#laschamp

[spacetimewithstuartgary]

Scientists recreate sound of Earth's magnetic flip 41,000 years ago

Approximately 41,000 years ago, Earth's magnetic field briefly reversed during what is known as the Laschamp event. During this time, Earth's magnetic field weakened significantly—dropping to a minimum of 5% of its current strength—which allowed more cosmic rays to reach Earth's atmosphere.

Scientists at the Technical University of Denmark and the German Research Center for Geosciences used data from ESA's Swarm mission, along with other sources, to create a sounded visualization of the Laschamp event. They mapped the movement of Earth's magnetic field lines during the event and created a stereo sound version which is what you can hear in the video.

The soundscape was made using recordings of natural noises like wood creaking and rocks falling, blending them into familiar and strange, almost alien-like, sounds. The process of transforming the sounds with data is similar to composing music from a score.

Data from ESA's Swarm constellation are being used to better understand how Earth's magnetic field is generated. The satellites measure magnetic signals not only from the core, but also from the mantle, crust, oceans and up to the ionosphere and magnetosphere. These data are crucial for studying phenomena such as geomagnetic reversals and Earth's internal dynamics.

The sound of Earth's magnetic field, the first version of the magnetic field sonification produced with Swarm data, was originally played through a 32-speaker system set up in a public square in Copenhagen, with each speaker representing changes in the magnetic field at different places around the world over the past 100,000 years.

[2sundowner69]

Sound of Earth’s magnetic flip 41 000 years ago

"Combining the satellite data with evidence of magnetic field line movements on Earth, European geoscientists mapped the so-called Laschamps event and represented it using natural noises like the creaking of wood and the crashing of colliding rocks.

The resulting compilation from the Technical University of Denmark and the German Research Center for Geosciences is unlike anything you've ever heard.

Generated by the swirling liquid metals in our planet's core, Earth's magnetic field reaches tens to hundreds of thousands of kilometers into space, protecting us all by deflecting atmosphere-stripping solar particles."

[unhonestlymirror]

😍 And again, the northern lights in Ukraine

The phenomenon was observed in Kharkiv region, Donetsk region, and Dnipro region

.

Living through Laschamp event😍😍😍

[monkeyandelf]

The Earth's magnetic field is getting weaker: Behold the atypical anomalies confirming the approaching of dark days for humanity

Every 12,000 years, global catastrophes occur on Earth. The conclusion about the presence of such a cycle was made on the basis of a large-scale interdisciplinary study of traces of catastrophes based on ice cores, bottom sediments, traces of floods, ash layers of eruptions, megafires, paleomagnetic events, tectonic reconstructions, archaeological materials, and much more. It is important to understand that these cyclic catastrophes on geological time scales occur almost instantly. In the last cycle of catastrophes between the sharp warming and the subsequent cooling of the Younger Dryas, in just a few decades, a planetary catastrophe occurred, leading the planet to the Great Flood. Due to the suddenness of these climatic events, non-specialists and journalists interpreted it as the result of a meteorite impact, that is, it happened so abruptly and unexpectedly, however, those who comprehensively studied the events of the Later Dryas are sure that a sharp warming and subsequent cooling occurred precisely because of volcanic eruptions. In addition, at the same time, a drift of the poles was taking place on the planet, which could in no way be connected with the fall of the meteorite. Catastrophic volcanic eruptions and sudden changes in the magnetic field have something in common, and one reason - this is the destabilization of the core of our planet by external cosmic influence, which affects the planets of the entire solar system once every 12 thousand years. In every 12,000-year cycle of catastrophes, the Earth's magnetic poles drift, which we still observe today. The pole shift 12 thousand years ago is called Gothenburg excursion, 24 thousand years ago - Lake Mungo, 36 thousand years ago - Mono Lake, 48 thousand years ago - Laschamp and so on. Also in past cycles, there was a weakening of the magnetic field. For example, according to paleomagnetic studies during the Laschamp event, the planet's magnetosphere shrank by about 3.8 times the Earth's radius. One hypothesis claims that the extinction of the Neanderthals was due to an increased flux of ultraviolet radiation, as a weakened magnetic field began to pass it more. According to the models of scientists at the same time, auroras were observed on Earth even in the equatorial zone. Today, the change in the Earth's magnetic field is already gaining momentum. It may seem to us that this is not such an important parameter, since we do not directly feel these changes, but in fact this is a catastrophic phenomenon that threatens all life on the planet. Let's look at what anomalies on the planet lead to changes in the Earth's magnetic field in the current cycle of 12 thousand years . In 1995, as a result of changes in the core of our planet, the North Magnetic Pole, previously moving at a speed of 15 kilometers per year, sharply accelerated by 3.5 times. This is the result of heating the outer core and accelerating the flow of molten iron inside it. Today, due to the weakening of the magnetic field, the South Atlantic Magnetic Anomaly is growing. Scientists tell us that over the past century, the intensity of the Earth's magnetic field has decreased by more than 10%, which means that we are threatened by a more powerful stream of cosmic radiation, such as ultraviolet radiation, and this also means that the stream of external cosmic influence is even greater. volume passes to the nucleus. There is another possibly unexpected indicator of changes in the Earth's magnetic field, indicating a destabilization of the core - these are atypical auroras. This year there were especially many anomalously bright and frequent auroras, including in atypical points of the planet. People posted a lot of photos and videos on social networks, admiring this phenomenon, but unfortunately there is nothing to admire here. 

