, it's not so sure.

00:36:03 Falling into a black hole won't necessarily kill you

00:36:06 or destroy your spaceship.

00:36:08 But you will have to choose a large black hole

00:36:10 to hope to survive.

00:36:12 If you fall into a small black hole,

00:36:14 its event horizon is too narrow

00:36:16 and the gravity increases by every centimeter.

00:36:19 So if you put your arm forward,

00:36:21 the gravity at your fingers will be much stronger

00:36:23 than at your elbow.

00:36:25 Your hand will therefore stretch

00:36:27 and you will feel a certain discomfort,

00:36:29 or even an atrocious pain.

00:36:31 But it's not the same story

00:36:33 if you fall into a supermassive black hole

00:36:35 like those in the center of galaxies.

00:36:37 They can be millions of times heavier than the Sun.

00:36:40 Their event horizon is wide

00:36:42 and gravity doesn't change that quickly.

00:36:44 The force you will feel on your heels

00:36:46 and at the top of your head

00:36:48 will be about the same

00:36:50 and you will be able to reach the heart of the black hole.

00:36:52 And that's it, this myth has been deconstructed.

00:36:54 The next one claims that we can save the Earth

00:36:58 from a giant asteroid by making it explode first.

00:37:01 The scenario is as follows.

00:37:03 A spaceship lands on the surface of the asteroid.

00:37:06 A team of astronauts quickly drill a hole there,

00:37:09 leave a trapped package there and fly away.

00:37:12 And then, boom!

00:37:14 The asteroid will actually break into several pieces,

00:37:17 but will continue its race to Earth.

00:37:20 Big pieces will fall on our surface,

00:37:23 causing big damage.

00:37:25 The mission is a failure.

00:37:27 To save the Earth,

00:37:29 we actually need a big boom.

00:37:31 Not inside the asteroid,

00:37:33 but just above its surface.

00:37:35 When the boom occurs,

00:37:37 the force of the explosion

00:37:39 will push the asteroid slightly down.

00:37:41 Even a slight change in trajectory

00:37:43 would be enough for the asteroid

00:37:45 to pass over the Earth.

00:37:47 Mission accomplished.

00:37:49 Oh, what if we caused a big boom on an asteroid?

00:37:53 We wouldn't be able to hear the noise.

00:37:55 In movies, we always hear the noise of spaceships

00:37:57 and battles in space.

00:37:59 But that's just a myth.

00:38:01 Sound is a wave

00:38:03 that propagates because of the vibrations of molecules.

00:38:05 A person applauds a few meters from you.

00:38:08 The sound wave starts pushing the first air molecule

00:38:11 next to the boom,

00:38:13 then the second, the third,

00:38:15 and so on, until the wave reaches your ear.

00:38:18 To propagate sound,

00:38:20 you need molecules like air or water.

00:38:22 In our atmosphere,

00:38:24 sound waves propagate very well,

00:38:26 but space is a vacuum, so there's nothing.

00:38:28 You can tap your hands,

00:38:30 there will simply be no molecule

00:38:32 capable of vibrating and transporting this sound.

00:38:35 Another myth about asteroids.

00:38:37 We'll have to go a little further than Mars.

00:38:40 Here we are in an asteroid belt,

00:38:42 and we constantly have to avoid

00:38:44 giant rocks and ice blocks.

00:38:46 We've entered a dense cloud of asteroids.

00:38:49 Uh, actually, no.

00:38:51 It turns out that space is huge

00:38:53 and that the distances there are incredible.

00:38:55 All the rocks and debris of the asteroid belt

00:38:58 only represent 4% of the weight of the Moon.

00:39:00 So there really isn't that much.

00:39:02 To understand the size of the vacuum in space,

00:39:05 let's take the case of the collision between two galaxies.

00:39:08 There are billions of stars in each of them.

00:39:10 If we mix them up,

00:39:12 it's unlikely that there will be collisions.

00:39:14 Another myth is that zero gravity exists in our orbit.

00:39:18 Imagine that you are in a huge box

00:39:20 16 km in the air.

00:39:22 Now we drop the box,

00:39:24 and it starts to fall.

00:39:26 You fall at the same time as the box, at the same speed.

00:39:28 And there, it's as if you felt zero gravity.

00:39:31 The same thing happens in orbit.

00:39:33 The International Space Station

00:39:35 is located 400 km above Earth.

00:39:38 And it continuously falls,

00:39:40 not on the surface of the planet,

00:39:42 but around it, in its orbit.

00:39:44 Its speed is about 7.6 km per second.

00:39:47 It could cross the United States

00:39:49 from the West Coast to the East Coast

00:39:51 in just 8 minutes.

00:39:53 Astronauts are experimenting with the same thing.

00:39:55 They fall with the ISS at the same speed.

00:39:59 Now let's look at the Moon.

00:40:02 It always shows us only one side.

00:40:04 Does this mean that the Moon has a dark side

00:40:06 and that the sun's rays never reach it?

00:40:08 No.

00:40:09 It's still a myth.

00:40:11 The fact is that the Moon is linked to the Earth by gravity.

00:40:14 There are days and nights there too.

00:40:16 But it turns out that this rotation

00:40:18 is perfectly synchronized with that of the Earth.

00:40:20 So when you look at the Moon,

00:40:22 you always see only one side.

00:40:24 Although there are days when the sun shines there too,

00:40:27 it is not the hidden side but the opposite side.

00:40:30 We even have pictures of this place.

00:40:32 And we find there one of the largest craters

00:40:34 of our entire solar system,

00:40:36 the basin of the South Pole, Hyde Cane.

00:40:39 It is twice as wide as Texas.

00:40:42 One of the myths that has turned out to be false

00:40:44 is that humans never went to the Moon.

00:40:46 Here is the original space suit

00:40:48 of the first astronauts who went there.

00:40:51 Look at the sole of the shoe.

00:40:53 Some people claim that it is impossible

00:40:55 that they could leave footprints like this one there.

00:40:58 In fact, yes, it is possible.

00:41:00 On the Moon, astronauts wore additional boots

00:41:02 over their suits,

00:41:04 and their soles perfectly matched

00:41:06 the footprints on the Moon.

00:41:08 The astronauts did not take them

00:41:10 when they left the Moon.

00:41:12 They left a lot of things there.

00:41:14 They even tore off the seats' cushions

00:41:16 in the lunar module to reduce their weight.

00:41:18 Today, the total weight of human waste on the Moon

00:41:21 is about 187 tons,

00:41:24 including several lunar rovers,

00:41:26 debris from space ships,

00:41:28 rocket floors and lunar probes.

00:41:30 It is the equivalent of three Boeing 737s.

00:41:33 The next myth concerns the summer.

00:41:35 It states that the hot season comes

00:41:37 because the Earth is at its closest distance

00:41:39 from the Sun for a year.

00:41:41 The Sun would then warm up our planet more,

00:41:44 and it would be time to go to the beach.

00:41:46 This is not true.

00:41:48 Let's draw an axis across our planet.

00:41:50 It is slightly tilted on one side.

00:41:52 Winter comes when the axis of our planet

00:41:54 is tilted away from the Sun.

00:41:56 But over time, the axis tilts towards the warm star.

00:41:59 Its rays then shine at an angle

00:42:01 such that it is warmer.

00:42:03 It is true, however, that the Earth

00:42:05 is at different distances from the Sun

00:42:07 depending on the season.

00:42:09 This is because our orbit is not a perfect circle,

00:42:11 but slightly flattened,

00:42:13 in other words, an ellipse.

00:42:15 Normally, the distance to our star

00:42:17 is about 150 million kilometers,

00:42:19 but this distance can vary from 5 million kilometers

00:42:21 depending on the point of our orbit

00:42:23 and the time of our planet's orbit.

00:42:25 Another myth about the Sun is that it is yellow.

00:42:27 Let's take a closer look to see it.

00:42:29 You look out the window and...

00:42:31 it is white.

00:42:33 The Sun appears yellow only through

00:42:35 the filter of our atmosphere.

00:42:37 The composition of the air and its thickness

00:42:39 distort the light of the star.

00:42:41 However, stars do indeed exist

00:42:43 in different colors.

00:42:45 The colder stars have orange and bright red colors.

00:42:47 They are generally very old stars,

00:42:49 older than our Sun.

00:42:51 But the young and very hot stars

00:42:53 are bright blue.

00:42:55 The Sun is about in the middle of this spectrum.

00:42:57 You have also heard that

00:42:59 if you remove your space suit in space,

00:43:01 you will explode like a balloon.

00:43:03 Well, our bodies are designed to function

00:43:05 under the pressure of the atmosphere,

00:43:07 but space is a void.

00:43:09 Imagine a huge metal barrel

00:43:11 from which we sucked all the air it contained.

00:43:13 Add to this a temperature of -270 ° C

00:43:15 and you get the conditions

00:43:17 for the explosion of the Sun.

00:43:19 If you put yourself in these conditions,

00:43:21 all the air pockets of your body,

00:43:23 such as your lungs, for example,

00:43:25 will begin to expand.

00:43:27 You could really explode like a balloon

00:43:29 if your tissues were not so elastic.

00:43:31 But they stretch and bend,

00:43:33 so you keep the shape of your body.

00:43:35 You will have enough oxygen in your body

00:43:37 to last about 20 seconds.

00:43:39 Then your brain will start to lack oxygen

00:43:41 and you will faint.

00:43:43 You will not explode,

00:43:45 and you will not even freeze,

00:43:47 because you will be in the void

00:43:49 that does not conduct the temperature.

