Naked Science Forum
Non Life Sciences => Physics, Astronomy & Cosmology => Topic started by: thedoc on 13/05/2015 19:50:02
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Daniel bush asked the Naked Scientists:
The earth is losing its magnetic field, why cant we send up umbrella like satellites between us an the sun to help protect us from solar wind an cosmic radiation being blasted towards us by the sun?
What do you think?
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The earth is losing its magnetic field
The Earth generates its magnetic field by means of electrical currents and chaotic convective flows within Earth's liquid core. It is a complex process, but isn't really expected to entirely stop until Earth's molten core solidifies (you could say "until hell freezes over"...). This is a very slow process, with the radius of the solid core increasing at something like a cm/century.
It is true that the strength of Earth's North-South ("dipole") magnetic field has been declining irregularly for the past 2000 years. This trend is not a strong predictor of it's future behaviour (http://en.wikipedia.org/wiki/Earth%27s_magnetic_field#Future)due to the chaotic processes driving it.
Residual magnetic fields in the seafloor rocks record periods where the Earth's magnetic field had the North and South poles reversed, compared to the current orientation. Averages don't mean much in a chaotic process, but on average, we are overdue for another reversal.
Even in case of a reversal, it is not expected that Earth's magnetic field will completely drop to zero everywhere at the same time, but a small "quadrupole" magnetic field should remain in various places during the reversal. This will allow people all over the Earth to observe auroras.
Provided the strong dipole field is restored fairly quickly (compared to the time between reversals), not too much damage should be done to Earth's atmosphere.
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Daniel bush asked the Naked Scientists:
The earth is losing its magnetic field, why cant we send up umbrella like satellites between us an the sun to help protect us from solar wind an cosmic radiation being blasted towards us by the sun?
What do you think?
No. The volume of material required to do that would be so enormous that it's impractical to do so. The Earth's magnetic field does a wonderful job as it is. Why bother?