switched places
Earths magnetic poles have switched places repeatedly in the past. As you can see in the Figure below , each time the switch occurred, Earths magnetic field was reversed. The magnetic field is the region around a magnet over which it exerts magnetic force. We think of todays magnetic field direction as normal, but thats only because its what were used to. You can watch a simulation of a magnetic field reversal at this URL: http://www. pbs. org/wgbh/nova/earth/when-our-magnetic-field-flips. html.