00:43:51 Water conducts temperature very well,

00:43:53 for example,

00:43:55 so you feel the cold instantly,

00:43:57 while you feel better in the air

00:43:59 at the same temperature.

00:44:01 If you are in the void of space,

00:44:03 very low temperature will not be a problem for you.

00:44:05 Solar radiation is much worse.

00:44:07 On Earth, we have a shield

00:44:09 against radiation,

00:44:11 in the form of an atmosphere

00:44:13 that blocks harmful rays.

00:44:15 In space, you will be defenseless.

00:44:17 Finally, between the absence of air,

00:44:19 cold temperatures and radiation,

00:44:21 you will really have only the choice.

00:44:23 Another myth is related to mobile phones.

00:44:25 People think that

00:44:27 when you make up your friend's number,

00:44:29 your phone sends a signal into space

00:44:31 that there are a whole bunch of satellites

00:44:33 that capture your signal and reflect it

00:44:35 like a mirror directly in your friend's phone.

00:44:37 No, it's not true.

00:44:39 However,

00:44:41 there are satellite phones in the world

00:44:43 that work this way.

00:44:45 But when you make a call on a cell phone,

00:44:47 your signal is transmitted

00:44:49 by a cellular tower system from one to the other

00:44:51 until it reaches your friend's phone.

00:44:53 We are in September 1977.

00:44:57 You play on one of the first

00:44:59 video game consoles

00:45:01 released in North America.

00:45:03 You go out and you see the whole neighborhood

00:45:05 waiting for the launch of "Traveler 1".

00:45:07 It's a very sunny day,

00:45:09 so you roll your eyes a little

00:45:11 to see what's going on.

00:45:13 You live in the neighborhood

00:45:15 right next to the launch station.

00:45:17 You buy yourself something to eat

00:45:19 and you watch "Traveler" take off into space.

00:45:21 You are so impressed

00:45:23 that you decide to make a career at NASA.

00:45:25 35 years later,

00:45:27 you are now a senior NASA official

00:45:29 specializing in the "Traveler 1" probe.

00:45:31 We are in 2012

00:45:33 and you are sitting in the control room

00:45:35 with your colleagues.

00:45:37 Everyone is staring at their computer screen

00:45:39 while working on the probe.

00:45:41 You are sitting up there,

00:45:43 watching everything,

00:45:45 making sure the systems are in order.

00:45:47 This day is special

00:45:49 because "Traveler 1" is about to leave the heliosphere,

00:45:51 which is a scientific term

00:45:53 to designate the outer envelope

00:45:55 of our solar system.

00:45:57 It is a space bubble affected by the solar wind

00:45:59 that comes from our aster.

00:46:01 In 2021,

00:46:03 the probe moved 22.5 billion kilometers away from Earth,

00:46:05 which is equivalent to

00:46:07 153 astronomical units.

00:46:09 An astronomical unit is the distance

00:46:11 between the Sun and the Earth.

00:46:13 Originally,

00:46:15 the probe was supposed to go through Uranus,

00:46:17 Saturn and Jupiter

00:46:19 and project from one planet to the other

00:46:21 thanks to their gravitational forces.

00:46:23 Everyone is impatiently waiting

00:46:25 for it to leave the heliosphere.

00:46:27 3, 2, 1

00:46:29 and it has officially left.

00:46:31 All systems are working properly.

00:46:33 All systems are working properly.

00:46:35 Congratulations to your team

00:46:37 for doing an excellent job.

00:46:39 With "Traveler 1" going so far,

00:46:41 there are still tons of places

00:46:43 to explore in space.

00:46:45 You were once a young adult

00:46:47 watching the launch of the ship

00:46:49 outside your neighborhood

00:46:51 and now you are the main person

00:46:53 in charge of the operations.

00:46:55 9 years later.

00:46:57 Since "Traveler 1" left the heliosphere,

00:46:59 you have been monitoring it from time to time

00:47:01 to make sure that all systems

00:47:03 and functions are in order.

00:47:05 You have sent measurements

00:47:07 of the interstellar environment.

00:47:09 This is the area between the stars

00:47:11 of our galaxy,

00:47:13 composed of ionized materials,

00:47:15 that is, more simply,

00:47:17 molecules or substances.

00:47:19 The interstellar environment

00:47:21 is a state of plasma charged electrically

00:47:23 or ionized plasma,

00:47:25 and it is very unstable.

00:47:27 It's like going from a strong storm

00:47:29 to a small calm rain in a few seconds.

00:47:31 The plasma up there

00:47:33 is different from the plasma on Earth,

00:47:35 in the sense that it is difficult to filter.

00:47:37 There is about one atom

00:47:39 per cubic centimeter

00:47:41 in the interstellar environment.

00:47:43 The air we breathe on Earth

00:47:45 contains billions of atoms.

00:47:47 By measuring the plasma in the interstellar environment,

00:47:49 we can better understand

00:47:51 the behavior and structure

00:47:53 of chemical products and gases.

00:47:55 It is possible that the oxygen

00:47:57 we breathe on Earth

00:47:59 is different from that of the interstellar space.

00:48:01 One of your main tasks

00:48:03 is to learn more about

00:48:05 how the solar wind and the interstellar environment

00:48:07 interact with each other

00:48:09 to create the heliosphere.

00:48:11 After having performed routine checks

00:48:13 and other maintenance work

00:48:15 on Voyager 1 from the control room,

00:48:17 you notice something strange

00:48:19 on the screen.

00:48:21 You are sitting in front of the computer,

00:48:23 you are crumpling the plasma vibrations

00:48:25 and converting them into an audio file

00:48:27 at 3 kHz.

00:48:29 You click on it and you listen

00:48:31 to a subtle and strange buzzing.

00:48:33 Your team and you are surprised

00:48:35 that these vibrations are produced

00:48:37 at such a low frequency.

00:48:39 Since space is massive,

00:48:41 this could mean the presence of life

00:48:43 on other planets.

00:48:45 All the other members of the station

00:48:47 rush into the control room

00:48:49 to listen to this sound from space.

00:48:51 It is monotonous and weak,

00:48:53 but it undoubtedly comes

00:48:55 from the interstellar environment.

00:48:57 You check the numbers again and again

00:48:59 to make sure that it is not a coincidence.

00:49:01 But it is very real.

00:49:03 You make sure that your team

00:49:05 does not reveal anything to anyone

00:49:07 from outside before everything is clearly determined.

00:49:09 You switch to "work" mode

00:49:11 and you try to capture the sound again.

00:49:13 And it is still there.

00:49:15 You can't sleep because you are thinking

00:49:17 about what could cause this noise.

00:49:19 A few days pass and the sound is quite constant.

00:49:21 If there was a life there

00:49:23 trying to communicate with you,

00:49:25 then it would have said something

00:49:27 that could have been deciphered.

00:49:29 You analyze the audio files again

00:49:31 to see if it is a phonetic language

00:49:33 that you do not know.

00:49:35 You call a linguist

00:49:37 to see if she can get something out of it.

00:49:39 Your team and you gather around her

00:49:41 impatiently waiting for answers.

00:49:43 After a while,

00:49:45 she thinks that there may be someone

00:49:47 there communicating with us.

00:49:49 But the only way to know it

00:49:51 is to send something.

00:49:53 You organize a meeting with your team

00:49:55 and you try to find what message

00:49:57 you could send.

00:49:59 After thinking a lot and drinking a lot of coffee,

00:50:01 you decide to send them the following sentence

00:50:03 "Who are you?"

00:50:05 You send the signal

00:50:07 through Voyager 1

00:50:09 and you wait for any change in the mess.

00:50:11 But you do not receive anything immediately.

00:50:13 It can take some time

00:50:15 before you get an answer.

00:50:17 You wait all night and still nothing.

00:50:19 You start to believe

00:50:21 that there is nothing there.

00:50:23 During the next two days,

00:50:25 you continue to send sentences

00:50:27 looking for a reaction to be captured.

00:50:29 As space is an empty space,

00:50:31 sound waves cannot move there.

00:50:33 So sending voice messages

00:50:35 on a giant speaker would not work.

00:50:37 You locate the source of the noise

00:50:39 and aim it when you send the audio file.

00:50:41 Every day you send something different.

00:50:43 Despite everything,

00:50:45 you have no news for a week.

00:50:47 It seems that intelligent life

00:50:49 in a distant world is not real.

00:50:51 The areas between stellar systems

00:50:53 of a galaxy are not necessarily

00:50:55 a complete void.

00:50:57 This is where the interstellar environment is.

00:50:59 It contains gases, dust

00:51:01 and cosmic rays,

00:51:03 which are energy particles.

00:51:05 After many months of recording

00:51:07 this constant noise,

00:51:09 you always try to understand what is happening.

00:51:11 You sit there, remembering the moment

00:51:13 when the Voyager probe was launched

00:51:15 for the first time.

00:51:17 You remember running outside

00:51:19 after playing your video games.

00:51:21 You could not see properly

00:51:23 because of the sun.

00:51:25 You stand there and you have a flash of genius.

00:51:27 You look at your notes taken in the past.

00:51:29 The answer was under your eyes

00:51:31 during all this time.

00:51:33 From time to time,

00:51:35 the sun sends an energy explosion

00:51:37 that vibrates the plasma of the interstellar space.

00:51:39 Scientists can measure the frequency of the waves

00:51:41 when the plasma vibrates

00:51:43 and how close they are to each other.

00:51:45 And the day the wave was emitted,

00:51:47 there were irregular frequencies

00:51:49 coming from the sun.

00:51:51 So this wave could be

00:51:53 the plasma vibrating in a strange way

00:51:55 because of the solar eruptions.