What is aurora?

Aurora is the interaction of solar wind particles with the Earth's magnetic field and atmosphere. In simple terms, when particles of the solar wind interact with particles of oxygen and nitrogen, this causes them to glow, which we observe as aurora. Depending on how deep charged particles can penetrate into the atmosphere and what their energy is, there will be a glow of different colors.

Each height has its own color, which is determined by the composition and density of the atmosphere. On Earth, we are used to seeing green aurorae, and mostly at the poles.

Green aurora occurs at altitudes from 100 to 200 kilometers above the earth when charged particles of the solar wind of medium energies interact with atomic oxygen. However, the glow can also be red, and it arises due to the interaction of high-energy solar wind particles with atomic oxygen. Such a poisonous red glow usually occurred at an altitude of over 200 km, since such high-energy particles were not transmitted below by the Earth's magnetic field.

Red auroras have occurred rarely and only during intense magnetic storms, so now we are seeing a very alarming anomaly. Not only did the auroras begin to occur very often, their manifestations are already observed at an altitude already below 90 kilometers, which means that, firstly, the Earth's magnetic field is weakening and those active high-energy particles of the solar wind that should have been reflected by the magnetic shield are freely penetrate deep into the atmosphere and begin to interact with atomic oxygen closer to the Earth. It is important to note this penetration of larger and more strongly charged particles, which act more destructively on all life on the planet, and the fact that today red auroras occur already in the lower layers of the atmosphere means that there is no longer any protection above. The second reason auroras behave anomalously is the lowering of the upper and middle layers of the atmosphere. Our atmosphere settles, that is, sinks, and the density of its upper and middle layers decreases. Moreover, its chemical composition changes. Now, according to satellite data, a decrease in oxygen concentration by 2-4 times at an altitude of 130 km has been revealed, and the loss rate significantly exceeds all calculated models, and this indicates a certain pathological process leading to a decrease in oxygen in the atmosphere. Scientists are also recording ozone depletion from the solar wind at 75 km, and we will soon see the ozone layer being destroyed already in the stratosphere below 50 km, which means that we will lose our protection from ultraviolet radiation. We already see examples of red auroras in mid-latitudes, especially in February and March 2023. And on January 5, 2023, the sky over Germany was painted red. It was an example of an anomalous static red aurora, but in addition to such red auroras, auroras of blue, turquoise, white and even pink hues have also begun to be observed, which also indicate the penetration of the solar wind closer to the Earth's surface and cracks in the magnetic field. https://twitter.com/bbroastro/status/1650285754562519044 During solar flares, the auroras move closer and closer to the equator. So, for example, during a strong magnetic storm on March 24, 2023, which scientists could not predict in advance and did not expect its arrival, the northern lights were observed in the United States and even in southern states such as Virginia, North Carolina, Oklahoma and Arizona. Auroras began to reach the southern latitudes of Europe, for example, to the Czech Republic, Ukraine and southern Russia. The occurrence of atypical, bright and frequent auroras, which are now observed far from the polar regions, cannot be explained by the activity of the Sun, since the Sun is now in a protracted minimum of its activity, and a smaller number of solar wind particles come to Earth. The only explanation for the aurora anomaly is that the Earth's magnetic field is critically weakening, the atmosphere is settling and the solar wind is sinking lower and lower to the Earth's surface. This is actually scary, because such large disturbances in the magnetic field are a sign that the core of the Earth is no longer working as it should. Few people know that there is another anomaly that indicates a local manifestation of the atypical behavior of the Earth's magnetic field. The so-called light pillars are a phenomenon that has become more frequent in the last few years. Previously, similar phenomena were observed only during the aurora, but now they began to occur without it. Now light pillars are observed mainly in the cold regions of the Earth at night, when there is light from lanterns. You can read that such phenomena occur due to the fact that hexagonal or columnar ice crystals hang one above the other in the air, and they illuminate the atmosphere, but remember winter night photographs 10-20 years ago, when there were lanterns, and light there were no pillars. What now began to keep them in limbo? In fact, this is not just an optical effect. Now we are finding more and more cases where light pillars appear in a group. Often they are brightly colored in the color of the lanterns that illuminate them, however, the intensity of the glow of the pillar does not match the brightness of the lantern, and moreover, another anomaly occurs - light pillars with a red tint or red color appear regardless of the light source. 

