The Earth’s Magnetic Field Begins at the Core of the Earth

The earth relies on the field of the planet to block many of the high-energy radiation in the universe. We also know from the geological record that the geomagnetic pole will experience a north-south flip, but how long the geomagnetic pole will flip once and once flip, how long it takes to talk about it, a recent new study shows It takes 22,000 years for the Earth’s magnetic pole to reverse, three times more than previously estimated.

The Earth’s magnetic field begins at the core of the Earth. When the solid core of the earth dissipates heat outward, it will cause convective movement of the outer core molten iron, such as the water on the stove circulates continuously and generates electric current, thereby forming a geomagnetic field extending beyond the atmosphere; and as the earth rotates, The magnetic field is roughly aligned with the axis of rotation, forming a magnetic north pole and a magnetic south pole.

The magnetic north pole and the magnetic south pole will drift, and may experience a north-south reversal. It has been flipped at least 10 times in the past 2.5 million years, and the last reversal occurred in the Stone Age. However, the pole flip is not a matter of “single moment” in a few days or a few years, but it may last for thousands to tens of thousands of years. However, scientists have no confidence in the information such as the duration of the flip, the average reversal, and the next reversal prediction.

Although the research of the National Taiwan University team pointed out that the geomagnetic pole could complete the flipping in a hundred years at the earliest; but other international teams believe that although the geomagnetic poles seem to be ready to turn around, they will eventually calm down and will not be in this. The century is reversed.

What is the reason for the pole flip? Some researchers believe that it may be caused by the interference between the earth’s rotation and the core temperature, which will change the convective motion of liquid iron, but the exact reversal process remains a mystery.

Recently, a team led by Brad Singer, a geoscientist and research lead author at the University of Wisconsin-Madison, used volcanic records to study the Earth’s last magnetic reversal event, which was the Bourne-Songshan reversal that occurred 780,000 years ago (Brunhes-Matuyama Reversal), surprised to find that the flipping process may be much longer than previously estimated – lasting 22,000 years.

Previously, other studies have estimated that it takes about 1,000 to 10,000 years to complete a major reversal of the north and south magnetic poles. That is to say, modern people do not have to worry about the natural phenomenon that the magnetic poles are reversed and the magnetic field is greatly weakened during the lifetime.

The team used seven samples of lava flow from around the world, combined with magnetic readings and radioisotope dating, to reconstruct the magnetic field changes of the past 70,000 years centered on the location of the Burongis-Songshan reversal, by measuring the radioactive decay of potassium in the rock. The argon is more accurate in determining the state of the magnetic field recorded by the lava flow.

The lava flow is an ideal magnetic field recorder because the interior contains a lot of iron ore. When the lava cools, the direction of the magnetic field of the iron ore will lock in the same direction as the magnetic field of the planet at that time. However, the volcano does not always erupt, so the maximum igneous rock is analyzed. The downside is that the geological record is incoherent, so in order to make up for the missing time, the researchers analyze the lava flow samples from all over the place.

The results of the study show that the Earth’s magnetic field began to collapse about 795,000 years ago and entered the geomagnetic drift period, during which several temporary reversals were experienced, but the overall turnover was completed for a total of 22,000 years.

In recent years, the geomagnetic North Pole has continued to move from Canada to Siberia, Russia. Due to the excessive drift, it is undoubtedly worried that the magnetic pole flip is imminent, which prompted geomagnetic scientists to update the global geomagnetic model in advance. However, Brad Singer said that there is no evidence that the current The phenomenon of a drop in the magnetic field and a rapid drift of the magnetic pole is an imminent reversal of the magnetic field in the next 2,000 years.

1 Comment