The magnetic north pole continues to move from Canada towards the Severnaya Zemlya archipelago at a speed of 55 kilometers per year. Scientists suggest: a change of poles is being prepared due to unrest in the liquid part of the planet's core, inaccessible to direct observations. It is difficult to understand what exactly is happening there, but there are many hypotheses.
Mission to the "iron world"
In 2022, NASA is going to send the device to the asteroid Psyche, located between Mars and Jupiter. It is called the Iron World. By the reflection of rays from the surface, by how quickly it heats up and cools, scientists realized that it is, if not completely, then mostly metal. It is possible that it is from there that iron meteorites fly to us. This happens very rarely; in total, no more than two hundred such events are known. It is assumed that Psyche is the core of the terrestrial planet, which has lost its outer shells. Together with the Earth and Venus, this planet was forming near the Sun, but then something happened. Maybe a catastrophe, or maybe it's all to blame for repeated warming up of planetary earths - clumps of matter from which planets are formed. Scientists certainly want to get into the "iron world",and not only for the sake of geological exploration of deposits in the interests of our descendants. First of all - to closely explore the analogue of the Earth's core.
Why is the core iron
The Earth's core is an interesting object. Its composition and temperature are reflected in the overlying layers and the atmosphere. The nucleus is the source of the magnetic field, thanks to which life arose. There is also the key to the secret of the formation of the terrestrial planets. The interior of the Earth is explored using seismic waves and modeling. Roughly speaking, the planet consists of an upper shell - the crust, mantle and core. The fact that the core is iron is evidenced by several facts. The Earth has its own magnetic field, like a dipole is inserted along the axis of rotation. The mantle cannot generate such a field; it conducts an electric current too weakly. According to the geodynamo model, only a conductive liquid is capable of this. This means that part of the core is liquid. Iron is one of the most abundant elements in the solar system. This is confirmed by its abundance in meteorites. Elastic S-waves do not pass in the outer part of the core,then it is liquid. The inner part of the core with a radius of about 1221 kilometers weakly propagates S-waves - accordingly, it is either solid or in a state that simulates hardness. The boundary between the two layers in the core is quite distinct, as is the case between the core and the lower mantle. It is believed that the core is iron, with small impurities of nickel (as indicated by the composition of iron meteorites), silicon, sulfides and oxygen. Several features of the seismic wave propagation suggest that the inner solid core rotates slightly faster than the mantle and crust, at about 0.15 degrees per year. When and how was the Earth's core formed? What is the ratio of chemical elements in it? Why is it not homogeneous? What's the temperature there? Where is the energy source? And most importantly, why did the core even form inside the planet? There are many hypotheses for each of these and many other questions.it is liquid. The inner part of the core with a radius of about 1221 kilometers weakly propagates S-waves - accordingly, it is either solid or in a state that simulates hardness. The boundary between the two layers in the core is quite distinct, as is the case between the core and the lower mantle. It is believed that the core is iron, with small impurities of nickel (as indicated by the composition of iron meteorites), silicon, sulfides and oxygen. Several features of the seismic wave propagation suggest that the inner solid core rotates slightly faster than the mantle and crust, at about 0.15 degrees per year. When and how was the Earth's core formed? What is the ratio of chemical elements in it? Why is it not homogeneous? What's the temperature there? Where is the energy source? And most importantly, why did the core even form inside the planet? There are many hypotheses for each of these and many other questions.it is liquid. The inner part of the core with a radius of about 1221 kilometers weakly propagates S-waves - accordingly, it is either solid or in a state that simulates hardness. The boundary between the two layers in the core is quite distinct, as is the case between the core and the lower mantle. It is believed that the core is iron, with small impurities of nickel (as indicated by the composition of iron meteorites), silicon, sulfides and oxygen. Several features of the seismic wave propagation suggest that the inner solid core rotates slightly faster than the mantle and crust, at about 0.15 degrees per year. When and how was the Earth's core formed? What is the ratio of chemical elements in it? Why is it not homogeneous? What's the temperature there? Where is the energy source? And most importantly, why did the core even form inside the planet? There are many hypotheses for each of these and many other questions. The inner part of the core with a radius of about 1221 kilometers weakly propagates S-waves - accordingly, it is either solid or in a state that simulates hardness. The