It’s time to eat humble pie. A sharp-eyed reader of my book, The New Creationism, has contacted me to point out that the labels on the figure illustrating the earth’s magnetic field (p.190) are not really right. Here’s the offending diagram. The field lines are correct but the image of the bar magnet has the poles the wrong way round.
The reason is that the magnetic north pole in fact has the polarity of a south magnetic pole. That’s why it attracts the north-seeking pole of a compass needle. Strictly speaking, then, the bar magnet in the diagram ought to have its poles labelled the other way round.
To be fair, some other diagrams of the geomagnetic field, such as this one on a National Oceanic and Atmospheric Administration (NOAA) site, use the same labels as my book. However, I accept that this isn’t really correct and if and when there’s a second edition it’s something I’ll look at again.