85 faits sur l'espace qui vont propulser votre esprit

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Transcript

00:00:00Millions of people around the world go out into the streets and onto the rooftops to observe this amazing cosmic phenomenon.

00:00:08Another planet, right next to the moon, big and red.

00:00:12At first, everyone is excited. Mars, which comes out of nowhere, has a strange effect on humanity.

00:00:19Just as the moon can affect the psychological and physical state of some people,

00:00:24the unexpected visit of Mars leads people to behave in a rather strange way.

00:00:29Every night, the sky is illuminated by the white light of the moon and the red glow of Mars.

00:00:35Many people feel a kind of instantaneous insomnia.

00:00:38Some even stop drinking coffee because they no longer feel tired.

00:00:43Mars brings out the energy, or even a little savagery in people.

00:00:47It makes them laugh more and even makes some poor people crazy.

00:00:51They start going out more often and enjoy this unusual night sky.

00:00:57A few days later, everyone can see what is happening.

00:01:00Mars is getting bigger.

00:01:02Scientists announce that the red planet is slowly heading towards Earth.

00:01:07The collision is inevitable.

00:01:09Earthlings only have a few more years to live.

00:01:12A few months ago, a huge asteroid crashed on the red planet with such force

00:01:17that Mars simply left its orbit and drifted away.

00:01:22The probability that Mars is getting closer to Earth has always been quite high.

00:01:26After about three seconds of announcement, the news went viral and panic set in.

00:01:32The situation is getting worse.

00:01:35The closer Mars gets, the more it affects people physically.

00:01:39Hundreds of videos appear showing collisions between Mars and Earth.

00:01:44And there is never a happy ending.

00:01:46You want to see what's going to happen? Ask a famous blogger to his subscribers.

00:01:50The Earth is almost entirely covered in water.

00:01:53And Mars is only dust, sand and rocks.

00:01:56Then she places a huge watermelon in the middle of her room.

00:02:00From the opposite corner, she throws a bowling ball towards the fruit.

00:02:03And it's a strike.

00:02:05Mars seems almost the same size as the Moon now.

00:02:09It is about to enter the orbit of the latter.

00:02:11And it affects the magnetic field of the Earth.

00:02:14Floods, hurricanes, tsunamis, powerful storms.

00:02:18It's getting worse and worse.

00:02:20The animals go crazy.

00:02:22The birds no longer migrate to the South.

00:02:25The auroras, formerly polar, appear in the Caribbean.

00:02:29The economy is not so well received by the news.

00:02:31People stop going to work.

00:02:33Why keep working?

00:02:35They just want to have fun and be with their loved ones.

00:02:38There are enough resources on the planet to hold out until the disaster.

00:02:42So no one tries to solve the problems of the Earth.

00:02:45Clothes, food, cars, yachts.

00:02:48Everything loses its value and becomes free.

00:02:52Every day, huge street parties appear all over the world.

00:02:56People decide to spend their last months in peace and harmony.

00:03:00The world catastrophe unites humanity like never before.

00:03:04To go off on a rampage,

00:03:06the earthlings come together to organize a huge rock concert.

00:03:10The red giant that destroys our beautiful blue planet.

00:03:13Yes, rock'n'roll and the band are perfect.

00:03:16There is just enough time to eat, dance, party and listen to good music.

00:03:21Huge stages are installed all over the planet.

00:03:24It is the last concert of each musician.

00:03:27During all this preparation, hope suddenly appears.

00:03:30Scientists have calculated all the events that will occur

00:03:33when Mars collapses on Earth.

00:03:36And they have a simple plan.

00:03:38Fortunately, humans had already planned to go to Mars,

00:03:41so they had started building spaceships for years.

00:03:44People will not have time to go to another planet before the collision.

00:03:48But they will be able to wait for the disaster just outside the Earth's orbit.

00:03:53You will be able to sit in a space station,

00:03:55nibble popcorn, relax and enjoy the show.

00:03:59When the dust settles, it may be possible to return to Earth.

00:04:03Or what is left of it.

00:04:05After learning about this plan,

00:04:08people start working day and night to finish the spaceships.

00:04:11Everyone participates.

00:04:13There are still two years before the big day.

00:04:16The huge concert stages are transformed into other space stations.

00:04:20Mars now gives people more energy.

00:04:22And thanks to an incredible teamwork,

00:04:24people manage to create thousands of stations in just a few months.

00:04:28This is what happens when 7 billion people work together.

00:04:32Farmers, kinesiotherapists, cooks, engineers, athletes, accountants.

00:04:37Everyone works together.

00:04:39Mars is now closer to us than the Moon.

00:04:42The red giant blocks the sun and our planet is plunged into darkness.

00:04:46There are only a few days left.

00:04:48People work like ants in a massive colony,

00:04:51putting the final touch on hundreds of thousands of space stations.

00:04:55It takes four whole days for everyone to get on board.

00:04:59Not to mention the loading of essential data.

00:05:02Animals, fish, seeds, plants, vegetables, fruits, video games.

00:05:08The red giant must enter Earth's orbit in a few days.

00:05:12It is at this moment that it will really pick up speed.

00:05:15Mars is only a little over half the size of Earth.

00:05:18But in the sky, it seems infinitely large.

00:05:22The spaceships begin to take off.

00:05:25People take a last look around them, memorizing every square centimeter.

00:05:29In a few hours, everything will change forever.

00:05:33The stations fly far enough to get out of orbit.

00:05:37People who collide should still get a bang.

00:05:41The rock stars of each ship organize a space music festival.

00:05:46To the impressive sound of hard rock, Mars enters Earth's atmosphere

00:05:50and burns a thin layer of its own surface.

00:05:53This releases an incredible amount of energy.

00:05:56It becomes faster and faster and crashes into the Pacific Ocean.

00:06:00The breath of a huge explosion swallows the entire planet.

00:06:04Everything is illuminated by flames,

00:06:07and everyone on the ships must wear sunglasses so as not to be blinded.

00:06:11Our blue planet is transforming into an incandescent ball.

00:06:15Mars dust mixes with Earth's water.

00:06:18The force of the impact travels through the Earth's crust to the liquid and hot magma.

00:06:23Hundreds of pieces of Mars, some of which are the size of entire countries,

00:06:27float in some way in the atmosphere.

00:06:30The collision generates so much energy that all the oceans boil and evaporate.

00:06:35Seas and melted-metal rivers now spread all over the Earth.

00:06:40Days, weeks, months pass.

00:06:43A belt made up of fragments of Mars forms around the Earth,

00:06:47like a burning version of Saturn's rings.

00:06:50It will take a long time to land safely,

00:06:53but humanity cannot stay alive on the ships during all this time.

00:06:57Food, water and oxygen will be depleted after a few years,

00:07:01but scientists already have a plan.

00:07:04The ships activate a switch and become huge cryogenic chambers.

00:07:08The ships are equipped with energy panels,

00:07:11and the burning Earth releases a lot of energy.

00:07:14This energy is used to operate the ships

00:07:17while everyone on board takes a few thousand year nap.

00:07:20As soon as the planet cools down, humans will wake up.

00:07:24Hundreds of thousands of years pass.

00:07:27One day, alarms go off simultaneously on all the ships.

00:07:31People wake up slowly.

00:07:33Their bodies are exhausted, but after a few billion cups of coffee,

00:07:37everyone is ready to go.

00:07:40New continents should be formed,

00:07:42and the atmosphere is probably different.

00:07:45The planet may have lost its original orbit,

00:07:48so it turns at a different angle.

00:07:50Seasons as we know them have disappeared.

00:07:53All the water on Earth evaporated in the first hours.

00:07:56But there were huge glaciers on Mars,

00:07:59which may have melted during the impact.

00:08:01Mars may have shared its water with our planet.

00:08:04Dust and dirt clouds should be receded now,

00:08:07and the soil should be fertile enough to grow things.

00:08:10All this magma has probably spat out a lot of minerals

00:08:13and useful chemical compounds.

00:08:15It will be difficult,

00:08:17but humanity must somehow adapt to the new Earth.

00:08:21People are ready for anything.

00:08:23All earthlings run to the nearest windows

00:08:25to see what their beloved planet looks like after all these centuries.

00:08:29But where is it?

00:08:31People turn their necks,

00:08:33look at the empty area where the Earth was.

00:08:37The impact of Mars was so strong

00:08:39that it pushed the Earth out of its orbit around the Sun,

00:08:42and it disappeared.

00:08:44Great, what are we going to do now?

00:08:47A bearded guy grabs a guitar and says,

00:08:50we just have to play.

00:08:53He looks at you and you look at him back.

00:08:56A giant eye that seems to attract you in the abyss.

00:08:59You fly it over your spaceship.

00:09:02But as scared as you can be,

00:09:04you still have to do your job.

00:09:06So you drive your ship to the surface of the red planet.

00:09:09And yes, that's where you are,

00:09:11flying over Mars.

00:09:12But everything in its time.

00:09:14You take a moment to remember everything you know

00:09:16about the fourth planet closest to the Sun.

00:09:19It is the last of the inner planets.

00:09:21These are the planets that are in the perimeter of the asteroid belt.

00:09:25They are also called telluric planets

00:09:27because they are made up of rocks and metals.

00:09:29The atmosphere of Mars is much thinner than that of Earth.

00:09:33It contains 95% carbon dioxide

00:09:36and barely 1% oxygen.

00:09:38In other words,

00:09:39do not even consider removing your helmet.

00:09:41Anyway, there is no time to waste.

00:09:43You land on the surface of the planet

00:09:45and you find yourself in the middle of a brunette red world.

00:09:48Fortunately, you are wearing a space suit.

00:09:50The place is glacial.

00:09:52The thermometer sewn into the sleeve of your suit

00:09:54indicates minus 62 degrees Celsius.

00:09:57It's time to take your first step on the Martian surface.

00:10:00The planet looks pretty colorful.

00:10:02And the shade of a specific area

00:10:04depends on the minerals that make up its soil.

00:10:06The ground under your feet is covered with a fine dust.

00:10:09It looks like rust.

00:10:11The same orange dust is suspended in the air.

00:10:14Fortunately, you have your own oxygen reserve

00:10:16and you do not need to breathe Martian air.

00:10:19This layer of dust that covers the surface of Mars

00:10:21can be 2 to 12 meters thick.

00:10:24You cross your fingers

00:10:25hoping not to be swallowed by the Martian moving sands.

00:10:28You start walking and you feel very light.

00:10:30Mars represents only 15% of the volume of our planet

00:10:33and barely 11% of the Earth's mass.

00:10:36This means that gravity is much weaker here.

00:10:39This attraction represents only 38% of what reigns on the surface of the Earth.

00:10:43You make small jumps

00:10:45and then you try to run for several hundred meters.

00:10:47You did not even sweat a drop.

00:10:50What makes walking exploration more difficult

00:10:53is that the surface of the planet is very rugged,

00:10:55covered with craters and volcanoes,

00:10:58old dry lake beds and canyons.

00:11:01You see something huge standing on the horizon.

00:11:04But you try to suppress your curiosity.

00:11:06You will have enough time to discover what it is later.

00:11:10Suddenly, a massive cloud appears in the distance.

00:11:13It looks like a huge herd is approaching you.

00:11:17In reality, you'd better get back on board your ship

00:11:20and fly as fast as you can.

00:11:22This is one of the famous Martian dust storms.

00:11:25They occur mainly during the summer in the southern hemisphere of the Red Planet.

00:11:29And they can sometimes cover the entire planet.

00:11:32You can even see the largest of them from Earth.

00:11:35You jump in your ship and you put the cap on the eye that had frightened you so much.

00:11:39Sinuous canyons, which look like veins, cross this ocular globe.

00:11:43But the closer you get, the less it really looks like an eye.

00:11:47Soon, you realize that it is a crater.

00:11:50It is gigantic, nearly 30 kilometers in diameter.

00:11:53Around the crater, which seems to have a pupil,

00:11:56there are other even larger craters.

00:11:58They probably formed billions of years ago.

00:12:01It was at this time that Mars had to wipe out the multiple assaults of rocks from space.

00:12:06But why is this ocular crater darker than the surrounding landscape?

00:12:10Scientists think that once, Martian water was in the huge pit.

00:12:14And do you remember these canals?

00:12:16They were probably carrying this water.

00:12:18As the crater was filled with water,

00:12:20it prevented certain substances and minerals from eroding.

00:12:24Now, do you remember this imposing thing on the horizon?

00:12:28It's time to explore it.

00:12:30When you get closer, you realize that this is the largest shielded volcano in the entire solar system.

00:12:36Olympus Mons.

00:12:37It is more than 595 kilometers in diameter,

00:12:41which is almost the same size as the state of Arizona.

00:12:44You tilt your head.

00:12:46Wow, the mountain is 25 kilometers high.

00:12:49It is also surrounded by cliffs 6 kilometers high.

00:12:52Let's make some comparisons to better visualize the size of this volcano.

00:12:56The largest volcano on Earth is the Mauna Loa,

00:12:59which rises to about 4,000 meters above sea level and extends over 120 kilometers.

00:13:05It seems impressive.

00:13:07But the volume of Olympus Mons is about 100 times larger than that of Mauna Loa.

00:13:12The Martian giant could swallow the entire chain of Hawaiian islands, from Kauai to Hawaii.

00:13:18But why is this volcano so large?

00:13:20This could be the result of lower gravity and a higher frequency of eruptions.

00:13:25Or the reason could be the crust of the red planet, which is very different from that of the Earth.

00:13:30It is static.

00:13:31On our planet, the crust is composed of 15 to 20 tectonic plates in constant motion.

00:13:36When the plates move on hot lava points,

00:13:40new volcanoes are formed and those that already existed are extinguished.

00:13:44This is why lava can reach the surface through numerous gutters.

00:13:48But on Mars, the crust is not sanded into plates similar to that of the Earth.

00:13:53And lava has nothing else to do than accumulate in a single very, very large volcano.

00:13:59So why not look at this huge mountain up close?

00:14:03But as soon as you get off your ship, the Martian soil under your feet starts shaking.

00:14:09It's a shaking of Mars.

00:14:11But how can this happen if Mars does not have active tectonic plates in motion?

00:14:16NASA specialists are convinced that these tremors occur when the energy inside the planet is suddenly released.

00:14:23This leads to rock fractures and cracks in the crust of the planet.

00:14:27Another powerful shake and one of these crevasses opens right next to you.

00:14:31You fall to the ground, too terrified to move.

00:14:34But soon everything calms down.

00:14:36You wait a few minutes, just to be sure, and you get up.

00:14:40Oh, look!

00:14:42This is a perfect opportunity to explore the entrails of the red planet.

00:14:46The crack is big enough to send a research robot there.

00:14:50The crust of the planet is thin and is made up of basaltic rocks.

00:14:54The mantle that surrounds the core of the planet is made up of silicate, oxygen and a few other minerals.

00:15:01You could compare it to a kind of toothpaste made of rock.

00:15:04The Martian mantle is also less imposing than that of the Earth.

00:15:08Its thickness is only 1,300 to 1,800 km.

00:15:11As for the core of the planet, it is mainly made up of iron, nickel and sulfur

00:15:16and measures between 1,400 and 1,900 km wide.

00:15:19This core does not move.

00:15:21This is why Mars does not have a magnetic field.

00:15:25Unfortunately, your drone is now lost in the depths of the red planet.

00:15:29You leave it there and continue your exploration.

00:15:32Your next destination is Valles Marineris.

00:15:35This name would almost evoke an Italian tomato sauce,

00:15:38but it is actually a huge canyon, or rather a system of canyons,

00:15:42that stretches along the equator of Mars.

00:15:44It is just as impressive as Olympus Mons,

00:15:46more than 4,200 km long and more than 6 km deep.

00:15:51It is so vast that it could extend over all of the United States,

00:15:55from the Pacific to the Atlantic Ocean.

00:15:58Let's make another comparison.

00:16:00One of the most famous canyons on Earth is the Grand Canyon in Arizona.

00:16:05But it is 10 times less long and about 4 times less deep than the Mars Canyon.

00:16:10Some scientists think that Valles Marineris is the edge of a huge tectonic plate.

00:16:15It moves so slowly that almost nothing has happened in this region for millions of years.

00:16:21And the movement of this plate probably began 3.5 billion years ago.

00:16:26In short, the only thing that remains on your list of things to do today

00:16:30is to visit the moons of Mars.

00:16:32You see, in the 1970s,

00:16:34scientists discovered a mysterious gravitational anomaly called the Grand Attractor.

00:16:39Wait, but that was my nickname in high school.

00:16:42In short, it is a place in the cosmos that attracts hundreds of galaxies,

00:16:46including our own Milky Way.

00:16:48You won't be able to see it because it is on the other side of our galaxy,

00:16:51about 150 million light years away.

00:16:54The Grand Attractor is actually in the direction

00:16:56that scientists usually call the avoidance zone.

00:17:00Ah, here, I have one too.

00:17:02It's my sock drawer.

00:17:04There is so much dust and gas in this region

00:17:06that we cannot distinguish what is happening there.

00:17:09This area blocks most of the visible light coming from beyond.

00:17:12But all this dust and gas does not block the X-rays

00:17:15or infrared light.

00:17:17So with the development of X-ray astronomy,

00:17:19researchers could finally start observing all the objects in this area,

00:17:23including this mysterious force that attracts everything.

00:17:26And until now, no one has yet understood why this was happening.

00:17:30Our Moon could be 200 million years younger than we thought before.

00:17:35Many scientists think that the Moon was formed

00:17:37during a powerful collision between our planet

00:17:39and an unknown body the size of Mars.

00:17:42Dust and fusion debris have gathered

00:17:45and formed a new object that we know as the Moon.

00:17:48The lunar crust has probably gone through a solidification process

00:17:51for more than 200 million years.

00:17:54Did you know that there was originally an ocean of magma on the Moon?

00:17:58Scientists noticed this reality

00:18:00after discovering large quantities of light minerals called plagioclases.

00:18:05This material crystallizes generally and floats on the surface of the magma.

00:18:09In any case, these minerals were 4.36 billion years old,

00:18:13which means that they formed 200 million years

00:18:15after the first solid materials of our solar system appeared.

00:18:19Thus, the theory that the Moon was formed during this cataclysmic chaos

00:18:23could be true.

00:18:25If you land on the Moon one day and leave your footprint on its surface,

00:18:28it can stay there for a million years.

00:18:31You will also see the footprints of other astronauts,

00:18:33even if no one has landed on its lunar surface for decades.

00:18:37The Moon has no atmosphere that is clean to it.

00:18:40There is no wind or anything else that can sweep away the dust

00:18:43and erase the footprints.

00:18:45We perceive it as a small dot somewhere in the distance.

00:18:48But in reality, the Sun is so big that if it were a hollow sphere,

00:18:52you could fill it with more than a million Earths.

00:18:56The Sun represents 99.86% of the mass of our entire solar system.

00:19:01Another huge object of our solar system is Jupiter.

00:19:05It is 11 times larger than our planet.

00:19:07For comparison, the Earth is not even the size of the Great Red Spot.

00:19:12This huge storm has been raging on Jupiter for more than a century.

00:19:15And no, it is not anchored to any solid,

00:19:17since Jupiter is a gas giant.

00:19:20It is similar to a colossal oval-shaped hurricane,

00:19:23reddish in color and quite large enough to swallow our entire planet.

00:19:28There was a time when it was three times larger than our planet.

00:19:31But over the centuries, it has shrunk while stretching.

00:19:36As for Jupiter itself, this gas giant is a kind of vacuum cleaner

00:19:40that keeps our solar system safe.

00:19:42Jupiter has an incredibly strong gravity

00:19:45that devours comets or asteroids

00:19:47that could potentially harm our home planet.

00:19:50In some other planetary systems,

00:19:52gas giants similar to Jupiter migrate from the position where they were formed.

00:19:56They spiral inward and get closer to their mother star.

00:20:00And during their journey, they swallow small telluric planets.

00:20:04Or their immense gravitational force projects these planets out of their solar system.

00:20:09Fortunately for us, Jupiter's gravitational force does not work that way.

00:20:14If planets similar to Jupiter stay away from their stars,

00:20:17they ensure the safety of their planetary system

00:20:19by protecting the small planets in their inner orbit.

00:20:22Jupiter, for example, can influence the orbits of small space bodies

00:20:26that are too close to the inner planets.

00:20:29This is why this gas giant is an excellent guardian of our solar system.

00:20:34There is a supermassive black hole

00:20:36that travels through space at a speed of 4,800,000 km per hour

00:20:40and leaves a trail of debris behind it.

00:20:43I had a little brother who did the same.

00:20:46It is about a million times heavier than our sun.

00:20:49And right now, it is 2 billion light years away from Earth.

00:20:52This black hole started like all the others in its own elliptical galaxy

00:20:56with many stars surrounding it.

00:20:58Supermassive black holes often form and remain in the center of galaxies.

00:21:02But this one escaped.

00:21:04A theory states that this black hole is different,

00:21:07because the galaxy where it formed may have met another galaxy at some point.

00:21:13Sometimes galaxies merge to form a new galaxy in full

00:21:16if this happens.

00:21:18But not this time.

00:21:19Instead of merging, the galaxy of this black hole

00:21:21crossed a much larger galaxy millions of years ago.

00:21:24This gigantic galaxy had already swallowed other galaxies on its way.

00:21:28And since it was so big,

00:21:30the galaxy that surrounded our supermassive black hole

00:21:33ended up being torn apart.

