Que Serait la Terre Sans la Lune ?

Sympa

Une Terre sans lune — ça sonne assez étrange, non ? Sans ce gros rocher dans le ciel, nos nuits seraient beaucoup plus sombres, sérieusement effrayantes. De plus, les marées seraient beaucoup moins spectaculaires sans l'attraction gravitationnelle de la lune, donc pas de vagues époustouflantes sur la plage, désolé les surfeurs. Mais voici le hic : notre inclinaison serait complètement déréglée sans la lune pour la stabiliser, donc dites adieu à ces saisons régulières. Et ne me lancez même pas sur la façon dont cela perturberait la faune et les écosystèmes — parlez d'un changement total de jeu pour la planète Terre ! Donc ouais, la vie sans la lune ? Certainement pas une journée ordinaire dans l'univers.  Animation créée par Sympa. ---------------------------------------------------------------------------------------- Musique par Epidemic Sound https://www.epidemicsound.com   Pour ne rien perdre de Sympa, abonnez-vous!: https://goo.gl/6E4Xna​ ---------------------------------------------------------------------------------------- Nos réseaux sociaux : Facebook: https://www.facebook.com/sympasympacom/ Instagram: https://www.instagram.com/sympa.officiel/  Stock de fichiers (photos, vidéos et autres): https://www.depositphotos.com https://www.shutterstock.com https://www.eastnews.ru ----------------------------------------------------------------------------------------  Si tu en veux encore plus, fais un tour ici:  http://sympa-sympa.com

Transcript

00:00You know how it all started 13.8 billion years ago with the Big Bang.

00:05BAM! No, no, wait, I can do better.

00:08Bada-boom! No, it's ... it doesn't matter.

00:11And the universe has not stopped expanding since.

00:14At its beginning, it was entirely composed of gas, mainly helium and hydrogen.

00:20Over billions of years, the gas has spread and cooled.

00:24During this time, galaxies, stars and other mysterious things in space

00:29that we are trying to explore today, have formed under the action of gravitational forces.

00:35And in this Capernaum, about 4.6 billion years ago,

00:39our magnificent planet also appeared.

00:42It all started with a gas and dust disk orbiting around our young sun,

00:47exactly as was the case for the rest of the planets of our solar system.

00:51This disk was made up of gas and dust particles of different sizes.

00:56They rotated around the sun at different speeds

00:59and on orbits that were no more stable than predictable.

01:02They constantly hit each other.

01:05These particles grew from very small grains of dust to become rocks.

01:09And later, larger bodies called planetesimals,

01:13which declined in size from a few kilometers to several hundred kilometers in diameter.

01:18Planetesimals that orbited around the sun within the disk had enough gravitational force

01:23to attract other objects from the neighborhood out of their orbits and collide with them.

01:29As they constantly hit each other, they became bigger and bigger,

01:33reaching diameters of several thousand kilometers.

01:37This is practically the size of Mars and our Moon.

01:40We know all this thanks to meteorites.

01:43They come from different places in our solar system

01:46and bring all kinds of materials to our planet.

01:50They give us something interesting to study and learn about our own system and its formation.

01:56These materials contain very small pieces of dust and rocks called chondra,

02:01which went through chaos and survived the difficult moments that preceded the creation of the planets.

02:07Meteorites also bring pieces of asteroids and planetesimals

02:11left after the end of the planet formation process.

02:14While these objects were forming,

02:16some radioactive elements such as uranium and hafnium were trapped inside the minerals

02:21and became an integral part of them.

02:23This is how scientists were able to determine their age.

02:27But the final phase of formation of our planet, and in general,

02:31all this chaos that shook our solar system may have taken a little longer,

02:36up to about 100 million years more.

02:39It was then that the last great impact occurred

02:42and that the Earth finally reached its current size.

02:45What really happened was that it hit another object almost as big as Mars.

02:51This collision was so powerful that the impact produced enough energy

02:55to vaporize part of the metal and rock, both on Earth and on this planetoid.

03:01And this steam created a disk that surrounded our planet.

03:04It cooled down and regrouped after a while.

03:08And this is how we got the Moon.

03:11Our Moon is the result of the debris of this impact,

03:14which was a combination of hot gas and molten rock.

03:18However, there are other theories about the formation of the Moon.

03:21The fission theory claims that it simply detached itself from the Earth.

03:25The capture theory suggests that the Moon would have formed elsewhere in our solar system.

03:30At some point, while it was walking, it would have gotten so close to the Earth

03:35that it would have ended up being captured by its gravity.

