00:00In May 2024, the amazing auroras that illuminated the night sky
00:05demonstrated all the power of the radiation emitted by solar storms.
00:09But sometimes, our sun does much more destructive things.
00:13I'm talking about events related to solar particles.
00:16During this time, protons explosions coming directly from the sun's surface
00:21can burst like gigantic cosmic projectors.
00:26According to the surveys, an extreme particle eruption strikes the Earth every thousand years.
00:31It often causes serious damage to the ozone layer
00:34and increases the levels of ultraviolet radiation on the surface of our planet.
00:39Fortunately, the Earth's magnetic field is a powerful protective cocoon.
00:44It repels radiation charged with electricity from the sun.
00:48In its normal state, this field functions like a huge magnet
00:52with field lines that start from one pole, go around the planet and end up at the other pole.
00:58This diagram is sometimes called inverted pamplemousse.
01:02This vertical orientation of the magnetic field at the poles
01:06allows some ionizing cosmic radiation to cross the field to the high atmosphere.
01:12There, it interacts with the gas molecules
01:15and produces the glows we know as auroras.
01:19But over time, the Earth's protective bubble changes.
01:23During the last century, the North magnetic pole moved at a speed of about 40 km per year
01:29through northern Canada.
01:31In addition, it weakened by more than 6%.
01:34Even more shocking, according to the geological archives,
01:38there were periods of several centuries and millennia
01:41during which the magnetic field of our planet was very weak or totally absent.
01:45But we will come back to these tragic periods later.
01:50It is easy to imagine what our planet would look like without its protective bubble while observing Mars.
01:56The red planet lost its global magnetic field a long time ago.
02:00And when this field disappeared, most of Mars' atmosphere also became volatile.
02:06In May 2024, the planet was hit by a powerful solar particle bombardment.
02:11This phenomenon disrupted the operation of the Mars-Odyssey probe
02:15and led to an increase in radiation levels on the surface of the red planet.
02:19They were 30 times higher than what a person receives during a thorax x-ray.
02:25The upper atmosphere of the Sun constantly emits a flux changing electrons and protons, the solar wind.
02:32At the same time, the surface of the star produces energy bubbles,
02:35mainly made up of protons, during events involving solar particles.
02:40These energy bubbles are linked to solar eruptions,
02:43extremely powerful explosions of electromagnetic radiation that can last from a few minutes to a few hours.
02:49Protons are much heavier than electrons and carry more energy.
02:53This is why they can reach the lower levels of the Earth's atmosphere
02:57and activate the gas molecules present in the air.
03:00These activated molecules emit invisible x-rays to the naked eye.
03:05Tens and hundreds of events of relatively weak solar particles occur during each solar cycle.
03:13Let's talk a little about these cycles.
03:15From a distance, the Sun seems calm and stable.
03:19But if you zoom in, you will see that its surface is constantly boiling and moving.
03:25It is constantly transforming,
03:27from a uniform ocean of fire to a chaos of deformed plasmas,
03:30and vice versa, according to a continuous cycle.
03:33Every 11 years or so, the magnetic field of our star literally gets mixed up.
03:38Imagine a ball made of tight elastic bands,
03:41and you will have an idea of what it looks like.
03:44And then, at some point, the field breaks and turns completely,
03:48transforming the North Pole into the South Pole.
03:52Just before this event, the Sun accelerates its activity.
03:56It starts to spit out gigantic balls of inflamed plasma,
03:59emitting powerful radiation flows,
04:01and releases spots the size of a planet to its surface.
04:05This period is called the Solar Maximum.
04:08It is a rather dangerous period for the Earth,
04:11because it is then regularly hit by solar storms.
04:14These storms can disrupt communications and damage electrical infrastructure.
04:20Worse still, solar storms can harm astronauts working in space
04:25and even crush satellites on the planet.
04:28When the cycle is over,
04:30they fade away to leave room for the Solar Minimum,
04:33and then a new cycle begins.
04:36Let's go back to our solar particle events.