00:21:35The black hole in its center managed to escape,

00:21:38with some of the stars nearby.

00:21:40This left this burning trail extending beyond the surrounding space.

00:21:45Super solar storms are so powerful

00:21:47that they can cause power cuts all over the world.

00:21:50Random sun-driven eruptions cause these solar storms,

00:21:54and they can really happen at any time.

00:21:57In 2012, we were lucky,

00:21:59because the most powerful solar storm of the last 150 years

00:22:02passed very close to us.

00:22:04It simply managed to cross the Earth's orbit.

00:22:07If it had happened only a week earlier,

00:22:09our planet would have had to face terrible consequences,

00:22:12including power cuts all over the globe.

00:22:15Gamma-ray bursts are powerful enough to destroy planets.

00:22:19We are talking about extremely powerful bursts,

00:22:21which mainly occur in very, very distant galaxies.

00:22:25If these rays are directed directly at a space object,

00:22:28they can completely destroy it,

00:22:30even if we are talking about an entire planet.

00:22:32The Earth is safe for now,

00:22:34and we have nothing to fear.

00:22:36A gamma-ray burst occurs in our galaxy

00:22:38about once every 5 million years.

00:22:42Fortunately, it occurs too far away,

00:22:44and does not affect life on Earth.

00:22:46All this, in short, does not look at us,

00:22:48but it is still scary.

00:22:50Burning ice exists.

00:22:52It may be difficult to imagine it here on Earth,

00:22:54but a strange planet called Gliese 436 b

00:22:57literally consists of a burning ball of ice.

00:23:00It may be covered in ice,

00:23:02but it also has a temperature of 440 degrees Celsius.

00:23:06You can't really see it burn,

00:23:08because there is too much water on this planet.

00:23:11It is because of its strong gravitational attraction

00:23:13that attracts water molecules to the heart of the planet

00:23:16and compresses them incredibly densely.

00:23:19In this way, water molecules cannot evaporate,

00:23:22and that is why the ice on the surface of the planet never melts.

00:23:25There are stars that can crush other stars.

00:23:28These space objects are mostly smaller stars,

00:23:31with a weaker mass.

00:23:33They target the closest stars

00:23:35and begin to absorb their hydrogen combustible

00:23:37in order to increase their own mass,

00:23:39and generally live longer.

00:23:41A vampire star is colored with a bright blue.

00:23:43It also becomes warmer.

00:23:45Thus, it gives the impression of being much younger

00:23:47than it really is.

00:23:49If a star, or any other object,

00:23:51falls into a black hole,

00:23:53it is stretched like a spaghetti dish.

00:23:55This process is called the Woosh process.

00:23:57Dust storms on Mars can be really crazy.

00:24:00They fall on the southern hemisphere of the Red Planet,

00:24:02especially during the summer.

00:24:04These storms can grow and engulf vast areas of the planet,

00:24:07as it happened in January 2022.

00:24:10At that time, a dust storm

00:24:12covered almost twice the surface of the United States.

00:24:15Could it be what caused the disappearance

00:24:17of one of the robots we sent to Mars?

00:24:20The atmosphere and climate are harsh on Mars.

00:24:23It is mainly a desert,

00:24:25with strong winds and average temperatures

00:24:27of minus 63 degrees Celsius.

00:24:29They go down to minus 140 degrees Celsius

00:24:31at the poles during the winter.

00:24:33A Martian lander must be equipped in a specific way

00:24:35and be very robust to resist these conditions.

00:24:38But researchers thought that it would be able

00:24:40to make the difficult journey to the Red Planet.

00:24:43On June 2, 2003,

00:24:45a team of researchers prepared one of the pioneering robots

00:24:48that they were about to send into space.

00:24:50It was a small compact lander

00:24:52called Beagle 2.

00:24:54Its mission was to land on Mars

00:24:56and to search for what the whole world

00:24:58has been looking for for decades.

00:25:00Life on the Red Planet.

00:25:02The landing was scheduled for December 25,

00:25:05but the signal never arrived.

00:25:08The team tried to contact the spacecraft,

00:25:10but at some point they had to accept

00:25:12that they would not be able to join it.

00:25:14Some estimated that the landing

00:25:16was ultimately too difficult and complex,

00:25:18and that the lander had probably crashed.

00:25:21But they did not fail to test the technical errors.

00:25:23Others put forward a theory

00:25:24that the module could have crashed into its own parachute

00:25:26and landed on the surface of Mars.

00:25:29In any case, the Beagle 2 was carried away

00:25:32until 2015,

00:25:34when NASA took pictures of what could be

00:25:36the remains of the lost module.

00:25:38It was not just damaged debris.

00:25:41The components actually seemed intact.

00:25:43The remains of the probe rested with its solar panels,

00:25:46partially deployed about 5 km from the site

00:25:48where it was supposed to land.

00:25:51Apparently, Beagle 2 managed to land,

00:25:53but its radio antenna got stuck.

00:25:56This is why researchers were unable to control it

00:25:58from Earth or communicate with it.

00:26:00But no one knows exactly why it happened.

00:26:04Have you ever heard of a face on Mars?

00:26:07In the 1970s, one of NASA's orbiters

00:26:09took the famous images of the Martian surface,

00:26:11which showed a formation resembling a face,

00:26:14as you can see in the upper part of the image.

00:26:17If you have a little imagination,

00:26:19you can easily see a nose,

00:26:21two eyes, a mouth,

00:26:23and an original haircut.

00:26:25Some even thought it was a monument

00:26:27built on the Red Planet by another civilization.

00:26:30And what do you think of other unusual things

00:26:32that people found on Mars,

00:26:34like the crater of the Happy Face?

00:26:36We can easily understand why it was nicknamed that.

00:26:39Or different-shaped rocks,

00:26:41a crepe,

00:26:42a brachiosaurus,

00:26:43or even a fish.

00:26:44Mars also has an island in the shape of a gopher on its surface.

00:26:47It is an element 2 km wide

00:26:49that can be seen in a lava flow zone.

00:26:52This could be the result of the lava

00:26:54that pushed this formation below.

00:26:56It seems that astronomers have also received images of blue dunes.

00:27:00These are superb dark sea dunes

00:27:03that violent winds have carved in long lines.

00:27:05They surround the northern polar cap of the planet

00:27:08and cover a region as large as Texas.

00:27:10Yee-haw!

00:27:11The Red Planet is generally known for its brown sand dunes.

00:27:14So these have certainly been a real surprise.

00:27:17But in reality, they are not really blue.

00:27:20If you could go to Mars right now to take a look,

00:27:23you would see that it is as dark and orange as the others.

00:27:27And the photo is a false color image.

00:27:30Scientists often use false colors

00:27:32to highlight the differences between two elements.

00:27:34For example, here is the difference in depth.

00:27:37In addition, the largest valley on Mars

00:27:39is so large that it could swallow our Grand Canyon at breakfast.

00:27:44It is a fascinating canyon system of 4,000 km long

00:27:47called Valles Marineris.

00:27:50And it is ten times longer than the Grand Canyon.

00:27:54If we could stretch this Martian canyon,

00:27:57it would go from one coast to the other of the United States.

00:28:00As Mars does not have active plate tectonics,

00:28:03no one knows for sure how this canyon was formed.

00:28:07According to a theory, a chain of volcanoes,

00:28:09Tarsus Dome, located on the other side of Mars,

00:28:12including Olympus Mons,

00:28:14curved the Martian crust from the opposite side of the planet.

00:28:17This powerful force caused cracks in the crust

00:28:20and moved the huge amounts of water

00:28:22that were under the surface.

00:28:24This water then emerged and carved the rock.

00:28:28This force also animated the glaciers.

00:28:30And it seems possible that they created new paths

00:28:33in this gigantic canyon system.

00:28:35Volcanoes on the Martian surface

00:28:37could have erupted about 50,000 years ago.

00:28:40Although the most powerful eruptions

00:28:42occurred 3 to 4 billion years ago.

00:28:45But the planet does not have active volcanoes today.

00:28:48Most of the heat stored inside the planet

00:28:51during its formation has dispersed.

00:28:53So now, the external crust of Mars

00:28:55is far too thick for the molten rock to reach its surface.

00:28:59But a long time ago,

00:29:00eruptions formed gigantic volcanoes.

00:29:03And these volcanoes probably played an important role

00:29:06in the melting of the ice deposits

00:29:08that released water crusts on the Martian surface.

00:29:12Mars has a thin atmosphere,

00:29:14with a gas volume, mainly carbon dioxide,

00:29:17less than 1% of that of Earth.

00:29:19But 4 billion years ago,

00:29:21it was much warmer and humid than now.

00:29:24Its atmosphere was also thicker than at that time.

00:29:27This is why it was able to generate a powerful greenhouse effect

00:29:29and trap sunlight.

00:29:31Mars also had a powerful magnetic field.

00:29:34Like Earth's, it was formed

00:29:36because of the melting metal currents in the planet's core.

00:29:39But unlike our planet,

00:29:41Mars lost its magnetic field

00:29:43due to the cooling of its core.

00:29:45And without it,

00:29:46the planet had no protection against solar winds,

00:29:49which are a flow of charged particles coming from the sun.

00:29:53Solar wind tore most of Mars' atmosphere

00:29:56in just 200 million years,

00:29:58or something like that.

00:29:59This is what makes these powerful Martian dust storms

00:30:01even more intense.

00:30:03Mars has a fascinating history,

00:30:05judging by the planet's glaciers.

00:30:07A planet that has probably experienced

00:30:09multiple periods of glaciers,

00:30:11just like Earth.

00:30:12A team of researchers obtained images

00:30:14of about 60,000 Martian rocks.

00:30:16These rocks were of different sizes

00:30:18and scattered all over the place,

00:30:20which means they probably formed

00:30:22during different periods of glaciers.

00:30:24Glaciers also have their own history.

00:30:26Who knows what type of gas, rocks or even microbes

00:30:28could be trapped inside?

00:30:31If you could go up in a time machine

00:30:33and stop it 4 billion years ago,

00:30:35on Mars of course,

00:30:36chances are you'd witness

00:30:38spectacular floods.

00:30:40Maybe there would even be a form of life

00:30:42on the planet's surface.

00:30:44A strong impact of meteorites

00:30:46responsible for the formation of the Gale crater

00:30:48on the Red Planet

00:30:49could be the cause of this mega-flood.

00:30:51After this collision,

00:30:52the temperatures on the planet

00:30:54have become incredibly high.

00:30:56This caused the melting of all the ice

00:30:58that was stored on the Martian surface

00:31:00at that time.

00:31:01The flood was so huge

00:31:03that it altered the geological structure

00:31:05of the planet's surface.

00:31:06It created large ridges

00:31:08and waves in the sedimentary rock.

00:31:10Speaking of water,

00:31:12we noticed that steam was escaping

00:31:14from the atmosphere of Mars.

00:31:16In addition,

00:31:17researchers have found evidence

00:31:19of water on the planet's surface.

00:31:21The soil has dark streaks

00:31:23that seem to grow in summer

00:31:25and shrink in winter.

00:31:27The planet has many valleys

00:31:29and rivers that have dried up.

00:31:31It is possible that liquid water

00:31:33once flowed there.

00:31:34Now, most of this water

00:31:35could be locked up

00:31:36in ice caps

00:31:37or even hidden under the surface.

00:31:39More and more things

00:31:40make us think that Mars

00:31:41will one day be...

00:31:43In space,

00:31:44no one can hear you scream.

00:31:47As everyone knows,

00:31:48star explosions,

00:31:49asteroids crashing,

00:31:51and planets on fire

00:31:52don't make any noise in space.

00:31:54Really?

00:31:56And what if we could

00:31:57hear some noise up there?

00:31:59OK, back to school.

00:32:01Sound is a mechanical wave

00:32:03coming from a vibration.

00:32:05But what exactly does that mean?

00:32:07The most famous example

00:32:08is that of guitar strings.

00:32:10If you scratch one of them,

00:32:11it starts to vibrate.

00:32:12The atoms inside the metal string

00:32:14start to vibrate

00:32:15and hit the atoms in the air

00:32:17around them.

00:32:18The atoms push each other

00:32:20until some reach our ears.

00:32:22It's like the wave

00:32:23created by a stone

00:32:24thrown into a pond.

00:32:25And it happens very quickly,

00:32:27at a speed of around

00:32:28340 meters per second.

00:32:31Then, our eardrums

00:32:32start to vibrate

00:32:33at the same frequency.

00:32:35And the little water

00:32:36inside our ears

00:32:37transmit this vibration

00:32:38to the brain.

00:32:40The brain then uses its magic,

00:32:42recognizes the pattern

00:32:43and transforms it into sound.

00:32:46Great!

00:32:47Now we know

00:32:48that we need

00:32:49certain particles

00:32:50to create sound.

00:32:51And we can find these particles

00:32:52in gases,

00:32:53liquids,

00:32:54and solid substances.

00:32:56But what about space?

00:32:58It's an almost perfect void.

00:33:00And you've probably

00:33:01already heard that

00:33:02there is no sound in space

00:33:03because it's a void.

00:33:05But what does that

00:33:06really mean?

00:33:08A perfect void

00:33:09is an area

00:33:10totally devoid of matter.

00:33:12This means

00:33:13that there is nothing

00:33:14in this place.

00:33:15Yes,

00:33:16despite all these celestial bodies

00:33:17in space,

00:33:18there is no air between them,

00:33:20no atoms,

00:33:21no particles,

00:33:22nothing at all.

00:33:24In fact,

00:33:25almost nothing.

00:33:26To be exact,

00:33:27the perfect void

00:33:28doesn't really exist.

00:33:29We can't get rid

00:33:30of atoms permanently,

00:33:32but space is very close

00:33:33to this notion.

00:33:34On average,

00:33:35there are 1 to 5 atoms

00:33:36per cubic centimeter.

00:33:38This may seem like a lot,

00:33:40but you have to keep in mind

00:33:41that these atoms

00:33:42are microscopic

00:33:43and the distance between them

00:33:44and the void

00:33:45that separates them

00:33:46is huge.

00:33:47For comparison,

00:33:48a cubic centimeter of air

00:33:49contains about 1000 atoms.

00:33:51So, of course,

00:33:52with such a low density,

00:33:54these atoms can't push

00:33:55each other,

00:33:56even if the vibration

00:33:57is very strong,

00:33:58as in the case

00:33:59of a supernova, for example.

00:34:01They still won't be able

00:34:02to do it.

00:34:04But then,

00:34:05movies are lying to us.

00:34:06All these epic

00:34:07space scenes

00:34:08take place

00:34:09in an almost embarrassing

00:34:10silence.

00:34:12Not so fast.

00:34:13What if we told you

00:34:14that there are,

00:34:15in reality,

00:34:16certain ways

00:34:17to hear the sound

00:34:18in space?

00:34:19First of all,

00:34:20there is always noise

00:34:21on other planets.

00:34:22If there is an atmosphere

00:34:23on a space body,

00:34:24or at least something

00:34:25like gas,

00:34:26water

00:34:27or a solid surface,

00:34:28there will be noise.

00:34:30In our case,

00:34:31the atmosphere

00:34:32becomes completely silent

00:34:33at about 100 km

00:34:34above the surface

00:34:35of the Earth.

00:34:37This is where the sky

00:34:38stops being blue

00:34:39and a black starry veil

00:34:40begins.

00:34:43In any case,

00:34:44you would have to land

00:34:45on another planet

00:34:46or at least get close

00:34:47to its atmosphere

00:34:48to hear something.

00:34:49But whatever it is,

00:34:50the sound

00:34:51would be very different.

00:34:52Let's take the example

00:34:53of our sister planet,

00:34:54Venus.

00:34:55The atmosphere

00:34:56is very dense there.

00:34:57Scientists even

00:34:58qualify it

00:34:59as having a thick

00:35:00chemical soup.

00:35:02If you managed

00:35:03to stay alive

00:35:04and speak there,

00:35:05your voice

00:35:06would be very different.

00:35:08It would be much

00:35:09stronger

00:35:10and deeper.

00:35:12So,

00:35:13if you have always

00:35:14wanted to sing

00:35:15like Pavarotti,

00:35:16now you know

00:35:17what to do.

00:35:20And what would happen

00:35:21if the Earth

00:35:22had a denser atmosphere?

00:35:23What would we hear?

00:35:25Well,

00:35:26you can vaguely imagine

00:35:27if you have ever

00:35:28been in the water.

00:35:30The water is very dense.

00:35:31The sound moves

00:35:32much faster

00:35:33and better than in the air,

00:35:35at a speed

00:35:36of almost 2 km per second.

00:35:41If you sat

00:35:42in an empty room

00:35:43without a sound source,

00:35:44you wouldn't hear

00:35:45much, would you?

00:35:46Now,

00:35:47immerse your head

00:35:48in the water

00:35:49and observe how

00:35:50the same silence

00:35:51resonates here.

00:35:52It's not silent at all.

00:35:53Even if you ignore

00:35:54the omnipresent sounds

00:35:55of the water itself,

00:35:56you will immediately notice

00:35:57how much you can hear

00:35:58your own body,

00:35:59how your blood

00:36:00pulses in your veins,

00:36:01how your heart beats,

00:36:02the slightest movement

00:36:03of your fingers.

00:36:04Pretty scary,

00:36:05isn't it?

00:36:07This gives us an idea

00:36:08of what would happen

00:36:09to us on a planet

00:36:10whose atmosphere

00:36:11is denser.

00:36:12And it's just crazy.

00:36:14We would hear everything.

00:36:16Animals running

00:36:17or the movement

00:36:18of tectonic plates.

00:36:22So it's obvious

00:36:23that there is sound

00:36:24on other planets.

00:36:26But what about space?

00:36:28There is also sound,

00:36:29for example,

00:36:30in a cloud of dust.

00:36:32You can find

00:36:33space dust

00:36:34almost everywhere in space.

00:36:35It can be

00:36:36the remains of a star

00:36:37or something else.

00:36:39And in these places,

00:36:40everything is a little

00:36:41denser than normal.

00:36:43This means

00:36:44that there are probably

00:36:45dust clouds

00:36:46where particles

00:36:47are very close

00:36:48to each other,

00:36:49which means

00:36:50that they can produce sounds.

00:36:51Of course,

00:36:52these will be very weak

00:36:53and transmitted

00:36:54over a very short distance.

00:36:55But it's still

00:36:56better than nothing,

00:36:57isn't it?

00:36:59It turns out

00:37:00that we have already

00:37:01recorded a spatial sound.

00:37:02It comes from

00:37:03Perseus' galactic lama

00:37:05which is 250 million

00:37:06light years away from us.

00:37:09NASA recorded it

00:37:10in 2003.

00:37:13It looks like

00:37:14a note in B flat.

00:37:17But its frequency

00:37:18is so low

00:37:19that the human ear

00:37:20unfortunately

00:37:21cannot perceive it.

00:37:23But apart from that,

00:37:24we can only hear

00:37:25something inside

00:37:26the spaceships.

00:37:27After all,

00:37:28they are small air pockets.

00:37:31In a space suit,

00:37:32you would also hear

00:37:33the sounds very well,

00:37:34including your breathing

00:37:35or the circulation

00:37:36of your breast.

00:37:38But two astronauts

00:37:39floating side by side

00:37:40would not hear each other,

00:37:42even if they were

00:37:43getting closer

00:37:44and shouting very loudly.

00:37:45It's actually quite funny.

00:37:47If you hit your head

00:37:48against something,

00:37:49the noise would be

00:37:50very loud for you,

00:37:51but your astronaut colleague

00:37:52would not hear anything.

00:37:54That's why astronauts

00:37:55use radio devices.

00:37:59Now,

00:38:00in a purely theoretical way,

00:38:01if you could,

00:38:02one way or another,

00:38:03get out of your

00:38:04space suit

00:38:05and survive,

00:38:06you would be able

00:38:07to hear the chatter

00:38:08and the sounds

00:38:09that are happening

00:38:10inside the spaceship.

00:38:11But how?

00:38:12Simply because

00:38:13there is air

00:38:14inside the ship

00:38:15that transmits the sound.

00:38:16The sound reaches

00:38:17the metal envelope

00:38:18and crosses it.

00:38:19If you pressed against

00:38:20the ship,

00:38:21by touching it

00:38:22preferably with your elbow

00:38:23or your knee,

00:38:24the sound would be

00:38:25transmitted to the brain

00:38:26directly by your bones,

00:38:27ignoring the ears.

00:38:30Yes,

00:38:31our bones drive the sound.

00:38:32That's how,

00:38:33for example,

00:38:34deaf people

00:38:35listen to music.

00:38:36That's what we call

00:38:37bone conduction,

00:38:38which is used

00:38:39in some helmets

00:38:40and other technologies.

00:38:42You can do

00:38:43this experiment.

00:38:44Cover your ears

00:38:45with your fingers.

00:38:46Close them tight

00:38:47so that you can

00:38:48hardly hear anything.

00:38:49Then try to touch

00:38:50a sound source.

00:38:51It can be

00:38:52anything that vibrates,

00:38:53for example,

00:38:54a speaker

00:38:55playing music,

00:38:56with a part of your body

00:38:57where the bone

00:38:58is close to the skin.

00:38:59Now observe,

00:39:00or rather listen

00:39:01for the miracle to happen.

00:39:02You can hear the sound

00:39:03not through your ears

00:39:04but directly

00:39:05in your brain.

