http://news.bbc.co.uk/2/hi/in_depth/629/629/7072715.stm
The World Digital Magnetic Anomaly Map (WDMAM) shows the variation in strength of the magnetic field after the Earth's dipole field has been removed. Earth's dipole field is generated by circulating electric currents in the planet's metal core. It varies from 35,000 nanoTesla (nT) at the Equator to 70,000 nT at the poles.
...that's way better than a bar magnet, & some iron filings sprinkled on a piece of paper in science class.
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