Les scientifiques ont découvert que, dans un lointain futur, notre Soleil subira une transformation massive ! Actuellement, c'est une étoile stable au milieu de sa vie, mais dans des milliards d'années, il commencera à manquer de combustible. À ce moment-là, il s'étendra pour devenir ce qu'on appelle une "géante rouge", atteignant jusqu'à 300 fois sa taille actuelle ! Cela signifie qu'il pourrait devenir si grand qu'il pourrait engloutir les planètes les plus proches de lui, comme Mercure, Vénus, et possiblement même la Terre. Les couches extérieures du Soleil dériveront, créant une belle enveloppe de gaz brillant appelée nébuleuse planétaire. Finalement, il se contractera pour devenir une petite étoile froide appelée naine blanche, terminant sa longue vie comme un faible point de lumière. 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
Category
😹
FunTranscript
00:00A recent study has involved nearly 200 gigantic stars that reach the end of their lives.
00:07It has provided scientists with more precise information on how the Sun will end one day.
00:13It turns out that the Sun will be about 200 to 300 times larger than it is now when its end will come.
00:21To begin with, let's address some basic information on the size of the stars.
00:26The big stars reach this stage because they have exhausted their nuclear fuel and are no longer burning hydrogen in their nucleus.
00:33Finally, the nucleus becomes hot enough to trigger the next stage of fusion, which is the combustion of helium.
00:40All the stars examined in this new study were either in this phase of combustion of hydrogen in the envelope or in the phase of combustion of helium in the nucleus.
00:49Even if the giant and supergiant stars represent less than 5% of all the stars, at least the ones we know,
00:57they are actually very visible from afar because they are very bright.
01:01In fact, according to scientists, about a third of all the stars you can see outside on a dark moonless night are giant or supergiant stars.
01:12This study will eventually provide astronomers with really useful information on massive stars.
01:18We will be able to determine their size and temperature, regardless of where they are or their evolution stage.
01:24This means that they can see the true color of a star and use it to discover its radius. Pretty cool, right?
01:32This raises the question, what will our Sun look like when it is old and grimy?
01:38In simple terms, it will expand when it starts to burn its hydrogen shell, but will shrink a little during its combustion phase of the helium nucleus.
01:46After a few hundred million years, it will eventually become a giant star about 200 to 300 times its current size.
01:54Finally, the Sun will expand so much that it will simply evaporate.
01:59So, what will happen when the Sun goes out?
02:03In fact, scientists have some predictions about what will happen, even if we will not be there to see it.
02:10They are pretty sure that the Sun will turn into a planetary nebula.
02:15These planetary nebulas are fragments of gas and dust in space from a star that goes out.
02:22They got their name because they looked like planets to people using telescopes in the 18th century,
02:28even if we now know that they have nothing to do with real planets.
02:32But here is what is extraordinary.
02:35Astronomers have discovered that they can use the level of luminosity of these planetary nebulas to calculate their distance from us.
02:43In 2018, scientists also discovered that the Sun is the smallest star that can still produce a visible nebula.
02:51Smaller, it would not be visible.
02:54Stars that have up to three times the mass of the Sun will produce brighter nebulas.
03:01The Sun is currently 4.6 billion years old, but it is estimated that it still has 10 billion years before its end.
03:09The Sun also becomes brighter every year.
03:13It does not seem like much at the moment, but it will actually cause big problems for the Earth.
03:19In about a billion years, the Sun will be too bright for life on Earth to survive.
03:25Our oceans will evaporate, and it will be too hot for water to reform.
03:30So, unless we find a way to leave this planet, humanity has about a billion years ahead of it.
03:38Will the Earth still exist when the Sun turns to dust?
03:42It is difficult to know with certainty the exact timeline.
03:46But even before that happens, the Earth will most likely be calcined and lifeless, without atmosphere or ocean.
03:53We do not know exactly how far the outer layers of the Sun will approach the Earth.