00:51:57 But these low-frequency vibrations

00:51:59 last longer than these quick jumps and peaks.

00:52:01 They are also weaker.

00:52:03 You do the tests again

00:52:05 and you discover that these are not

00:52:07 intelligent life forms trying to talk to you.

00:52:09 These are the small vibrations

00:52:11 caused by solar eruptions.

00:52:13 You inform your team of this breakthrough

00:52:15 and everyone is celebrating.

00:52:17 But after all these tests

00:52:19 and all these researches,

00:52:21 you still do not know why the plasma

00:52:23 of the interstellar space vibrates in this way.

00:52:25 These answers will have to wait.

00:52:27 2027

00:52:29 It's been 50 years

00:52:31 since Voyager 1 was launched.

00:52:33 You are now an advanced age

00:52:35 and you have just retired from NASA.

00:52:37 You have created numerous

00:52:39 programs for young people

00:52:41 who want to know more about space and science.

00:52:43 You return once again

00:52:45 to the control room

00:52:47 where you thought you had discovered

00:52:49 an intelligent life on a distant world.

00:52:51 Then you remember all the good times you've had.

00:52:53 You say goodbye to all this

00:52:55 knowing that these are the last moments

00:52:57 of Voyager.

00:52:59 The probe was designed to last up to 50 years.

00:53:01 After that, it will be

00:53:03 just a floating object in the vastness of space.

00:53:05 It is already surprising to know

00:53:07 that it is the most distant human object

00:53:09 on Earth.

00:53:11 But it's time to let other people

00:53:13 take your place.

00:53:15 You turn off the lights and you close the door.

00:53:17 The Voyager probe emits

00:53:19 a last beep before the eternal silence.

00:53:21 A single parking space in Hong Kong

00:53:27 sold for the astronomical sum

00:53:29 of 1.3 million dollars.

00:53:31 The sale has broken

00:53:33 the world record for the most expensive

00:53:35 parking space in the world.

00:53:37 The space is part of a residential

00:53:39 luxury complex called The Peak.

00:53:41 And this is where some of Asia's

00:53:43 most expensive housing is located.

00:53:45 One of the houses was rented in May

00:53:47 for the phenomenal sum of 210,000 dollars

00:53:49 per month.

00:53:51 That's 2.5 million dollars

00:53:53 per year. And the person

00:53:55 is not even the owner of the house.

00:53:57 The supreme history

00:53:59 breaks the records of the world's

00:54:01 largest and most expensive superyacht.

00:54:03 It is made of massive gold and is 30 meters long.

00:54:05 The yacht has

00:54:07 a water statue made of T-Rex,

00:54:09 a meteorite rock wall

00:54:11 in the main suite,

00:54:13 a panoramic gold

00:54:15 24-karat mural aquarium,

00:54:17 and a rare 18.5-karat

00:54:19 diamond on board.

00:54:21 Its manufacture cost

00:54:23 4.8 billion dollars in total.

00:54:25 A horse named Fusaichi

00:54:27 Pegasus was once sold

00:54:29 for 60 million dollars,

00:54:31 and a horse named Kintoki

00:54:33 was sold for 90 million dollars

00:54:35 in the current equivalent.

00:54:37 The heels were in high demand

00:54:39 after winning the Kentucky Derby

00:54:41 in 2000. In 2012,

00:54:43 a 14-karat gold Lego brick

00:54:45 sold for 12,500 dollars.

00:54:47 But it was not intended to be sold.

00:54:49 The company distributed bricks

00:54:51 as gifts to its long-time employees.

00:54:53 The Koh-i-Noor diamond

00:54:55 is the most precious in the world

00:54:57 and is literally priceless.

00:54:59 It is the main diamond

00:55:01 in the British Crown's jewels.

00:55:03 A single taco in Los Cabos,

00:55:05 Mexico, could cost you

00:55:07 25,000 dollars.

00:55:09 Made by a Michelin-starred chef,

00:55:11 its ingredients include

00:55:13 caviar, beef,

00:55:15 and a tortilla made with a 24-karat gold leaf.

00:55:17 Do you really have to eat it?

00:55:19 At 150,000 dollars per night,

00:55:21 the Lovers Deep luxury submarine hotel

00:55:23 is the most expensive hotel in the world.

00:55:25 It is located

00:55:27 underwater in the coral reef

00:55:29 off the coast of St. Lucie.

00:55:31 You need a submarine to get there.

00:55:33 For this price, you get

00:55:35 your own captain, your private chief,

00:55:37 and your captain's hat,

00:55:39 as well as other privileges.

00:55:41 The mermaids are an extra.

00:55:43 In November 2016, the franchise

00:55:45 Replace Believe It or Not

00:55:47 set a new Guinness World Record

00:55:49 for the most expensive dress ever sold

00:55:51 at auction.

00:55:53 It is the dress worn by Marilyn Monroe

00:55:55 when she sang "Happy Birthday"

00:55:57 to President John Kennedy

00:55:59 for his 45th birthday.

00:56:01 The dress, Jean-Louis Berthoud,

00:56:03 would include 2,500 crystals

00:56:05 and 6,000 hand-sewn straps,

00:56:07 and was sold for more than 500,000 dollars.

00:56:09 You're looking for a car you don't have

00:56:11 to sell to your friends?

00:56:13 It's the Ferrari 250 GTO.

00:56:15 It was sold during a private sale

00:56:17 by the German racing driver Christian Gleisel

00:56:19 for 70 million dollars.

00:56:21 It is part of the history

00:56:23 of the automobile industry,

00:56:25 winning the Tour de France in 1964.

00:56:27 It never had an accident,

00:56:29 which, experts say,

00:56:31 explains its great value.

00:56:33 One day, a woman took a plane

00:56:35 from Italy to the United Kingdom

00:56:37 to get a $16,400 haircut.

00:56:39 For this price, she was allowed

00:56:41 to take a limousine ride

00:56:43 to the airport, a head massage,

00:56:45 personalized hair products,

00:56:47 and a lunch.

00:56:49 In 2019, a Japanese sushi chef

00:56:51 sold it for $20 million

00:56:53 for a red tuna.

00:56:55 The 278-kilo fish was sold

00:56:57 at the Tokyo Fish Market.

00:56:59 It must have been a great sushi!

00:57:01 Developed by Chinese agronomists,

00:57:03 the Orchid Shenzhen Nongke

00:57:05 won the big prizes in 2005.

00:57:07 It took eight years to create it,

00:57:09 and the flower bloomed every four or five years.

00:57:11 It became the most expensive flower

00:57:13 ever sold when someone bought it

00:57:15 for $290,000.

00:57:17 The famous musician

00:57:19 Peter Scheidloff owned

00:57:21 one of the ten Stradivarius violins

00:57:23 still intact to this day.

00:57:25 It was auctioned in 2014

00:57:27 for a minimum price of $45 million.

00:57:29 There was no confirmed buyer,

00:57:31 so you can always put your hand

00:57:33 on the instrument,

00:57:35 the most expensive in the world.

00:57:37 The most expensive teddy bear

00:57:39 is a Louis Vuitton Steiff.

00:57:41 In 2000, it was sold for the

00:57:43 outrageous sum of $182,000.

00:57:45 A painting by Léonard de Vinci

00:57:47 won the big prizes

00:57:49 when it sold for $450 million.

00:57:51 After a 19-minute

00:57:53 auction,

00:57:55 the painting, called "Salvador Mundi",

00:57:57 was sold to the Saudi Arabian prince.

00:57:59 But experts are still debating

00:58:01 whether De Vinci

00:58:03 is the real author,

00:58:05 many believe it is a copy

00:58:07 of a lost work.

00:58:09 The most expensive house ever built

00:58:11 belongs to the business man

00:58:13 Mukesh Anbani.

00:58:15 He built this 37,000-square-foot

00:58:17 house in Mumbai in 2012.

00:58:19 It has 27 floors

00:58:21 and is worth $22.3 billion.

00:58:23 It has a spa,

00:58:25 a 168-seat garage,

00:58:27 a movie theater

00:58:29 that can accommodate 50 people,

00:58:31 three heliports, a ballroom,

00:58:33 a two-story leisure center

00:58:35 and, of course, a terrace garden.

00:58:37 An Easter egg cost

00:58:39 an astronomical sum of $8.4 million.

00:58:41 It has a shell

00:58:43 that is embedded with over a thousand diamonds.

00:58:45 Inside is a gold globe,

00:58:47 18 carats,

00:58:49 which contains a crystal-peaked dove

00:58:51 on a branch of gold olive.

00:58:53 The most expensive

00:58:55 company toy is an exclusive monopoly.

00:58:57 The set is covered in gold,

00:58:59 23 carats, ruby and sapphire.

00:59:01 The dice alone contain 42 diamonds

00:59:03 for the points.

00:59:05 If you want to play, it will cost you $200,000.

00:59:07 In Salerno, Italy,

00:59:09 the price of a pizza can reach $12,000.

00:59:11 It takes no less than 72 hours

00:59:13 to prepare the pizza Louis XIII.

00:59:15 When you order, a pizza YOLO

00:59:17 and a sommelier arrive at your house

00:59:19 with exclusive cutlery and plates

00:59:21 in limited edition.

00:59:23 The Blacky Boree coffee

00:59:25 often reaches the $675 per kilo bar,

00:59:27 but the manufacturing process

00:59:29 could be a bit of a challenge.

00:59:31 The grains go through the digestive tube of the elephant.

00:59:33 The stomach acids, the pachyderms,

00:59:35 break down the protein of the coffee,

00:59:37 which creates a unique and sweet flavor.

