Page:Illustrated Astronomy.pdf/47

 • • • Both magnetic and Earth’s geographic poles are not aligned. The first ones actually change in time, which means that our compasses show where is the north or the south with a slight difference as the years pass by.

In the following figure, we can see how the northern magnetic pole has been moving in time. It seems that the mentioned changes happen due to the movement variation of the outer core, but that is research in progress.

Lastly, throughout Earth’s history, the magnetic poles have turned upside down multiple times, and we know it thanks to the rocks found in the mid-ocean ridges, structures in the sea bottom formed by magma material which elements are sensitive to magnetic fields (such as iron, for instance).

These particles and the terrestrial field of that moment line up and then get solidified, making impossible to change their position again.

On these rocks, we have found orientation changes; that’s why we know the magnetic field have been upside-down and passed through constant changes.



The magnetic north pole changes its exact position in time. Currently, it is nearby Canada and is moving to the Siberian land, located in Russia. Over the last 30 years, the geographic position of the magnetic pole north has changed more than in the previous 90 years. • • • 47