National Center for Scientific Research | 2016 Mar 31
[img3="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.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 until the present day, the classical model required the Earth's core to have cooled by around 3 000 °C over the past 4.3 billion years. Now, a team of researchers from CNRS and Université Blaise Pascal1 suggests that, on the contrary, its temperature has fallen by only 300 °C. The action of the Moon, overlooked until now, is thought to have compensated for this difference and kept the geodynamo active. Their work is published on 30 march 2016 in the journal Earth and Planetary Science Letters.
This mechanical forcing applied to the whole planet causes strong currents in the outer core, which is made up of a liquid iron alloy of very low viscosity.
Such currents are enough to generate the Earth’s magnetic field.
© 2016 Julien Monteux and Denis Andrault."]http://www2.cnrs.fr/sites/en/image/diap ... 1_en_a.jpg[/img3][hr][/hr]
The classical model of the formation of Earth's magnetic field raised a major paradox. For the geodynamo to work, the Earth would have had to be totally molten four billion years ago, and its core would have had to slowly cool from around 6800 °C at that time to 3800 °C today. However, recent modeling of the early evolution of the internal temperature of the planet, together with geochemical studies of the composition of the oldest carbonatites and basalts, do not support such cooling. With such high temperatures being ruled out, the researchers propose another source of energy in their study. ...
The deep Earth may not be cooling down - Denis Andrault, Julien Monteux, Michael Le Bars, Henri Samuel
- Earth and Planetary Science Letters (online 30 March 2016) DOI: 10.1016/j.epsl.2016.03.020