SPACE — Earth, a rocky, watery oasis in the universe is an ideal place for life to thrive for a number of reasons. We are at the right distance from our home star for liquid water to exist on the planet’s surface. The gravitational pull of other large planets also protects us from apocalyptic collisions with millions of roaming meteorites.
Then, there is a magnetic field that surrounds the Earth with a layer that protects us from charged particles that glide freely through space. So, we will discuss this magnetic field next.
Earth’s magnetic field is generated by a complex flow of liquid metallic material in the planet’s outer core. The flow of material, influenced by the Earth’s rotation and the presence of a solid iron core, produces a dipolar magnetic field. Its axis is approximately parallel to the planet’s axis of rotation.
In the chemical composition of ancient rocks are hidden clues that the Earth’s magnetic field is a dynamic and changing phenomenon. Cooling magma rich in iron minerals is pulled parallel to the Earth’s magnetic field, similar to how a compass needle is pulled north. Research on ancient geomagnetic fields recorded in rocks is the subject of the scientific discipline of paleomagnetism.
Also Read: Why Does Earth Have Magnetic Poles?
Paleomagnetic research shows that the Earth’s magnetic field has shifted and even reversed its polarity many times in the geological past. So, what causes the magnetic poles to reverse?
The Earth’s magnetic field varies over very short and long timescales, from milliseconds to millions of years. The interaction of magnetic fields with charged particles in space can change them in short timescales. Meanwhile, disturbances in the magnetic field over longer periods are usually caused by internal processes in the Earth’s outer liquid core.
“Secular variations of the geomagnetic field result from the advection effect of the magnetic field by flows in the outer core of the fluid and from the diffusion effect of the magnetic field in the Earth’s core and mantle,” geophysicist Leonardo Sagnotti told Space.com.
Several times in the past, magnetic field fluctuations by the movement of metallic material in the outer core have caused a complete reversal of the polarity of the Earth’s magnetic field. Previous research on the state of the magnetic field stated that there are two possible states of polarity. First, the current situation, where the magnetic field force lines enter the center of the Earth in the northern hemisphere and exit towards the outside of the Earth in the southern hemisphere. The second polarity is the opposite of that, which can also be as stable as the current state.
Also Read: Strange Radio Signals from Earth-like Planets Suspected of Magnetic Fields Requiring Life
Paleomagnetic studies show that polarity reversals in the Earth’s magnetic field are not periodic and cannot be predicted. “The flow of liquid metal (mostly liquid iron) in the outer core of the Earth is chaotic and turbulent. Polarity reversal occurs during periods of low geomagnetic field intensity, where the intensity of the dipolar component decreases drastically, and the spatial structure is unstable,” said Sagnotti. Geologically, the period polarity reversal shifts occur in an instant, with periods of up to several thousand years.
The Effect of Magnetic Pole Reversal on Life on Earth
When the magnetic field tends to reverse, its intensity decreases, leaving the Earth’s atmosphere more exposed to the solar wind and cosmic rays in the form of charged particles. Recently, a study showed that during the Laschamps journey, namely a period of low magnetic field intensity 41,000 years ago, the flow (flux) of cosmic rays entering the Earth’s atmosphere was three times higher than today.
To date, there is no significant evidence of a correlation between the mass extinction of life on Earth and the reversal of geomagnetic polarity. However, linking rates of species extinction and speciation to periods of low magnetic field intensity is hampered by uncertainties in the time scale of the magnetic rotation.
2024-01-23 21:34:00
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