The north magnetic pole is restless.

Distinct from the geographic North Pole, where all the lines of longitude meet at the top of the world, the magnetic pole is the point that a compass recognizes as north. At the moment, it’s located four degrees south of the geographic North Pole, which lies in the Arctic Ocean at 90 degrees north.

But that wasn’t always the case.

In the mid-19th century, the north magnetic pole floated much further south, roaming around Canada. For the past 150 years, however, the pole has been sprinting away from Canada and toward Siberia.

That change of address cannot be ignored, given that magnetic compasses still underpin modern navigation, from the systems used by civilian and military airplanes to those that orient your iPhone.

In 1965, scientists launched a data-based, mathematical representation of Earth’s magnetic field in order to better keep track of the pole’s ever-changing home. The World Magnetic Model is updated every five years — most recently in 2015 — because the magnetic field is constantly shifting.