🌌 Préparez-vous pour un événement unique que vous ne voulez absolument pas manquer. Un phénomène céleste rare est sur le point d'illuminer le ciel nocturne, et la meilleure partie? Vous pouvez le voir depuis la Terre de vos propres yeux ! 👀✨ Les astronomes disent que cet événement ne se reproduira pas avant des décennies—ou peut-être même des siècles—c'est donc vraiment spécial. Que ce soit une comète, une supernova ou un alignement planétaire (pas de révélations !), ce sera un spectacle éblouissant. Prenez votre télescope, une couverture et quelques collations, et passez une nuit sous les étoiles. 🌟 N'oubliez pas de partager l'expérience avec des amis ou en famille—c'est un moment à ne pas oublier ! Animation créée par Sympa.
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Musique par Epidemic Sound https://www.epidemicsound.com
Pour ne rien perdre de Sympa, abonnez-vous!: https://goo.gl/6E4Xna
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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
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Si tu en veux encore plus, fais un tour ici:
http://sympa-sympa.com
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FunTranscript
00:00This year, before the month of September, a star of the constellation of the Boreal crown will explode.
00:07And in the northern hemisphere, we will be able to see it with the naked eye.
00:11It is T-Coronae Borealis, a white dwarf star located 3,000 light years away from our solar system.
00:18It will transform into a nova. We will talk about it a little later, in the spring or summer.
00:23Even if this event is predictable, since it happens every 80 years,
00:27there is no doubt that we can only see it once in our life, when we are a human being.
00:32T-Coronae Borealis is not an ordinary star.
00:35It is in fact a binary star, that is to say two stars in orbit, one around the other.
00:40This pair of stars is incredibly special.
00:43It happens that the two stars increase their luminosity to the point of being visible from Earth.
00:48The white dwarf star is the most massive of the two.
00:51But the most amazing thing is that it could contain the same mass as the Sun in a volume equivalent to that of the Earth.
00:57The star that accompanies it, an aging red giant, has already developed so much that it now pours its matter on the white dwarf.
01:05The time has come. These two stars will explode again.
01:09Their luminosity will go from magnitude 11 to magnitude 2.
01:13In astronomy, magnitude is used to measure the brightness of a star or another celestial object.
01:19The brighter the star, the lower the magnitude.
01:24In the case that concerns us, this means that we will be able to see the star with the naked eye, even in a sky polluted by artificial light.
01:31Currently, we can only see this beautiful binary star with binaries in a completely black sky.
01:36After the explosion, T-Coronae Borealis will become the brightest star in the constellation of the Boreal crown for a few days, before gradually extinguishing.
01:46This event must not be confused with a supernova.
01:49During a supernova, the heart of the star collapses, which leads to its complete destruction.
01:54This can only happen to a star whose mass is 8 times greater than that of the Sun.
01:59Instead of disappearing forever in a flash of blinding light, T-Coronae Borealis will know a nova,
02:05that is to say an explosion of surface, which will project matter into space without destroying the star itself.
02:12Such recurring novas occur at regular intervals.
02:16In the past, astronomers called T-Coronae Borealis the fire star.
02:21The last time it exploded was in 1866, then in 1946.
02:27NASA astronomers think it will explode again before September of this year.
02:32The constellation of the Boreal crown is one of the most beautiful there is.
02:36It is an incurved semicircle made up of 7 stars, easy to observe in April.
02:42Go out 2 hours after nightfall and look east-northeast.
02:47Once you have found the Great Bear, use the curve of its wrist to go from the bow to Arcturus,
02:53and you will find the bright star of the constellation of the Bouvier to the east.
02:57If you go down diagonally to the east-northeast horizon, you will see the Boreal crown.
03:02If you want to observe the illumination of T-Coronae Borealis,
03:06it is advisable to familiarize yourself with the region and the stars of the constellation in which it is located.
03:12Once the event has begun, you can compare its brightness to that of the other stars
03:17and observe it without using sophisticated devices.
03:20A nova is a sudden and short-lived explosion involving a compact star the size of the Earth or a little bigger.
03:27The explosion comes from a white dwarf that rotates very close to a normal star.
03:31So close that a gas flow flows between them.
03:34This gas begins to accumulate until it forms a layer on the surface of the white dwarf.
