The earth's magnetic field and reversals

The problem of the origin of the Earth's magnetic field is one of the oldest in science. Although much has been learned about it, particularly in the last 10 years with the advent of more powerful computers, we still do not know the details of its generation in the Earth's liquid outer core. The discovery that the field reverses its polarity has heightened interest in the problem. It is suspected that the Earth's solid inner core may play a much more important role than has been supposed in the dynamics of the outer core and in the maintenance of the Earth's magnetic field.