The Earth's magnetic field reverses itself every 100,000 years or so, without respect this periodicity. This magnetic field (geodynamo) is produced by the movements of the alloys of iron and nickel in the molten liquid portion of the core of the Earth. According to geophysicists from the CNRS and the Institut de Physique du Globe, these irregularities are related to changes in the distribution of continents over the last 300 million years. The mantle rock Earth floats on the core of iron and nickel whose upper part is liquid. The magnetic field, causing the Earth's magnetosphere varies but slightly over long periods, it is reversed. There are over 780 000 years, a compass would have pointed to the South Pole. Researchers are studying these mechanisms in laboratory inversions that appear to be chaotic and stochastic (under the random). The study of geomagnetic records of the Earth does not really show the frequency of inversions, 100, 000 years of quiet periods, without inversion, can last 10 million years.
* Reversal of the Earth's magnetic field according to Hubert Reeves: what impact on us or nature?
Eccentricity and magnetic field
The eccentricity of the orbit of the planet would have an effect on the fluctuations of the angle and intensity of the geomagnetic field. This was said Toshitsugu Yamazaki and Oda Hirokuni, scientists from the Geological Survey of Japan. Earth's magnetic field is generated by the movements of liquid metal core, the deep layers of the Earth. By studying the long-term variations of the magnetic field, the two researchers examined the magnetic properties of a column of marine sediments, 42 meters long, deposited over a period of 2.25 million years. This enabled them to establish the intensity and direction of the geomagnetic field change over a cycle lasting 100,000 years. The eccentricity measures the deviation of the Earth's orbit from a circular orbit.
It ranges from 0 for a circular orbit at 1 for a highly elliptical orbit. But the eccentricity of Earth's orbit varies between 0 and 0.06 every 100,000 years.
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