[thedoc (OP)]

Nagarjunrao asked the Naked Scientists:
   Is there any relation between the sun and earth magnetic field?

What do you think?

[evan_au]

Coronal Mass Ejections (CME), driven by sudden changes in the Sun's surface magnetic field spit out large masses of the Sun's outer atmosphere. See: https://en.wikipedia.org/wiki/Coronal_mass_ejection

If the CME happens to head towards Earth, the charged particles will follow Earth's magnetic field, producing bright Auroras at the North and South Poles. These massive electrical currents produce small changes in the Earth's magnetic field, which can be measured far from the poles. In severe cases, it has burnt out electrical transformers in areas close to the North Pole.

But these effects are relatively small and short-lived. The Sun undergoes massive changes in its magnetic field, reversing about every 11 years for the past two centuries. See: https://en.wikipedia.org/wiki/Solar_cycle

Earth's magnetic field also reverses, but somewhat more erratically, and with an average interval of about half a million years. (The last one was about 750,000 years, so we are "overdue" for one, now.) See: https://en.wikipedia.org/wiki/Geomagnetic_reversal

The fact that magnetic reversals on the Earth and the Sun occur on vastly different timescales suggest that the magnetic fields of the Earth and the Sun are not strongly coupled.