So what are the light pillars?

Light pillars are an atypical manifestation of the properties of magnetic fields, not fixed by our devices. It speaks of a local weakening of the magnetic field. During such appearances, along the lines of force of the Earth's magnetic field, cosmic radiation penetrates to its surface and interacts with air molecules, which paints the pillars in different colors, like aurora borealis. Therefore, along the lines of force of magnetic fields, ice crystals hang and remain in a suspended state. Just like in the northern lights, the red color in the light pillars indicates that the molecular oxygen we breathe is being destroyed by hard cosmic radiation. Molecular oxygen turns into atomic oxygen, which glows red. This, in turn, suggests that more and more anomalous zones appear in the magnetic field, and the magnetic field lines are distorted. As a result, our atmosphere is subjected to even more severe attacks from cosmic radiation. Now you understand why such a phenomenon as light pillars does not delight at all, but is very frightening. The protective magnetic field of the Earth is very much weakened. Hard cosmic radiation penetrates deeper and deeper to the surface of the Earth, and oxygen in the atmosphere decreases, and all this progresses very quickly. We, being smart and educated people, do not see this. We admire the anomalous aurora with light pillars and say : What a beautiful scenery? But what can be beautiful in the coming Armageddon? Thus, atypical anomalies in the magnetic field are due to the fact that the core of our planet is destabilized due to cosmic impact, which comes to our planet every 12 thousand years. A climatic Cerberus and dark days to us in the literal sense of the word. Read the full article

[gazetadoleste]

Confira o Olhar Digital News na íntegra (15/10/2024)

Estes são alguns destaques da edição desta terça-feira (15): Ouça uma inversão dos polos magnéticos da Terra ocorrida há mais de 40 mil anos Uma animação baseada em dados da Agência Espacial Europeia (ESA) permite “ouvir” uma representação sonora do campo magnético da Terra durante o Evento Laschamp, uma breve inversão dos polos magnéticos ocorrida há cerca de 41 mil anos.  James Webb consegue…

[3acesnews]

Laschamp Event: Listen To The Eerie "Sound" Of Earth's Magnetic Fields Flipping

[the-eternal-quest-for-balance]

Space Weather, Hurricane, Galactic Cores, Laschamp | S0 News Sep.11.2024

[xtruss]

Geoinformatics, Geodynamos & Superchrons: Will Humanity Survive Next Geomagnetic Pole Flip?

© Photo: Dr. Gary A. Glatzmaier, Los Alamos National Laboratory

The magnetic North Pole’s accelerating march toward Russia from Canada has fascinated and frightened millions of people around the world in recent years amid the prospect of a complete reversal of Earth’s Dipole Magnetic field. The director of the Russian Academy of Sciences’ Geophysical Center delves into the processes taking place under our feet.

The force generating the magnetic field shielding us from deadly solar winds has a fascinating life of its own, and one definitely worth exploring more closely if humanity is to get a fundamental understanding of the planet we call home, according to Veteran Russian Geophysicist, Geoinformatics Expert and Schmidt Institute of Physics of the Earth Head Researcher Anatoly Solovyov.

“The task of geoinformatics is to develop mathematical tools capable of handling the immense quantities of information that we began receiving recently thanks to modern networks digitally recording various natural process,” Dr. Solovyov explained.

“The ability to obtain new knowledge by processing large, often heterogeneous data from different disciplines in the field of Earth sciences, be it geomagnetism, gravity field anomalies, seismological observations, tsunamis,” and other phenomena, including the study of rapid fluctuations in Earth’s magnetic field has become possible only with modern technology and computing power, the academic said.

“Until recently, the characteristic temporal variations in the magnetic field were subject to study measured in centuries, with magnetic field reversals measured in the hundreds of thousands of years. With the advent of modern magnetic field recording systems, rapid variations in the magnetic field have been detected on characteristic time scales of one to ten years,” Solovyev noted. “We’ve learned to record such changes in the magnetic field – caused mainly by processes occurring at the boundary of the Earth’s liquid core, the mantle. We can observer them on the surface of Earth and from near-Earth space using high-precision geomagnetic observatories and low-orbit satellite systems.”

Dr. Anatoly Alexandrovich Solovyev, Geophysicist, Specialist in Geoinformatics, Doctor of Physical and Mathematical Sciences, Corresponding Member and Professor with the Russian Academy of Sciences. © Sputnik/Olga Merzlyakova

Earth Geomagnetic Poles’ Past…..and Future

Solovyev, coauthor of the Atlas of the Earth’s Magnetic Field, a comprehensive 2012 study of the evolution of Earth’s magnetic field from the years 1500 to 2010, and a top scholar involved in the creation of geomagnetic monitoring centers, says these observatories provide scientists the ability to study the temporal variability of Earths’ magnetic field over long periods of time.