00:59:39 You're looking for a cup

00:59:41 to taste your deluxe coffee?

00:59:43 The most expensive coffee cup in the world

00:59:45 was made for Nestlé

00:59:47 and is gold 23 carats.

00:59:49 It will cost you $33,000.

00:59:51 The Interstate highway system

00:59:53 of the United States

00:59:55 is the most expensive transport project

00:59:57 of all time.

00:59:59 It took 46 years to finish

01:00:01 and its realization cost about $500 billion.

01:00:03 But it brought its fruits.

01:00:05 The system has brought back

01:00:07 economic productivity for every dollar

01:00:09 it has cost.

01:00:11 In 2019, a Patek Philippe watch

01:00:13 broke records by selling

01:00:15 at auction for the amazing sum

01:00:17 of $31 million.

01:00:19 It's a unique watch

01:00:21 and it was made especially

01:00:23 for a charity auction,

01:00:25 which helped raise the prices

01:00:27 of the auctions.

01:00:29 As its name suggests,

01:00:31 the billionaire couture umbrella

01:00:33 is the most expensive umbrella in the world.

01:00:35 It's waterproof and costs $50,000.

01:00:37 The price tag of the dress

01:00:39 of the most famous bride

01:00:41 is $3.5 million.

01:00:43 It has a cascading cape

01:00:45 and a neckline.

01:00:47 The dress was designed by Sarah Burton

01:00:49 for one of the most famous

01:00:51 tennis players of our time.

01:00:53 The royal melon, You Barry,

01:00:55 reaches prices up to $14,000.

01:00:57 It can only be found

01:00:59 in one region of the world

01:01:01 and it has a unique sweetness,

01:01:03 which explains its price.

01:01:05 Hawaii is the US state

01:01:07 where the cost of living is the highest.

01:01:09 The main factor is that it is

01:01:11 in the middle of the Pacific Ocean.

01:01:13 Basically, all physical goods

01:01:15 cost more because they must be shipped

01:01:17 from the continent.

01:01:19 The most expensive card in the world

01:01:21 is the Topps Mickey Mantle card

01:01:23 from 1952. Mantle was the centerpiece

01:01:25 and first base of the New York Yankees

01:01:27 from 1951 to 1968.

01:01:29 It was named three times

01:01:31 after the American League.

01:01:33 Only three of its collection cards

01:01:35 would be in circulation.

01:01:37 Rob Gau bought one of his cards

01:01:39 for the staggering sum of $5.2 million

01:01:41 in November 2020.

01:01:43 In first place, among the most expensive

01:01:45 dogs in the world, is the Samoyed.

01:01:47 It is from Siberia

01:01:49 and is known for its very affectionate nature.

01:01:51 It costs between $600 and $3,000.

01:01:53 An investment fund manager

01:01:55 bought the most expensive house

01:01:57 in the history of the United States.

01:01:59 The man bought the last four floors

01:02:01 of a building located in Central Park,

01:02:03 New York, for $238 million.

01:02:05 The house was sold unfinished,

01:02:07 so the price does not even include

01:02:09 the cost of decoration, furniture

01:02:11 or facilities.

01:02:13 The same man also holds the record

01:02:15 for the most expensive house purchases

01:02:17 in New York, Florida and Illinois.

01:02:19 The most expensive motorcycle in the world

01:02:21 is the Neyman Marcus Limited Edition Fighter.

01:02:23 It was put up for auction

01:02:25 with a starting price of $110,000.

01:02:27 But since Neyman Marcus is a chain

01:02:29 of luxury stores,

01:02:31 it received such a media coverage

01:02:33 that it was sold for $11 million.

01:02:35 The most expensive land plot

01:02:37 is located in China,

01:02:39 at the De Muret Road,

01:02:41 in the central district of Hong Kong Affairs.

01:02:43 The plot was sold in May 2017

01:02:45 for an astronomical sum of $3 billion.

01:02:47 It measures 2,900 square meters,

01:02:49 which means that each square meter

01:02:51 costs about $1 million.

01:02:53 The Zaha Hadid office,

01:02:55 an architect,

01:02:57 is currently designing

01:02:59 a 36-story skyscraper to occupy it.

01:03:01 Certainly, there is nothing more exciting

01:03:03 than a space battle full of lasers

01:03:05 that cross the darkness of the interstellar void

01:03:07 and cause joyful flames.

01:03:09 But that's not exactly what happens

01:03:11 when something explodes in space.

01:03:13 It is essentially empty,

01:03:15 which means that there is no oxygen

01:03:17 as on Earth.

01:03:19 And oxygen is an essential component

01:03:21 of any combustion process.

01:03:23 You're going to tell me that stars burn

01:03:25 and explode in supernovae,

01:03:27 but that's not quite true either.

01:03:29 Stars do not consume oxygen,

01:03:31 so they do not burn,

01:03:33 but they are the stage

01:03:35 for constant thermonuclear reactions.

01:03:37 A space ship could therefore

01:03:39 only explode in this way

01:03:41 if it transported a nuclear power plant.

01:03:43 Without that, the only thing you would see

01:03:45 would be a brief flash,

01:03:47 dissipating in a blink of an eye.

01:03:49 Liquid oxygen, which is often

01:03:51 a space gas, burns extremely quickly

01:03:53 in the vacuum of space.

01:03:55 As for the boom, oxygen plays

01:03:57 a crucial role here too.

01:03:59 Sound travels only through the air molecules

01:04:01 that collide with each other.

01:04:03 As there is no air in space,

01:04:05 the place is absolutely silent.

01:04:07 And that's not necessarily a bad thing.

01:04:09 Imagine how deafening the sun would be

01:04:11 if sound could travel in space.

01:04:13 Despite what many science fiction directors

01:04:15 want us to believe,

01:04:17 the moon has no dark side.

01:04:19 The moon is under a gravitational lock,

01:04:21 which means it is always

01:04:23 facing us on one side.

01:04:25 The sun is much further away from us

01:04:27 than the moon, and we turn with it

01:04:29 around it, heated and lit

01:04:31 from all sides successively.

01:04:33 This means that once in a while,

01:04:35 each side of the moon is lit by the sun.

01:04:37 Only we can see only one.

01:04:39 While things seem to be

01:04:41 weightless in space,

01:04:43 there is actually gravity everywhere.

01:04:45 The further we move away from a heavy object,

01:04:47 the more it weakens,

01:04:49 but it is always present.

01:04:51 In fact, there is not a single place in the universe

01:04:53 that is not affected by the gravity

01:04:55 of such or such cosmic object.

01:04:57 Everything that has mass has gravity.

01:04:59 Yes, even you and me.

01:05:01 But objects in space are so massive

01:05:03 that they attract smaller things.

01:05:05 That's why the planets of the solar system

01:05:07 rotate around the sun,

01:05:09 and why our galaxy, the Milky Way,

01:05:11 rotates around its own center.

01:05:13 Scientists think there is a supermassive

01:05:15 gravity system, about 4 million times

01:05:17 heavier than the sun, which prevents

01:05:19 all the stars and all systems

01:05:21 from moving away from each other.

01:05:23 Our movie heroes leave the orbit of Mars,

01:05:25 board their faithful spaceship,

01:05:27 and head for Jupiter.

01:05:29 They have serious and resolute faces,

01:05:31 because they know that a threat awaits them.

01:05:33 The asteroid belt.

01:05:35 They maneuver as best they can,

01:05:37 avoiding the asteroids that fly at high speed

01:05:39 towards them, but one of them still hits them.

01:05:41 Well, it's just a scratch, fortunately.

01:05:43 In the end, our heroes leave

01:05:45 this dangerous area and sponge the sweat

01:05:47 of their forehead with a trembling hand.

01:05:49 Does it sound familiar to you?

01:05:51 Well, it couldn't be further

01:05:53 from the truth.

01:05:55 The asteroids of the belt between Mars and Jupiter

01:05:57 are so few and so far

01:05:59 from each other that if you ever

01:06:01 had to go through there, you may not

01:06:03 see any on your journey.

01:06:05 There are about 1.5 million

01:06:07 significant-sized space rocks

01:06:09 in this belt. About half a million.

01:06:11 But let's not forget that space is vast.

01:06:13 There is still a distance of several

01:06:15 million kilometers between two important asteroids.

01:06:17 So a chase between

01:06:19 two spaceships, flapping between

01:06:21 rocks suspended in the void,

01:06:23 wouldn't be as fun as we want to make it seem.

01:06:25 Space is often described

01:06:27 as a dark, cold and desolate place,

01:06:29 especially when a movie star

01:06:31 leaves the safety of his spaceship.

01:06:33 And all of this is correct, except for the cold.

01:06:35 It wouldn't be true if you were

01:06:37 in a very far corner of our galaxy,

01:06:39 without a star nearby.

01:06:41 But if you are, for example, orbiting

01:06:43 the Earth and directly in front of the Sun,

01:06:45 the temperature in the cosmic void

01:06:47 is close to 120 degrees.

01:06:49 That's why space suits

01:06:51 are white. This color reflects

01:06:53 the light better than all the others.

01:06:55 However, you can literally have a very cold

01:06:57 back if it is not exposed

01:06:59 to the sun's rays.

01:07:01 Heat does not spread equally in space.

01:07:03 And if you don't turn to a source of

01:07:05 heat, you will be cold. Very cold.

01:07:07 And since we are talking about the Sun,

01:07:09 it always appears yellow in the movies.

01:07:11 But the color we see from the Earth

01:07:13 is actually an optical illusion

01:07:15 created by the atmosphere of our planet.

