London, April 3 (IANS): The Moon plays a major role in maintaining the Earth's magnetic field, say researchers, adding that the lunar action, overlooked till now, is thought to have kept the geodynamo active.

The Earth's magnetic field permanently protects us from the charged particles and radiation that originate in the Sun.

This shield is produced by the geodynamo, the rapid motion of huge quantities of liquid iron alloy in the Earth's outer core.

To maintain this magnetic field till the present day, the classical model required the Earth's core to have cooled by around 3,000 degrees Celsius over the past 4.3 billion years.

Now, a team of researchers from the National Centre for Scientific Research and Universite Blaise Pascal in France suggests that on the contrary, its temperature has fallen by only 300 degrees Celsius.

According to the researchers, the Earth has a slightly flattened shape and rotates about an inclined axis that wobbles around the poles.

The Earth continuously receives 3,700 billion watts of power through the transfer of the gravitational and rotational energy of the Earth-Moon-Sun system and over 1,000 billion watts is thought to be available to bring about this type of motion in the outer core.

This energy is enough to generate the Earth's magnetic field, which together with the Moon resolves the major paradox in the classical theory.

The effect of gravitational forces on a planet's magnetic field has already been well documented for two of Jupiter's moons, Io and Europa, and for a number of exoplanets.

This new model shows that the Moon's effect on the Earth goes well beyond merely causing tides.

The work was published in the journal Earth and Planetary Science Letters.