00:39:06However,

00:39:07don't repeat

00:39:08this experience

00:39:09in space.

00:39:11Now,

00:39:12you have probably

00:39:13heard of things

00:39:14like the sounds of space

00:39:15where you can listen,

00:39:16for example,

00:39:17to the sounds emitted

00:39:18by the sun

00:39:19or different planets.

00:39:20How do we

00:39:21record them?

00:39:22It's quite easy.

00:39:23We use another way

00:39:24to hear the sound

00:39:25in space,

00:39:26electromagnetic waves.

00:39:27In other words,

00:39:28a radio.

00:39:29The radio

00:39:30is based on the same

00:39:31form of electromagnetic

00:39:32radiation

00:39:33as light.

00:39:34These waves

00:39:35can travel in space

00:39:36without any problem.

00:39:37Astronaut emitters

00:39:38work this way.

00:39:39If you have ever seen

00:39:40pictures taken

00:39:41from a spaceship

00:39:42or from the International

00:39:43Space Station

00:39:44showing celestial bodies

00:39:45illuminated by the sun,

00:39:46like the Earth

00:39:47or the Moon,

00:39:48you may have noticed

00:39:49something wrong.

00:39:50Space seems

00:39:51too empty.

00:39:52A magnificent background

00:39:53filled with stars

00:39:54is missing.

00:39:55It seems

00:39:56that it would be

00:39:57very boring

00:39:58to go and observe

00:39:59the stars

00:40:00directly from space

00:40:01since the sky

00:40:02is always so dark.

00:40:03During the day,

00:40:04the sky above our heads

00:40:05is blue

00:40:06because of the diffusion

00:40:07of light

00:40:08in the atmosphere.

00:40:09This happens

00:40:10when the sun's light

00:40:11passes through the atmosphere.

00:40:12But if you are on the Moon

00:40:13or elsewhere in space,

00:40:14there is no atmosphere

00:40:15to diffuse this light.

00:40:16This is why

00:40:17the sun always seems

00:40:18to be black.

00:40:19But this does not mean

00:40:20that there is less light.

00:40:21If you look

00:40:22through a window

00:40:23of the space station,

00:40:24you will see

00:40:25as much direct sunlight

00:40:26as if you were looking

00:40:27through the window

00:40:28of your apartment

00:40:29during a day

00:40:30without clouds.

00:40:31Maybe even more.

00:40:32When you take a picture

00:40:33of a sunny day,

00:40:34you are probably

00:40:35using a color

00:40:36that is not

00:40:37as bright as the sun.

00:40:38You are probably

00:40:39using a short exposure

00:40:40and the narrow aperture

00:40:41of your camera.

00:40:42In this way,

00:40:43only a short burst

00:40:44of light

00:40:45enters the lens.

00:40:46The same principle

00:40:47applies when our pupils

00:40:48contract to the sunlight

00:40:49so as not to have

00:40:50to manage

00:40:51too much light.

00:40:52And since it is

00:40:53just as bright

00:40:54up there in space,

00:40:55the process is the same

00:40:56when you take pictures

00:40:57of objects

00:40:58illuminated by the sun.

00:40:59By using a short exposure,

00:41:00you can get

00:41:01good pictures

00:41:02of the Earth

00:41:03or the surface

00:41:04of the Moon.

00:41:05But this also means

00:41:06that there will be

00:41:07no stars in the picture.

00:41:08Even up there,

00:41:09the stars are

00:41:10relatively dull.

00:41:11They do not emit

00:41:12enough light

00:41:13to appear

00:41:14in the pictures

00:41:15taken with such settings.

00:41:16Our planet

00:41:17has a blue sky

00:41:18that slowly turns

00:41:19into a magnificent

00:41:20orange-red palette

00:41:21at dusk

00:41:22and the other way around

00:41:23at dawn.

00:41:24But if one day

00:41:25you have the opportunity

00:41:26to observe a sunset

00:41:27on Mars,

00:41:28you have to expect

00:41:29the opposite,

00:41:30a brown-orange diurnal sky

00:41:31that takes a bluish hue

00:41:32at sunset.

00:41:33First of all,

00:41:34Mars is further away

00:41:35from the sun

00:41:36than our planet.

00:41:37So when you look

00:41:38at the sun

00:41:39from the Martian surface,

00:41:40it looks duller

00:41:41and smaller.

00:41:42And that's not all.

00:41:43The sun observed

00:41:44from Mars

00:41:45is only a bluish white dot

00:41:46surrounded by a blue halo.

00:41:48The fine atmosphere

00:41:49of the red planet

00:41:50contains large particles

00:41:51of dust

00:41:52that create an effect

00:41:53called

00:41:54Mie diffusion.

00:41:55This occurs

00:41:56when the diameter

00:41:57of the particles

00:41:58in the atmosphere

00:41:59is almost the same

00:42:00as the wavelength

00:42:01of the diffused light.

00:42:02This effect filters

00:42:03the red light

00:42:04of the sun's halo.

00:42:05Thus,

00:42:06only the blue light

00:42:07would reach your eyes

00:42:08on Mars.

00:42:09How is it

00:42:10that the Earth

00:42:11has no rings?

00:42:12All the gas giants

00:42:13of our solar system

00:42:14Jupiter,

00:42:15Saturn,

00:42:16Uranus

00:42:17and Neptune

00:42:18have such rings,

00:42:19while the telluric planets

00:42:20Mercury,

00:42:21Venus,

00:42:22Earth

00:42:23and Mars

00:42:24do not.

00:42:25There are two theories

00:42:26about the way

00:42:27rings can appear

00:42:28around a planet.

00:42:29They could only be

00:42:30remnants of materials

00:42:31from the time

00:42:32when the planet was formed.

00:42:33Or they could be

00:42:34the remnants of a moon

00:42:35that was destroyed

00:42:36by a collision

00:42:37with a space body

00:42:38or ripped apart

00:42:39by the strong gravitational

00:42:40attraction

00:42:41of its mother planet.

00:42:42The gas giants

00:42:43were formed

00:42:44in the outer regions

00:42:45of our solar system,

00:42:46while all the telluric planets

00:42:47are located

00:42:48in the inner part.

00:42:49So,

00:42:50maybe the inner planets

00:42:51were better protected

00:42:52from potential collisions

00:42:53that could have

00:42:54formed their rings.

00:42:55There are also

00:42:56more moons

00:42:57in the outer regions

00:42:58of our solar system,

00:42:59which could be

00:43:00another reason

00:43:01why the rings

00:43:02of the planets

00:43:03that are there

00:43:04are stronger.

00:43:05In addition,

00:43:06the bigger planets

00:43:07have a stronger gravity.

00:43:08This means

00:43:09that they can

00:43:10keep their rings

00:43:11stable

00:43:12after their formation.

00:43:13Some experts

00:43:14think that the Earth

00:43:15had a ring system

00:43:16a long time ago.

00:43:17An object the size of Mars

00:43:18could collide

00:43:19with our mother planet,

00:43:20which probably

00:43:21created a dense ring

00:43:22of debris around it.

00:43:23Some scientists

00:43:24think that these debris

00:43:25did not form a ring,

00:43:26but what we know

00:43:27today as the Moon.

00:43:28A giant planet

00:43:29is probably

00:43:30hidden

00:43:31on the edge

00:43:32of the solar system,

00:43:33far beyond Neptune.

00:43:34Scientists have named

00:43:35this mysterious

00:43:36hypothetical world

00:43:37the New Planet.

00:43:38If it really exists,

00:43:39it is probably

00:43:40similar to Uranus

00:43:41or Neptune

00:43:42and ten times

00:43:43more massive

00:43:44than our planet.

00:43:45It is probably

00:43:46orbiting the Sun,

00:43:47but in the confines

00:43:48of the solar system,

00:43:49about 20 times

00:43:50farther than Neptune.

00:43:51Another interesting

00:43:52theory stipulates

00:43:53that the New Planet

00:43:54could actually be

00:43:55a black hole

00:43:56the size of a pamplum,

00:43:57which would

00:43:58probably be

00:43:59as large as

00:44:00a large planet.

00:44:01While we used to think

00:44:02that water

00:44:03was a rare substance

00:44:04in space,

00:44:05it actually exists

00:44:06everywhere

00:44:07in our solar system.

00:44:08For example,

00:44:09it can be found

00:44:10in asteroids

00:44:11and comets,

00:44:12as well as

00:44:13in the craters

00:44:14of the Moon

00:44:15and Mercury.

00:44:16We still do not know

00:44:17if there is enough water

00:44:18to allow us

00:44:19to live in

00:44:20any human colony

00:44:21if we decide

00:44:22to settle there.

00:44:23But a certain amount

00:44:24of water

00:44:25is certainly

00:44:26present there.

00:44:27Mars,

00:44:28on the other hand,

00:44:29also houses water

00:44:30at its poles.

00:44:31It is mainly

00:44:32hidden in the layers

00:44:33of ice

00:44:34and probably

00:44:35under the dusty

00:44:36surface of the planet.

00:44:37Europe,

00:44:38the moon of Jupiter,

00:44:39also has water.

00:44:40It is the most

00:44:41likely candidate

00:44:42we knew

00:44:43to welcome life

00:44:44outside the Earth.

00:44:45There is probably

00:44:46a whole ocean

00:44:47of liquid water

00:44:48under its frozen surface,

00:44:49and it could also

00:44:50contain twice

00:44:51as much water

00:44:52as all the oceans

00:44:53of the Earth combined.

00:44:54Neptune is

00:44:55surprisingly warm,

00:44:56even if it is

00:44:57much further away

00:44:58from the Sun

00:44:59than our planet

00:45:00and receives less

00:45:01solar light

00:45:02and heat.

00:45:03But it emits

00:45:04much more heat

00:45:05than it receives.

00:45:06Its atmosphere

00:45:07is also much more

00:45:08active than we thought,

00:45:09especially if we compare

00:45:10it to its neighbor,

00:45:11Uranus.

00:45:12These two planets

00:45:13emit the same

00:45:14amount of heat,

00:45:15even if Uranus

00:45:16is much closer

00:45:17to the Sun.

00:45:18But no one

00:45:19knows why.

00:45:20Neptune also

00:45:21has extremely strong

00:45:22winds

00:45:23that can reach

00:45:24a speed

00:45:25of 2,400 kmh.

00:45:26Could it be

00:45:27responsible for this heat?

00:45:28Or maybe

00:45:29it's because of

00:45:30the core of the planet

00:45:31or its gravitational force?

00:45:33A monstrous black hole

00:45:34rushes into space

00:45:35at a speed

00:45:36of 8 million kmh.

00:45:37Scientists have

00:45:38located it

00:45:39thanks to

00:45:40the Hubble Space Telescope.

00:45:41They think it weighs

00:45:42as much as

00:45:43a billion suns.

00:45:44It was supposed

00:45:45to stay in its place

00:45:46in the center

00:45:47of its original galaxy,

00:45:48but gravitational forces

00:45:49push it

00:45:50in all directions.

00:45:51At some point,

00:45:52this black hole

00:45:53will free itself

00:45:54from its galaxy

00:45:55and continue

00:45:56to hover in the universe.

00:45:57Fortunately,

00:45:58it is still

00:45:598 billion light years

00:46:00away from us.

00:46:01Solar storms

00:46:02are so powerful

00:46:03that they could

00:46:04plunge us

00:46:05into complete darkness.

00:46:06In July 2012,

00:46:07the most powerful

00:46:08solar storm

00:46:09in the last

00:46:10150 years

00:46:11barely missed Earth.

00:46:13The coronal mass ejections,

00:46:15or CME,

00:46:16are large ionized

00:46:17gas bubbles.

00:46:19They crossed

00:46:20our orbit

00:46:21at the time.

00:46:22If they had

00:46:23our planet

00:46:24as a direct target,

00:46:25we would have faced

00:46:26solar matter

00:46:27rushing towards Earth,

00:46:29damaging computers

00:46:30and causing

00:46:31power outages

00:46:32that would have

00:46:33lasted months.

00:46:34A surprise solar storm

00:46:35struck us

00:46:36on June 25, 2022.

00:46:38A photographer

00:46:39even managed

00:46:40to capture

00:46:41superb luminous auroras

00:46:42that crossed

00:46:43the dawn sky

00:46:44in Calgary, Canada

00:46:45and lasted

00:46:465 minutes.

00:46:47They were caused

00:46:48by the storm.

00:46:50Vampire stars

00:46:51really exist.

00:46:52They are part

00:46:53of a binary star system

00:46:54and they can

00:46:55literally

00:46:57The Sun is

00:46:58a medium-sized star

00:46:59and yet

00:47:00it could contain

00:47:011,300,000 Earths.

00:47:04The star is also

00:47:05333,000 times

00:47:06heavier than

00:47:07our planet.

00:47:09NASA

00:47:10translated radio waves

00:47:11created by the atmosphere

00:47:12of the planets

00:47:13into audible sounds.

00:47:14This is how

00:47:15astronomers discovered

00:47:16that the sound

00:47:17produced by Neptune

00:47:18looks like the waves

00:47:19of the ocean,

00:47:20that Jupiter

00:47:21seems to be underwater,

00:47:22and that Saturn's voice

00:47:23sounds like the music

00:47:24of horror movies.

00:47:26The Earth,

00:47:27sounds a bit like

00:47:28bebop jazz.

00:47:29OK,

00:47:30I made that up.

00:47:32The surface of the Sun

00:47:33is burning,

00:47:34but a flash

00:47:35is 5 times hotter.

00:47:38The Earth

00:47:39is hit by 100 flashes

00:47:40every second,

00:47:42which represents

00:47:438 million lightning

00:47:44strikes per day

00:47:45and about

00:47:463 billion per year.

00:47:47Unbelievable!

00:47:49If you ever get

00:47:50to go to the Moon

00:47:51and see

00:47:52recent footprints,

00:47:53that doesn't mean

00:47:54there's someone

00:47:55else with you.

00:47:56Footprints

00:47:57or other marks

00:47:58of the same type

00:47:59can last

00:48:00a million years

00:48:01there,

00:48:02because the Moon

00:48:03doesn't have an atmosphere.

00:48:04There's no wind,

00:48:05not even a small breeze

00:48:06that could

00:48:07slowly erase

00:48:08these footprints.

00:48:10Astronomers

00:48:11found the biggest hole

00:48:12we've ever seen

00:48:13in the Universe.

00:48:14It's called

00:48:15the Giant Void,

00:48:16and it extends

00:48:17over a surface

00:48:18of a billion light years.

00:48:19It was by accident

00:48:20that it was discovered.

00:48:21One of the members

00:48:22of the research team

00:48:23got a little bored

00:48:24and wanted to check

00:48:25how things were going

00:48:26in the direction

00:48:27of the cold point.

00:48:28It's an anomaly

00:48:29in the cosmological

00:48:30diffuse background map,

00:48:31or FDC in abbreviated.

00:48:33It's a faint glow

00:48:34that reaches our planet

00:48:35from different directions

00:48:36and fills the Universe.

00:48:38It's been crossing space

00:48:39for nearly

00:48:4014 billion years

00:48:41and constitutes

00:48:42what's left

00:48:43of the light production

00:48:44that followed the Big Bang.

00:48:47So,

00:48:48you fall in the middle

00:48:49of a black hole

00:48:50and you prepare

00:48:51for a sad ending.

00:48:53Don't panic.

00:48:55Falling in a black hole

00:48:56won't necessarily

00:48:57destroy you,

00:48:58you or your spaceship.

00:48:59You'd have to choose

00:49:00a large black hole

00:49:01to survive.

00:49:02If you fall

00:49:03in a small black hole,

00:49:04what's called

00:49:05the event horizon

00:49:06is very narrow.

00:49:07Gravity,

00:49:08on the other hand,

00:49:09increases a little more

00:49:10every centimeter.

00:49:11So,

00:49:12if you put your arm

00:49:13forward,

00:49:14there will be

00:49:15a big difference

00:49:16in gravity

00:49:17between your fingers

00:49:18and the fact

00:49:19of extending your hand

00:49:20causing a rather

00:49:21unpleasant feeling.

00:49:22Very unpleasant

00:49:23to be honest.

00:49:24Things wouldn't be

00:49:25quite the same

00:49:26if you fell

00:49:27in a supermassive black hole

00:49:28like the ones

00:49:29in the center of galaxies.

00:49:30These objects

00:49:31can be millions

00:49:32of times heavier

00:49:33than the Sun.

00:49:34Their event horizon

00:49:35is vast

00:49:36and gravity

00:49:37doesn't change

00:49:38as quickly.

00:49:39So,

00:49:40the force you'd feel

00:49:41on your heels

00:49:42and at the top of your head

00:49:43would be about the same

00:49:44and you could go

00:49:45to the heart of the black hole.

00:49:46Finally,

00:49:47if you watch

00:49:48a very touching movie

00:49:49in space

00:49:50and you start crying,

00:49:51your tears won't flow.

00:49:53They will accumulate

00:49:54around your eyeballs.

00:49:56Your eyes will become

00:49:57too dry

00:49:58and you'll feel

00:49:59like they're burning.

00:50:00All the liquid

00:50:01exposed to your body

00:50:02will evaporate,

00:50:03including

00:50:04at the surface

00:50:05of your tongue.

00:50:06Speaking of burning,

00:50:07it's something

00:50:08that fire can't do

00:50:09in space.

00:50:10Indeed,

00:50:11fire can spread

00:50:12when there's

00:50:13a flow of oxygen.

00:50:14And since there isn't

00:50:15any in space,

00:50:17once they've exploded,

00:50:18the stars

00:50:19aren't supposed

00:50:20to come back to life.

00:50:21But some stars

00:50:22have somehow survived

00:50:23a big supernova explosion.

00:50:26These zombie stars

00:50:27are rather rare.

00:50:28Scientists have found

00:50:29a very large one

00:50:30called

00:50:31LP40365.

00:50:33It's a partially burned

00:50:34white dwarf.

00:50:36A white dwarf

00:50:37is a star

00:50:38that has burned

00:50:39all its hydrogen.

00:50:40And this hydrogen

00:50:41used to be

00:50:42its nuclear fuel.

00:50:44In this case,

00:50:45the final explosion

00:50:46was perhaps weaker

00:50:47than it usually is.

00:50:49Not powerful enough

00:50:50to destroy the star

00:50:51as a whole.

00:50:52It's as if a star

00:50:53wanted to explode

00:50:54but couldn't,

00:50:55which explains

00:50:56that part of the matter

00:50:57survived.

00:50:59If you ever go into space,

00:51:00don't take off

00:51:01your suit,

00:51:02except if you're

00:51:03in a spaceship.

00:51:04In space,

00:51:05the air in your lungs

00:51:06will spread,

00:51:07as will the oxygen

00:51:08in the rest of your body.

00:51:09You'll be like a balloon,

00:51:11twice as big

00:51:12as your normal size.

00:51:13Good news,

00:51:14your skin

00:51:15is elastic enough

00:51:16to contain you,

00:51:17which means

00:51:18you won't explode.

00:51:19A little consolation.

00:51:21When an object

00:51:22enters a black hole,

00:51:23it changes shape

00:51:24and stretches

00:51:25like spaghetti.

00:51:27This happens

00:51:28because the gravitational force

00:51:29attracts an object

00:51:30in one direction

00:51:32while compressing it

00:51:33in another.

00:51:34A kind of

00:51:35paradox of pasta.

00:51:37Besides,

00:51:38a black hole

00:51:39as big as an atom

00:51:40has the mass

00:51:41of a very large mountain.

00:51:44There are some

00:51:45in the centre of the Milky Way

00:51:46called Sagittarius A.

00:51:48It has a mass

00:51:49equivalent to

00:51:50one billion suns,

00:51:51but fortunately,

00:51:52it's very far from us.

00:51:55If you made

00:51:56a big boom

00:51:57on an asteroid,

00:51:58you wouldn't be able

00:51:59to hear its sound.

00:52:01Yes,

00:52:02we often hear

00:52:03the sound of spaceships

00:52:04and space battles

00:52:05in movies,

00:52:06but it's just a myth.

00:52:08Sound is a wave

00:52:09that spreads

00:52:10due to the vibrations

00:52:11of molecules.

00:52:12A person

00:52:13hits hands

00:52:14a few meters away from you.

00:52:15The sound wave

00:52:16begins to push

00:52:17the first air molecule

00:52:18next to the explosion,

00:52:19then the second,

00:52:20the third,

00:52:21and so on

00:52:22until the wave

00:52:23reaches your ear.

00:52:24To spread the sound,

00:52:25we need molecules

00:52:26like air or water.

00:52:28In the atmosphere,

00:52:29sound waves

00:52:30spread very well,

00:52:31but space is empty.

00:52:33So,

00:52:34there's nothing to hear.

00:52:35You can hit

00:52:36loudly in your hands,

00:52:37but there won't be

00:52:38any molecule

00:52:39able to vibrate

00:52:40and transport this sound.

00:52:41So,

00:52:42to have a conversation,

00:52:43you need either a radio

00:52:45or a very good

00:52:46reading of the lips.

00:52:48Meteoroids

00:52:49are orbiting

00:52:50around the Sun,

00:52:51while most

00:52:52of the debris

00:52:53of human origin

00:52:54are orbiting

00:52:55around our planet.

00:52:56For example,

00:52:57we've launched

00:52:58nearly 9,000

00:52:59spacecraft in the world,

00:53:00from satellites

00:53:01to rockets.