03:38It then reaches a stage where it causes an uncontrolled thermonuclear explosion.
03:43According to astronomers, about fifty novas occur each year in our galaxy, but none are visible.
03:50The NASA Fermi Gamma Ray Space Telescope has observed several novas taking place in our neighborhood,
03:56at the scale of the universe, of course.
03:58They discovered that these explosions produced gamma rays.
04:02This is the most energetic form of light.
04:05Researchers also believe that these gamma rays result from collisions between numerous shock waves
04:11that escape the site of the explosion in a shell of debris in rapid expansion.
04:15Now that we have talked about novas, it is time to address a much more spectacular subject, supernovas.
04:22It is the most powerful explosion that man can witness.
04:26A gigantic deflagration accompanied by an incredible and brief illumination.
04:31A supernova is, in a way, the final bouquet of a massive star that goes out.
04:36This can happen to stars whose mass is at least five times greater than that of our sun.
04:41When they approach the end of their lives, they go out with a huge boom.
04:46Massive stars burn an incredible amount of nuclear fuel in their bodies, producing tons of energy.
04:54This gives their hearts a phenomenal heat.
04:57This heat generates a pressure that prevents these stars from collapsing.
05:01But every star is in balance between two opposing forces.
05:05Its gravity tries to compress it into a tiny and tight ball,
05:09while the nuclear fuel, which burns at the heart of the star, produces a powerful pressure outward.
05:15When a giant star starts to run out of fuel, it starts to cool down.
05:20The pressure decreases and gravity takes it away.
05:23The star collapses.
05:24This huge object, whose mass is millions of times greater than that of the Earth,
05:29implodes in the space of 15 seconds.
05:31It is not surprising that this rapid process produces huge shock waves.
05:36They burst the outer layers of the star.
05:39Finally, there is only an incredibly dense core left,
05:42in addition to a cloud of hot gases called nebulae.
05:46A black hole, the densest object in the universe,
05:49is the result of the supernova of a star about ten times larger than our sun.
05:54There is another type of supernova, which generally occurs in systems
05:58where two stars gravitate around each other,
06:01and where at least one of them is a white dwarf the size of our planet.
06:05If such a star collides with another star, or if it draws too much matter from its neighbor,
06:10it can explode into a supernova.
06:12Supernovas are often so bright that they can eclipse the combined light of entire galaxies
06:18for several days, or even several months.
06:21Supernovas are not common.
06:23Astronomers think that there are only a few per century in galaxies like ours.
06:28But since the universe contains a very large number of galaxies,
06:31we can observe a few hundred supernovas each year out of the Milky Way.
06:36Unfortunately, space dust prevents us from seeing most of the supernovas closest to us.
06:41Betelgeuse, a red giant at an advanced stage, exploded in 2019.
06:46But it was not the event we expected to see.
06:49This star, located in the Orion constellation, is huge.
06:53So big that if we moved it in the middle of our solar system,
06:57its outer edge would go well beyond Jupiter's orbit.
07:01When Betelgeuse approaches its end,
07:03it will explode into a supernova of amazing luminosity,
07:07visible on Earth even during the day.
07:09This explosion could occur tomorrow or in hundreds of thousands of years.
07:13So no need to hold your breath.
07:16But then, what happened in 2019?
07:19Astronomers noticed that the star was weakening.
07:22They thought it was the beginning of the big show.
07:25But instead, Betelgeuse returned to normal a few months later.
07:29A further analysis revealed that the star had not darkened.
07:33If we had the impression,
07:35it was because we were observing it through a cloud of stellar debris.
07:39At the same time, the amount of light in Betelgeuse's photosphere increased,
07:43as if a massive explosion of matter had occurred on the surface of the star.
07:48Events of this type occur permanently in the sun,
07:51especially when the activity of our star is high.
07:54Pieces of the surface of the sun get tangled and detached.
07:57This is what we call coronal mass ejections.
08:00They do not damage our planet,
08:02but they can disrupt satellites and electrical equipment.
08:05To go back to Betelgeuse,
08:07we have never seen such a large mass ejection on the surface of a star.
08:12This is a new phenomenon that we can observe directly,
08:15and that we can even see in detail with the Hubble telescope.
08:19According to astronomers,
08:21we are witnessing for the first time live the evolution of a star.