01:07:17 Just like the blue sky during the day.

01:07:19 The light of the Sun spreads

01:07:21 in the atmosphere and distorts,

01:07:23 which gives colorful shows at dawn and dusk.

01:07:25 In the void of space,

01:07:27 there is nothing that can refract the light,

01:07:29 so that the Sun appears

01:07:31 as it really is, white.

01:07:33 And yes, this incandescent gas ball

01:07:35 is as hot as that.

01:07:37 There is an intense flash in the sky,

01:07:39 followed by a smoke stream,

01:07:41 and a burning space rock

01:07:43 comes crashing on the ground,

01:07:45 leaving a huge crater

01:07:47 carbonized after the impact.

01:07:49 Although there was real in this

01:07:51 smoke stream and this crater,

01:07:53 meteorites cannot reach such high temperatures

01:07:55 during their fall. A meteorite is an asteroid

01:07:57 which, for one reason or another,

01:07:59 has entered the Earth's atmosphere

01:08:01 and has sufficiently resisted its friction

01:08:03 to fall on the Earth.

01:08:05 We rarely see these rocks,

01:08:07 because they are usually very small

01:08:09 and fall in uninhabited areas.

01:08:11 But even if one of these bolides

01:08:13 fell on a city, its crater would have

01:08:15 its speed and not its heat.

01:08:17 They become very hot because of the friction,

01:08:19 but not to the point of burning everything

01:08:21 to the ground during the impact.

01:08:23 Although we love to think that

01:08:25 instantaneous communication between

01:08:27 space shuttles and planets is possible,

01:08:29 this is not the case.

01:08:31 We rely on radio signals,

01:08:33 and these are quite slow,

01:08:35 considering the vast expanses of space.

01:08:37 It would take years for such a signal

01:08:39 to travel, if not a light year.

01:08:41 So imagine what it would be for hundreds

01:08:43 and thousands!

01:08:45 If you wanted to send a message to a very distant galaxy,

01:08:47 you would have to wait a few millennia

01:08:49 before it arrives, then a few thousand years

01:08:51 before receiving an answer.

01:08:53 And space is not as crowded

01:08:55 and full of events as it is presented in the cinema.

01:08:57 It is a rather deserted place,

01:08:59 where planets, stars and other objects

01:09:01 are separated by billions of kilometers of void.

01:09:03 Even if you had a spaceship

01:09:05 that could travel at the speed of light,

01:09:07 most of the time you would only see

01:09:09 a black void made up of stars

01:09:11 and very distant planets.

01:09:13 The distances are immense,

01:09:15 even between the closest objects to each other.

01:09:17 To better understand, the Moon,

01:09:19 which you can see so well at night,

01:09:21 is located about 384,400 km from us.

01:09:23 This represents almost ten times

01:09:25 the circumference of the Earth.

01:09:27 Distortion engines can distort space-time

01:09:29 and make you reach a corner

01:09:31 far from another galaxy in a blink of an eye.

01:09:33 It is one of the basic elements

01:09:35 of space fiction.

01:09:37 We still see spaceships,

01:09:39 capable of such a feat,

01:09:41 accelerating instantly from zero

01:09:43 to faster than light.

01:09:45 According to the laws of physics,

01:09:47 passengers should at least feel

01:09:49 crushed in their seats.

01:09:51 More precisely, no one could survive

01:09:53 such an acceleration because gravity

01:09:55 is too immense for the human body.

01:09:57 As long as we have not found a way

01:09:59 to reduce its effects from the Earth,

01:10:01 it is useless to think about distortion engines.

01:10:03 Water is not the rarest and

01:10:05 most precious resource in the universe.

01:10:07 In fact, there is a huge cloud

01:10:09 several million light years away from us

01:10:11 and it is entirely made up of water.

01:10:13 Its reserves would be enough

01:10:15 to fill our oceans 140 billion times.

01:10:17 And many planets,

01:10:19 some even in our solar system,

01:10:21 seem to contain liquid water.

01:10:23 Life is a great deal,

01:10:25 and a great many elements are necessary

01:10:27 for its appearance, not just liquid water.

01:10:29 We often see astronauts training

01:10:31 on the ISS and space ships in science fiction.

01:10:33 And it's true, they need physical activity.

01:10:35 But it's not because they have to be

01:10:37 very strong to work in space.

01:10:39 Gravity is much weaker there,

01:10:41 and astronauts do not use

01:10:43 as much of their muscles as on Earth.

01:10:45 So when they go back down,

01:10:47 gravity catches up with them

01:10:49 and they feel extremely weak.

01:10:51 We often say that it is possible

01:10:53 to see millions of stars

01:10:55 by a beautiful clear night,

01:10:57 but it's far from true.

01:10:59 You can count about 3,000.

01:11:01 The other bright spots you see

01:11:03 are luminous objects that are confused

01:11:05 with stars, planets, distant galaxies

01:11:07 and even artificial satellites.

01:11:09 These objects are simply illuminated

01:11:11 by real stars or the moon

01:11:13 and become visible.

01:11:15 But because they are so far from us,

01:11:17 we can't know if they are or not stars.

01:11:19 We have to admit it.

01:11:21 We will start with one of the most recent

01:11:23 and most shocking discoveries of 2020.

01:11:25 Maybe our solar system

01:11:29 is sheltering life elsewhere than on Earth.

01:11:31 Here is Venus, the second planet

01:11:35 from the Sun and the sister

01:11:37 of our original planet.

01:11:39 It is called that because it has a similar

01:11:43 size and mass.

01:11:45 But the conditions that reign there are simply terrible.

01:11:47 The surface temperature reaches

01:11:49 477 ° C because of the greenhouse effect.

01:11:51 And the atmospheric pressure there is as high

01:11:55 as if you were 900 meters under water.

01:11:57 But in this hostile world,

01:11:59 there could be life.

01:12:01 For many years,

01:12:03 there have been discussions on this subject.

01:12:05 In 2007, scientists discovered

01:12:07 that there was an ocean on Venus.

01:12:09 That is to say that in the distant past,

01:12:11 there could have been a form of life.

01:12:13 But in the fall of 2020,

01:12:15 there was a heated debate

01:12:17 during which scientists tried to discover

01:12:19 if life on Venus actually existed.

01:12:21 In September, the discovery

01:12:23 of a new life marker on Venus

01:12:25 was announced.

01:12:27 The ALMA telescope in the Atacama Desert

01:12:29 found phosphine gas

01:12:31 above the planet.

01:12:33 And the amount of this gas suggested

01:12:35 that it could have been produced

01:12:37 by some microorganisms.

01:12:39 But in October,

01:12:41 the data were analyzed again

01:12:43 and the results indicated that it was a mistake.

01:12:45 Today, we consider

01:12:47 that Venus was uninhabited.

01:12:49 But who knows,

01:12:51 maybe soon we will have new data

01:12:53 and new debates will arise in the scientific circles.

01:12:55 And while some scientists

01:12:57 scratch their heads and focus

01:12:59 on Venus,

01:13:01 others have looked into the distant space

01:13:03 and discovered 24 planets

01:13:05 on which life could exist.

01:13:07 And on all these planets,

01:13:09 the living conditions are much better than on Earth.

01:13:11 These super planets

01:13:13 must be 1.3 times larger

01:13:15 than Earth

01:13:17 and twice as massive.

01:13:19 Thus, they will have a stronger gravity

01:13:21 and therefore a denser and warmer atmosphere.

01:13:23 The climate of the super-inhabitable planets

01:13:25 must therefore be similar to the tropical climate of Earth.

01:13:27 This will ensure

01:13:29 a maximum diversity of living organisms.

01:13:31 The high star

01:13:33 of such a planet

01:13:35 must be a red dwarf.

01:13:37 They are much smaller than the Sun

01:13:39 and less bright,

01:13:41 but their lifespan can reach 70 billion years.

01:13:43 For comparison,

01:13:45 the lifespan of the Sun

01:13:47 is 7 times shorter

01:13:49 and it has already exceeded half.

01:13:51 However, it is better to prioritize

01:13:53 slowness and stability.

01:13:55 This will give enough time to life

01:13:57 to develop and evolve.

01:13:59 Here is a planet that suits the title

01:14:01 of super-inhabitable,

01:14:03 Kepler 1649 c.

01:14:05 In 2020, it was named

01:14:07 the most similar planet to Earth.

01:14:09 It is only 6% larger than our original world.

01:14:11 It revolves around a red dwarf

01:14:13 that is a quarter the size of our Sun.

01:14:15 The planet is in the habitable zone

01:14:17 of the star and makes a complete circle

01:14:19 around it in 19.5 days.

01:14:21 The climate on Kepler

01:14:23 remains a mystery.

01:14:25 We know that it receives about 75%

01:14:27 of the light we receive from the Sun.

01:14:29 The temperature at its surface

01:14:31 can therefore be close to that of Earth.

01:14:33 But we still do not know

01:14:35 the composition of its atmosphere

01:14:37 and the other conditions necessary

01:14:39 for life to appear there.

01:14:41 The next discovery is one of the most

01:14:43 amazing shows ever seen by humanity.

01:14:45 It is the collision of a star

01:14:47 with a black hole.

01:14:49 In September 2019, scientists

01:14:51 began to observe how, for 6 months,

01:14:53 a star similar to the Sun

01:14:55 had spaghettized.

01:14:57 The light of this event has traveled

01:14:59 215 million light years

01:15:01 and we have seen a star

01:15:03 that is about a million kilometers wide

01:15:05 sucked by a black hole.

