00:00Solar eclipses are amazing.
00:03The Moon and the Sun seem to overlap perfectly in our sky,
00:06while in reality, the Sun is much larger, about 400 times.
00:11The thing is that the Moon is also about 400 times closer to our planet,
00:16so that we have the impression that they are the same size.
00:20Unfortunately, at some point in the history of our planet,
00:24there will be no more solar eclipses.
00:26Indeed, the Moon moves away from the Earth by about 4 cm per year.
00:32Because of this phenomenon, the Moon will no longer completely hide the Sun.
00:37NASA experts have calculated the date of the last solar eclipse.
00:42According to them, it will still have to wait about 600 million years.
00:46So we can say without the risk of being wrong,
00:48that none of us will be there to see it.
00:51Speaking of things that we will not see from our living,
00:54it may be necessary to add the explosion of stars.
00:57Thanks to telescopes, we know what stars look like when they go out,
01:01but we have never witnessed this phenomenon with our own eyes.
01:06Betelgeuse may not be a familiar name to you.
01:09It is a super red giant, located about 1000 light-years from Earth.
01:15What it has in particular is that it could explode
01:18and offer us an unprecedented spectacle seen from here on Earth.
01:22The date of the explosion of this star has always been a bit mysterious.
01:27What we know is that Betelgeuse is in the last stages of carbon combustion of its core.
01:32And this phase of carbon combustion usually lasts a thousand years.
01:37As a result, we will not see stars collapse immediately.
01:41But as this event will most likely be harmless for our planet,
01:45it will be highly anticipated by future generations.
01:49If you want to see Betelgeuse in the night sky,
01:52know that it is generally visible in January and February,
01:55and that at the beginning of August, it is visible before sunrise.
02:00Its attenuated red-orange hue is unique
02:03and proves to us that the stars do have colors.
02:07Our planet will also undergo many changes in the future.
02:10If we could travel a few million years into the future,
02:13it may well be that we no longer recognize the geography of our pretty globe.
02:18Currently, the Earth has seven continents, but it has not always been so.
02:22And it is very likely that this will change again in the future.
02:25About 310 million years ago, the Earth had a megacontinent called the Pangaea.
02:31About 180 million years ago, it began to disintegrate.
02:35Today, scientists think that in the next 200 million years,
02:39we could witness the formation of another great continent.
02:43In fact, it could be in the process of forming right now.
02:47And there are four main scenarios on how this could happen,
02:52each with its own particularities.
02:54They all bring us back to the division of the Pangaea
02:57and to the way our continents continue to move.
03:00Our day, the 24-hour cycle in which we live, also stretches slowly.
03:06This progressive change will ultimately lead us to 25-hour days.
03:10And this is why the rotation of the Earth,
03:14this movement that we make every day, slows down a little more every year,
03:18and this thanks to the Moon.
03:20Indeed, our satellite flies us to incite a part of our terrestrial energy.
03:26We are aware of this phenomenon thanks to the Laser Ranging Retroreflector.
03:31It sends laser beams to the Moon,
03:34and after bouncing, it takes a little more time to return to Earth.
03:39This little delay is an indication that our days are stretching.
03:43So, how long will it take before we have one more hour to finish our daily chores?
03:50NASA experts have made some calculations.
03:53Over the last century, our days have extended by about 1.4 milliseconds.
03:58If we zoom back and examine the last two millennia,
04:02based on historical data from solar eclipses,
04:06our days have extended by an average of 2.5 milliseconds per century.
04:12I spare you the calculation.
04:14It will take about 50,000 years for a single second to add up to our day.
04:19This means that it will take 180 million years for a day on Earth to count 25 hours.
04:25And this, of course, if nothing else happens in the meantime at the level of the rotation of our planet.
04:32The Milky Way is one of its closest neighbors.
04:35It is also expected to merge one day or the other.
04:38We will not be there to witness this meeting,
04:41but we will not see any major changes at Earth level anyway.
04:45The collision of galaxies may seem a little unusual,
04:48especially since we know that the universe is expanding.
04:52If galaxies are moving away from each other more and more,
04:55how can they still meet?
04:58Close galaxies do not just float.
05:01They each have an effect on the other, thanks to gravity.
05:04This is the reason why the Milky Way and Andromeda
05:07are approaching at a speed of about 300 km per second.
05:11If we do the math,
05:13this means that their collision will not occur before 4 or 5 billion years.
05:18And there is a good chance that they will meet gently,
05:21without any notable change within our solar system.
05:26In the distant future,
05:28the amazing ice rings of Saturn will no longer be there either.
05:33At least, according to recent research.
05:37NASA's Cassini mission,
05:39which spent time orbiting Saturn between 2004 and 2017,
05:42has collected new information on these rings
05:45and on the date of their disappearance.
05:48Scientists have long debated the age of Saturn's rings.
05:53Some thought they were relatively young,
05:56their ice still being fresh and bright.
05:59Over billions of years,
06:01the rings would be worn out and darkened
06:03due to the various objects that came to intermingle with them.
06:06But these rings were perhaps still at an embryonic stage
06:09at the time when dinosaurs inhabited the Earth.
06:12When foreign bodies filter between the rings,
06:15they push some of the innermost circle matter towards the planet
06:18at a fairly fast rate.
06:21Cassini thus found that the rings were losing a lot of mass every second.
06:25This means that they will no longer be visible for a very long time.
06:28In cosmic terms, at least.
06:30It is estimated that they will only last a few hundred million years at most.
06:35We could also miss this next cosmic event,
06:38but very little.
06:40Indeed, according to some estimates,
06:42it could only happen in a hundred years.
06:46The Earth's magnetic field could collapse
06:49and reverse the North and South Poles.
06:51Researchers have stated that for 3,000 years,
06:54our planet's magnetic field has been constantly declining.
06:58If this trend continues,
07:00we could reach a critical point in less than a millennium.
07:04For the planet's poles to tilt,
07:06the magnetic field must weaken by about 90%,
07:09which can take thousands of years.
07:12During this phase of vulnerability,
07:14our planet loses its protective shield
07:16and lets more rays pass from space.
07:21The last time such an inversion of the poles occurred
07:24was nearly 800,000 years ago.
07:26The problem is that we are currently in one of the most risky phases.
07:30The magnetic field is weakening,
07:32but it is possible that it will regain vigor.
07:35However, at this rate,
07:37it could brutally fall within a few centuries or a millennium.
07:41We can already see the effects of the weakening of the magnetic field on our satellites.
07:46In the vast expanse of the Atlantic Ocean,
07:49between South America and Africa,
07:51there is a region where the Earth's magnetic field
07:53is three times weaker than the poles.
07:55Scientists call this the South Atlantic Anomaly.
07:59The satellites that cross this zone
08:01regularly experience electronic problems.
08:04No one knows why the magnetic field is so weak in this region,
08:08and no one knows what will happen to it in the future.
08:11According to a theory,
08:13a massive whirlwind in the outer metallic core of the Earth
08:16could be responsible for it.
08:18It would push the magnetic field away from the South Atlantic.
08:21Another idea is that this field, in this region,
08:24is pointing in the wrong direction,
08:26like a spinning mini-pole.
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