03:38Finally, supporters of the third theory, that of co-formation,

03:42believe that the Moon and the Earth formed simultaneously

03:45from the same protoplanetary disk.

03:48Before the formation of the Moon, the Earth was a very different place.

03:52If you could spend a single day on this Earth without the Moon,

03:55you would be surprised by the cycle of days and nights.

03:59It would not be as regular as it is today

04:01because the Moon helps to stabilize the axis of the Earth.

04:05The days were shorter at the time because the Earth was spinning much faster

04:09before the formation of its satellite.

04:11Its gravitational force slowed the rotation of our planet,

04:15which means that the days got longer.

04:18The rotation of the Earth slows down over time,

04:21but at a really slow pace.

04:23According to some forecasts, within a billion years,

04:26a typical day would last between 25.5 and 31.7 hours.

04:32If 24 hours are not enough for you,

04:34just wait a billion years.

04:38But yes, if you are the kind of person who likes to take his time,

04:41you would certainly have had to hurry at that time.

04:44Although there was not much to do to pass the time,

04:47except sailing on lava, picking up stones

04:50or hoping not to be hit by a meteorite.

04:54Not only was the Earth very likely a lava ball in fusion,

04:58but its landscape was also rocky and sterile.

05:01The Moon at its early stages was also extremely hot.

05:04It was probably similar to a partially melted ball

05:07suspended above our planet.

05:12But if you were patient enough,

05:14maybe you would witness something really cool.

05:17Water coming to our planet for the very first time.

05:20A rain of flaming meteors fell from the sky

05:23and they kept falling on our young Earth.

05:26It may have seemed devastating at first,

05:28but some of these debris probably contained water.

05:32Many believe that asteroids and comets

05:35that hit our planet transported small amounts of water.

05:38But since this rain of meteorites lasted more than 20 million years,

05:42maybe even up to 200 million,

05:45it is not so unlikely that after a while,

05:48puddles of water began to form on the surface.

05:52And when the water evaporated into the atmosphere,

05:55it finally fell again,

05:57forming lakes, rivers, seas and finally oceans.

06:01It was only from this moment that primitive life had the chance to evolve.

06:05The Earth began its transition from an incandescent magma ball

06:09to the world we know today.

06:11Before that, it would have been too difficult for life to exist.

06:15And even if it had happened one way or another,

06:18all these meteor collisions would probably have destroyed it.

06:23You could not survive here either without oxygen bottles.

06:27The Earth had an atmosphere,

06:29but it was not like the one we know today.

06:32Scientists believe that it consisted of water vapor,

06:35methane, ammonia and other gases released by volcanic activity.

06:39Basically, it was far too toxic

06:41because volcanic eruptions occurred all the time.

06:44And the temperatures were much higher.

06:47So that existing at these early stages of our Earth

06:50would not have been a very pleasant experience.

06:53However, there could have been some forms of life at this time.

06:57At its chaotic beginnings,

06:59the Earth was not covered with oceans, trees

07:02or breathtaking landscapes of today,

07:04but with fusion magma.

07:06The oldest form of life we know

07:08are fossils of microorganisms found in hydrothermal chimneys.

07:12And we think they are about 3.4 billion years old.

07:16Scientists estimate that the time when life could have appeared

07:19for the first time on Earth

07:21would be about 4.2 billion years ago, more or less.

07:27Thus, with the right equipment,

07:29you could even observe unicellular organisms,

07:32like bacteria somewhere on the surface of our planet,

07:35and even before the appearance of the Moon.

07:38The gravitational attraction of this on the Earth

07:40creates tides of our oceans,

07:43which means that it probably helped to mix

07:46and circulate the water of the seas,

07:48and perhaps even to shape them.

07:50Tides without the Moon would be much less important,

07:53because it is its attraction that causes the rise and fall of the waters.

07:59The Moon also affects life in the ocean.

08:01Over time, marine animals have evolved

08:04and adapted to the alteration of the water level

08:06caused by lunar gravity.

08:08Even the light of the Moon has a great effect on marine creatures.

08:12Corals, for example,

08:14use the cycle of the Moon to release their eggs at the same time,

08:17when stronger tides help to transport their eggs.

08:23Baby sea turtles use the light of the Moon

08:26shining on the water to guide them from their birthplace to the ocean.

08:29Who knows what direction life on Earth would have taken

08:32if, at some point, a few billion years ago,

08:36we did not have our lunar companion to accompany us?

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