01:15:07 This black disc is so heavy

01:15:09 that it has an incredibly strong gravity.

01:15:11 Nothing can leave its gravitational field.

01:15:13 And today, we can observe

01:15:15 a star that is slowly approaching it.

01:15:17 First, the luminous layers of the star

01:15:19 begin to spread towards the black hole.

01:15:21 It looks like the star is unfolding

01:15:23 like a thread.

01:15:25 Then we can see the hot plasma

01:15:27 linger on the edges of the black hole

01:15:29 and it seems that these particles

01:15:31 are coming from here.

01:15:33 But this is just an illusion.

01:15:35 This ring of light is called

01:15:37 the event horizon.

01:15:39 The black hole not only curves space

01:15:41 but also time.

01:15:43 In this proximity, time slows down.

01:15:45 For the observer, it seems that the light

01:15:47 near the edge of the black disc

01:15:49 has almost stopped.

01:15:51 But in fact, it has been absorbed

01:15:53 for a long time by the dark abyss.

01:15:55 When a black hole swallows

01:15:57 a certain amount of stellar matter,

01:15:59 it is absorbed at a speed of more than

01:16:01 9,700 km/s.

01:16:03 It is this light that attracted

01:16:05 the attention of scientists.

01:16:07 In the end, the black hole

01:16:09 completely absorbed about half of the star

01:16:11 and spit out the other half in space.

01:16:13 And even if we have observed

01:16:15 this process for only a few minutes,

01:16:17 it took place for 6 months.

01:16:19 And here is one of the youngest

01:16:21 planetary systems that humanity

01:16:23 has ever observed.

01:16:25 AU Microscopy.

01:16:27 It is estimated that there is still a disc

01:16:29 around it, coming from debris

01:16:31 in which this system was formed.

01:16:33 But this time, we do not even hope

01:16:35 to find life here.

01:16:37 The high star of this exoplanet

01:16:39 continuously emits radiation eruptions

01:16:41 that would annihilate any form of life

01:16:43 on the planet's surface.

01:16:45 The planet orbiting this dangerous star

01:16:47 is called AU Mic B.

01:16:49 And it is only a new born

01:16:51 according to astronomical standards.

01:16:53 It is so close to its star

01:16:55 that it is estimated to be 8.5 days away.

01:16:57 The age of this planet is only 12 million years.

01:16:59 Thus, at the time

01:17:01 when AU Mic B was born,

01:17:03 mastodons were already walking

01:17:05 on the surface of our planet.

01:17:07 And meadows and savannas

01:17:09 covered the face of the Earth.

01:17:11 So, the earthlings can consider themselves

01:17:13 as old, because the age of the Earth

01:17:15 is almost 4.5 billion years.

01:17:17 The next discovery took place

01:17:19 at the beginning of 2020,

01:17:21 and it looks a lot like a science fiction landscape.

01:17:23 The first star of the universe

01:17:25 is a planet with two suns.

01:17:27 More precisely, it does not orbit

01:17:29 around a single star,

01:17:31 as we are used to in our solar system,

01:17:33 but around a binary stellar system,

01:17:35 TOI 1338.

01:17:37 The first big star is like our sun,

01:17:39 while the other is a red dwarf,

01:17:41 three times smaller.

01:17:43 These stars orbit completely

01:17:45 one around the other in a little over 14 days.

01:17:47 The planet orbiting these stars

01:17:49 is the size of Saturn,

01:17:51 and it is a very beautiful planet.

01:17:53 Although sunsets and sunrises

01:17:55 are incredibly beautiful,

01:17:57 it is unlikely that this planet

01:17:59 is suitable for any form of life.

01:18:01 It is outside the habitable zone

01:18:03 of these high stars,

01:18:05 so it probably has no liquid water.

01:18:07 Mysterious radio signals

01:18:09 from space were also captured in 2020.

01:18:11 These are fast radio surges.

01:18:13 Scientists have already recorded

01:18:15 such signals before,

01:18:17 but recently they have managed to prove

01:18:19 that the moon is rusted.

01:18:21 The new data has forced scientists

01:18:23 to develop a very bold theory

01:18:25 that their source could be a magnetar.

01:18:27 A magnetar is a small neutron star

01:18:29 with a huge mass compared

01:18:31 to ordinary stars like the sun.

01:18:33 But they have the strongest magnetic field

01:18:35 in the universe.

01:18:37 Their lifespan is, however, very short,

01:18:39 only one million years.

01:18:41 But what disconcerted scientists the most

01:18:43 this year was to discover

01:18:45 that the moon is rusty.

01:18:47 It needs oxygen and water to produce it.

01:18:49 But the moon does not have its own atmosphere

01:18:51 to have both.

01:18:53 The main theory suggests

01:18:55 that the solar wind would be responsible for this.

01:18:57 It moves at high speed

01:18:59 and erases oxygen from the upper layers

01:19:01 of the Earth's atmosphere.

01:19:03 The wind continues to transport

01:19:05 oxygen molecules into space,

01:19:07 and finally they reach the surface of the moon

01:19:09 and rust the metallic ore.

01:19:11 Moreover, the characteristic red color

01:19:13 of Mars was created because of rust.

01:19:15 For a long time,

01:19:17 there was an atmosphere and water.

01:19:19 In combination with the iron on its surface,

01:19:21 it triggered a long process of rust

01:19:23 that has been going on since ancient times.

01:19:25 Another amazing discovery was made

01:19:27 on the surface of the moon

01:19:29 with a stratospheric telescope.

01:19:31 It is a telescope transported by a plane.

01:19:33 The latter raises it to an altitude of 13 km,

01:19:35 which allows it to have a quality of image

01:19:37 comparable to that of space telescopes.

01:19:39 And thanks to such an unusual observatory,

01:19:41 scientists were able to find water

01:19:43 on the surface of the moon.

01:19:45 Water molecules have been found

01:19:49 in one of the largest craters

01:19:51 of the visible phase of the satellite.

01:19:53 But the number of water molecules

01:19:55 is still extremely low.

01:19:57 The Sahara Desert contains

01:19:59 about 100 times more water

01:20:01 than the surface of the moon.

01:20:03 Houston, we have good news.

01:20:07 A group of carefully selected people

01:20:09 is being interviewed

01:20:11 to board the first commercial volume

01:20:13 to the extraspheric space.

01:20:15 The space agency offers you

01:20:17 to answer a questionnaire.

01:20:19 It wants to know what you would bring

01:20:21 in this space adventure.

01:20:23 Depending on your answers,

01:20:25 you could be one of the chosen people.

01:20:27 What if we looked at this list together?

01:20:29 Pencils!

01:20:33 I would never have thought of it,

01:20:35 but it makes sense.

01:20:37 The legend says that the United States

01:20:39 tried to design a pen that works

01:20:41 in space.

01:20:43 Indeed, as the absence of gravity

01:20:45 is an important factor,

01:20:47 I mean, essential,

01:20:49 of life in space,

01:20:51 the pens do not work.

01:20:53 The ink does not flow like here on Earth.

01:20:55 On the other hand,

01:20:57 pencils are very convenient.

01:20:59 You can play word games

01:21:01 with other space tourists

01:21:03 or even draw pictures

01:21:05 representing your adventure.

01:21:07 The toothbrushes are extremely simple,

01:21:09 but their technology is enough

01:21:11 for space.

01:21:13 If you squeeze a bottle of water

01:21:15 inside a spaceship,

01:21:17 the water molecules float in small bubbles.

01:21:19 But if you wet your toothbrush,

01:21:21 it naturally retains water,

01:21:23 which allows it to stay moist

01:21:25 to support the toothpaste.

01:21:27 Oh, I was going to say funny socks!

01:21:29 Glad you put me in front of C.

01:21:31 But there are two things to know.

01:21:33 First, we do not walk a lot

01:21:35 in space. People do not

01:21:37 tend to touch the ground up there.

01:21:39 Secondly, space is not

01:21:41 the best place to show your style.

01:21:43 Astronauts tend to wear

01:21:45 special clothes when they are

01:21:47 on a space mission.

01:21:49 It will be the same for you as a holiday astronaut.

01:21:51 Socks will keep

01:21:53 your feet warm, but they will also

01:21:55 testify to your interest in fashion.

01:21:57 Maybe one day you will wear

01:21:59 a sock with a smiling face,

01:22:01 while the other day you will opt for a sock

01:22:03 with a Grinch theme.

01:22:05 Of course, socks are very useful

01:22:07 on a plane, because they allow you

01:22:09 to sneak more easily between objects.

01:22:11 The next time I go to the

01:22:13 Super 8, I will not forget to buy

01:22:15 wet wipes for the space trip.

01:22:17 The space travelers love them.

01:22:19 And it was not even NASA

01:22:21 who invented them, huh?

01:22:23 As water is not allowed inside

01:22:25 a spaceship, wet wipes

01:22:27 are the best option.

01:22:29 Even better if they are scented.

01:22:31 Astronauts even use different types

01:22:33 of wipes. They buy the disinfectant

01:22:35 and the one they use on their bodies.

01:22:37 Just make sure you know

01:22:39 the difference between the two when you are up there.

01:22:41 A popular myth

01:22:43 wants NASA to have invented Velcro.

01:22:45 In reality, we tend to

01:22:47 think that everything used in space

01:22:49 was invented by NASA for a very

01:22:51 intelligent and specific purpose.

01:22:53 But this is not the case.

01:22:55 Velcro was invented for banal reasons

01:22:57 in the 1950s

01:22:59 by a Swiss company.

01:23:01 Space travelers adopted it because

01:23:03 it works as an anti-gravity accessory.