“Modern models allow us to reconstruct the magnetic field not only of the past 500 years, but over tens of thousands of years, based on paleomagnetic and archeomagnetic data. We can say that, for example, that the movement of the North Magnetic Pole has significantly accelerated recently, and there is speculation that an inversion can be expected in the near future,” the academic explained.

Of course, there are counterarguments to the pole flip thesis, Solovyev noted.

“For example, 40,000 years ago, the Laschamp event geomagnetic excursion occurred when the dipole axis deviated significantly from the rotation axis. Thus, the North Magnetic Pole can shift to angles of 30-40 degrees, with this process accompanied by a major weakening of the magnetic field. 40,000 years ago, it weakened several times over compared to its present intensity. Nevertheless, everything later returned to its normal place.”

“On the scale we’re talking about, this is related to processes occurring in the liquid core. These have not been fully studied yet, because we only have indirect data. There’s actually very little data. Modern field observation systems were introduced only in the late 1980s, when digital data recordings became possible. Vector-based measurements using low-earth orbit satellites began to be conducted systematically only in the late 1990s, so a thorough reconstruction of the processes occurring in the liquid core, especially over such large intervals, is only possible using theoretical approximations,” Dr. Solovyev explained.

On top of that, it’s an issue of computing power, according to the academic. “For example, one of the latest achievements in the field of numerical modeling of such processes was the possibility to recreate variations associated with rapid changes to the magnetic field – so-called geomagnetic jerks, something achieved only in the last 50 years.”

Scientists have some idea about how the redistribution of magnetic flux occurs at the boundary of the liquid core and mantle, and theoretical concepts explaining the recent acceleration of the movement of the North Magnetic Pole in Russia’s direction, Solovyev said.

Life-Giving Force Shielding the Earth

As for the creation of Earth’s magnetic field itself, scientists postulate that the heterogeneity of states in the Earth’s mantle led to the non-stationary processes that generate the magnetic field.

“They are affected, in particular, by the Coriolis force, thermal convection, compositional convection. Such heterogeneities in Earth’s depths have apparently given rise to process of the creation of the geodynamo and its consequent maintenance,” Solovyev noted, referring to the theory about the mechanisms through which celestial bodies, including Earth, generate their magnetic fields.

“Geophysics is largely a science dedicated to heterogeneities and anomalies, starting with the fact that our planet consists of core-shells that are heterogeneous both in their composition and state of aggregation…In order to start up the dynamo in the form we see today, there must be a solid and a liquid core. The dynamo’s operating modes change depending on the radio of radii of the inner and outer cores. As the inner core grows, the dynamo’s operating modes (inversion frequency and intensity) also change,” the academic said.

In turn, the magnetic sphere contributed to the formation of life on Earth, given its role shielding us from the deadly effects of solar radiation.

At the same time, powerful magnetic storms can have an indirect impact on human health, with the dense flow of high-speed solar winds affecting the magnetosphere, in turn affecting atmospheric pressure, blood pressure, hormonal background, and various environmental factors.

Then, there is solar radiation. “At high altitudes, where high-energy particles penetrate close to the Earth’s surface and can reach the altitude of commercial aviation, the influence of precisely this radiation plan can be felt. Therefore, the [Russian] Space Weather Prediction Center provides a forecast for the level of geomagnetic activity on the Earth’s surface, including for the benefit of aviation. The trajectory of transpolar flights is adjusted accordingly depending on space weather. After all, in a powerful magnetic storm, a human being at such an altitude could receive a dose of radiation in one hour comparable to the average annual dose of radiation,” Solovyev noted.

Humans Adopt to Survive

Humanity has evolved by adapting to the natural changes in our geomagnetic environment over past millennia, and Dr. Solovyev is confident the species can adapt to abrupt changes in the magnetic field, should they take place once again.

“[Such changes] will not happen instantly. On a geological scale, it’s an instant, but on the scale we’re accustomed to, it’s quite a significant period of time, amounting to thousands of years, with the duration of the inversion itself lasting several thousand years…The magnetic field will gradually weaken. We have no documentary evidence about what will accompany this. Perhaps our species will be preserved, because the ionosphere and atmosphere will remain. Currents will be generated in the ionosphere, acting as a kind of shield in relation to those harmful particles flying toward us from the Sun, and may well protect us from solar radiation.”

Flips in the geomagnetic poles occur an average of 500,000 years or so, with the last one taking place about 750,000 years ago.

“No one knows when to expect the next one. It does not happen regularly. Moreover, periods know as superchrons were discovered when no inversion would occur for millions of years, with the field maintaining some fixed polarity. We know of three such superchrons,” Solovyev pointed out.

With homo erectus dating back about two million years, and the last inversion taking place three quarters of a million years ago, that means that the last time a pole flip occurred, it didn’t wipe out our ancestors.

