the South Pole are highly magnetic. A least-squares fit to the magnetic field measurements gives the Earth's field as the sum of spherical harmonics, each multiplied by the best-fitting Gauss coefficient gm. Geomagnetic storms can cause a lot of disruption; the "Halloween" storm of 2003 damaged more than a third of nasa's satellites. "A three-dimensional self-consistent computer simulation of a geomagnetic field reversal". Eos, Transactions American Geophysical Union.

If the Earth's dynamo shut off, the dipole part would disappear in a few tens of thousands of years. The Great Magnet, the Earth, History of the discovery of Earth's magnetic field by tides of Change and People David. A b "Secular variation". 52 The term B / t is the time derivative of the field; 2 is the Laplace operator and is the curl operator. Space Weather Prediction Center. Main article: Geomagnetic reversal Although generally Earth's field is approximately dipolar, with an axis that is nearly aligned with the rotational axis, occasionally the North and South geomagnetic poles trade places. The 11th-generation model, igrf11, was developed using data from satellites ( rsted, champ and SAC-C ) and a world network of geomagnetic observatories. Retrieved Further reading edit Campbell, Wallace. A magnetic field is a vector field, but if it is expressed in Cartesian components X, Y, Z, each component is the derivative of the same scalar function called the magnetic potential. As the fluid moved, the magnetic field would go with.

Thus, only the components with large wavelengths can be noticeable at the surface. Do they have magnetism too? "Dynamos in planets, stars and galaxies".