04:39Researchers have found extremely powerful traces of this throughout the history of the Earth.
04:45Some of these events were thousands of times more powerful
04:48than anything our modern instruments have ever recorded.
04:52These extreme solar events occur every few millennia.
04:56The most recent is around the year 993 of our era.
05:02Beyond their immediate effect,
05:04solar particle events can trigger a chain of chemical reactions in the high atmosphere.
05:10These processes often lead to a decrease in ozone,
05:14which is not a good thing.
05:16Ozone absorbs UV rays that can damage not only our vision,
05:20but also the DNA of all living beings.
05:24In addition, changing the amount of ozone in the atmosphere can have an impact on the climate.
05:29In a recent study,
05:31researchers used large computer models
05:34to examine how extreme solar particle events affect the Earth.
05:38They discovered that if a proton bomb hits us
05:41at a time when the magnetic field of our planet is very weak,
05:45the damage caused to ozone can last six years.
05:48In addition, the level of UV radiation can increase by 25%,
05:53which increases the damage caused by solar energy by about 50%.
05:59Apparently, this spectacular combination of a weak magnetic field
06:03and a proton eruption occurs quite often.
06:07Some researchers think that this could even explain some mysterious events
06:11that occurred in the past of our planet.
06:14For example, the most recent period of weak magnetic field
06:18began 42,000 years ago and lasted about 1,000 years.
06:23This period led to a temporal inversion of the north and south poles.
06:27Several major events of evolution occurred during this period.
06:31For example, the last Neanderthals disappeared in Europe
06:35and the marsupial megafauna went extinct in Australia.
06:39Yes, unfortunately, we will no longer see wombats or giant kangaroos.
06:44Another event related to evolution, even more important,
06:48could also have been associated with the geomagnetic field of the Earth.
06:52Multicellular animals appeared at the end of the Ediacarian period,
06:56which began about 635 million years ago.
07:00This appearance took place after a period of 26 million years,
07:03during which the magnetic field was extremely weak, even non-existent.
07:08The rapid evolution of different groups of animals during the Cambrian explosion
07:12about 539 million years ago
07:15could also have been linked to high levels of UV and geomagnetism.
07:20The simultaneous evolution of hard and hard-shelled shells
07:23in many non-related groups
07:25could be the result of the need to detect UV rays and protect against them.
07:30A complete inversion of the magnetic poles of the Earth
07:33could have a serious impact on the climate of our planet.
07:36Fortunately, such revolutions do not occur overnight.
07:41The process extends over thousands of years.
07:43In addition, even if the magnetic field weakens during an inversion of the poles,
07:47it does not disappear completely.
07:49This is why the magnetosphere continues to protect the planet
07:52against cosmic rays and charged solar particles,
07:56even if a certain amount of particular radiation reaches the surface of the Earth.
08:00The magnetic fields of our planet are generated by electric charges in motion.
08:05If a material allows these charges to move easily,
08:08it is called a conductor.
08:10Metal is an excellent conductor
08:12and we often use it to transfer electric currents from one place to another.
08:17In this case, the electric current is made up of negative charges
08:21called electrons that move in the metal.
08:23The current is what generates a magnetic field.
08:26The outer core of the Earth is made up of iron and liquid nickel.
08:30In other words, there are layers and layers of conductive materials inside our planet.
08:35Charging currents move constantly in the core
08:39and liquid metal moves there and also circulates there, generating the magnetic field.
08:44This magnetic field then forms like a bubble around the planet.
08:48This is the magnetosphere, located above the upper part of the atmosphere.
08:53This layer protects us by deflecting cosmic high-energy radiation
08:58which, without it, would be extremely dangerous for all forms of life on Earth.
09:03The magnetosphere also interacts with the ionosphere.
09:07This layer of the atmosphere of our planet contains a large amount of free ions and electrons
09:12and is able to reflect radio waves.
09:15The interaction between these two layers and the magnetized solar winds
09:18is what scientists call the space weather.
09:22But the solar wind is generally moderate and time remains at a constant pace.
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