More Data Can Lead to Fundamental Discoveries

Solovyev and his colleagues worked to build the Rotkovets Geobiosphere station in Popovka, Arkhangelsk region in 2012, providing researchers with pristine data free of electromagnetic interference and allowing for a range of geophysical observations.

“Since I have a background in engineering education, although it is a mathematical one, I would like to significantly expand the network of magnetic field observations using observatories of the highest class. This would make it possible to study the subtle effects in the change of the Earth’s magnetic field over a long-term basis,” Solovyev stressed.

With this knowledge, humanity would gain “information about the structure and arrangement of our planet. This is undoubtedly of fundamental importance,” he added.

“We will be able, for example, to study in greater detail the movement of the Magnetic North Pole, around which all the most intense changes in the magnetic field occur and, as a result, the most negative effects of space weather are observed. We’ll be able to adjust the trajectories of aircraft, be prepared for the impact of solar radiation on satellite systems. It’s a wide range of problems, from purely theoretical to important applied aspects,” Dr. Solovyev summed up.

— Sputnik International | Sunday August 18, 2024

[xneontragedyx]

41,000 Years Ago Earth’s Shield Went Down

Earth is naked without its protective barrier. The planet’s magnetic shield surrounds Earth and shelters it from the natural onslaught of cosmic rays. But sometimes, the shield weakens and wavers, allowing cosmic rays to strike the atmosphere, creating a shower of particles that scientists think could wreak havoc on the biosphere.

This has happened many times in our planet’s history, including 41,000 years ago in an event called the Laschamps excursion.

Cosmic rays are high-energy particles, usually protons or atomic nuclei, that travel through space at relativistic speeds. Normally, they’re deflected into space and away from Earth by the planet’s magnetic shield. But the shield is a natural phenomenon and its strength fluctuates, as does its orientation. When that happens, cosmic rays strike the Earth’s atmosphere.

That creates a shower of secondary particles called cosmogenic radionuclides. These isotopes become embedded in sediments and ice cores and even in the structure of living things like trees. There are different types of these isotopes, including ones like Calcium 41 and Carbon 14.

Showers of high-energy particles occur when energetic cosmic rays strike the top of the Earth’s atmosphere. Illustration Credit: Simon Swordy (U. Chicago), NASA.

Some of the isotopes are stable, and some are radioactive. The radioactive ones have half-lives ranging from only 20 minutes (Carbon 11) up to 15.7 million years (Xenon 129.)

When Earth’s shield weakens, more of these isotopes reach the planet’s surface and collect in sediments and ice. By studying these cores and sediments, scientists can determine the magnetic shield’s history. Their observations show that Earth experienced a geomagnetic excursion or reversal 41,000 years ago. It’s called the Laschamps excursion after the Laschamps lava flows in France, where geomagnetic anomalies revealed its occurrence.

Every few hundred thousand years, the Earth’s magnetic poles flip. North becomes South and vice versa. In between those major events are more minor events called excursions. During excursions, the poles shift around for a while without swapping places. The excursions weaken the Earth’s shield and can last from a few thousand to tens of thousands of years. When that happens, more cosmic rays strike the atmosphere, creating more radionuclides that shower down onto Earth.

Scientists often focus on one particular radioactive isotope in paleomagnetic studies. Beryllium 10 has a relatively long half-life of 1.36 million years and tends to accumulate on the soil surface.

Sanja Panovska is a researcher at GFZ Potsdam, Germany, who studies geomagnetism. At the recent European Geosciences Union (EGU) General Assembly 2024, Panovska presented new research on the Laschamps excursion. She found that during the Laschamps excursion, production of Be 10 was twice as high as normal.

To understand the Laschamps excursion more thoroughly, Panovska combined cosmogenic radionuclide and paleomagnetic data to reconstruct the Earth’s magnetic field at the time. She found that when the field decreased in strength, it also shrank. The transition from normal field to reversed field took about 250 years, and it stayed flipped for about 440 years. During the transition, the Earth’s shield weekend to as little as 5% of its normal strength. When it was fully reversed, it was at about 25% of its regular strength. This weakening allowed more Be 10 and other cosmogenic radionuclides to reach Earth’s surface.

Each map shows the intensity of Earth’s geomagnetic field at different snapshots in time, according to Panovska’s reconstructions that are constrained by both paleomagnetic data and records of cosmogenic beryllium-10 radionuclides. DM stands for Dipole Moment, which is a measure of the field’s polarity or separation of positive and negative. Age [ka BP] is the age measures in thousands of years before the present. Image Credit: Sanja Panovska.

These radionuclides do more than collect in sediments and ice. Some of them are radioactive. The weakening of the shield also weakened the ozone layer, letting more UV radiation reach Earth’s surface. The high-altitude atmosphere also cooled, which changed the wind flows. This could’ve caused drastic changes on the Earth’s surface.

