Внутреннее ядро Земли вращается со своей скоростью, очень горячее и, скорее всего, помогло сохранить жизнь и
How could the Earth restore its magnetic field so quickly?
Scientists are increasingly beginning to believe thatthis was due to the emergence of the Earth's inner core. It is a sphere of solid iron that sits inside a molten outer core. The latter consists of seething metal that generates the planet's magnetic field.
Researchers suggest that the inner coreappeared approximately 4 billion years after the birth of the planet itself. It grew slowly, a few millimeters a year. This, scientists believe, led to activity in the outer core and provoked an increase in the power of the magnetic field.
"The inner core has restored the magnetic fieldEarth: and it happened at the most opportune moment in evolution, says John Tarduno, a geophysicist at the University of Rochester. “What would have happened if it hadn’t formed?”
Scientists are still wondering how and why the internalthe core appeared during this period. “The inner core is a planet within a planet,” said Hrvoe Tkalcic, a seismologist at the Australian National University (ANU). “It has its own topography, its own rotation speed and structure. It's under our feet, but there's still a lot we don't understand about it."
How is our inner "planet" studied?
To study the inner core, researchers use rare seismic waves from earthquakes or nuclear tests that penetrate or reflect from the inner core.
So seismologists discovered that the inner corerotates independently of the rest of the planet. Using computer models, they predicted its structure, as well as the unusual behavior of iron alloys under high pressure.
For a long time mankind had incompleteideas about the internal structure of the Earth. It wasn't until the early 1930s that Inge Lehmann, a Danish seismologist, noticed a new variety of P-waves, or pressure waves. They pointed out that the core of the Earth is not completely liquid. By 1936, Lehmann had concluded that the Earth had a solid inner core. Further, the researchers noticed that every year the P-waves passing through the inner core are slightly accelerated. This could be explained in only one way - the inner core rotates faster than the rest of the planet, about 1 ° per year. Every 400 years, they suggested in a 1996 Nature paper, the inner core made an extra revolution inside the Earth.
This discovery shocked many geophysicists, whothe inner core was assumed to rotate at the same speed as the mantle. If you study its rotation, it will help to understand how the inner core connects to the outer one and affects the magnetic field. It will also explain why the Earth's magnetic poles wander and flip over from time to time.
So the inner core is moving faster than the Earth, right?
Not really.Researcher Yi Yang later compiled the world's most extensive earthquake database. After analyzing them, Yang discovered that the inner core rotates at the same speed as the mantle. Then came an even more unusual fact: according to a 2021 study, the inner core was spinning slower than the rest of the planet, by about 0.05° per year.
Researchers have begun to speculate thatthe inner core has its own rhythm. For decades, radio astronomers have tracked minute changes in the Earth's rotation. They were observed according to the space reference system: they tracked changes in the position of distant space objects. Most of the fluctuations throughout the year are due to hurricanes and earthquakes, but there is a small, regular 6-year fluctuation that cannot be easily explained.
“We don’t yet know why this is happening, but everyone is betting on the core,” Benjamin Chao, a surveyor at Academia Sinica.
What is the inner core made of?
The inner core is the most metallic placeon the ground. It contains even more metals than the outer one. Both are made primarily of iron with a touch of nickel. Iron is also believed to contain traces of lighter elements such as oxygen, carbon and silicon.
When iron crystallizes on a growingsurface of the inner core, it ejects some of these elements from itself. The result is almost pure iron. It's like ice forming in a bucket of salt water: it displaces the salt and becomes mostly fresh water. Elements ejected from the core are lighter than iron: they rise and rush forward: this process causes up to 80% of convection, which generates the Earth's magnetic field.
Convection is a type of heat transfer and heat transfer, during which internal energy is transferred by jets and flows of the substance itself.
What do we still not know about the inner core?
What happens to the remaining iron - on this topicthere is ongoing debate. Iron atoms on the Earth's surface - like those in a cast iron frying pan - have a cubic structure. But if tiny samples of iron are squeezed between two diamonds and created a pressure similar to that in the inner core, the atoms rearrange themselves into hexagons.
The difficulty is that no one has yetknows what happens to iron when it is simultaneously compressed and heated to thousands of degrees, says Lidunka Vochadlo, a computational mineral physicist at University College London.
These conditions are difficult to recreate in the laboratory,because the carbon in diamonds often contaminates iron when heated, Vochadlo noted. His team ran computer simulations and found that the shape of a hexagon, or hexagon, is the most stable structure in the conditions of the inner core. The models also show that pure iron becomes soft when it is at 98% of its melting point.
For example, water must cool below the pointfreezing to form ice. The researchers suggested that iron could not solidify into a hexagonal shape if it was nearly 1,340°C cooler than the inner core. In early 2022, atomic-scale modeling was published suggesting that iron accumulating in the inner core may first crystallize in a cubic form before transitioning to a hexagonal form.
How are the inner core and life on Earth connected?
According to information from a volcanic formation that appeared 565 million years ago on the north bank of the St. River in Lawrence, the magnetic field at that time was one tenth of what it is today.
This was probably due to the fact that the externalthe core was losing heat quickly, says Peter Driscoll, a geodynamicist at the Carnegie Institution for Science. If the Earth's magnetic field were to disappear completely, life as it developed would be heavily exposed to radiation from solar flares. Increased radiation could deplete oxygen, a valuable resource for all life.
Just 30 million years later, the intensity of the magneticfields rose to 70% of the current values. Around the same time, the active development of life produced a revolution on Earth. It was then that most groups of animals originated, the first terrestrial species appeared.
Perhaps the nascent world and all living thingson planet Earth owe their existence to the inner iron core, which is located 5,000 km below, under our feet. Now researchers are trying to reproduce the conditions found in the core in the laboratory: a difficult but necessary task. With the help of such an experiment, it is possible to confirm the conclusions that researchers made earlier based on mathematical models.