Why didn’t Earth have the same fate as Mars?

The planet Mars is now desert. Somewhere in its past, it lost the water that flowed over its surface. She also lost a lot of her atmosphere. In question, according to astronomersthe dissipation of magnetic field who protected her until then from solar winds.

Our Earth remains sheltered from its own magnetic field. It is the result of the movements of liquid iron bubbling some 2,900 kilometers below our feet. In what scientists call the outer core. Movements of convection on a very large scale that produce a Electric power. It is this electric current which generates a magnetic field by dynamo effect.

But about 565 million years ago, the intensity of this magnetic field dropped by about 10%. Before suddenly returning to normal. Just before what researchers call thecambrian explosion. One of the most significant events in the history of life on Earth. The sudden appearance of multicellular life forms.

Note that, when geologists evoke a process which occurred “all of a sudden”, it must be understood that it took a few tens of millions of years… only. Of the University of Rochester scientists (USA) now show that the process in question coincided with the formation of the Earth’s solid inner core.

A story to read in the rocks

“Just before the inner core begins to expand, the Earth’s magnetic field was about to collapse. But as soon as the inner core grew, the magnetic field regenerated.”underlines John Tarduno, geophysicist, in a statement from the University of Rochester.

To determine how the magnetic field and the core of our Earth have evolved over time, the researchers relied on an analysis of minerals brought to the surface and containing tiny magnetic particles that record the direction and strength of the magnetic field as the minerals cool. They were thus able to fix two new important dates in the history of the inner core of our planet.

550 million years ago, the Earth’s magnetic field renewed itself after a near collapse only 15 million years earlier. A renewal in connection with the formation of a solid inner core which has somehow recharged the outer core in merger ; and 450 million years ago a boundary was formed between the innermost inner core and the outermost inner core. An evolution that coincides with changes in the structure of the coat underlying, due to the tectonic plates.

Better understand the inner core dynamics and the magnetic field allows us to better understand the past of our Earth. But also, to consider its future. “It’s hard to know if our Earth would have ended up like Mars if thecollapse of its magnetic field had continued. But it is almost certain that our planet would be much drier today. What to show the importance of an inner core growing to maintain a magnetic field throughout the lifetime of a planet»concludes John Tarduno.