For these reasons, the Laschamps event has been linked to the extinction of the Neanderthals, the extinction of Australian megafauna, and even to the appearance of cave art. Those links haven’t withstood scientific scrutiny, but that doesn’t mean that events like the Laschamps event aren’t hazardous. If it occurred now, it would knock out our power grids. The Earth’s equatorial region would light up with aurorae.

“Understanding these extreme events is important for their occurrence in the future, space climate predictions, and assessing the effects on the environment and on the Earth system,” Panovska said.

Scientists are learning that the magnetic shield isn’t static. There are anomalies. One of them is the South Atlantic Anomaly, a region where the magnetic field is weakest near Earth. When satellites pass over this region, they’re exposed to higher levels of ionizing radiation. The anomaly is likely caused by a reservoir of dense rock inside Earth, illustrating how complex the magnetic shield is.

Scientists are uncertain about what effect the cosmic rays have on life when the magnetic shield is weak. It’s tempting to correlate extinctions with events like the Laschamps excursion when they line up temporally. But the poles have shifted, weakened, and reversed many times and life is still here and still thriving.

If humanity lasts long enough, we’ll go through one of these reversals. Then we’ll know.

CATEGORIESCHEMISTRY, EARTH, SCIENCETAGSBERYLLIUM 10, COSMIC RAYS, COSMOGENIC RADIONUCLIDES, EXTINCTION, HALF LIFE DECAY, MAGNETIC SHIELD, PALEOMAGNETISM, RADIONUCLIDES

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[gaetaniu]

I raggi cosmici hanno attraversato l'atmosfera terrestre 41.000 anni fa: Nuove scoperte sull'escursione di Laschamps

Il campo magnetico terrestre ci protegge dalle pericolose radiazioni dello spazio, ma non è così permanente come si potrebbe credere. In occasione dell’Assemblea generale dell’Unione europea delle geoscienze, gli scienziati hanno presentato nuove informazioni su una “escursione” avvenuta 41.000 anni fa, durante la quale il campo magnetico del nostro pianeta è diminuito e i raggi spaziali nocivi…

[levysoft]

Il campo magnetico terrestre ci protegge dalla pericolosa radiazione dello spazio, ma non è così permanente come potremmo credere. "Gli scienziati dell'Assemblea generale dell'Unione europea per le geoscienze presentano nuove informazioni su un'"escursione" 41.000 anni fa in cui il campo magnetico del nostro pianeta è diminuito e i raggi spaziali dannosi hanno bombardato il pianeta."

Il campo magnetico terrestre avvolge il nostro pianeta dall'assalto delle radiazioni cosmiche che scorrono attraverso lo spazio mentre ci protegge anche dalle particelle cariche lanciate verso l'esterno dal sole. Ma il campo geomagnetico non è stazionario. Non solo il nord magnetico oscilla, allontanandosi dal vero nord (una posizione geograficamente definita), ma occasionalmente, si capovolge. Durante queste inversioni, il nord diventa sud, il sud diventa nord, e nel processo, l'intensità del campo magnetico diminuisce.

Ma c'è anche qualcosa chiamato escursioni del campo magnetico, brevi periodi in cui l'intensità del campo magnetico diminuisce e il dipolo (o due poli magnetici) che conosciamo può scomparire, sostituito da più poli magnetici. L'escursione di Laschamps avvenuta circa 41.000 anni fa è tra le meglio studiate. Presenta una bassa intensità del campo magnetico che implica meno protezione per la superficie terrestre dai raggi spaziali dannosi. Periodi di bassa intensità del campo magnetico potrebbero correlare a grandi sconvolgimenti nella biosfera.

Per vedere quando i raggi cosmici stavano bombardando pesantemente la superficie terrestre, gli scienziati possono misurare i radionuclidi cosmogenici nei nuclei sia del ghiaccio che dei sedimenti marini. Questi isotopi speciali sono prodotti dall'interazione tra i raggi cosmici e l'atmosfera terrestre; nascono dai raggi cosmici, quindi sono cosmogenici.

I tempi di minore intensità del campo paleomagnetico - meno schermatura - dovrebbero essere correlati a tassi più elevati di produzione di radionuclidi cosmogenici nell'atmosfera. Sanja Panovska, ricercatrice presso GFZ Potsdam, in Germania, presenterà le sue scoperte sulla relazione tra l'intensità del campo paleomagnetico e i nuclidi cosmogenici durante l'escursione di Laschamps, con particolare attenzione al clima spaziale, la prossima settimana durante l'Assemblea generale 2024 dell'Unione europea delle geoscienze (EGU).

Le variazioni dei radionuclidi cosmogenici come il berillio-10 forniscono un proxy indipendente di come è cambiata l'intensità paleomagnetica della Terra. In effetti, Panovska ha scoperto che il tasso medio di produzione di berillio-10 durante l'escursione di Laschamps era due volte superiore alla produzione attuale, il che implica un'intensità del campo magnetico molto bassa e molti raggi cosmici che raggiungono l'atmosfera terrestre.

