The Earth's magnetic field constantly protects us from charged particles and radiation that come to us from the Sun. This shield is created by the rapid movement of a huge amount of molten iron in the outer core of the Earth (geodynamo). In order for the magnetic field to survive to this day, the classical model calls for a core cooling of 3,000 degrees Celsius over the past 4.3 billion years.
However, a team of researchers from France's National Center for Scientific Research and Blaise Pascal University reported that the core temperature had dropped by only 300 degrees. The action of the moon, previously ignored, compensated for the temperature difference and maintained the geodynamo. The work was published on March 30, 2016 in the journal Earth and Planetary Science Letters.
The classical model of the formation of the Earth's magnetic field gave rise to a paradox. For the geodynamo to work, the Earth must have been completely melted 4 billion years ago, and its core must have slowly cooled from 6800 degrees at that time to 3800 degrees today. But recent modeling of the early evolution of the planet's internal temperature, coupled with geochemical studies of the composition of the oldest carbonatites and basalts, do not support such cooling. Thus, the researchers suggest that the geodynamo has another source of energy.
The earth has a slightly flattened shape and an inclined axis of rotation that swings around the poles. Her mantle deforms elastically due to the tidal effects caused by the Moon. The researchers showed that this effect can constantly stimulate the movement of molten iron in the outer core, which in turn generates the Earth's magnetic field. Our planet continuously receives 3700 billion watts of power through the transfer of gravitational energy of rotation of the Earth-Moon-Sun system, and more than 1000 billion watts, according to scientists, are available for the geodynamo. This energy is enough to generate the Earth's magnetic field, and together with the Moon, this explains the main paradox of the classical theory. The influence of gravitational forces on the planet's magnetic field has long been confirmed on the example of Jupiter's moons Io and Europa, as well as for a number of exoplanets.
Since neither the rotation of the Earth around its axis, nor the direction of the axis, nor the orbit of the Moon are regular, their combined effect is unstable and can cause oscillations in the geodynamo. This process can explain some of the heat impulses in the outer core and at its border with the Earth's mantle.
Thus, the new model shows that the influence of the Moon on the Earth goes far beyond the ebb and flow.