Scientists agree: the Earth’s magnetic field protects our planet from particles and radiation that come from the Sun. This invisible shield is created by the quick movement of massive amounts of liquid iron alloy present in the outer core of the Earth. Until recently it was believed that in order to maintain this magnetic field, the Earth’s core had to cool by about 3,000 degrees Celsius over the past 4.3 billion years. However, astronomers now believe that the number is missing a zero, making the change in temperature a mere 300 degrees Celsius. The question this information leaves behind: how then is the magnetic field still consistent?

A team of researchers from CNRS and Université Blaise Pascal published their findings in the Earth and Planetary Science Letters journal at the end of March 2016. They say the moon has helped compensate for the drastic difference in temperature, maintaining the geodynamo, and keeping us shielded. The geodynamo is the mechanism responsible for the Earth’s magnetic field. The Earth is not perfectly round, but is partially flattened as it spins on an inclined axis that rotates around the poles. Tidal effects created by the moon cause the Earth’s mantle to ‘deform elastically’ or not bounce back to its original shape like a rubber band would. The latest findings show that these movements may just stimulate continued motion of liquid iron alloy located in the outer core. This would in turn continue to generate the magnetic field of Earth regardless of temperature changes.

The gravitational effects associated with the presence of the Moon and Sun cause cyclical deformation of the Earth’s mantle and wobbles in its rotation axis. This mechanical forces are applied to the whole planet, which in return cause strong currents in the outer core (which consists of liquid iron alloy with very low viscosity). These currents are strong enough to produce the Earth’s magnetic field.

Image Credits: Denis Andrault and Julien Monteux





A lot of power is needed to create a stable magnetic field. Researchers took into account the 3,700 billion watts of power through the transfer of both gravitational and rotational energy within the system containing the Earth, Sun and Moon, combined with over 1,000 billion watts believed to be available in order to cause this type of motion within the outer core. Those numbers alone offer enough energy to maintain the Earth’s magnetic field. When you add those numbers to those created by the moon, the problematic paradox described in the classical theory is no longer an issue. Gravitational forces and their effects on the magnetic fields of planets have been documented in depth for the moons Lo and Europa (owned by planet Jupiter) as well as many other exoplanets, so these findings do not come as a complete surprise.

Geodynamo fluctuations are to be expected, because the Earth’s rotation, direction of the Earth’s axis and the orbit of the moon are not 100% consistent. They are naturally altered, even if slightly. This may be why there are pulses of heat in Earth’s outer core and along the Earth’s mantle. These peaks could have led to mantle melting, which in turn could have created volcanic activity on a large scale, proving the moon does not simply affect tides, but helps keep our world protected and stable.

Full study has been published in the journal Earth and Planetary Science Letters.