13 juillet 2016

La Terre a un troisième bouclier...

... grâce à un tsunami spatial!

Extrait de la nouvelle:

Earth’s incredible magnetic field is not only useful when using a compass. It is there to protect us, and life on Earth would not be possible without it.

The magnetic field stops energetic particles and it traps them in large swarms around the planet in zones that we call Van Allen radiation belts. Two of these are well established and we now understand quite well how they behave, but in 2013 a third one was discovered.

According to a new study published in Nature Physics, the third belt is created by a space tsunami, large ultra-low frequency waves of plasma from the Sun, which allows particles to escape the outer belt and form a new structure in the magnetic field.  

(...) The third Van Allen belt was only discovered three years ago when the Van Allen probes observed it for about four weeks before it was destroyed by a shockwave from the Sun. The probes are there to understand better how the magnetic field reacts to the complex interaction with the solar wind.

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