01:23:05 They cannot eliminate gravity,

01:23:07 of course. But you can stick Velcro

01:23:09 on everyday objects,

01:23:11 then hang these objects on Velcro

01:23:13 fixed to the walls of the spaceship.

01:23:15 It is a very intelligent system.

01:23:17 But it is better to take your own share,

01:23:19 isn't it?

01:23:21 If you spend a long time in space,

01:23:23 photos from your home can be useful.

01:23:25 But choose them well.

01:23:27 The spaceship is not very big,

01:23:29 the other people on board will know

01:23:31 which photo you decided to take.

01:23:33 It is better to keep the Harry Styles poster

01:23:35 in your bedroom, isn't it?

01:23:37 Just bring real photos

01:23:39 of people you know and love.

01:23:41 Did I hear pizza?

01:23:43 Traveling and exploring new places

01:23:49 is above all tasting different flavors

01:23:51 of food.

01:23:53 In space, it is a little more complicated.

01:23:55 But at least you can take pizza

01:23:57 with you.

01:23:59 In fact, it should be delivered in a cargo ship.

01:24:01 So the ingredients would be fresh

01:24:03 and ready to be consumed.

01:24:05 It would not be the first time

01:24:07 that people in space would try to eat

01:24:09 terrestrial food.

01:24:11 Some astronauts even ate crepes and hot dogs.

01:24:13 The most beautiful thing about this pizza party

01:24:15 is that the food can float.

01:24:17 Isn't that a very pleasant way

01:24:19 to taste terrestrial food?

01:24:21 Hmm...

01:24:23 I understand your desire to take

01:24:25 toilets with you on this space trip.

01:24:27 It's practically impossible.

01:24:29 Finally, I understand you.

01:24:31 Some people are attached to the toilets

01:24:33 of their homes.

01:24:35 And those of space are far from being the ideal experience.

01:24:37 But NASA has not stopped improving

01:24:39 these toilets, which have never been

01:24:41 as well equipped as now.

01:24:43 So we'll have to settle for it.

01:24:45 Here's something I'd take too.

01:24:47 A laptop.

01:24:49 But what would it be used for in space?

01:24:51 Apparently, there is internet

01:24:53 everywhere in the International Space Station.

01:24:55 So even if you don't spend

01:24:57 most of your journey at sea at the ISS,

01:24:59 you can enjoy Netflix

01:25:01 the days you will be there.

01:25:03 Internet in the entire International Space Station.

01:25:05 It's crazy, isn't it?

01:25:07 Speaking of leisure,

01:25:09 I love that you thought of taking a yo-yo.

01:25:11 I'm not sure it's very effective

01:25:13 in space, since there is no gravity

01:25:15 to make it bounce.

01:25:17 But it would be nice to see how it would react

01:25:19 in an environment devoid of gravity.

01:25:21 I love puzzles.

01:25:23 It would also be part of my list.

01:25:25 Imagine that you are trying to build a puzzle

01:25:27 that keeps floating in the air.

01:25:29 You may have to create a system to prevent

01:25:31 the different pieces from floating freely

01:25:33 in the spacecraft.

01:25:35 But imagine that once the puzzle of the turtle is finished,

01:25:37 it looks like it's swimming through the ship.

01:25:39 It is impossible to take away a window,

01:25:41 but windows are an important element

01:25:43 of life in space.

01:25:45 Let's keep in mind some of the rules of travel.

01:25:47 Each traveler will have the opportunity

01:25:49 to go out into space during their stay.

01:25:51 It's already huge, be happy.

01:25:57 Because some elite astronauts have the opportunity

01:25:59 to go out into space only once

01:26:01 throughout their career.

01:26:03 Indeed, going out into space is risky

01:26:05 and requires a lot of training.

01:26:07 But you will receive your training

01:26:09 once you are up there.

01:26:11 The fact is that every other day,

01:26:13 you will be stuck inside a box

01:26:15 of floating cans.

01:26:17 The windows are therefore very useful.

01:26:19 They will help you remember where you are.

01:26:21 They will give you a perspective

01:26:23 of space and the Earth.

01:26:25 Of course, you have to take your camera.

01:26:27 Otherwise, how could you

01:26:29 remember this unique experience?

01:26:31 Make sure your camera

01:26:33 works inside a plane or ISS

01:26:35 and you will be ready to go.

01:26:37 Mmm, coffee.

01:26:39 Don't worry, you don't need

01:26:41 to take yours.

01:26:43 In the past, astronauts had to

01:26:45 be content with instant coffee cups

01:26:47 when they were in space.

01:26:49 But you are lucky,

01:26:51 coffee experts have already solved this problem.

01:26:53 Today, there is the ISSpresso machine.

01:26:55 The latter is the same size

01:26:57 as a terrestrial espresso machine.

01:26:59 But to drink coffee,

01:27:01 space travelers must use

01:27:03 a special cup in weight

01:27:05 and a straw.

01:27:07 If you try to drink normally,

01:27:09 hot coffee will not hit you directly

01:27:11 but on the contrary, it will stay stuck

01:27:13 at the bottom of the cup.

01:27:15 I must say that I really like this invention.

01:27:17 Finally, why not take your guitar?

01:27:19 I noticed that you were missing

01:27:21 a musical instrument.

01:27:23 If it was a classic volume,

01:27:25 you might have to pay an extra for the luggage.

01:27:27 But as everything is included,

01:27:29 don't be embarrassed and take your guitar.

01:27:31 Astronauts like Chris Hadfield

01:27:33 take their musical instruments

01:27:35 when they are in space.

01:27:37 He even became famous for his version

01:27:39 to the point that Bowie himself told him

01:27:41 that he loved his version.

01:27:43 It allows you to pass the time

01:27:45 but it is also an excellent way to socialize.

01:27:47 Can you imagine a semblance of fire of joy

01:27:49 in the void of space?

01:27:51 I do, and it looks super cool.

01:27:53 Well, I think you're ready to go.

01:27:55 I will personally call NASA

01:27:57 to ask them to designate you

01:27:59 as one of the happy space travelers.

01:28:01 See you soon in space, amigo!

01:28:03 Hi friends!

01:28:07 Today, we are going to unravel

01:28:09 some myths about space.

01:28:11 Get on board our shuttle

01:28:13 and let's clear it all up

01:28:15 once and for all.

01:28:17 Imagine this.

01:28:19 You float in space

01:28:21 drinking a cup of hot chocolate

01:28:23 when a strange thought

01:28:25 comes to your mind.

01:28:27 Can we scream in space?

01:28:29 And if so, would anyone hear this scream?

01:28:35 If you've seen Alien,

01:28:37 you know the answer.

01:28:39 You can't hear sounds in space.

01:28:41 It's not that sounds don't exist.

01:28:43 It's just that you can't hear them.

01:28:45 There is no one better placed

01:28:47 to unravel this myth than Chris Hadfield.

01:28:49 He participated in several

01:28:51 space trips during his astronaut life.

01:28:53 Once in the darkness of space,

01:28:55 you can't hear anything anymore.

01:28:57 All you hear is silence.

01:28:59 Absolute silence.

01:29:01 But,

01:29:03 just next to it,

01:29:05 there is a huge fireball,

01:29:07 the Sun.

01:29:09 We can't hear these explosions

01:29:11 because there is nothing to carry the sounds.

01:29:13 But it probably wouldn't be very pleasant

01:29:15 for the astronauts

01:29:17 if they could hear all the sounds of space.

01:29:19 Imagine that you are

01:29:23 sailing in space,

01:29:25 like a superhero of the future,

01:29:27 when a shooting star passes by you.

01:29:29 But wait, is it really a star?

01:29:31 No,

01:29:33 shooting stars are not stars at all.

01:29:35 They are little pebbles

01:29:37 called meteoroids

01:29:39 that penetrate the Earth's atmosphere

01:29:41 and create a beautiful light show.

01:29:43 And since we are unraveling

01:29:45 the myths,

01:29:47 here is another one.

01:29:49 You probably heard that

01:29:51 meteors only rarely crash on Earth,

01:29:53 like when a violent apocalypse

01:29:55 decimates all the dinosaurs.

01:29:57 It's not true.

01:29:59 Scientists estimate

01:30:01 that about 48 tons of meteorological material

01:30:03 falls on Earth every day.

01:30:05 But almost all of these materials

01:30:07 evaporate in the atmosphere.

01:30:09 The luminous trail

01:30:11 we see in the sky

01:30:13 is what we call a shooting star.

01:30:15 The next time you make a wish,

01:30:17 remember that it is

01:30:19 actually a tiny space debris.

01:30:21 It's not that romantic after all.

01:30:27 Can we fly in the stratosphere

01:30:29 in a mongolian style?

01:30:31 Apparently, it's possible.

01:30:33 The Earth's stratosphere

01:30:35 starts relatively close to the ground.

01:30:37 It rises to about 11 or 12 km

01:30:39 above the Earth's surface.

01:30:41 But it continues

01:30:43 very high.

01:30:45 If you want to fly to the stratosphere

01:30:47 with a mongolian style,

01:30:49 you will need a very good equipment.

01:30:51 You will need a special suit

01:30:53 and a respirator,

01:30:55 which is getting rarer as you get taller.

01:30:57 Of course, if you go all the way,

01:30:59 don't forget to photograph

01:31:01 the curvature of the Earth.

01:31:03 So, get yourself a chest harness

01:31:05 to hang a camera or a camera.

01:31:07 And if you broadcast all of this

01:31:09 live, it would be a first.

