... Listed below are questions submitted by e-mail to the author of "The Great Magnet, the Earth." ... Only some of the questions that arrive are listed, either because they keep coming up again and again--on the reversal of the Earth's magnetic field, for instance-- or because the answers add extra details, which might interest other users. ... Pole shifts? ... Measuring Earth's magnetic field . ... So, my question is: Why isn't the Earth's magnetic north pole a "true" magnetic north pole? ...