00:53:02Even the smallest pieces

00:53:03can damage

00:53:04a spacecraft

00:53:05at such high speeds.

00:53:07Galaxies,

00:53:08planets,

00:53:09comets,

00:53:10stars,

00:53:11spacecrafts

00:53:12are things

00:53:13we can actually see

00:53:14in space,

00:53:15but they represent

00:53:16less than 5%

00:53:17of the total Universe.

00:53:19Black matter,

00:53:20one of the greatest

00:53:21mysteries of space,

00:53:22is the name we use

00:53:23to designate

00:53:24the entire mass

00:53:25of the Universe

00:53:26that is still invisible.

00:53:27And there's a lot of it.

00:53:28It could even

00:53:29make up 25%

00:53:30of the Universe.

00:53:31Dark energy

00:53:32makes up

00:53:33the remaining 70%

00:53:34of the Universe.

00:53:35Hmm,

00:53:36that's 100%,

00:53:37isn't it?

00:53:38Now,

00:53:39let's look at the Moon.

00:53:40It's always

00:53:41looking at us

00:53:42from one side.

00:53:43This means

00:53:44that the Moon

00:53:45has a dark side

00:53:46and that the sun's rays

00:53:47never reach it.

00:53:48It's a myth.

00:53:49The fact is

00:53:50that the Moon

00:53:51is connected to the Earth

00:53:52by gravity.

00:53:53There are days

00:53:54and nights

00:53:55there too.

00:53:56It's just that

00:53:57its rotation

00:53:58is perfectly aligned

00:53:59with that of the Earth.

00:54:00So,

00:54:01when you look at the Moon,

00:54:02you only see one side.

00:54:04Although there are

00:54:05also days

00:54:06when the sun shines,

00:54:07it's not

00:54:08the hidden side.

00:54:09It's the distant side.

00:54:10And we even have

00:54:11pictures of this place.

00:54:12And there is

00:54:13one of the biggest craters

00:54:14in the entire solar system,

00:54:15the pool of the pole

00:54:16south of Aitken.

00:54:17It's as wide

00:54:18as two states

00:54:19in Texas.

00:54:20Yee-haw!

00:54:21A myth

00:54:22that also turned out

00:54:23to be false

00:54:24insinuated that

00:54:25no one

00:54:26would ever

00:54:27go to the Moon.

00:54:28This is the original

00:54:29space suit

00:54:30of the first astronauts

00:54:31who went there.

00:54:32Look at the sole

00:54:33of the shoe.

00:54:34Some people claim

00:54:35that it's impossible

00:54:36to go to the Moon

00:54:37without shoes.

00:54:38In fact,

00:54:39it's possible.

00:54:40On the Moon,

00:54:41astronauts wore

00:54:42extra boots

00:54:43over their suits.

00:54:44And their soles

00:54:45matched perfectly

00:54:46to the footprints

00:54:47on the Moon.

00:54:48Astronauts

00:54:49didn't need them

00:54:50when they left the Moon

00:54:51and threw them away

00:54:52when the lunar walk

00:54:53was over.

00:54:54They also left

00:54:55a lot of things there.

00:54:56They even threw

00:54:57the seats of the lunar module

00:54:58to reduce their weight.

00:54:59By counting

00:55:00all the lunar missions

00:55:01to Apollo,

00:55:02the total weight

00:55:03of the waste on the Moon

00:55:04rises to

00:55:05a total of

00:55:06187 tonnes,

00:55:07including

00:55:08several lunar rovers,

00:55:09debris from space ships,

00:55:10six lunar modules

00:55:11and all the experiments

00:55:12left behind.

00:55:13It's like

00:55:14three Boeing 737s.

00:55:15Another myth

00:55:16about the Sun

00:55:17is that it's yellow.

00:55:18We'll send you

00:55:19into space

00:55:20for this one.

00:55:21You look

00:55:22through the window

00:55:23and it's white.

00:55:24The Sun

00:55:25seems yellow to us

00:55:26only through

00:55:27the filter

00:55:28of our atmosphere.

00:55:29The composition

00:55:30of the air

00:55:31and its thickness

00:55:32just distort

00:55:33the light

00:55:34and make it

00:55:35just the light

00:55:36of the star.

00:55:37But the stars

00:55:38still have

00:55:39different colours.

00:55:40You're sitting

00:55:41in a cafe on Mars,

00:55:42head down,

00:55:43trying not to

00:55:44draw attention

00:55:45to yourself.

00:55:46There's a lot of people

00:55:47and a lot of people

00:55:48sing, dance

00:55:49and speak

00:55:50the high voice

00:55:51of life on Mars.

00:55:52Your drink arrives

00:55:53and you sip it.

00:55:54For the moment,

00:55:55no one recognizes you.

00:55:56You wear a cap

00:55:57with a big cap wish

00:55:58to cover your face

00:55:59and hide

00:56:00in the eyes of the world.

00:56:01But someone

00:56:02accidentally hits you

00:56:03and sees your face.

00:56:04The music stops

00:56:05and now

00:56:06everyone is looking at you.

00:56:07You have nowhere

00:56:08to hide or run.

00:56:09You ignore

00:56:10the insistent looks

00:56:11and you continue

00:56:12to sip your drink.

00:56:13An old bearded man

00:56:14is sitting in front of you,

00:56:15surprised to be

00:56:16in your presence.

00:56:17So it's true!

00:56:18No one thought

00:56:19you would make it!

00:56:20he says.

00:56:21You don't answer

00:56:22and continue

00:56:23to drink your drink.

00:56:24All the others

00:56:25gather around you.

00:56:26Another man

00:56:27speaks.

00:56:28Well,

00:56:29you're not going

00:56:30to tell us

00:56:31how you managed

00:56:32to escape

00:56:33the Kraken's claw

00:56:34from space?

00:56:35Everyone

00:56:36is in shock.

00:56:37No one has ever

00:56:38managed to tell

00:56:39the story of the Kraken.

00:56:40Except you.

00:56:41Your plan

00:56:42was to find

00:56:43a passer-by

00:56:44to take you

00:56:45to a spaceship

00:56:46far from this planet.

00:56:47But it's too late,

00:56:48now that everyone

00:56:49knows you're there.

00:56:50And the messenger

00:56:51ran away,

00:56:52knowing that

00:56:53all the attention

00:56:54was on you.

00:56:55You then put on

00:56:56your hood

00:56:57and explain

00:56:58what happened.

00:56:59Two days earlier.

00:57:01Two days earlier.

00:57:02You are in

00:57:03your full equipment,

00:57:04ready to travel

00:57:05to the most

00:57:06distant space.

00:57:07You have a solo

00:57:08spaceship designed

00:57:09to maneuver

00:57:10through all the

00:57:11obstacles of the cosmos.

00:57:12You prepare the rest

00:57:13of the equipment

00:57:14and you fill it up.

00:57:15Everyone is looking at you,

00:57:16knowing that you

00:57:17could never come back.

00:57:18But the Kraken

00:57:19has been floating

00:57:20in space

00:57:21for too long

00:57:22and disrupts

00:57:23the transport

00:57:24of goods.

00:57:25A small ship

00:57:26like yours

00:57:27can escape

00:57:28its smell

00:57:29and its view.

00:57:30But the biggest

00:57:31ships will be destroyed.

00:57:32Your mission

00:57:33is to find

00:57:34this Kraken

00:57:35and study it.

00:57:37If you learn

00:57:38its habits,

00:57:39you will be able

00:57:40to find a way

00:57:41to get rid of it.

00:57:42Everyone

00:57:43says goodbye

00:57:44and you take off.

00:57:45You know

00:57:46that the journey

00:57:47will be very long

00:57:48to get there.

00:57:49Maybe three days

00:57:50in the void of space.

00:57:51You saw

00:57:52some quick images

00:57:53of the Kraken,

00:57:54but no one

00:57:55knows exactly

00:57:56where it sleeps.

00:57:57Or even

00:57:58if it really sleeps.

00:57:59You play music

00:58:00and adjust

00:58:01your ship

00:58:02on the speed regulator.

00:58:03You take notes

00:58:04and adjust the camera

00:58:05to document yourself

00:58:06while you prepare

00:58:07everything you need.

00:58:08You also have

00:58:09some cameras

00:58:10outside

00:58:11that record

00:58:12everything that moves,

00:58:13even thermal sensors

00:58:14to catch

00:58:15the living creatures

00:58:16that float in space.

00:58:17After a few hours,

00:58:18you leave

00:58:19the secured neighborhoods

00:58:20of Mars

00:58:21and you enter

00:58:22hostile territory.

00:58:23There is no place

00:58:24to hide

00:58:25or anyone

00:58:26to help you.

00:58:27Some small ships

00:58:28like yours

00:58:29pass by from time to time.

00:58:30They watch you

00:58:31go further

00:58:32towards the Kraken.

00:58:33You notice

00:58:34many floating panels

00:58:35powered by machines

00:58:36that put you

00:58:37on guard

00:58:38against the Kraken.

00:58:39The cameras

00:58:40start recording you

00:58:41and you start

00:58:42your video diary

00:58:43which is transmitted

00:58:44to your network

00:58:45at home.

00:58:46For the moment,

00:58:47nothing.

00:58:48It's calm

00:58:49and dark.

00:58:50The hours pass

00:58:51and you float

00:58:52in the middle of nowhere.

00:58:53You almost want

00:58:54to turn around.

00:58:55But you notice

00:58:56something strange

00:58:57in the sensors.

00:58:58You see a large object

00:58:59living nearby.

00:59:00You turn off the lights

00:59:01and you slow down

00:59:02your ship.

00:59:03You resume recording

00:59:04and you start

00:59:05talking to yourself,

00:59:06explaining everything.

00:59:07The object

00:59:08gets closer

00:59:09and closer.

00:59:10You shift

00:59:11to avoid it

00:59:12and you hang on

00:59:13to a floating rock.

00:59:14But you still

00:59:15see nothing.

00:59:16Suddenly,

00:59:17you see

00:59:18luminous creatures

00:59:19that look like

00:59:20jellyfish

00:59:21and that gather

00:59:22in a group.

00:59:23On your thermal sensors,

00:59:24they seem

00:59:25to be big objects.

00:59:26But in fact,

00:59:27they are only

00:59:28small creatures.

00:59:29According to your studies,

00:59:30these creatures

00:59:31are part of

00:59:32the main food

00:59:33of the jellyfish.

00:59:34So,

00:59:35they are probably

00:59:36fleeing it.

00:59:37After a few minutes,

00:59:38the creatures

00:59:39move away

00:59:40while floating

00:59:41and you take off

00:59:42and turn on the lights again.

00:59:43A few more hours pass

00:59:44and you still

00:59:45don't see

00:59:46any jellyfish.

00:59:47Suddenly,

00:59:48a breath shakes

00:59:49your ship

00:59:50and you are slightly

00:59:51deviated

00:59:52from your trajectory.

00:59:53You notice

00:59:54that a big object

00:59:55has penetrated

00:59:56your thermal sensors

00:59:57and got out of it.

00:59:58You keep moving

00:59:59and check

01:00:00the reading parameters

01:00:01to see if your cameras

01:00:02have managed

01:00:03to capture something.

01:00:04You try to look

01:00:05carefully

01:00:06but it seems

01:00:07that a gust of wind

01:00:08passed in front of you.

01:00:09Which is weird

01:00:10because there is

01:00:11no wind in space.

01:00:12You check

01:00:13the thermal sensors

01:00:14and you notice

01:00:15that a big object

01:00:16with the shape

01:00:17of a kraken

01:00:18passed in front of you.

01:00:19It is still there

01:00:20and it probably

01:00:21spotted your smell.

01:00:22Your systems

01:00:23try to recover

01:00:24DNA particles

01:00:25and study them.

01:00:26After a while,

01:00:27they show that

01:00:28the kraken's skin

01:00:29can change color

01:00:30depending on its environment.

01:00:31Its skin is thick

01:00:32and composed

01:00:33of a fluorescent

01:00:34cosmic matter

01:00:35which is new

01:00:36compared to

01:00:37all the other creatures

01:00:38you have encountered.

01:00:39The system

01:00:40continues to study it.

01:00:41After a while,

01:00:42the kraken

01:00:43gets out of your radar

01:00:44and disappears.

01:00:45You turn around

01:00:46to try to find it.

01:00:47People on Mars

01:00:48can see the data

01:00:49and already have

01:00:50information on its size

01:00:51and the quality

01:00:52of its skin.

01:00:53They have even seen

01:00:54images that you

01:00:55managed to capture.

01:00:56As you continue

01:00:57to move towards it,

01:00:58you turn on

01:00:59your projectors

01:01:00to try to see something.

01:01:01Your cameras

01:01:02are still rolling.

01:01:03Suddenly,

01:01:04the kraken

01:01:05changes skin color

01:01:06and appears

01:01:07right in front of you.

01:01:08Its large tentacles

01:01:09flash

01:01:10and whip

01:01:11the space debris

01:01:12that is nearby.

01:01:13Its huge eye,

01:01:14as big as

01:01:15a bus,

01:01:16looks at you.

01:01:17It opens its mouth

01:01:18and you see

01:01:19rows of pointed teeth

01:01:20that turn around you

01:01:21like a grinder.

01:01:22It has a big beak

01:01:23that can break

01:01:24your ship easily.

01:01:25It starts to blink

01:01:26quickly

01:01:27as a warning sign.

01:01:28It expels liquid

01:01:29to move

01:01:30in a space environment

01:01:31without gravity.

01:01:32It moves

01:01:33and throws itself

01:01:34towards you.

01:01:35Your ship

01:01:36has an automatic

01:01:37force field

01:01:38to protect you,

01:01:39but it cannot

01:01:40stand

01:01:41the powerful bite

01:01:42of the kraken.

01:01:43After only a few seconds,

01:01:44the shield

01:01:45breaks

01:01:46and your ship

01:01:47falls down

01:01:48on the ground

01:01:49and you are stuck

01:01:50on another planet.

01:01:51You are crushed

01:01:52on a swampy land.

01:01:53Your ship has survived,

01:01:54but it cannot take off.

01:01:55The analysis

01:01:56of the kraken

01:01:57is ready.

01:01:58It shows

01:01:59that it does not need

01:02:00oxygen to breathe

01:02:01and that its DNA

01:02:02is evolving.

01:02:03Now that it has

01:02:04tasted

01:02:05your force field,

01:02:06it can adapt

01:02:07to create

01:02:08a similar

01:02:09bio force field.

01:02:10But you are crushed

01:02:11on a planet

01:02:12that is foreign to you.

01:02:13You put on

01:02:14your safety suit

01:02:15and you observe

01:02:16the environment.

01:02:17Your ship

01:02:18is full

01:02:19of nitrogen

01:02:20and sulfur.

01:02:21You go out

01:02:22and you walk around.

01:02:23Gravity

01:02:24is similar

01:02:25to that of the Earth.

01:02:26As you venture

01:02:27into the swamp,

01:02:28you begin to see

01:02:29small skin particles

01:02:30similar to those

01:02:31that your ship

01:02:32has caught.

01:02:33The liquid

01:02:34below you

01:02:35is a foreign substance

01:02:36that seems

01:02:37to deteriorate

01:02:38your suit.

01:02:39So,

01:02:40you choose

01:02:41to do overtime.

01:02:42The trees are strange

01:02:43and seem to live

01:02:44from the atmosphere,

01:02:45but there is

01:02:46no sign of life

01:02:47on the surface.

01:02:48Suddenly,

01:02:49you see

01:02:50a huge crater

01:02:51that leads

01:02:52to the center

01:02:53of the planet.

01:02:54You go inside

01:02:55and you see

01:02:56ships

01:02:57identical to yours.

01:02:58It seems

01:02:59that the Kraken

01:03:00made them

01:03:01deviate

01:03:02from their path

01:03:03and that they

01:03:04crashed

01:03:05on this planet.

01:03:06Many of them

01:03:07seem to be intact

01:03:08while others

01:03:09are completely destroyed.

01:03:10Your sensors

01:03:11detect

01:03:12another creature

01:03:13that lives

01:03:14in the center.

01:03:15You try

01:03:16to reach it

01:03:17but you feel

01:03:18the ground

01:03:19shaking under you.

01:03:20You go down

01:03:21to try

01:03:22to avoid

01:03:23the rocks

01:03:24that fall

01:03:25over your head.

01:03:26A large tentacle

01:03:27arises from nowhere,

01:03:28then another

01:03:29and another.

01:03:30It swings

01:03:31and rumbles

01:03:32in the open air.

01:03:33Do you see?

01:03:34In the 1970s,

01:03:35scientists discovered

01:03:36a mysterious

01:03:37gravitational anomaly

01:03:38called

01:03:39the Great Attractor.

01:03:40Wait,

01:03:41but that was

01:03:42my nickname

01:03:43in high school.

01:03:44In short,

01:03:45you won't be able

01:03:46to see it

01:03:47because it is

01:03:48on the other side

01:03:49of our galaxy,

01:03:50about 150 million

01:03:51light years away.

01:03:52The Great Attractor

01:03:53is actually

01:03:54in the direction

01:03:55that scientists

01:03:56usually call

01:03:57the avoidance zone.

01:03:58Oh,

01:03:59I have one too.

01:04:00It's my sock drawer.

01:04:01There is so much

01:04:02dust and gas

01:04:03in this region

01:04:04that we can't

01:04:05distinguish

01:04:06what's going on.

01:04:07This zone blocks

01:04:08most of the visible light

01:04:09coming from beyond.

01:04:10But all this dust

01:04:11and gas

01:04:12don't block

01:04:13X-rays

01:04:14and with the development

01:04:15of X-ray astronomy,

01:04:16researchers could

01:04:17finally begin

01:04:18to observe

01:04:19all the objects

01:04:20in this zone,

01:04:21including

01:04:22this mysterious force

01:04:23that attracts everything.

01:04:24But so far,

01:04:25no one has yet

01:04:26understood

01:04:27why this was happening.

01:04:28Our Moon

01:04:29could be

01:04:30200 million years

01:04:31younger

01:04:32than we thought

01:04:33before.

01:04:34Many scientists

01:04:35think that the Moon

01:04:36was formed

01:04:37during a powerful

01:04:38collision

01:04:39between our planet

01:04:40and an unknown body

01:04:41the size of Mars.

01:04:42The dust

01:04:43that we know

01:04:44as the Moon.

01:04:45The lunar crust

01:04:46probably went through

01:04:47a solidification process

01:04:48for more than

01:04:49200 million years.

01:04:50Did you know

01:04:51that there was

01:04:52originally

01:04:53a magma ocean

01:04:54on the Moon?

01:04:55Scientists have

01:04:56observed this reality

01:04:57after discovering

01:04:58large quantities

01:04:59of light minerals

01:05:00called plagioclases.

01:05:01This material

01:05:02generally crystallizes

01:05:03and floats

01:05:04on the surface

01:05:05of the magma.

01:05:06In any case,

01:05:07these minerals

01:05:08were 4.36 billion years old,

01:05:09which means

01:05:10they formed

01:05:11200 million years

01:05:12after the first

01:05:13solid materials

01:05:14of our solar system

01:05:15appeared.

01:05:16Thus,

01:05:17the theory

01:05:18that the Moon

01:05:19was formed

01:05:20during this cataclysmic chaos

01:05:21could be true.

01:05:22If you land

01:05:23on the Moon one day

01:05:24and you leave

01:05:25your footprint

01:05:26on its surface,

01:05:27it can stay there

01:05:28for a million years.

01:05:29You will also see

01:05:30the footprints

01:05:31of other astronauts,

01:05:32even if no one

01:05:33has landed

01:05:34on its lunar surface

01:05:35for decades.

01:05:36The Moon

01:05:37does not have

01:05:38an atmosphere

01:05:39that is clean to it.

01:05:40There is no wind

01:05:41and there are no footprints.

01:05:42We perceive it

01:05:43as a small dot

01:05:44somewhere in the distance.

01:05:45But in reality,

01:05:46the Sun is so big

01:05:47that if it were

01:05:48a hollow sphere,

01:05:49you could fill it

01:05:50with more than

01:05:51a million Earths.

01:05:52The Sun

01:05:53represents

01:05:5499.86%

01:05:55of the mass

01:05:56of our

01:05:57entire solar system.

01:05:58Another huge object

01:05:59of our solar system

01:06:00is Jupiter.

01:06:01It is 11 times

01:06:02larger than our planet.

01:06:03For comparison,

01:06:04the Earth

01:06:05is not even

01:06:06the size

01:06:07of the Great Red Spot.

01:06:08This huge storm

01:06:09has been raging on Jupiter

01:06:10for more than a century.

01:06:11And no,

01:06:12it is not anchored

01:06:13to any solid,

01:06:14since Jupiter

01:06:15is a gas giant.

01:06:16It is similar

01:06:17to a colossal

01:06:18oval-shaped

01:06:19hurricane,

01:06:20reddish in color

01:06:21and quite large

01:06:22to swallow

01:06:23our entire planet.

01:06:24There was a time

01:06:25when it was

01:06:26three times

01:06:27larger than our planet.

01:06:28But over the centuries,

01:06:29it shrank

01:06:30as it stretched.

01:06:33As for Jupiter itself,

01:06:34this gas giant

01:06:35is a kind of vacuum cleaner

01:06:36that keeps

01:06:37our solar system

01:06:38safe.

01:06:39Jupiter has

01:06:40an incredibly strong

01:06:41gravity

01:06:42that devours

01:06:43comets

01:06:44or asteroids

01:06:45that could potentially

01:06:46harm our home planet.