Per strizzare più informazioni sia dai dati radionuclidi cosmogenici che da quelli paleomagnetici, Panovska ha ricostruito il campo geomagnetico utilizzando entrambi i set di dati. Le sue ricostruzioni mostrano che durante l'escursione di Laschamps, la magnetosfera si è ridotta quando il campo è diminuito drasticamente, "riducendo così la schermatura del nostro pianeta", ha detto.

"La comprensione di questi eventi estremi è importante per il loro verificarsi in futuro, le previsioni del clima spaziale e la valutazione degli effetti sull'ambiente e sul sistema terrestre".

[bnkbgvbzbuf876986387nogj]

Earth's magnetic field, predominantly dipolar at its surface, is distorted further out by the solar wind. This is a stream of charged particles leaving the Sun's corona and accelerating to a speed of 200 to 1000 kilometres per second. They carry with them a magnetic field, the interplanetary magnetic field (IMF).[25]

The solar wind exerts a pressure, and if it could reach Earth's atmosphere it would erode it. However, it is kept away by the pressure of the Earth's magnetic field. The magnetopause, the area where the pressures balance, is the boundary of the magnetosphere. Despite its name, the magnetosphere is asymmetric, with the sunward side being about 10 Earth radii out but the other side stretching out in a magnetotail that extends beyond 200 Earth radii.[26] Sunward of the magnetopause is the bow shock, the area where the solar wind slows abruptly.[25]

Inside the magnetosphere is the plasmasphere, a donut-shaped region containing low-energy charged particles, or plasma. This region begins at a height of 60 km, extends up to 3 or 4 Earth radii, and includes the ionosphere. This region rotates with the Earth.[26] There are also two concentric tire-shaped regions, called the Van Allen radiation belts, with high-energy ions (energies from 0.1 to 10 MeV). The inner belt is 1–2 Earth radii out while the outer belt is at 4–7 Earth radii. The plasmasphere and Van Allen belts have partial overlap, with the extent of overlap varying greatly with solar activity.[27]

As well as deflecting the solar wind, the Earth's magnetic field deflects cosmic rays, high-energy charged particles that are mostly from outside the Solar System. Many cosmic rays are kept out of the Solar System by the Sun's magnetosphere, or heliosphere.[28] By contrast, astronauts on the Moon risk exposure to radiation. Anyone who had been on the Moon's surface during a particularly violent solar eruption in 2005 would have received a lethal dose.[25]

Some of the charged particles do get into the magnetosphere. These spiral around field lines, bouncing back and forth between the poles several times per second. In addition, positive ions slowly drift westward and negative ions drift eastward, giving rise to a ring current. This current reduces the magnetic field at the Earth's surface.[25]Particles that penetrate the ionosphere and collide with the atoms there give rise to the lights of the aurorae and also emit X-rays.[26]

The varying conditions in the magnetosphere, known as space weather, are largely driven by solar activity. If the solar wind is weak, the magnetosphere expands; while if it is strong, it compresses the magnetosphere and more of it gets in. Periods of particularly intense activity, called geomagnetic storms, can occur when a coronal mass ejection erupts above the Sun and sends a shock wave through the Solar System. Such a wave can take just two days to reach the Earth. Geomagnetic storms can cause a lot of disruption; the "Halloween" storm of 2003damaged more than a third of NASA's satellites. The largest documented storm, the Carrington Event, occurred in 1859. It induced currents strong enough to disrupt telegraph lines, and aurorae were reported as far south as Hawaii.[25][29]

Main article:

Geomagnetic reversal

Although generally Earth's field is approximately dipolar, with an axis that is nearly aligned with the rotational axis, occasionally the North and South geomagnetic poles trade places. Evidence for these geomagnetic reversals can be found in basalts, sediment cores taken from the ocean floors, and seafloor magnetic anomalies.[41] Reversals occur nearly randomly in time, with intervals between reversals ranging from less than 0.1 million years to as much as 50 million years. The most recent geomagnetic reversal, called the Brunhes–Matuyama reversal, occurred about 780,000 years ago.[24][42] A related phenomenon, a geomagnetic excursion, takes the dipole axis across the equator and then back to the original polarity.[43][44] The Laschamp event is an example of an excursion, occurring during the last ice age (41,000 years ago).