boundary between the two layers in the core is quite distinct, as is the case between the core and the lower mantle. It is believed that the core is iron, with small impurities of nickel (as indicated by the composition of iron meteorites), silicon, sulfides and oxygen. Several features of the seismic wave propagation suggest that the inner solid core rotates slightly faster than the mantle and crust, at about 0.15 degrees per year. When and how was the Earth's core formed? What is the ratio of chemical elements in it? Why is it not homogeneous? What's the temperature there? Where is the energy source? And most importantly, why did the core even form inside the planet? There are many hypotheses for each of these and many other questions. The inner part of the core with a radius of about 1221 kilometers weakly propagates S-waves - accordingly, it is either solid or in a state that simulates hardness. The boundary between the two layers in the core is quite distinct, as is the case between the core and the lower mantle. It is believed that the core is iron, with small impurities of nickel (as indicated by the composition of iron meteorites), silicon, sulfides and oxygen. Several features of the seismic wave propagation suggest that the inner solid core rotates slightly faster than the mantle and crust, at about 0.15 degrees per year. When and how was the Earth's core formed? What is the ratio of chemical elements in it? Why is it not homogeneous? What's the temperature there? Where is the energy source? And most importantly, why did the core even form inside the planet? There are many hypotheses for each of these and many other questions.
Which of the twins is lucky
Venus is considered the twin of the Earth - it is only slightly smaller in mass and size. But the current conditions on its surface are completely different. The Earth has its own magnetic field, atmosphere and biosphere. Venus on this list has only a toxic atmosphere with clouds of sulfuric acid. There are no traces of a magnetic field in the geological past, although they could have disappeared. Probably it's all about the origin of the twins. Venus and the Earth formed in one part of the gas and dust nebula that surrounded the Sun. The embryos of the planets expanded, attracting more and more material to themselves. When the mass became critical, heating and melting began. The substance was divided into fractions: heavy elements settled inside, the lungs rose upward. Scientists from Germany, Japan and France believe that the stratification of bodies like the Earth is uniform and stable, each layer is homogeneous. In order for the core to turn out to be two-layer and inhomogeneous, somewhere near the end of the process, the planet had to experience a very strong impact from another massive body. Part of the "alien" substance remained in the bowels of the Earth, part was knocked out into orbit, where the Moon was then formed. From the impact, the interior of the planet was mixed, and this led to the partial melting of the core. But the evolution of Venus went smoothly, without a cosmic emergency. The stratification ended safely with the formation of a solid iron core, unable to generate a magnetic field. There is another hypothesis: spontaneous crystallization of an iron melt. However, for this he needs to cool down to a thousand Kelvin, which is impossible. This means that the nuclei of crystallization penetrated from the outside, the scientists from the USA concluded. For example, from the lower mantle. These are large pieces of iron tens and hundreds of meters in size. Where they come from there is a big question. One of the answers lies on the surface of the Earth in the form of ancient ferruginous quartzites. Perhaps more than three billion years ago, these rocks formed the bottom of the oceans. Due to the movement of the plates, it plunged into the mantle and from there into the core.
More than four billion years ago, the Earth collided with a massive cosmic body. As a result of the impact, its forming core was mixed, a liquid outer part was released in it, and this led to the appearance of a magnetic field. The blow knocked out part of the Earth's substance, from which the Moon arose / Illustration by RIA Novosti. Alina Polyanina, NASA.
Promotional video:
Making a magnetic shield
The ratio of the radioactive isotopes of lead indicates the age of the core: about four and a half billion years. When the magnetic field arose is unknown. Its traces are already found in the oldest rocks of the Earth, 3.5 billion years old.
In accordance with the geodynamo model, the Earth's magnetic field requires a conducting fluid, the rotation of which is accompanied by mixing.
The problem is that the magnetic field of rapidly rotating fluids dies out sooner or later. Judging by the geological data, the intensity of the Earth's magnetic field did not change over the time interval visible to us. There must be some kind of constant powerful source of energy.
There are two candidates for this role. Thermal convection, possible if the inner core is hotter than the outer, and compositional convection, that is, the movement of elements from one part to another. This means that the solid part of the nucleus is enlarged. But you should not be afraid of complete solidification. This will take more than one billion years.
Tatiana Pichugina