01:06:47In some other

01:06:48planetary systems,

01:06:49gas giants

01:06:50similar to Jupiter

01:06:51migrate from

01:06:52the position

01:06:53where they were formed.

01:06:54They spiral

01:06:55inward

01:06:56and get closer

01:06:57to their star.

01:06:58And during their journey,

01:06:59they swallow

01:07:00small,

01:07:01telluric planets.

01:07:02Or their

01:07:03immense gravitational force

01:07:04projects these planets

01:07:05out of their solar system.

01:07:06Fortunately for us,

01:07:07Jupiter's

01:07:08gravitational force

01:07:09doesn't work

01:07:10that way.

01:07:11If similar planets

01:07:12like Jupiter

01:07:13stay away

01:07:14from their stars,

01:07:15they ensure

01:07:16the safety

01:07:17of their planetary system

01:07:18by protecting

01:07:19the small planets

01:07:20that are

01:07:21in their

01:07:22inner orbit.

01:07:23Jupiter,

01:07:24for example,

01:07:25can influence

01:07:26the orbits

01:07:27of small

01:07:28space bodies

01:07:29that are

01:07:30too close

01:07:31to the

01:07:32inner planets.

01:07:33This is why

01:07:34this gas giant

01:07:35is an excellent

01:07:36guardian

01:07:37for Jupiter.

01:07:38It leaves

01:07:39a trail

01:07:40of debris

01:07:41behind it.

01:07:42I had

01:07:43a little brother

01:07:44who did the same.

01:07:45It is about

01:07:46a million times

01:07:47heavier than

01:07:48our Sun.

01:07:49And right now,

01:07:50it is two billion

01:07:51light years

01:07:52away from Earth.

01:07:53This black hole

01:07:54started like all the others

01:07:55in its own

01:07:56elliptical galaxy

01:07:57with numerous

01:07:58stars

01:07:59surrounding it.

01:08:00Supermassive black holes

01:08:01often form

01:08:02and stay

01:08:03in the center

01:08:04of galaxies.

01:08:05But this one

01:08:06met another

01:08:07galaxy

01:08:08at some point.

01:08:09Sometimes,

01:08:10galaxies merge

01:08:11to form

01:08:12a new galaxy

01:08:13if this happens.

01:08:14But not this time.

01:08:15Instead of merging,

01:08:16the galaxy of this black hole

01:08:17went through

01:08:18a much larger galaxy

01:08:19millions of years ago.

01:08:20This gigantic galaxy

01:08:21had already

01:08:22swallowed other galaxies

01:08:23on its way.

01:08:24And because it was

01:08:25so big,

01:08:26the galaxy

01:08:27surrounding

01:08:28our supermassive

01:08:29black hole

01:08:30ended up being

01:08:31torn apart.

01:08:32The black hole

01:08:33in its center

01:08:34managed to escape

01:08:35with some

01:08:36nearby stars.

01:08:37What left

01:08:38this burning haze

01:08:39spreading beyond

01:08:40the surrounding space.

01:08:41Super solar storms

01:08:42are so powerful

01:08:43that they can

01:08:44cause

01:08:45power cuts

01:08:46all over the world.

01:08:47Random eruptions

01:08:48coming from the sun

01:08:49cause these solar storms

01:08:50and they can really

01:08:51happen at any time.

01:08:52In 2012,

01:08:53we were lucky

01:08:54because the most powerful

01:08:55solar storm

01:08:56of the last 150 years

01:08:57passed very close to us.

01:08:58It simply

01:08:59managed to cross

01:09:00the Earth's orbit.

01:09:01If it had

01:09:02happened

01:09:03only once,

01:09:04our planet

01:09:05would have had to

01:09:06face terrible consequences.

01:09:07In particular,

01:09:08power cuts

01:09:09all over the globe.

01:09:10Gamma-ray surges

01:09:11are powerful enough

01:09:12to destroy

01:09:13planets.

01:09:14We are talking

01:09:15about extremely strong

01:09:16surges,

01:09:17which mainly occur

01:09:18in very,

01:09:19very distant galaxies.

01:09:20If these rays

01:09:21are directed

01:09:22directly towards

01:09:23a space object,

01:09:24they can completely

01:09:25destroy it,

01:09:26even if we are

01:09:27talking about

01:09:28an entire planet.

01:09:29The Earth is safe

01:09:30for the moment

01:09:31and we don't have

01:09:32much to fear.

01:09:33A gamma-ray surge

01:09:34occurs in our galaxy

01:09:35about once

01:09:36every 5 million years.

01:09:39Fortunately,

01:09:40it occurs too far

01:09:41and does not affect

01:09:42life on Earth.

01:09:43All of this,

01:09:44in short,

01:09:45does not concern us,

01:09:46but it is still

01:09:47frightening.

01:09:48Burning ice

01:09:49does exist.

01:09:50It may be difficult

01:09:51to imagine it

01:09:52here on Earth,

01:09:53but a strange planet

01:09:54called Gliese 436 b

01:09:55literally consists

01:09:56of a burning

01:09:57ball of ice.

01:09:58It may be

01:09:59covered in ice,

01:10:00but at the same time

01:10:01it has a temperature

01:10:02of about 3 °C.

01:10:03You can't really

01:10:04see it burn

01:10:05because there is

01:10:06too much water

01:10:07on this planet.

01:10:08It is because of

01:10:09its strong gravitational

01:10:10attraction that

01:10:11attracts the water

01:10:12molecules to the

01:10:13heart of the planet

01:10:14and compresses them

01:10:15incredibly densely.

01:10:16In this way,

01:10:17the water molecules

01:10:18cannot evaporate

01:10:19and that is why

01:10:20the ice on the surface

01:10:21of the planet

01:10:22never melts.

01:10:23There are stars

01:10:24that can

01:10:25pierce other stars.

01:10:26These space objects

01:10:27are for the most part

01:10:28smaller stars

01:10:29with a weaker mass.

01:10:30They target

01:10:31the closest star

01:10:32and begin to absorb

01:10:33their hydrogen fuel

01:10:34to increase

01:10:35their own mass

01:10:36and generally

01:10:37live longer.

01:10:38A vampire star

01:10:39is colored

01:10:40with a bright blue.

01:10:41It also becomes

01:10:42warmer.

01:10:43Thus,

01:10:44it gives the impression

01:10:45of being much younger

01:10:46than it actually is.

01:10:47If a star

01:10:48or any other object

01:10:49falls into a black hole,

01:10:50it is stretched

01:10:51like a spaghetti dish.

01:10:52This process

01:10:53is even called

01:10:54spaghettification.

01:10:55In space,

01:10:56no one

01:10:57hears you scream.

01:10:58As everyone knows,

01:10:59star explosions,

01:11:00asteroids crashing

01:11:01and planets on fire

01:11:02do not make

01:11:03any noise

01:11:04in space.

01:11:05Really?

01:11:06What if we could

01:11:07indeed hear

01:11:08some noise up there?

01:11:09Ok,

01:11:10back to school.

01:11:11Sound

01:11:12is a mechanical wave

01:11:13coming from

01:11:14a vibration.

01:11:15Hm,

01:11:16but what exactly

01:11:17does that mean?

01:11:18The most famous example

01:11:19is that of

01:11:20guitar strings.

01:11:21If you scratch

01:11:22one of them,

01:11:23it starts to vibrate.

01:11:24The atoms inside

01:11:25the metal string

01:11:26start to vibrate

01:11:27and hit the atoms

01:11:28of the air

01:11:29around them.

01:11:30The atoms

01:11:31push each other

01:11:32until some

01:11:33reach our ears.

01:11:34It's like the wave

01:11:35created by a stone

01:11:36thrown into a pond.

01:11:37And this happens

01:11:38very quickly,

01:11:39at a speed

01:11:40of about

01:11:41340 meters per second.

01:11:42Then,

01:11:43our eardrums

01:11:44start to vibrate

01:11:45at the same frequency

01:11:46and the small water

01:11:47inside our ears

01:11:48transmit this vibration

01:11:49to the brain.

01:11:50The brain

01:11:51then operates

01:11:52its magic

01:11:53by recognizing

01:11:54the sound

01:11:55and transforming it

01:11:56into sound.

01:11:57Great!

01:11:58Now,

01:11:59we know

01:12:00that we need

01:12:01some particles

01:12:02to create sound

01:12:03and we can find

01:12:04these particles

01:12:05in gases,

01:12:06liquids

01:12:07and solid substances.

01:12:08But what about

01:12:09space?

01:12:10It's an almost

01:12:11perfect vacuum

01:12:12and you've probably

01:12:13already heard

01:12:14that there is

01:12:15no sound

01:12:16in space

01:12:17because it's

01:12:18a vacuum.

01:12:19But what does

01:12:20that really mean?

01:12:21A perfect vacuum

01:12:22is a totally

01:12:23empty area

01:12:24of matter.

01:12:25This means

01:12:26that there is

01:12:27nothing in this place.

01:12:28Yes,

01:12:29despite all

01:12:30these celestial bodies

01:12:31in space,

01:12:32there is no air

01:12:33between them,

01:12:34no atoms

01:12:35or particles,

01:12:36nothing at all.

01:12:37In fact,

01:12:38almost nothing.

01:12:39To be quite exact,

01:12:40the perfect vacuum

01:12:41doesn't really exist.

01:12:42We can't get rid

01:12:43of atoms

01:12:44definitively,

01:12:45but space

01:12:46is very close

01:12:47to this notion.

01:12:48On average,

01:12:49there are

01:12:501 to 5 atoms

01:12:51per cubic centimeter.

01:12:52This can seem

01:12:53to be a lot,

01:12:54but keep in mind

01:12:55that these atoms

01:12:56are microscopic

01:12:57and the distance

01:12:58between them

01:12:59is huge.

01:13:00For comparison,

01:13:01a cubic centimeter

01:13:02of air

01:13:03contains about

01:13:04a thousand atoms.

01:13:05So, of course,

01:13:06with such a low density,

01:13:07these atoms

01:13:08can't push

01:13:09each other,

01:13:10even if the vibration

01:13:11is very strong,

01:13:12as in the case

01:13:13of a supernova,

01:13:14for example.

01:13:15They still

01:13:16can't do it.

01:13:18But then,

01:13:19movies are lying to us.

01:13:20All these

01:13:21epic space scenes

01:13:22take place

01:13:23in an almost

01:13:24annoying silence.

01:13:26Not so fast.

01:13:27What if we told you

01:13:28that there are,

01:13:29in reality,

01:13:30certain ways

01:13:31to hear the sound

01:13:32in space?

01:13:33First of all,

01:13:34there is always

01:13:35noise on other planets.

01:13:36If there is an atmosphere

01:13:37on a space body,

01:13:38or at least

01:13:39something like

01:13:40gas,

01:13:41water

01:13:42or a solid surface,

01:13:43there will be noise.

01:13:44In our case,

01:13:45the atmosphere

01:13:46becomes completely

01:13:47silent

01:13:48about 100 km

01:13:49above the surface

01:13:50of the Earth.

01:13:51This is where

01:13:52the sky stops being blue

01:13:53and a starry

01:13:54black veil begins.

01:13:57In any case,

01:13:58we would have to land

01:13:59on another planet

01:14:00or at least

01:14:01get close to its atmosphere

01:14:02to hear something.

01:14:04But, whatever it is,

01:14:05the sound

01:14:06would be very different.

01:14:07Let's take the example

01:14:08of our sister planet,

01:14:09Venus.

01:14:10The atmosphere

01:14:11is very dense there.

01:14:12Scientists

01:14:13even call it

01:14:14to make fun of

01:14:15thick chemical soup.

01:14:17If you manage

01:14:18to stay alive

01:14:19and talk there,

01:14:20your voice

01:14:21would be very different.

01:14:23It would be

01:14:24much louder

01:14:25and deeper.

01:14:27So,

01:14:28if you have always

01:14:29wanted to sing

01:14:30like Pavarotti,

01:14:31now you know

01:14:32what to do.

01:14:33And what would happen

01:14:34if the Earth

01:14:35had a denser atmosphere?

01:14:36What would we hear?

01:14:38Well,

01:14:39you can vaguely

01:14:40imagine it

01:14:41if you have ever

01:14:42been in the water.

01:14:43The water is very dense.

01:14:44The sound moves

01:14:45much faster

01:14:46and better

01:14:47than in the air.

01:14:48At a speed

01:14:49of almost 2 km per second.

01:14:54If you sit

01:14:55in an empty room

01:14:56without a sound source,

01:14:57you won't hear much,

01:14:58will you?

01:14:59Now,

01:15:00immerse your head

01:15:01in the water

01:15:02and observe

01:15:03how the same silence

01:15:04resonates here.

01:15:05It is not silent at all.

01:15:06Even if you ignore

01:15:07the omnipresent sounds

01:15:08of the water itself,

01:15:09you will immediately notice

01:15:10how much

01:15:11you can hear

01:15:12your own body,

01:15:13how your blood

01:15:14pulsates in your veins,

01:15:15how your heart beats,

01:15:16the slightest movement

01:15:17of your fingers.

01:15:18Pretty scary,

01:15:19isn't it?

01:15:21This gives us an idea

01:15:22of what would happen

01:15:23to us on a planet

01:15:24whose atmosphere

01:15:25is denser.

01:15:26And it's just crazy.

01:15:27We would hear everything.

01:15:30Animals running

01:15:31or the movement

01:15:32of tectonic plates.

01:15:35It is therefore obvious

01:15:36that there is sound

01:15:37on other planets.

01:15:39But what about space?

01:15:41There is also sound,

01:15:42for example,

01:15:43in a cloud of dust.

01:15:45You can find

01:15:46space dust

01:15:47almost everywhere in space.

01:15:49It can be the remains

01:15:50of a star

01:15:51or something else.

01:15:52And in these places,

01:15:53everything is a little denser

01:15:54than normal.

01:15:56This means

01:15:57that there are probably

01:15:58clouds of dust

01:15:59where the particles

01:16:00are very close

01:16:01to each other.

01:16:02This means

01:16:03that they can produce sounds.

01:16:05Of course,

01:16:06these will be very weak

01:16:07and transmitted

01:16:08over a very short distance.

01:16:09But it's still

01:16:10better than nothing, isn't it?

01:16:13It turns out

01:16:14that we have already

01:16:15recorded a spatial sound.

01:16:16It comes from

01:16:17Perseus' Galactic Lama,

01:16:18which is located

01:16:19250 million light years away

01:16:20from us.

01:16:23NASA recorded it

01:16:24in 2003.

01:16:26It looks like

01:16:27a note in B flat.

01:16:31But its frequency

01:16:32is so low

01:16:33that the human ear

01:16:34unfortunately

01:16:35cannot perceive it.

01:16:37But apart from that,

01:16:38we can only hear

01:16:39something inside

01:16:40spaceships.

01:16:41After all,

01:16:42they are small air pockets.

01:16:44In a space suit,

01:16:45you would also

01:16:46hear the sounds very well,

01:16:47including your breathing

01:16:48or the circulation

01:16:49of your breast.

01:16:51But two astronauts

01:16:52floating side by side

01:16:53would not hear each other,

01:16:54even if they were

01:16:55getting closer

01:16:56and shouting very loudly.

01:16:58It's also quite funny.

01:16:59If you hit your head

01:17:00against something,

01:17:01the noise would be

01:17:02very loud for you,

01:17:03but your astronaut colleague

01:17:04would not hear anything.

01:17:06This is why astronauts

01:17:07use radio devices.

01:17:12Now,

01:17:13in a purely theoretical way,

01:17:14if you could,

01:17:15one way or another,

01:17:16get out of your space suit

01:17:17and survive,

01:17:18you would be able

01:17:19to hear the noise

01:17:20inside the spaceship.

01:17:21But how?

01:17:23Simply because

01:17:24there is air inside

01:17:25the ship

01:17:26that transmits the sound.

01:17:27The air reaches

01:17:28the metal envelope

01:17:29and crosses it.

01:17:31If you pressed against

01:17:32the ship,

01:17:33by touching it preferably

01:17:34with your elbow

01:17:35or your knee,

01:17:36the sound would be

01:17:37transmitted to the brain

01:17:38directly by your bones,

01:17:39ignoring the ears.

01:17:42Or,

01:17:44yes,

01:17:45our bones drive the sound.

01:17:46This is how,

01:17:47for example,

01:17:48deaf people

01:17:49listen to music.

01:17:50This is called

01:17:51bone conduction,

01:17:52which is used

01:17:53in some headphones

01:17:54and other technologies.

01:17:56You can do

01:17:57a little experiment.

01:17:58Cover your ears

01:17:59with your fingers.

01:18:00Close them tight

01:18:01so that you can

01:18:02hardly hear anything.

01:18:03Then try to touch

01:18:04a sound source.

01:18:05It can be

01:18:06anything that vibrates,

01:18:07for example,

01:18:08a speaker

01:18:09playing music,

01:18:10with a part of your body

01:18:11where the bone

01:18:12is located.

01:18:13Now observe,

01:18:14or rather listen,

01:18:15the miracle happening.

01:18:16You can hear the sound

01:18:17not through your ears

01:18:18but directly

01:18:19in your brain.

01:18:20However,

01:18:21don't repeat

01:18:22this experience

01:18:23in space.

01:18:25Now,

01:18:26you have probably

01:18:27heard of things

01:18:28like the sounds

01:18:29of space,

01:18:30where you can listen,

01:18:31for example,

01:18:32to the sounds emitted

01:18:33by the sun

01:18:34or different planets.

01:18:35How do you

01:18:36record them?

01:18:37It's quite easy.

01:18:38We use another way

01:18:39to hear the sound

01:18:40in space,

01:18:41electromagnetic radiation.

01:18:42In other words,

01:18:43a radio.

01:18:44The radio

01:18:45is based on the same form

01:18:46of electromagnetic radiation

01:18:47as light.

01:18:48These waves

01:18:49can travel in space

01:18:50without any problem.

01:18:51Astronaut emitters

01:18:52work this way.

01:18:53If you have ever seen

01:18:54pictures taken

01:18:55from a space ship

01:18:56or from the International

01:18:57Space Station

01:18:58showing celestial bodies

01:18:59illuminated by the sun,

01:19:00like the Earth

01:19:01or the Moon,

01:19:02you may have noticed

01:19:03something wrong.

01:19:04Space seems too empty.

01:19:05There is a lack

01:19:06of a magnificent background

01:19:07filled with stars.

01:19:08This is not

01:19:09the case.

01:19:11It seems that it would be

01:19:12very boring

01:19:13to observe the stars

01:19:14directly from space

01:19:15since the sky

01:19:16is always so dark.

01:19:17During the day,

01:19:18the sky above our heads

01:19:19is blue

01:19:20because of the diffusion

01:19:21of light.

01:19:22This happens

01:19:23when the light

01:19:24of the sun

01:19:25crosses the atmosphere.

01:19:26But if you are on the Moon

01:19:27or elsewhere in space,

01:19:28there is no atmosphere

01:19:29to diffuse this light.

01:19:30This is why

01:19:31the sun

01:19:32always seems black.

01:19:34But this does not mean

01:19:35that there is less light.

01:19:36If you take a look

01:19:37through a space station

01:19:38skylight,

01:19:39you will see

01:19:40as much direct sunlight

01:19:41as if you were looking

01:19:42through the window

01:19:43of your apartment

01:19:44during a day without clouds,

01:19:45maybe even more.

01:19:47When you take a picture

01:19:48during a sunny day,

01:19:49you probably use

01:19:50a short exposure

01:19:51as well as the narrow

01:19:52aperture setting

01:19:53of your camera.

01:19:55In this way,

01:19:56only a short burst of light

01:19:57enters the lens.

01:19:58The same principle

01:19:59applies when our pupils

01:20:00contract to the sunlight

01:20:01in order not to have

01:20:02to manage

01:20:03too much light.

01:20:05And as it is

01:20:06just as clear up there

01:20:07in space,

01:20:08the process is the same

01:20:09when you take pictures

01:20:10of objects lit up

01:20:11by the sun.

01:20:12By using a short exposure,

01:20:13you can get

01:20:14good luminous pictures

01:20:15of the Earth

01:20:16or the surface

01:20:17of the Moon.

01:20:18But this also means

01:20:19that there will be

01:20:20no stars in the picture.

01:20:21Even up there,

01:20:22the stars are

01:20:23relatively dull.

01:20:24They do not emit

01:20:25enough light

01:20:26to appear in the pictures

01:20:27taken with such settings.

01:20:29Our planet

01:20:30has a blue sky

01:20:31that slowly turns

01:20:32into a magnificent

01:20:33orange-red palette

01:20:34at dusk

01:20:35and the other way around

01:20:36at dawn.

01:20:37If one day

01:20:38you have the opportunity

01:20:39to observe a sunset

01:20:40on Mars,

01:20:41you must expect

01:20:42the opposite,

01:20:43an orange-brown

01:20:44diurnal sky

01:20:45with a bluish hue

01:20:46at sunset.

01:20:47First of all,

01:20:48Mars is further away

01:20:49from the sun

01:20:50than our planet.

01:20:51So when you look

01:20:52at the sun

01:20:53from the Martian surface,

01:20:54it looks duller

01:20:55and smaller.

01:20:56And that's not all.

01:20:57The sun observed

01:20:58since Mars

01:20:59is only a bluish white dot

01:21:00surrounded by a blue halo.