03:58But if they get too close, it could cause the Earth to spiral into the Sun and disappear completely.
04:04Even if our planet manages in one way or another to survive the giant phase of the Sun,
04:10it will orbit around a hot white dwarf, that is, a star that has exhausted its fuel.
04:16In this distant future, the Sun will be barely larger than our planet.
04:21Finally, the Sun will cool down and darken completely.
04:25It will enter another phase called a black dwarf.
04:28This will close the orbit of the Earth, and our planet will spiral towards the sun.
04:34But it is interesting to note that the Sun has no last word on what happens to the Earth.
04:39Gravity keeps planets in orbit, but it also attracts them to each other,
04:44which can lead to a flexion and drift of their orbits.
04:47This could lead to the destabilization of the solar system and the ejection of planets, including the Earth.
04:52Basically, a lot of things could happen in the next 5 billion years, before the Sun becomes a red giant.
05:00There is also another scenario.
05:03Although most of the stars remain far from our solar system,
05:07there is a chance that one of them may approach over the next billion years.
05:11Even a small star or a black hole could disrupt the orbit of our planet if it gets too close.
05:17But don't worry too much.
05:19The chances of this happening are low because of the distance between the stars.
05:24Our Sun is a solitary star, so there is little chance that we could mount another star nearby.
05:31However, many stars in our universe have companions.
05:36Among these stars is Castor, a magnificent system that includes 6 stars,
05:41and which is one of the brightest objects in the night sky.
05:45Although humans have admired Castor for centuries,
05:49they were not aware of its true nature until the invention of telescopes and spectroscopes.
05:54Even with the help of a small telescope, it is obvious that Castor is composed of two main stars,
06:01Castor AA and BA, which gravitate around each other.
06:05These stars are larger than the Sun and require 467 years to complete an orbit.
06:11In total, Castor is composed of 6 different stars.
06:16The largest, called Castor AA, is about twice as large as the Sun,
06:21while the smallest has about 0.5 the mass of the Sun.
06:26If humans want to survive for the next billion years,
06:30we should perhaps set up a camp somewhere else in the universe.
06:33It may seem straight out of a science fiction movie,
06:36but it could become our reality one day.
06:38Fortunately, NASA is already examining a few options.
06:42They have discovered two new planets,
06:45Tau 700E and Tau 700D,
06:49which could be new hot spots for us, humans.
06:53Tau 700E is in the optimistic zone,
06:56which means it could have water and even an atmosphere.
07:00Tau 700D is in the habitable zone,
07:04so scientists are not yet certain about it.
07:06But hey, we take what we can get.
07:10But wait, before you start packing your bags,
07:14there is a little problem.
07:16How are we going to get there?
07:18It took months of preparation for John Glenn
07:20just to go around the Earth three times.
07:22So, we should perhaps start working on our astronaut training.
07:26Well, at least we have a few options
07:29for our future intergalactic holiday projects.
07:32Wouldn't it be nice to be able to travel back in time
07:34to see what our solar system will look like in billions of years?
07:38An American physicist named Ron Mallett
07:41has proposed an interesting theory for time travel.
07:44It uses light, an abundant resource in the universe.
07:48His idea involves the use of a rotating cylinder of light
07:52that could transport an object both in space and in time,
07:55in a similar way to the way a bubble moves in a moving liquid.
07:59Mallett suggests that a cylinder of the right shape
08:01could allow us to travel in the past and the future.
08:05To test his theory,
08:07he tried to get funding for an experiment.
08:10However, some scientists consider
08:13that Mallett's theory is impossible and useless to test.
08:16We could also be able to travel in time
08:20if we move fast enough.
08:22According to Einstein,
08:24the way we live time can change
08:26depending on our speed of travel.
08:28If we go really fast, time slows down.
08:31For example, astronauts in space age a little slower than people on Earth.
08:36This is important for things like the GPS,
08:39which would be incorrect without special adjustments
08:42because of how time is affected.