The past magnetic field is recorded mostly by strongly magnetic minerals, particularly iron oxides such as magnetite, that can carry a permanent magnetic moment. This remanent magnetization, or remanence, can be acquired in more than one way. In lava flows, the direction of the field is "frozen" in small minerals as they cool, giving rise to a thermoremanent magnetization. In sediments, the orientation of magnetic particles acquires a slight bias towards the magnetic field as they are deposited on an ocean floor or lake bottom. This is called detrital remanent magnetization.[8]

Thermoremanent magnetization is the main source of the magnetic anomalies around mid-ocean ridges. As the seafloor spreads, magma wells up from the mantle, cools to form new basaltic crust on both sides of the ridge, and is carried away from it by seafloor spreading. As it cools, it records the direction of the Earth's field. When the Earth's field reverses, new basalt records the reversed direction. The result is a series of stripes that are symmetric about the ridge. A ship towing a magnetometer on the surface of the ocean can detect these stripes and infer the age of the ocean floor below. This provides information on the rate at which seafloor has spread in the past.[8]

Radiometric dating of lava flows has been used to establish a geomagnetic polarity time scale, part of which is shown in the image. This forms the basis of magnetostratigraphy, a geophysical correlation technique that can be used to date both sedimentary and volcanic sequences as well as the seafloor magnetic anomalies.[8]

[earthstory]

What is happening to the Earth’s Magnetic field? Is it the next disaster? Over recent weeks, you may have seen articles about the Earth’s Magnetic Field, specifically focused on the “South Atlantic Anomaly” – a zone in the Atlantic Ocean where the magnetic field is notably weaker than it is elsewhere on the Earth. This zone has been growing larger and the intensity overall weakening over the past few years. Is this something we should be concerned about? The best answer to that comes from geophysics and geology, which allow us to know how the magnetic field is generated and how it has behaved in the past.

Earth’s magnetic field is generated by convection in the outer core, a molten layer of iron-nickel metal that is capable of carrying and moving electrical charges. This is an extremely complicated process which humans currently don’t have the full capability to simulate. Imagine a river flowing – every little rock, every little difference in the flow path of the water, can cause turbulent flow in the river. Although there are dominant features to the convection in the outer core, complexity in the flow will show up as complexity at the surface. Earth’s magnetic field is dominantly a dipole field, meaning that it has north and south pole components closely aligned with the north and south poles around which the planet rotates. However, some portion of the magnetic field is always taken up by the more complicated components generated by the complex circulation in the core; this will cause some areas to be stronger and other areas to be weaker than the average magnetic field at any given time. Sometimes, the Earth’s dipole, north-south magnetic field appears to decrease in strength to zero, and then suddenly flip – with the south pole and north pole changing places. Because there are minerals on earth that record the magnetic field direction and intensity when they form, these magnetic reversals can be quite precisely recognized and studied. The last time the magnetic field fully flipped was about 781,000 years ago. Since then, the magnetic pole has mostly remained aligned with the north rotation pole, but the magnetic field is constantly in a state of change. The graph with this post shows the strength of the magnetic field over the past 100,000 years in the red curve, with today at 0 on the x axis. As you can see, the magnetic field has slightly weakened over the past 2000 years, but that was after a long period of strengthening of the field. Thus, weakening of the field right now is totally normal and not a sign of any pending 2020 apocalypse. At present, the South Atlantic Magnetic Anomaly has a strength that is about ½ that of the strongest magnetic field zone on Earth, and maybe about 3/4 that of the average, overall magnetic field. While this is the largest weak area on earth, you can also see from this graph that a weaker magnetic field than the one observed today is a common feature in recent geologic history, and does not portend an upcoming reversal. The blue line on that plot shows one other thing – how far away from the rotational pole is the current magnetic field. For most of the last 100,000 years the field has remained nearly north-south, but of course you can see one anomaly – 41,000 years ago, during an event called the Laschamp excursion, the north-south magnetic field weakened to nearly zero, and a weak east-west magnetic field seemed to dominate. Even though this event occurred and the total magnetic field shifted substantially, within a few centuries it snapped back to the previous orientation without reversing. If the magnetic field were to decay away, anything on the surface would be exposed to additional radiation and magnetic currents associated with the sun. This would generally be bad for humans, and in particular for electronic equipment, much of which would need additional shielding. In fact, satellites heading over the South Atlantic Magnetic Anomaly do need to prepare for these effects right now. But, if it helps to put your mind at ease – geologic history tells us that small changes in the magnetic field are normal and have happened constantly over the past 100,000 years. Not only do they not necessarily mean anything big is about to happen, we also see that it requires centuries of weakening before we would be concerned about the magnetic field truly dropping to zero, and that should be time for the next generations of electronics to receive extra shielding. If you’re wondering what the next hazard of 2020 will be, weakening of the magnetic field doesn’t have to be on your list, unless you’re designing a satellite. -JBB Image credit and references: https://eos.org/editors-vox/the-global-geomagnetic-field-of-the-past-hundred-thousand-years https://www.livescience.com/nasa-monitoring-dent-earth-magnetic-field.html https://www.nbcnews.com/science/science-news/dent-earth-s-magnetic-field-puzzles-scientists-n1237328

[lapingarou]

[3acesnews]

Laschamp Event: Listen To The Eerie "Sound" Of Earth's Magnetic Fields Flipping