01:21:02The fine atmosphere

01:21:03of the red planet

01:21:04contains large particles

01:21:05of dust

01:21:06that produce

01:21:07an effect called

01:21:08Mie diffusion.

01:21:09This occurs

01:21:10when the diameter

01:21:11of the particles

01:21:12in the atmosphere

01:21:13is almost the same

01:21:14as the wavelength

01:21:15of the diffused light.

01:21:16This effect filters

01:21:17the red light

01:21:18from the sun's rays.

01:21:19Thus,

01:21:20only the blue light

01:21:21would reach your eyes

01:21:22on Mars.

01:21:23How is it

01:21:24that the Earth

01:21:25has no rings?

01:21:26All the gas giants

01:21:27of our solar system

01:21:28Jupiter,

01:21:29Saturn,

01:21:30Uranus and Neptune

01:21:31have such rings,

01:21:32while the telluric planets

01:21:33Mercury,

01:21:34Venus,

01:21:35and Mars

01:21:36do not.

01:21:37There are two theories

01:21:38about the way

01:21:39rings can appear

01:21:40around a planet.

01:21:41They could only be

01:21:42remnants of materials

01:21:43from the time

01:21:44when the planet was formed.

01:21:46Or they could be

01:21:47remnants of a moon

01:21:48that was destroyed

01:21:49by a collision

01:21:50with a space body

01:21:51or torn apart

01:21:52by the strong gravitational

01:21:53attraction

01:21:54of its mother planet.

01:21:56The gas giants

01:21:57formed in the

01:21:58outer regions

01:21:59of our solar system,

01:22:00while all the telluric planets

01:22:01are located

01:22:02in the inner part.

01:22:03So,

01:22:04maybe the inner planets

01:22:05were better protected

01:22:06from potential collisions

01:22:07that could have

01:22:08formed their rings.

01:22:09There are also

01:22:10more moons

01:22:11in the outer regions

01:22:12of our solar system,

01:22:13which could be

01:22:14another reason

01:22:15why the planets

01:22:16that are there

01:22:17have rings.

01:22:18In addition,

01:22:19the bigger planets

01:22:20have a stronger gravity.

01:22:21This means

01:22:22that they can keep

01:22:23their rings stable

01:22:24after their formation.

01:22:25Some experts

01:22:26think that the Earth

01:22:27had a ring system

01:22:28a long time ago.

01:22:29An object the size of Mars

01:22:30could collide

01:22:31with our mother planet,

01:22:32which probably

01:22:33created a dense ring

01:22:34of debris around it.

01:22:35Some scientists

01:22:36think that these debris

01:22:37did not form a ring,

01:22:38but what we know

01:22:39today as the Moon.

01:22:41A giant planet

01:22:42is probably

01:22:43hidden on the edge

01:22:44of the solar system,

01:22:45far beyond Neptune.

01:22:47Scientists have named

01:22:48this mysterious

01:22:49hypothetical world

01:22:50the New Planet.

01:22:52If it really exists,

01:22:53it is probably similar

01:22:54to Uranus or Neptune

01:22:55and ten times

01:22:56more massive

01:22:57than our planet.

01:22:59It probably rotates

01:23:00around the Sun,

01:23:01but in the confines

01:23:02of the solar system

01:23:03about twenty times

01:23:04farther than Neptune.

01:23:06Another interesting theory

01:23:07states that the New Planet

01:23:08could actually be

01:23:09a black hole

01:23:10the size of a foam bubble,

01:23:11which deforms space

01:23:12as a large planet would.

01:23:14While we used to think

01:23:15that water was

01:23:16a rare substance in space,

01:23:17it actually exists

01:23:18everywhere

01:23:19in our solar system.

01:23:20For example,

01:23:21it can be found

01:23:22in asteroids and comets,

01:23:24as well as in the craters

01:23:25of the Moon

01:23:26and Mercury.

01:23:27We do not know

01:23:28exactly where

01:23:29it is,

01:23:30but we know

01:23:31that it is somewhere

01:23:32in the atmosphere.

01:23:33We still do not know

01:23:34if there is enough water

01:23:35to allow

01:23:36any human colony to live

01:23:37if we decide

01:23:38to settle there.

01:23:39But a certain amount

01:23:40of water is certainly

01:23:41present there.

01:23:42Mars also houses

01:23:43water at its poles.

01:23:44It is mainly

01:23:45hidden in the layers

01:23:46of ice

01:23:47and probably

01:23:48under the dusty

01:23:49surface of the planet.

01:23:50Europe,

01:23:51the moon of Jupiter,

01:23:52also has water.

01:23:53It is the most likely

01:23:54candidate we knew

01:23:55to welcome life

01:23:56outside the Earth.

01:23:57There is probably

01:23:58an entire ocean

01:23:59of liquid water

01:24:00under its frozen surface

01:24:01and it could also

01:24:02contain twice as much

01:24:03water as all the oceans

01:24:04of the Earth combined.

01:24:05Neptune is surprisingly

01:24:06warm,

01:24:07even if it is

01:24:0830 times farther

01:24:09from the Sun

01:24:10than our planet

01:24:11and receives less

01:24:12solar light

01:24:13and heat.

01:24:14But it emits

01:24:15much more heat

01:24:16than it receives.

01:24:17Its atmosphere

01:24:18is also much more active

01:24:19than we thought,

01:24:20especially if we compare

01:24:21it to its neighbor,

01:24:22Uranus.

01:24:23These two planets

01:24:24emit the same amount

01:24:25of heat,

01:24:26even if Uranus

01:24:27is much closer

01:24:28to the Sun

01:24:29than Neptune.

01:24:30But no one

01:24:31knows why.

01:24:32Neptune also has

01:24:33extremely strong winds

01:24:34that can reach

01:24:35a speed of

01:24:362,400 km per hour.

01:24:37Could it be

01:24:38responsible for this heat?

01:24:39Or maybe it's because

01:24:40of the core of the planet

01:24:41or its gravitational force?

01:24:42A monstrous black hole

01:24:43rushes into space

01:24:44at a speed

01:24:45of 8 million km per hour.

01:24:46Scientists have

01:24:47located it

01:24:48thanks to

01:24:49the Hubble Space Telescope.

01:24:50They think

01:24:51it weighs

01:24:52as much as

01:24:53a billion suns.

01:24:54It was supposed

01:24:55to stay in its place

01:24:56for a long time

01:24:57in the center

01:24:58of its original galaxy,

01:24:59but gravitational forces

01:25:00push it

01:25:01in all directions.

01:25:02At some point,

01:25:03this black hole

01:25:04will free itself

01:25:05from its galaxy

01:25:06and continue

01:25:07to wander

01:25:08in the universe.

01:25:09Fortunately,

01:25:10it is still

01:25:118 billion light years

01:25:12away from us.

01:25:13Solar storms

01:25:14are so powerful

01:25:15that they could

01:25:16plunge us

01:25:17into complete darkness.

01:25:18In July 2012,

01:25:19the most powerful

01:25:20solar storm

01:25:21in the last 150 years

01:25:22was about to hit Earth.

01:25:23The Earth's

01:25:24atmosphere

01:25:26The coronal mass ejections,

01:25:27or CMEs,

01:25:28are large ionized

01:25:29gas bubbles.

01:25:30They crossed

01:25:31our orbit

01:25:32at the time.

01:25:33If they had

01:25:34had our planet

01:25:35as a direct target,

01:25:36we would have

01:25:37faced solar matter

01:25:38rushing towards Earth,

01:25:39damaging computers

01:25:40and causing

01:25:41power outages

01:25:42that would have

01:25:43lasted months.

01:25:44A surprise

01:25:45solar storm

01:25:46struck us

01:25:47on June 25, 2022.

01:25:48A photographer

01:25:49even managed

01:25:50to capture

01:25:51superb aurorae

01:25:52in the sky

01:25:53at Calgary,

01:25:54Canada,

01:25:55which lasted

01:25:565 minutes.

01:25:57They were caused

01:25:58by the storm.

01:25:59Vampire stars

01:26:00really exist.

01:26:01They are part

01:26:02of a binary star system

01:26:03and can literally

01:26:04suck the life

01:26:05out of the other

01:26:06star in the system.

01:26:07Venus was

01:26:08most likely

01:26:09covered by an ocean

01:26:10with a depth

01:26:11of 10 to 300 meters.

01:26:12In addition,

01:26:13a certain amount

01:26:14of water

01:26:15was trapped

01:26:16on the planet's

01:26:17surface.

01:26:18It had

01:26:19the ability

01:26:20to absorb

01:26:22This planet

01:26:23had stable temperatures

01:26:24of 20 to 50 degrees Celsius,

01:26:26which were therefore

01:26:27quite tolerable

01:26:28and not so different

01:26:29from the current

01:26:30temperatures on Earth.

01:26:31In short,

01:26:32for 3 billion years,

01:26:33until something

01:26:34irrevocable

01:26:35happened

01:26:36700 million years ago,

01:26:37Venus could have

01:26:38been habitable,

01:26:39but today

01:26:40it is no longer.

01:26:44The Moon

01:26:45is the second

01:26:46brightest object

01:26:47in our sky.

01:26:48However,

01:26:49among the other

01:26:50astronomical objects,

01:26:51it is one of the darkest

01:26:52and least reflective.

01:26:53But our natural satellite

01:26:54seems bright

01:26:55because it is

01:26:56very close to us.

01:26:57In the same way,

01:26:58our planet

01:26:59seems much brighter

01:27:00when you look at it

01:27:01from space.

01:27:02This is because

01:27:03clouds, ice

01:27:04and snow

01:27:05reflect much more

01:27:06light than

01:27:07most rocks.

01:27:08Triton,

01:27:09Neptune's moon,

01:27:10has its entire surface

01:27:11covered with

01:27:12several layers of ice.

01:27:13If this satellite

01:27:14replaced our current moon,

01:27:15the night sky

01:27:16would become

01:27:17seven times brighter.

01:27:19Neutron stars

01:27:20are among

01:27:21the smallest

01:27:22and most massive

01:27:23objects in space.

01:27:24They usually have

01:27:25a diameter of

01:27:26about 18 km,

01:27:27but they are

01:27:28several times heavier

01:27:29than the Sun.

01:27:30And they rotate

01:27:31about 600 times

01:27:32per second,

01:27:33much faster

01:27:34than a professional

01:27:35figure skater.

01:27:36Saturn

01:27:37is the planet

01:27:38with the least density

01:27:39in the solar system.

01:27:40It has a density

01:27:41equivalent to

01:27:42one eighth of

01:27:43the Earth's.

01:27:44And yet,

01:27:45because of its

01:27:46immense volume,

01:27:47it is

01:27:48seven times

01:27:49more massive

01:27:50than the Earth.

01:27:51The transitory

01:27:52lunar phenomenon

01:27:53is one of the most

01:27:54enigmatic things

01:27:55that happens

01:27:56on the Moon.

01:27:57It is an

01:27:58ephemeral change

01:27:59of light,

01:28:00color

01:28:01or other

01:28:02on the surface

01:28:03of the satellite.

01:28:04Most often,

01:28:05it is

01:28:06random

01:28:07light flashes.

01:28:08Astronomers

01:28:09have observed

01:28:10this phenomenon

01:28:11since the 1950s.

01:28:12They noticed

01:28:13that flashes

01:28:14happened

01:28:15in an unpredictable

01:28:16way.

01:28:17Some of them

01:28:18did not last

01:28:19more than a few minutes,

01:28:20but some lasted

01:28:21several hours.

01:28:22In 1969,

01:28:23a day before

01:28:24Apollo 11

01:28:25landed on the Moon,

01:28:26one of the members

01:28:27of the mission

01:28:28noticed that

01:28:29a part of the

01:28:30lunar surface

01:28:31was brighter

01:28:32than the

01:28:33surrounding landscape.

01:28:34It was said

01:28:35that this area

01:28:36had a kind

01:28:37of fluorescence.

01:28:38Unfortunately,

01:28:39we still do not

01:28:40know if this phenomenon

01:28:41was linked

01:28:42to the mysterious

01:28:43lunar flash.

01:28:44Waste is not

01:28:45only

01:28:46produced

01:28:47on Earth.

01:28:48There are

01:28:49what we call

01:28:50space waste,

01:28:51that is,

01:28:52any object

01:28:53man-made

01:28:54that has been

01:28:55left in space

01:28:56and is useless.

01:28:57There are also

01:28:58natural debris

01:28:59from meteorites

01:29:00and other

01:29:01cosmic objects.

01:29:02There are currently

01:29:03more than 500,000

01:29:04space debris

01:29:05orbiting the Earth

01:29:06at speeds

01:29:07high enough

01:29:08to cause

01:29:09significant damage

01:29:10if they collide

01:29:11with a spaceship

01:29:12or a satellite.

01:29:13NASA

01:29:14is working

01:29:15to ensure

01:29:16that all

01:29:17space debris

01:29:18can reach

01:29:19their destination

01:29:20safely.

01:29:21Our sun

01:29:22is incredibly

01:29:23massive.

01:29:24For proof,

01:29:2599.86%

01:29:26of the entire

01:29:27mass of the

01:29:28solar system

01:29:29consists of

01:29:30the mass of the sun,

01:29:31in particular

01:29:32the hydrogen

01:29:33and helium

01:29:34it is composed of.

01:29:35The remaining

01:29:360.14%

01:29:37are mainly

01:29:38the mass

01:29:39of the

01:29:408 planets

01:29:41of the solar system.

01:29:42The atmosphere

01:29:43reaches millions

01:29:44of degrees.

01:29:45If we could dig

01:29:46a tunnel

01:29:47directly in the

01:29:48center of the planet

01:29:49and go out

01:29:50by the opposite side

01:29:51and you were

01:29:52adventurous enough

01:29:53to jump in,

01:29:54it would take you

01:29:5542 minutes

01:29:56to cross it.

01:29:57You would accelerate

01:29:58as you fell

01:29:59to reach

01:30:00the maximum speed

01:30:01when you would

01:30:02reach the core

01:30:03of the Earth.

01:30:04After half the journey,

01:30:05you would then

01:30:06fall up

01:30:07more and more

01:30:08slowly.

01:30:09When you would

01:30:10reach the opposite

01:30:11surface,

01:30:12you would

01:30:13reach 0.

01:30:14Unless you manage

01:30:15to get out of the hole,

01:30:16you would immediately

01:30:17start falling again

01:30:18to go down

01:30:19or go up

01:30:20to the other side

01:30:21of the planet.

01:30:22This journey

01:30:23would last

01:30:24an eternity

01:30:25because of the

01:30:26bizarre effects

01:30:27of gravity.

01:30:28There could be

01:30:29more metals,

01:30:30for example

01:30:31titanium or iron

01:30:32in the lunar craters

01:30:33than astronomers

01:30:34thought.

01:30:35The biggest problem

01:30:36with this discovery

01:30:37is that it contradicts

01:30:38the main theory

01:30:39about the way

01:30:40the Moon

01:30:41was formed.

01:30:42This theory

01:30:43states that

01:30:44the Earth's

01:30:45natural satellite

01:30:46detached from our planet

01:30:47after a collision

01:30:48with a massive

01:30:49space object.

01:30:50But then,

01:30:51why does the Earth's crust,

01:30:52poor in metals,

01:30:53contain much less

01:30:54iron oxide

01:30:55than the Moon's?

01:30:56This could mean

01:30:57that the Moon

01:30:58was formed

01:30:59from materials

01:31:00that were

01:31:01much deeper

01:31:02inside our planet.

01:31:03Or these metals

01:31:04could have appeared

01:31:05when the lunar surface

01:31:06in fusion

01:31:07cooled down slowly.

01:31:08Or maybe,

01:31:09as it has been said

01:31:10before,

01:31:11it is made of cheese.

01:31:12The Earth

01:31:13could have been purple

01:31:14before becoming

01:31:15blue and green.

01:31:16A scientist

01:31:17has a theory

01:31:18according to which

01:31:19a substance existed

01:31:20in the ancient microbes

01:31:21before chlorophyll,

01:31:22this thing

01:31:23that makes plants green,

01:31:24evolved on Earth.

01:31:25This substance

01:31:26reflected the sunlight

01:31:27in red and mauve,

01:31:28colors that combined

01:31:29to give purple.

01:31:30If this is true,

01:31:31the young Earth

01:31:32may have fed

01:31:33strange purple-colored plants

01:31:34before all

01:31:35these green things

01:31:36appeared.

01:31:37The highest mountain

01:31:38in the solar system

01:31:39is Olympus Mons

01:31:40on Mars.

01:31:41It is three times

01:31:42higher than Mount Everest,

01:31:43the highest peak

01:31:44on Earth

01:31:45compared to

01:31:46the sea level.

01:31:47If you stood

01:31:48at the top of Olympus Mons,

01:31:49you would not understand

01:31:50that you are

01:31:51on a mountain.

01:31:52These slopes

01:31:53would be hidden

01:31:54by the curvature

01:31:55of the planet.

01:31:56Astronomers

01:31:57have found

01:31:58a huge water reservoir

01:31:59in space,

01:32:00the largest

01:32:01ever detected.

01:32:02Too bad

01:32:03it is also

01:32:04the farthest.

01:32:05It is located

01:32:0612 billion light years

01:32:07from us.

01:32:08It contains

01:32:09140 billion times

01:32:10more water

01:32:11than all the oceans

01:32:12of the Earth combined.

01:32:13Venus

01:32:14rotates at its own pace,

01:32:15without rushing.

01:32:16A complete rotation

01:32:17takes 243 Earth days,

01:32:18and it takes

01:32:19the planet

01:32:20a little less

01:32:21than 225 Earth days

01:32:22to go around

01:32:23the Sun.

01:32:24This means

01:32:25that one day

01:32:26on Venus

01:32:27is longer

01:32:28than a year.

01:32:29There is very little

01:32:30seismic activity

01:32:31inside the Moon.

01:32:32However,

01:32:33small lunar eclipses

01:32:34caused by

01:32:35the gravitational force

01:32:36of our planet

01:32:37sometimes occur

01:32:38several kilometers

01:32:39below the surface.

01:32:40Then,

01:32:41tiny cracks

01:32:42and fractures

01:32:43appear on the surface

01:32:44of the satellite,

01:32:45and gases escape.

01:32:46Mars

01:32:47is the last

01:32:48of the four inner planets,

01:32:49which are also called

01:32:50telluric

01:32:51because they are

01:32:52composed of rocks

01:32:53and metals.

01:32:54The red planet

01:32:55has a core

01:32:56mainly made of

01:32:57iron,

01:32:58nickel

01:32:59and sulfur.

01:33:00It measures between

01:33:011,500 and 1,900 km in diameter.

01:33:02But this core

01:33:03does not move.

01:33:04This is why

01:33:05Mars does not have

01:33:06a magnetic field

01:33:07on the scale of the planet.

01:33:08The weak magnetic field

01:33:09it has

01:33:10is only

01:33:11one hundredth

01:33:12of that of the Earth.

01:33:13When the planets

01:33:14of the solar system

01:33:15began to form,

01:33:16the Earth

01:33:17did not have a moon

01:33:18for a very long time.

01:33:19It took

01:33:20100 million years

01:33:21for our natural satellite

01:33:22to appear.

01:33:23There are several theories

01:33:24about the way

01:33:25the Moon appeared,

01:33:26but the one that prevails

01:33:27is the fission theory.

01:33:28It states that the Moon

01:33:29formed when an object

01:33:30collided

01:33:31with the Earth

01:33:32in a collision

01:33:33with the Earth.

01:33:35Gravity gathered

01:33:36the particles

01:33:37and the Moon

01:33:38was created.

01:33:39It ended up

01:33:40landing on the ecliptic

01:33:41plane of the Earth,

01:33:42which is the current

01:33:43trajectory of the Moon.

01:33:46The largest living being

01:33:47on Earth

01:33:48turns out to be

01:33:49a mushroom in Oregon.

01:33:50This huge mushroom,

01:33:51Armillaria,

01:33:52lives in the

01:33:53National Forest of Malheur

01:33:54and covers an area

01:33:55of 9.7 km2.

01:33:56It is the largest

01:33:57mushroom

01:33:58in the world.

01:33:59It is the largest

01:34:00mushroom

01:34:01in the world.

01:34:02It is the largest

01:34:03mushroom

01:34:04in the world.

01:34:05It is the largest

01:34:06mushroom

01:34:07in the world.

01:34:08It is the largest

01:34:09mushroom

01:34:10in the world.

01:34:11Its diameter

01:34:12is around

01:34:139.5 km2.

01:34:14Its diameter

01:34:15is around

01:34:169.5 km2.

01:34:17Its diameter

01:34:18is around

01:34:199.5 km2.

01:34:20It could be

01:34:21up to 8,500 years old!

01:34:22But we can forgive you

01:34:23for missing it,

01:34:24because it is

01:34:25largely

01:34:26hidden underground.

01:34:27When the individual

01:34:28roots of Armillaria

01:34:29meet,

01:34:30they can fuse

01:34:31to become

01:34:32The largest asteroid in the solar system is called Vesta, and it is so big that it is sometimes called a dwarf planet.

01:34:41A trip to the second star closest to us, after the sun, would take you 5 million years by plane.

01:34:47This is what is called an ultra-long-haul flight.

01:34:50Space is not supposed to be black. There are stars everywhere.

01:34:54Shouldn't it illuminate everything around?