01:31:11 Imagine that 102 days ago

01:31:15 you left Earth.

01:31:17 You have adapted well to life in space.

01:31:19 But something strange

01:31:21 happens in your body.

01:31:23 You grow.

01:31:25 How is this possible?

01:31:27 Don't worry, it's perfectly normal.

01:31:29 In fact, you don't really grow.

01:31:31 It's just that

01:31:33 your body no longer undergoes

01:31:35 the effect of gravity.

01:31:37 Your body has a natural space

01:31:39 between the vertebrae and the joints.

01:31:41 On Earth, this space

01:31:43 is almost entirely compressed

01:31:45 by the force of gravity.

01:31:47 But in space, the body,

01:31:49 released from this force,

01:31:51 is still a little bit smaller.

01:31:53 So, yes,

01:31:55 astronauts grow by 3%

01:31:57 when they carry out long missions.

01:31:59 And here's a curiosity.

01:32:01 NASA doesn't forget this

01:32:03 when they make custom space suits.

01:32:05 So, astronauts will always have

01:32:07 an extra space in their suit.

01:32:09 Once astronauts return to Earth,

01:32:11 the anti-gravity effect will fade away.

01:32:13 They may spend a few days

01:32:15 in a short-sleeved shirt

01:32:17 before they find a normal size,

01:32:19 but they will never be able

01:32:21 to fit in a suit.

01:32:23 So, astronauts will always

01:32:25 have to wear a suit.

01:32:27 And astronauts will always

01:32:29 have to wear a suit.

01:32:31 So, astronauts will always

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01:46:33 have to wear a suit.

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01:46:37 have to wear a suit.

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01:47:09 have to wear a suit.

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01:47:13 have to wear a suit.

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01:47:17 have to wear a suit.

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01:47:21 have to wear a suit.

01:47:23 And astronauts will always

01:47:25 have to wear a suit.

01:47:27 And astronauts will always

01:47:29 have to wear a suit.

01:47:31 And astronauts will always

01:47:33 have to wear a suit.

01:47:35 And astronauts will always

01:47:37 have to wear a suit.

01:47:39 And astronauts will always

01:47:41 have to wear a suit.

01:47:43 And astronauts will always

01:47:45 have to wear a suit.

01:47:47 Researchers from the University

01:47:49 of Denmark have collected

01:47:51 magnetic waves recorded

01:47:53 by the Swarm satellite.

01:47:55 They then converted them

01:47:57 into audio tracks and

01:47:59 obtained a rather frightening

01:48:01 result.

01:48:03 In fact, it looks more like

01:48:05 the noise of a terrible

01:48:07 nocturnal creature.

01:48:09 And if you have in mind

01:48:11 the sound of a bird,

01:48:13 you will know that

01:48:15 it is a bird.

01:48:17 And it's not the only strange

01:48:19 sound we've captured on Earth.

01:48:21 Recently, we caught another

01:48:23 radio signal from space.

01:48:25 Scientists have discovered

01:48:27 that it came from a very

01:48:29 distant place,

01:48:31 billions of light years away

01:48:33 from us.

01:48:35 These waves generally

01:48:37 don't last more than

01:48:39 a few seconds.

01:48:41 This signal was very precise,

01:48:43 to the point that scientists

01:48:45 even compared it to a

01:48:47 heartbeat.

01:48:49 Scientists think this signal

01:48:51 is caused by pulsars

01:48:53 or neutron stars.

01:48:55 In the past, Nikola Tesla

01:48:57 captured something similar.

01:48:59 Unfortunately, at the time,

01:49:01 we didn't know the pulsars.

01:49:03 Tesla was therefore convinced

01:49:05 that he had captured the

01:49:07 pulsars.

01:49:09 Let's now go from Earth to the Moon.

01:49:11 In 1969, the astronauts

01:49:13 of the Apollo 10 mission,

01:49:15 the shuttle that made the

01:49:17 last test flight to the Moon,

01:49:19 flew over its surface.

01:49:21 They then captured strange signals

01:49:23 coming from the hidden side

01:49:25 of our satellite.

01:49:27 We never see this side

01:49:29 because the Moon is in a

01:49:31 gravitational lock.

01:49:33 The sound was so strange

01:49:35 that it was impossible

01:49:37 to participate in the next space mission.

01:49:39 Here's what it looked like.

01:49:41 According to NASA,

01:49:47 it's not at all an alien music.

01:49:49 It may be simply radio waves

01:49:51 that have changed

01:49:53 because of their proximity.

01:49:55 But the astronauts who heard it

01:49:57 for the first time were still a little scared.

01:49:59 What about other planets?

01:50:01 40 years ago,

01:50:03 scientists explored

01:50:05 the surface of Venus.

01:50:07 They sent dozens of probes

01:50:09 to record sounds and images.

01:50:11 We now know

01:50:13 what kind of noise Venus emits,

01:50:15 which could easily destroy us

01:50:17 if we approached it.

01:50:19 We didn't expect anything else

01:50:23 from the planet

01:50:25 that is the most dangerous in the solar system.

01:50:27 Unfortunately,

01:50:29 Venus is even more toxic

01:50:31 than the Earth.

01:50:33 And these probes didn't last long.

01:50:35 They quickly broke down

01:50:37 after their arrival.

01:50:39 Then we have Jupiter.

01:50:41 This space giant,

01:50:43 which is 11 times larger than Earth,

01:50:45 is absolutely terrifying.

01:50:47 One of NASA's probes, Juno,

01:50:49 revolves around Jupiter every few weeks.

01:50:51 It moves at a phenomenal speed,

01:50:53 at 209,214 km/h.

01:50:55 One day,

01:50:57 Juno recorded one of the most powerful

01:50:59 invisible signals ever encountered.

01:51:01 The violent solar winds

01:51:03 had just entered into conflict

01:51:05 with Jupiter's magnetic field.

01:51:07 It caused a huge cosmic boom.

01:51:09 The original sound lasted 2 hours,

01:51:13 but was reduced to a few seconds.

01:51:15 In fact, it looks a lot like

01:51:17 the sound of a wave breaking

01:51:19 on a rock.

01:51:21 But none of this is comparable

01:51:23 to the horror of one of Jupiter's

01:51:25 small moons, Ganymede.

01:51:27 In 2021,

01:51:29 the Galileo space probe overflew it.

01:51:31 During its flight,

01:51:33 it captured something quite strange.

01:51:35 These sounds are satellite radiation.

01:51:41 It looks a bit like the sound

01:51:43 of a jungle or that of thousands

01:51:45 of bats waiting to surprise you

01:51:47 in the middle of the night.

01:51:49 Let's move on to Saturn.

01:51:51 This signal was captured

01:51:53 by the Cassini-Huygens

01:51:55 automatic radio

01:51:57 launched into space in 1997.

01:51:59 While passing in front of Saturn,

01:52:01 Cassini recorded a rather frightening sound.

01:52:03 These screams straight out of hell

01:52:09 are just simple radio waves.

01:52:11 And it's not very different

01:52:13 from what the auroras of Boreal emit on Earth.

01:52:15 A little later, Cassini captured

01:52:17 another signal, the sound of lightning

01:52:19 and storms on Saturn.

01:52:21 These sounds are quite interesting.

01:52:23 It looks a bit like popcorn

01:52:25 bursting or a counting clock,

01:52:27 doesn't it?

01:52:29 But it's simply because these lightning

01:52:31 are extremely fast.

01:52:33 We're now going to leave the solar system.

01:52:35 The famous Voyager 1 probe

01:52:37 was launched in 1977

01:52:39 and continues to send us data

01:52:41 40 years after its takeoff.

01:52:43 In 2012, it left the solar system

01:52:45 to enter interstellar space.

01:52:47 It was then that Voyager 1

01:52:49 recorded plasma waves

01:52:51 in the atmosphere.

01:52:53 The original recording

01:52:55 lasted 7 months.

01:52:57 But scientists were kind

01:52:59 and reduced it to 12 seconds.

01:53:01 It's not really sinister,

01:53:05 but it's not very reassuring either.

01:53:07 And although it seems that nothing

01:53:09 can surpass the horrors of Saturn,

01:53:11 we are now going to examine

01:53:13 one of the most frightening objects

01:53:15 in the universe, a black hole.

01:53:17 This sound was recorded

01:53:19 by the Chandra Space Telescope.

01:53:21 While studying a galaxy cluster

01:53:23 in the Perseid constellation,

01:53:25 we discovered something strange.

01:53:27 Undulating movements

01:53:29 in the center of the cluster.

01:53:31 They extend in all directions,

01:53:33 like circles on water.

01:53:35 Scientists have declared

01:53:37 that this phenomenon was due

01:53:39 to a supermassive black hole.

01:53:41 But black holes don't always

01:53:43 devour all objects in space.

01:53:45 Sometimes they spit them out.

01:53:47 This causes gas vibrations

01:53:49 that can be converted into sound waves.

01:53:51 What's interesting is that

01:53:55 each of these waves oscillates

01:53:57 for about 10 million years.

01:53:59 This recording is therefore

01:54:01 very fast.

01:54:03 Scientists have reduced the delay

01:54:05 between oscillations to about

01:54:07 144 quadrillion times.

01:54:09 And here's what it sounds like.

01:54:11 It's probably the most sinister

01:54:13 sound on our list.

01:54:15 It's neither very powerful

01:54:17 nor very violent.

01:54:19 It's rather dark and disturbing.

01:54:21 Here are the scariest

01:54:23 space sounds captured by NASA.

01:54:25 As I said, most of them

01:54:27 are just radio waves.

01:54:29 But it's always fun

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