01:34:56In reality, we don't see stars everywhere, because some of them haven't existed for long enough for their light to reach Earth.

01:35:04No one will hear you scream in space, or something like that.

01:35:08We've all heard that phrase that's cold in the back.

01:35:11And it's true, space is largely made up of a gigantic void.

01:35:16There is a lot of space in space.

01:35:18But that doesn't mean there's no noise.

01:35:21In fact, there is a lot of it.

01:35:23And some of them could even make you shiver.

01:35:26We're going to look at the scariest sounds in space.

01:35:29First of all, how are cosmic noises recorded?

01:35:32Sound is just the vibration of molecules.

01:35:35When you scream, the molecules grow furiously from one another until they reach the person's ear in front of you.

01:35:42These vibrations are then transmitted to the brain, and we recognize them as something that we sometimes have to apologize for.

01:35:49To hear something, we need molecules.

01:35:53And that's where it gets complicated.

01:35:55There are none in space.

01:35:57The universe is almost entirely made up of voids.

01:36:00Yes, absolute voids.

01:36:03However, NASA magicians still manage to record the sounds of space.

01:36:08How do they do it?

01:36:10Well, there are certain types of waves that have nothing to do with molecules.

01:36:14We, ordinary people, cannot perceive them without certain devices.

01:36:18Among these waves, there are, for example, radio waves.

01:36:21We need a radio or a device of this type to recognize them.

01:36:24And that's exactly what NASA satellites do.

01:36:27They capture radio waves.

01:36:30Thanks to them, we can know the noise that cosmic bodies make.

01:36:34These satellites record a multitude of waves, the fluctuation of plasmas, magnetic fields, and other things.

01:36:41NASA scientists then transform all this into ordinary sound tracks.

01:36:46And some of these things make a rather frightening noise.

01:36:49That's the least we can say.

01:36:51Let's take, for example, our magnetic field.

01:36:53It surrounds our planet like an invisible shield,

01:36:56protecting us from all kinds of damage, such as radiation or solar winds.

01:37:00We can neither see nor feel it, but today we can hear it.

01:37:07Researchers from the Technical University of Denmark have collected magnetic waves

01:37:11recorded by the SWARM satellite.

01:37:14They then converted them into audio tracks and obtained a rather frightening result.

01:37:22In fact, it sounds more like the noise of a terrifying nocturnal creature.

01:37:27And if you have the Earth's magnetic field map in your head,

01:37:30you'll get the impression that a spider is crawling in the cliffs.

01:37:34And it's not the only strange sound we've captured on Earth.

01:37:38Recently, we've captured another radio signal from space.

01:37:42Scientists have discovered that it came from a very distant place,

01:37:45billions of light-years away from us.

01:37:49These waves don't usually last more than a few milliseconds,

01:37:52but this one was exceptional.

01:37:54It lasted about three seconds,

01:37:56which is thousands of times longer than usual.

01:37:59At the same time, the signal was very precise,

01:38:03so much so that scientists have even compared it to a heartbeat.

01:38:07Scientists think that this signal is caused by pulsars or neutron stars.

01:38:12In the past, Nikola Tesla captured something similar.

01:38:16Unfortunately, at the time, we didn't know about pulsars.

01:38:20Tesla was therefore convinced that he had captured the message of extraterrestrial creatures.

01:38:25But the truth turned out to be much less fascinating.

01:38:29Now let's go from Earth to the Moon.

01:38:31In 1969, the astronauts of the Apollo 10 mission,

01:38:35the shuttle that made the last test flight to the Moon,

01:38:38flew over its surface.

01:38:40They then captured strange signals coming from the hidden side of our satellite.

01:38:45We never see this side because the Moon is in a gravitational lock state.

01:38:49The sound was so strange that the astronauts didn't know if they should report it to NASA.

01:38:54They feared not being taken seriously,

01:38:56or even not being allowed to participate in the next space missions.

01:39:01Here's what it looked like.

01:39:06According to NASA, this is not at all a strange extraterrestrial music.

01:39:10It may simply be radio waves that have changed one after the other due to their proximity.

01:39:16But the astronauts who heard it for the first time were still a little scared.

01:39:21And what about other planets?

01:39:2340 years ago, scientists explored the surface of Venus.

01:39:28They sent dozens of probes to record sounds and images.

01:39:33We now know what kind of noise Venus emits,

01:39:36which could easily destroy us if we approached it.

01:39:43We didn't expect anything else from the most dangerous planet on the solar system.

01:39:49Unfortunately, Venus is even more toxic than the trolls on Twitter.

01:39:54And these probes didn't last long.

01:39:56They quickly went out of order after they arrived.

01:40:00Then we have Jupiter.

01:40:02This space giant, which is 11 times larger than Earth, is absolutely terrifying.

01:40:08One of NASA's probes, Juno, revolves around Jupiter every few weeks.

01:40:12It moves at a phenomenal speed, at 209,214 km per hour.

01:40:17One day, Juno recorded one of the most powerful invisible signals it has ever encountered.

01:40:23The violent solar winds had just entered into conflict with Jupiter's magnetic field.

01:40:29This caused a huge cosmic boom.

01:40:33The original sound lasted two hours, but was reduced to a few seconds.

01:40:37In fact, it looks a lot like the sound of a wave breaking on a rock.

01:40:42But none of this is comparable to the horror of one of Jupiter's small moons, Ganymede.

01:40:49In 2021, the space probe Galileo flew over it.

01:40:53During its flight, it captured something quite strange.

01:41:00These noises are satellite radiation.

01:41:03It looks a bit like the noise of a jungle, or that of thousands of bats waiting to surprise you in the middle of the night.

01:41:11Now let's move on to Saturn.

01:41:13This signal was captured by the Cassini-Huygens automatic interplanetary station, launched into space in 1997.

01:41:20Passing in front of Saturn, Cassini recorded a rather frightening sound.

01:41:26These screams straight out of hell are just simple radio waves.

01:41:30And it's not very different from what the auroras of Boreal emit on Earth.

01:41:34A little later, Cassini captured another signal.

01:41:37The noise of lightning and storms on Saturn.

01:41:40These sounds are quite interesting.

01:41:45It looks a bit like popping popcorn or a Geiger counter, doesn't it?

01:41:49But it's simply because these lightnings are extremely fast.

01:41:52We're now going to leave the solar system.

01:41:55The famous Voyager 1 probe was launched in 1977,

01:41:59and continues to send us data 40 years after its takeoff.

01:42:03In 2012, it left the solar system to enter interstellar space.

01:42:09That's when Voyager 1 recorded plasma waves.

01:42:14The original recording lasted 7 months.

01:42:17But scientists took pity on us and reduced it to 12 seconds.

01:42:22It's not really sinister, but it's not very reassuring either.

01:42:26And although it seems that nothing can surpass the horrors of Saturn,

01:42:30we are now going to examine one of the most frightening objects in the universe.

01:42:34A black hole.

01:42:36This sound was recorded by the Chandra space telescope.

01:42:39By studying a bunch of galaxies in the Perseid constellation,

01:42:42we discovered something very interesting.

01:42:45The undulating movements in the centre of the mass.

01:42:49They extend in all directions, like circles on water.

01:42:53Scientists have declared that this phenomenon was due to a supermassive black hole.

01:42:57But black holes don't always devour entire objects in space.

01:43:02Sometimes they spit them out.

01:43:05This causes gas vibrations that can be converted into sound waves.

01:43:10What's interesting is that the black holes in the Perseid constellation

01:43:14oscillate for about 10 million years.

01:43:18This recording is therefore very fast.

01:43:22Scientists have reduced the delay between oscillations by about 144 quadrillion times.

01:43:27And this is what it sounds like.

01:43:30It's probably the most sinister sound on our list.

01:43:33It's neither very powerful nor very violent.

01:43:35It has something rather dark and disturbing.

01:43:38So here are the most frightening spatial sounds captured by a black hole.

01:43:42As I said, most of them are just radio waves.

01:43:46But it's always fun to be scared from time to time.

01:43:49The centre of the Milky Way is a scene where there is an intense radiation,

01:43:53a strong gravity and many mysteries.

01:43:56A place where the forces of nature are pushed to their limits.

01:43:59But what would happen if our own planet was in this cosmic theatre?

01:44:04What would happen if the Earth managed to survive in one way or another?

01:44:08Let's start this journey to the heart of our galaxy to discover it.

01:44:14Imagine this.

01:44:15You float in space, surrounded by billions and billions of stars.

01:44:19Suddenly, you see in the distance a bright and turbulent mass of gas and dust.

01:44:25This is, my friend, the Milky Way.

01:44:27In other words, our home in the vast expanses of the universe.

01:44:32It is estimated that the Milky Way is one of the largest galaxies in the universe.

01:44:37It is estimated that the Milky Way contains more than 100 billion stars

01:44:40and that it extends over about 100,000 light years.

01:44:46In other words, if we traveled at the speed of light,

01:44:49it would take 100,000 years to cross it from one end to the other.

01:44:52This represents a few thousand billion kilometres.

01:44:57And it's not just a static set of stars and gas,

01:45:00but a dynamic system in constant evolution.

01:45:03In fact, the Milky Way is currently moving in space

01:45:06at a speed of about 2.1 million kilometres per hour.

01:45:12One of the most fascinating aspects of our galaxy is its shape.

01:45:16The Milky Way is a spiral galaxy,

01:45:18which means it looks like a disc with a central bulb and spiral arms.

01:45:24The spiral arms are the areas where new stars are born.

01:45:28This is where the most stars, gas and dust, are concentrated

01:45:32And what is the solar system?

01:45:36Our system is like a tiny spot in the great cosmic tapestry of the Milky Way.

01:45:41It is located about 26,000 light years from the center of the galaxy.

01:45:45A rather large distance, isn't it?

01:45:49The solar system also moves in the Milky Way,

01:45:52orbiting around the center of the galaxy.

01:45:55It takes it approximately 230 million years

01:45:58to make a complete orbit around the galaxy.

01:46:03Imagine, since the time of the dinosaurs,

01:46:06we have only traveled a quarter of this path.

01:46:10The position of the solar system in the galaxy

01:46:13has many repercussions on our lives.

01:46:16For example, the amount of radiation and cosmic rays we are exposed to,

01:46:21and even the probability of asteroid impact, etc.

01:46:24In addition, thanks to our location,

01:46:27we can enjoy amazing views of the universe around us.

01:46:31From our observation point in the Milky Way,

01:46:34we can observe other galaxies, nebulae and star clusters

01:46:37in breathtaking details.

01:46:40We also evolve in a very active neighborhood,

01:46:43with many other stars and planets nearby.

01:46:46So we are lucky.

01:46:48But what would happen if we didn't have these opportunities?

01:46:51What would happen if we didn't have these opportunities?

01:46:54What if the Earth was located in the center of the Milky Way?

01:46:59The center of the Milky Way is home to a region of space

01:47:02called the central bulb.

01:47:05It is filled with stars.

01:47:07It's like a disco ball, but instead of a bright mirror,

01:47:10it is covered with stars.

01:47:12But this disco ball is really huge.

01:47:15It has a diameter of about 10,000 light years.

01:47:19The center of the Milky Way is also home to extreme environments

01:47:22that would make even the bravest astronauts tremble.

01:47:26High-energy particles and intense magnetic fields

01:47:29can wreak havoc on electronic devices and spacecraft.

01:47:33Intense radiation fields can burn everything in their path.

01:47:37So it's not really a place suitable for life as we know it.

01:47:42If the Earth were located near the center of the Milky Way,

01:47:45it would be very different.

01:47:48Let's take a look at some of the potential effects.

01:47:52First of all, radiation.

01:47:55As we mentioned earlier,

01:47:57the center of the Milky Way is one of the most irradiated regions in the galaxy.

01:48:02This would make life on Earth very difficult, if not impossible.

01:48:07Of course, we have terrestrial magnetic field.

01:48:10It's a kind of giant shield that protects us from harmful radiation

01:48:13coming from extra-atmospheric space.

01:48:15But could it save us if we were located in the center of the Milky Way?

01:48:19Unfortunately, the answer is no.

01:48:21It's a bit like trying to use a tiny umbrella to shelter from a huge storm.

01:48:27The galaxy would therefore win easily.

01:48:31But the picture is not so dark.

01:48:33Some brave organisms are able to adapt to high levels of radiation.

01:48:39We have seen that life on Earth has evolved

01:48:42to survive everywhere, from the depths of the ocean to the icy poles of the planet.

01:48:48So let's imagine what would happen if we became, one way or another,

01:48:52evolved to survive in these difficult conditions.

01:48:56Let's imagine humans with hard and scaly skin that protects them from radiation,

01:49:00and plants with unique structures that allow them to thrive in this bright environment.

01:49:06But even so, radiation could have very frightening effects on humans.

01:49:12For example, it could damage DNA molecules and cause mutations.

01:49:16Imagine a world where plants would have 5 leaves instead of 4,

01:49:20where animals would have a strangely colored fur,

01:49:23where people would have eyes of an unusual color,

01:49:26or other original characteristics.

01:49:28And these are just a few of the best examples.

01:49:31Let's not even talk about the ugliest.

01:49:34In addition, it could make us undergo metabolic changes.

01:49:37Our body could treat food and other resources more quickly,

01:49:41which could lead to faster growth rates and larger sizes.

01:49:46Plants could become big and wide,

01:49:48and animals would be much more imposing than normal.

01:49:52There are also organisms on Earth that can produce bioluminescence.

01:49:58Thanks to high levels of radiation, they could shine even more than usual.

01:50:04Imagine that you are walking in a forest at night,

01:50:07and you see trees, mushrooms, and even insects,

01:50:10shining with a strange open blue light.

01:50:13Both frightening and surprising, isn't it?

01:50:17But let's move on to the next big change, gravity.

01:50:21At the center of the Milky Way, gravity is incredibly strong.

01:50:24All thanks to a supermassive black hole,

01:50:27whose mass is about 4 million times greater than that of the Sun.

01:50:32This black hole is called Sagittarius A.

01:50:35And yes, it's our neighbor now. Great!

01:50:39And assuming that we are not swallowed up by this black hole,

01:50:42or crushed by this incredibly strong gravity,

01:50:45it could still trigger many earthquakes and volcanic eruptions.

01:50:49This black hole would be like a gravitational tyrant,

01:50:52pulling and tearing everything in its path.

01:50:55In fact, if we survived this black hole,

01:50:58we would participate every day in a kind of grandiose surf competition.

01:51:02All you have to do is add a little thrill by risking your life.

01:51:05And let's forget the idea of escaping the planet.

01:51:07It wouldn't be so easy to launch rockets at all.

01:51:10Water and physical objects would not be the only ones to be affected by gravity.

01:51:14Time would flow very differently for us.

01:51:17According to Einstein's theory of relativity,

01:51:20time flows more slowly in areas of high gravity.

01:51:24In other words, earthlings would age less quickly

01:51:27than a person far from the center of our galaxy.

01:51:31In addition, the center of the Milky Way is a very lively place.

01:51:35Stars, planets and other celestial objects

01:51:38move there every day at incredibly high speeds.

01:51:42The positions of the stars and other objects change constantly.

01:51:46In other words, we have to say goodbye to normal navigation.

01:51:50GPS systems would probably not be reliable

01:51:53due to the intensity of gravitational forces and radiation.

01:51:56If you accidentally get lost in a phosphorescent forest

01:51:59with scary animals, good luck!

01:52:03But there is more than negative.

01:52:05The center also houses molecular clouds.

01:52:08These are regions of space where new stars are born.

01:52:12And the Milky Way in general offers amazing landscapes.

01:52:17For example, amazing nebulae like the Orion Nebula

01:52:20and the Eagle Nebula, which are visible with telescopes

01:52:24or even simply with a good pair of binoculars.

01:52:28If the Earth were located in the center of the Milky Way,

01:52:31we would be the first to witness some of the most spectacular cosmic events.

01:52:36Wouldn't that be great?

01:52:39In short, if the Earth were located in the center of the Milky Way,

01:52:42it would be very different.

01:52:45Of course, we all know that our planet would not have survived such a change.

01:52:50But it is still interesting to imagine how our life would unfold if we were there.

01:52:55And judging by what we have just talked about, it would not be nice to see.

01:52:59So let's cherish and appreciate our peaceful little solar system.

01:53:04Here is Neptune. Our next stop is Pluto.

01:53:08Do not put your hands on the door, you risk getting pinched very hard.

01:53:12One day, with cutting-edge technologies of the future,

01:53:14a trip from Neptune to Pluto will not be longer than a subway journey.

01:53:18There are huge mountains of ice on Pluto,

01:53:21valleys that extend well beyond what your eyes can see,

01:53:24craters 257 km wide,

01:53:27almost as large as the largest on Earth,

01:53:29and no life.

01:53:31The reasons for this are obvious.

01:53:33The immense distance that separates Pluto from the Sun

01:53:36is translated by glacial temperatures on this dwarf planet.

01:53:39This also guarantees you a trip of a few billion kilometers.

01:53:43In addition, this planet is smaller than the Moon.

01:53:46So there would be a lot of people very soon, if people started to live there.

01:53:50However, there is a reason that makes us think that life there would not be so improbable.

01:53:55The Sun has a known life span, and it is cut in cycles.

01:53:59In the past, our solar system was just a cloud of gas and dust.

01:54:03Following a gravitational collapse in the center of this cloud,

01:54:07gas and dust began to gather in specific and denser places.

01:54:13These gradually attracted more and more matter,

01:54:16and the phenomenon of conservation of the amount of movement

01:54:19caused all this mass to start spinning and warming up,

01:54:23causing immense pressure.

01:54:25Later, a disk similar to Saturn's rings appeared,

01:54:29but it was made up of very different substances.

01:54:32And in its center, there was the ball that finally became the Sun.

01:54:36A protostar is a young star that still accumulates mass,

01:54:40and it is exactly what the Sun was before the temperatures and pressure in its bosom burned its core.

01:54:46Millions of years later, it became this Sun that we see every day,

01:54:50but it will not remain in this state forever.

01:54:53It will warm up even more and eventually become bigger and denser,

01:54:58turning into a red giant.

01:55:01It could one day become big enough to swallow Venus and Mercury.

01:55:05There is a good chance that it will even swallow Earth.

01:55:08Even if it does not swallow our planet, the Sun could get close enough to touch us.

01:55:13If that happened, life on Earth would no longer be possible.

01:55:17But then, in just a few minutes, the Sun would lose about 40% of its mass

01:55:22and shrink about ten times its size.

01:55:25It would no longer be as bright or as hot as before.

01:55:28At that point, the Earth would have already been deserted.

01:55:31Its inhabitants may go on a space trip,

01:55:34or settle on another planet where life is possible,

01:55:37like on the exoplanet Kepler-62f,

01:55:40which, by the way, is even bigger than Earth.

01:55:43And during this time, Pluto will be changing.

01:55:46Before, all the resources were frozen inside the dwarf planet.

01:55:50Water, gases such as methane, carbon monoxide, and so on.

01:55:55But as the Sun would reach its peak of luminosity,

01:55:58Pluto would slowly warm up and abandon a large part of its mass

01:56:02in the vast expanse of space.

01:56:04At the same time, an atmosphere would form.

01:56:07If the atmosphere became thick enough, it would create favorable conditions for life.

01:56:12So, instead of going to live in spaceships,

01:56:15a small percentage of our population could go and settle in colonies on the dwarf planet.

01:56:20The temperature there is comfortable, a time to walk around in a T-shirt.

01:56:24It even looks a little bit like Earth.

01:56:27Water-filled canyons, beautiful fields with trees,

01:56:31plenty of space to run, and mineral water deposits in the ground,

01:56:35pure enough to be drunk.

01:56:37Pluto's rotations are different from Earth's.

01:56:40A day on Earth lasts 24 hours,

01:56:42and we sometimes feel like it's never going to end.

01:56:45But Pluto rotates on itself in 153 hours,

01:56:48which is 6 and a half days.

01:56:50After several hours without sleep, we are tired and our eyes turn red.

01:56:54This means that we will have to take several naps throughout the same day on Pluto.

01:56:58One year on Pluto is equivalent to 248 Earth years.

01:57:02Unless we find a technology that allows us to live that long,

01:57:06our total lifespan would be less than half a year on the dwarf planet.

01:57:10So, Pluto's houses may have to be equipped with cryogenic chambers.

01:57:15Every time you feel like dreaming for a long time,

01:57:17you'll jump in and wake up 50 days later on Pluto.

01:57:21On the dwarf planet, there will also be seas and beaches.

01:57:24So it will really look like a very small Earth, far from the real Earth.

01:57:29Pluto's food could be tastier.

01:57:32We could find a way to improve the taste of the ingredients

01:57:35and even try to grow them faster during our trip.

01:57:38You plant a carrot, and two days later, it is ready to integrate your salad.

01:57:43There could also be new ingredients for our salads on Pluto.

01:57:46Maybe mushrooms 2 meters high, never seen before.

01:57:50The animals we would take with us would be released in their new habitat,

01:57:54and over time, they would evolve and adapt to their environment.

01:57:58The jungle law could also change a bit.

01:58:01Lions may no longer be kings. Why not deer?

01:58:04With woods twice as big as before, and even with larger and stronger bodies too.

01:58:09Most of the animals that were already there lived underwater.

01:58:12But over time, amphibians will have started to move to the surface,

01:58:16just like on Earth, at the beginning of life.

01:58:19But Pluto could only be a temporary home.

01:58:22Once the Sun has reached its final phase, Pluto would become frozen again,

01:58:26and life would disappear.

01:58:28People would then have to try to find a planet in the golden loop area of another galaxy.

01:58:33The golden loop area means that a planet is at the right distance from a star similar to the Sun,

01:58:38with an ideal temperature for the water to remain liquid there.

01:58:42This is what scientists are looking for when they probe the universe

01:58:45in search of planets likely to welcome life.

01:58:48We could try to found new colonies on a planet of this type,

01:58:51or even, why not, create our own artificial home.

01:58:55Something between a planet and a spaceship, a combination of the two.

01:58:59A huge machine built directly in space.

01:59:02Let's say, a wheel with a gravity equal everywhere, so as not to fall.

01:59:06It would float in space towards a new exoplanet, capable of welcoming entire countries.

01:59:11All this travel, simply because the Sun would have grown too big first,

01:59:15and then, having reached the culminating point of its life cycle,

01:59:18it would have become a white dwarf.

01:59:20It would be quite a long journey, and entire generations would be born along the way.

01:59:25You would have the choice to sleep until humans finally reach their new exoplanet,

01:59:30or to enjoy the journey in this fantastic spaceship.

01:59:33There is everything you need on board.

01:59:35Larger shopping malls than those on Earth,

01:59:38large futuristic cities, and even places to cultivate the Earth.

01:59:42Fields with rich soil, artificially made.

01:59:45And finally, after a long journey, the exoplanet.

01:59:49It's even a little better than on Earth.

01:59:51The planet is giant and has even more continents.

01:59:54The center of the continents is not so far from the oceans,

01:59:57which means that there are not as many desert areas.

02:00:00Although the Sun of this planet is an orange dwarf,

02:00:03it is not as hot as our current Sun, a yellow dwarf.

02:00:06It is a little smaller, but here's the thing,

02:00:09the orange dwarfs live a little longer.

02:00:11They remain stable for 14 to 45 billion years.

02:00:15Despite this, this new planet is full of tropical forests because it is warmer.

02:00:20This means more biodiversity and creatures that we have never seen before.

02:00:25But if we decide that the conditions on this exoplanet do not suit us,

02:00:29we could always try terraforming.

02:00:31For example, on Mars, we could create a greenhouse effect

02:00:35by crushing comets rich in ice to release the ammonia they contain,

02:00:39which would make the planet warmer.

02:00:41We could also start planting trees.

02:00:43We would probably need a little bit of land from home to do that.

02:00:47Or we would have to modify Mars' soil to make it similar to ours.

02:00:51Sooner or later, the atmosphere would end up getting closer to the one we have on Earth.

02:00:56We would be able to breathe thanks to the trees.

02:00:58Then we could melt Mars' polar caps and here's some water.

02:01:02The problem is the winds and solar eruptions

02:01:05that could quickly, even very quickly,

02:01:07wipe out this precious atmosphere.

02:01:10Mars does not have a magnetosphere either,

02:01:12which means that we would not be able to protect it from radiation.

02:01:16So in the long run, this planet would not be a good choice.

02:01:19Maybe somewhere, in the vastness of space,

02:01:22there is a perfect planet waiting for us.

02:01:25The vast expanses of the universe contain an infinity of secrets and possibilities.

02:01:31And here is one of the most intriguing questions.

02:01:33What would life be like for us as humans on other planets?

02:01:38Imagine a world where the laws of physics,

02:01:40the conditions and the environment are so different from what we are used to.

02:01:45How would we evolve to adapt to these new strange lands?

02:01:50Let's see.

02:01:52Mercury is the planet closest to the sun and has a very fine atmosphere.

02:01:56The temperatures there are extreme,

02:01:58the day reaching more than 426 ° C

02:02:01and the night going down to less than 179 ° C.

02:02:07So what can we do to survive at these insane temperatures

02:02:10and constant solar radiation?

02:02:12We can maybe turn into metal as if by magic.

02:02:16Titanium and platinum, for example,

02:02:17perfectly withstand these high temperatures.

02:02:20But more seriously, there is a solution.

02:02:23We could settle underground,

02:02:25where the temperatures are not so extreme.

02:02:27If we lived underground,

02:02:29we could develop big eyes to better capture the light.

02:02:32We could also have a thicker skin to protect us from intense radiation.

02:02:37In fact, we have two options.

02:02:39Become Iron Man or become moles.

02:02:43Let's move on to Venus.

02:02:45This planet is extremely hostile.

02:02:47First of all, Venus is known for its thick atmosphere,

02:02:50more toxic than your ex.

02:02:53The whole planet is covered with carbon dioxide

02:02:56and its surface is completely dehydrated,

02:02:58which makes it incredibly suffocating.

02:03:00The average temperature there is about 452 ° C,

02:03:04which makes it one of the warmest planets in our solar system.

02:03:08Do not forget the incredible pressure that reigns there.

02:03:11Staying on Venus is like diving 920 meters underwater.

02:03:15Only the most resistant terrestrial microbes

02:03:18could survive in such conditions.

02:03:20So if you want to live on Venus,

02:03:22you may have to turn into a microbe.

02:03:24Unfortunately, as we are not microorganisms,

02:03:27we would have to wear special equipment to survive.

02:03:31Maybe we should develop an exoskeleton

02:03:34resistant to heat to protect us,

02:03:36as well as new lungs capable of filtering

02:03:38the toxic particles from this atmosphere.

02:03:41Let's talk about our favorite cousin, Mars.

02:03:45The first notable change, after a few hundred years,

02:03:48would be a new skeleton.

02:03:50Gravity on Mars is much weaker than on Earth,

02:03:53so your muscles and bones will tend to atrophy.

02:03:56To compensate for this difference, you will have to eat more

02:03:59and probably go to the gym.

02:04:01You will also have to adapt to low atmospheric pressure

02:04:03and colder temperatures.

02:04:05You need a way to keep the heat, right?

02:04:08This means that you will have to have a thicker layer of fat.

02:04:11Sorry, but on Mars, we risk gaining weight.

02:04:15One more reason to do sports.

02:04:17Another important change would occur at the skin level.

02:04:20Your skin is like a big barrier that protects you

02:04:22from discomforts such as bacteria, UV rays,

02:04:25or the fact of looking like a scorched monster.

02:04:28What would happen then?

02:04:30Well, you would probably turn orange,

02:04:33because of carotenoids.

02:04:35Carotenoids are a type of nutrient found in foods

02:04:38such as carrots, potatoes, tomatoes, etc.

02:04:42They protect very well against the ultraviolet rays of planet Mars.

02:04:46They have only one drawback.

02:04:48If you eat too many pumpkins grown on the spot,

02:04:51you will gradually turn orange.

02:04:53But it may not be so bad.

02:04:55Maybe life on Jupiter would be easier?

02:04:58Oh yes, surely.

02:04:59Except that there is no solid ground.

02:05:01This planet is composed of hydrogen and helium,

02:05:04and that's why it's called a gas giant.

02:05:06You would simply fall through huge clouds.

02:05:10And even if you managed to land and walk on something,

02:05:13it would be as if you were walking in a fog, cut with a knife.

02:05:16So how would we evolve there?

02:05:18First, our size could change to resist the immense pressure.

02:05:22Second, the fluctuations of temperature on Jupiter are enormous.

02:05:27The surface is terribly cold,

02:05:29and the temperature increases considerably

02:05:31under the outer layers of the atmosphere.

02:05:34Third, if you lived on Jupiter,

02:05:36there would be no oral language.

02:05:38This gas giant absorbs radio waves.

02:05:40So even if you spoke, no one could hear you.

02:05:43There would be no music either,

02:05:45so no party.

02:05:46What's the point then?

02:05:48Maybe we could communicate in sign language?

02:05:51But it's not that simple.

02:05:53Jupiter is perpetually agitated by violent winds and powerful storms,

02:05:56so it is unlikely that you can see anything there.

02:05:59Even if we evolve in one way or another,

02:06:01our life would not be really easy there.

02:06:04Before landing on Saturn,

02:06:06you will probably want to admire its emblematic rings closely.

02:06:09But unfortunately, this is impossible,

02:06:11because Saturn's rings are made up of a lot of ice particles floating in space.

02:06:15So it would be extremely difficult to land.

02:06:18So let's go straight to Saturn.

02:06:21At first glance, this planet doesn't seem so bad.

02:06:24Some layers of this gas giant have rather pleasant temperatures.

02:06:27If we dive deeper into the planet,

02:06:29it is even relatively hot,

02:06:31up to minus 3 degrees in its second layer.

02:06:35This is an average temperature in countries like Sweden and Canada.

02:06:39Unfortunately, this is only one of its many layers.

02:06:42The rest of the planet is incredibly cold.

02:06:45To survive on Saturn, we would have to make a lot of effort.

02:06:49In addition to the cold,

02:06:51we would have to accommodate the hostile environment of the planet,

02:06:54in particular its extreme storms, its violent winds and its radiation.

02:06:57To protect us from these conditions,

02:06:59we would still need to develop a resistant skin,

02:07:02isolation techniques, etc.

02:07:06The next planet is Uranus.

02:07:08The environment of Uranus is very different from that of Earth,

02:07:11with much colder temperatures,

02:07:13the absence of solid surfaces and a very different atmosphere.

02:07:16It's like another Jupiter, but in blue tones.

02:07:18But we could fall worse.

02:07:20There is even water on Uranus.

02:07:22The only problem is that the planet is full of ammonia,

02:07:24this radical product that we use for cleaning.

02:07:27So don't be surprised if you smell unbreathable.

02:07:30In addition, it is incredibly cold there,

02:07:32as if winter never ended.

02:07:34How to survive in such a dark and hostile environment?

02:07:37We would need a thicker skin

02:07:39to face these extreme temperatures.

02:07:42We would also need bigger eyes

02:07:44to see better in the dark.

02:07:46Finally, we could be led to develop a new auditory system,

02:07:49like that of dolphins.

02:07:50It would be pretty funny, wouldn't it?

02:07:52Let's move on to Neptune.

02:07:54If human beings were to evolve on Neptune,

02:07:56they would have to adapt to these difficult conditions.

02:07:59Neptune, the eighth planet furthest from the sun,

02:08:02is another gas giant.

02:08:04The only difference is that this planet

02:08:06could well have a solid core.

02:08:08If we were to live on Neptune,

02:08:10we would have no choice but to float

02:08:12or swim through its methane-rich atmosphere.

02:08:14We would also have to develop branches

02:08:16or a similar device to breathe.

02:08:18In fact, we would become either reptiles from space

02:08:20or cosmic fish.

02:08:22On Neptune, gravity is slightly higher than on Earth,

02:08:26but violent winds make it very difficult to stay in place.

02:08:29To resist the winds, we would have to be much heavier.

02:08:33Again, we would have to eat a lot and work out.

02:08:37Yes, yes, technically, this is not a planet,

02:08:40but we still love it and we can't leave it alone.

02:08:43A small, distant and incredibly cold world,

02:08:45Pluto is even smaller than our Moon.

02:08:48And for this reason, there is almost no gravity.

02:08:51It will therefore be very difficult to stand on it.

02:08:53To avoid accidentally flying into space while playing football,

02:08:56we would have to create machines simulating gravity.

02:08:59And if we don't want to have vertigo,

02:09:01we would have to develop a whole new nervous system.

02:09:04But Pluto could be worse.

02:09:06For example, there is liquid water under its surface

02:09:08and even a few frozen mountains.

02:09:10It might be possible to survive there

02:09:12if we had adequate equipment,

02:09:14clothes, supplies and...

02:09:16No, forget it, life is too complicated.

02:09:19Whatever the temperature of Mercury

02:09:21or the ice temperature of Neptune,

02:09:23each planet presents a unique set of environmental challenges

02:09:26and opportunities for evolution.

02:09:28Even if we will never really know

02:09:30what humans would look like on these other worlds,

02:09:33it is exciting to consider the infinite possibilities that are offered to us.

02:09:36Let's never stop looking towards the stars

02:09:38and asking ourselves such questions.

02:09:41On January 7, 1610,

02:09:43the famous Italian astronomer,

02:09:45Galileo Galilei,

02:09:47made an amazing discovery

02:09:49using his homemade telescope.

02:09:51Four moons in orbit around Jupiter.

02:09:55Nowadays, you can make your own version of your telescope

02:09:59using cardboard tubes,

02:10:01lenses and superglue.

02:10:03The principle of this telescope

02:10:05is to place two lenses

02:10:07at the right distance from each other.

02:10:09You will need two lenses,

02:10:11a concave and a convex.

02:10:13In other words, one curved inward

02:10:15and the other outward.

02:10:17Galilei's first telescope

02:10:19was able to magnify objects

02:10:21about eight times.

02:10:23He continued to improve it

02:10:25until it reached a magnification factor of about 20.

02:10:27But let's go back to the main story.

02:10:29When he first saw

02:10:31these four moons of Jupiter,

02:10:33he thought he was just looking at a pile of stars.

02:10:36But he quickly noticed

02:10:38that these space objects

02:10:40seemed to move along a regular pattern.

02:10:42It took him a few weeks

02:10:44to understand that what he was seeing

02:10:46were not stars,

02:10:48but moons orbiting Jupiter.

02:10:50Galilei first named his moons

02:10:521, 2, 3 and 4.

02:10:54But let's be honest,

02:10:56these were not the most creative names.

02:10:58As other moons of our galaxy

02:11:00were discovered later,

02:11:02the numerical system to name them

02:11:04became confused and impractical.

02:11:06And it only lasted a few centuries.

02:11:08Nowadays,

02:11:10these four largest satellites of Jupiter

02:11:12are called Io,

02:11:14Europa,

02:11:16Ganymede and Callisto.

02:11:18They are collectively called

02:11:20the Galilean moons,

02:11:22in honor of the man

02:11:24who noticed them first.

02:11:26Galilei's discovery was crucial

02:11:28for our further understanding

02:11:30of astronomy.

02:11:32At first,

02:11:34we thought that other objects

02:11:36were orbiting the Earth

02:11:38because it was considered

02:11:40as the center of the Universe.

02:11:42We often refer to large moons

02:11:44as those discovered by Galilei.

02:11:46A moon is considered large

02:11:48when it is the size of our planet,

02:11:50or even larger.

02:11:52Ganymede, for example,

02:11:54is larger than Mercury.

02:11:56In fact, we call Ganymede a moon

02:11:58simply because it orbits Jupiter.

02:12:00Otherwise,

02:12:02it has all the other characteristics

02:12:04of a planet.

02:12:06It is no surprise that Jupiter

02:12:08is the largest moon in the Solar System.

02:12:10It passes through all the other planets

02:12:12in size and mass.

02:12:14It is therefore not surprising

02:12:16that it has attracted many other objects.

02:12:18We think that Jupiter has

02:12:20a total of nearly 80 moons,

02:12:22of which only 53 have received

02:12:24an official name to this day.

02:12:26The first of these Jupiterian moons

02:12:28to be discovered by Galilei

02:12:30was Io.

02:12:32What distinguishes it is that it has many volcanoes.

02:12:34Io is the only space object

02:12:36to have active volcanoes

02:12:38on Earth.

02:12:40It is also nicknamed

02:12:42the moon of fire and ice

02:12:44because of its snowfields

02:12:46composed of sulfur dioxide.

02:12:48The outer layer of Io

02:12:50is stained with multiple colors

02:12:52like orange, black, yellow,

02:12:54white and red.

02:12:56This is probably the reason

02:12:58why NASA described it

02:13:00as a giant pizza

02:13:02covered in melted cheese

02:13:04and splashes of tomato and olive oil.

02:13:06When discovered, Io does not smell very good.

02:13:08It smells like a rotten egg.

02:13:10There are more than 100 mountains

02:13:12on the surface of this moon

02:13:14and they are much larger

02:13:16than those we see on Earth.

02:13:18Some are even higher than Everest.

02:13:20On average, these mountain ranges

02:13:22measure 6,000 meters high

02:13:24and 157 kilometers long.

02:13:26Because of these active volcanoes

02:13:28and intense radiation on Io,

02:13:30there is little chance that life

02:13:32as we know it can exist here.

02:13:34But who can say

02:13:36that there can not be another form of life?

02:13:38The next moon on the list

02:13:40of the Galilean moons

02:13:42is Europe, the smallest of the four.

02:13:44Its size is comparable

02:13:46to that of our own moon.

02:13:48Europe has an entirely icy surface

02:13:50with just a few craters

02:13:52scattered here and there.

02:13:54Thanks to this outer layer,

02:13:56Europe is very reflective,

02:13:58making it one of the brightest moons.

02:14:00As for its age,

02:14:02it is estimated that its surface

02:14:04is between 20 and 180 million years old,

02:14:06while the moon itself

02:14:08is about 4.5 billion years old.

02:14:10What is hidden under this icy surface

02:14:12is impressive.

02:14:14It could even hold the secret

02:14:16of life outside the Earth.

02:14:18Ice is formed here in two ways.

02:14:20The first is freezing,

02:14:22a rather explicit process.

02:14:24Ice simply grows

02:14:26as the surrounding environment

02:14:28becomes colder and colder.

02:14:30The other method

02:14:32is much more fascinating.

02:14:34An overmelted layer of water

02:14:36under the ice envelope

02:14:38reacts when it is shaken.

02:14:40It then generates crystals

02:14:42that give the impression

02:14:44that it is snowing upside down,

02:14:46floating up to the layer of ice

02:14:48under which it is.

02:14:50You can recreate this environment

02:14:52yourself at home.

02:14:54Take a bottle of purified water

02:14:56and put it in the freezer.

02:14:58It will help you get rid

02:15:00of as much impurity as possible.

02:15:02As there will be no particles inside,

02:15:04once in the freezer,

02:15:06it will not become solid.

02:15:08But if you then take out

02:15:10the bottle from the freezer

02:15:12and shake it,

02:15:14the impact will quickly crystallize the water,

02:15:16giving it a consistency

02:15:18similar to melted snow.

02:15:20There may be water on Europe,

02:15:22but so far there is little evidence

02:15:24that life exists on this moon.

02:15:26It is one of the best candidates

02:15:28of the Solar System for potential

02:15:30habitability.

02:15:32Some forms of life could adapt

02:15:34to live in its ocean under the ice.

02:15:36This environment is very likely

02:15:38similar to the one found

02:15:40in the hydrothermal vents of our planet,

02:15:42hidden at the bottom of our oceans.

02:15:44The amount of oxygen

02:15:46in the atmosphere of Europe

02:15:48is very low, but in 2013,

02:15:50NASA found promising clues

02:15:52that support the theory

02:15:54that there is a potential

02:15:56for life on this moon.

02:15:58Indeed, it seems that Europe

02:16:00could eject water into space.

02:16:02If this is confirmed by future observations,

02:16:04it could also mean

02:16:06that Europe is geologically active.

02:16:08It could also be useful

02:16:10if we one day

02:16:12manage to study the sources of water.

02:16:14The largest of the Galilean moons

02:16:16is Ganymede.

02:16:18It is also the largest moon

02:16:20of our Solar System.

02:16:22It is a low-density

02:16:24space object whose size is similar

02:16:26to that of Mercury, but which

02:16:28represents only half of its mass.

02:16:30However, Ganymede is the only

02:16:32moon to have its own magnetic field.

02:16:34However, it is quite weak

02:16:36and we can barely notice it

02:16:38from Earth, because it is

02:16:40eclipsed by Jupiter's much more

02:16:42powerful magnetic field.

02:16:44Another interesting aspect of Ganymede

02:16:46is that its atmosphere contains

02:16:48oxygen.

02:16:50If we don't talk too much,

02:16:52it is far from enough

02:16:54for life forms to proliferate there.

02:16:56In December 2021,

02:16:58a 50-second audio clip

02:17:00was published.

02:17:02It was recorded by NASA's probe

02:17:04during its Ganymede flight.

02:17:06For the uninitiated,

02:17:08the sounds were more like

02:17:10those of an old Internet connection.

02:17:12But because of its eccentric airs,

02:17:14Ganymede was quickly nicknamed

02:17:16Jupiter's singing moon.

02:17:18To sum up the list of Galilean moons,

02:17:20we find Callisto,

02:17:22the most heavily cratered object

02:17:24in our solar system.

02:17:26What is interesting about this moon

02:17:28is that its landscape has barely

02:17:30changed since its formation,

02:17:32and scientists are still debating

02:17:34the reason for this phenomenon.

02:17:36Most other space objects undergo

02:17:38a lot of changes throughout their lives,

02:17:40due to events such as collisions

02:17:42with other objects,

02:17:44orientation or speed changes,

02:17:46or chemical reactions

02:17:48that occur on their surface.

02:17:50Callisto is also about the size

02:17:52of Mercury, but its density

02:17:54is also lower.

02:17:56Jupiter's magnetic field

02:17:58has less impact on Callisto

02:18:00because it is the farthest

02:18:02from the gas giant.

02:18:04It is estimated that its surface

02:18:06has a staggering age of 4 billion years.

02:18:08Unlike Io,

02:18:10Callisto is not geologically active,

02:18:12but scientists think

02:18:14that a gas giant could hide

02:18:16under its surface,

02:18:18which could potentially

02:18:20shelter life.

02:18:22The fact that it is less affected

02:18:24by Jupiter's magnetic field

02:18:26means that it has lower

02:18:28radiation levels.

02:18:30Given this appropriate environment,

02:18:32we may one day install

02:18:34a human base there

02:18:36for future exploration.

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