Magnetic north just changed. Here's what that means.

While magnetic north has always wandered, its routine plod has shifted into high gear, sending it galloping across the Northern Hemisphere—and no one can entirely explain why. PHOTOGRAPH BY NASA/JSC

While magnetic north has always wandered, its routine plod has shifted into high gear, sending it galloping across the Northern Hemisphere—and no one can entirely explain why. PHOTOGRAPH BY NASA/JSC

Magnetic north has never sat still. In the last hundred years or so, the direction in which our compasses steadfastly point has lumbered ever northward, driven by Earth's churning liquid outer core some 1,800 milesbeneath the surface. Yet in recent years, scientists noticed something unusual: Magnetic north's routine plod has shifted into high gear, sending it galloping across the Northern Hemisphere—and no one can entirely explain why.

The changes have been so large that scientists began working on an emergency update for the World Magnetic Model, the mathematical system that lays the foundations for navigation, from cell phones and ships to commercial airlines. But then the U.S. government shut down, placing the model's official release on hold, as Nature News first reported earlier this year.

Now, the wait for a new north is over. The World Magnetic Model update was officially released on Monday, and magnetic north can again be precisely located for people around the world.

Questions still likely abound: Why is magnetic north changing so fast? What were the impacts of the update's delay? Was there really a geologic reason Google maps sent me off course? We've got you covered.

What is magnetic north?

Magnetic north is one of three “north poles” on our globe. First, there's true north, which is the northern end of the axis on which our planet turns.

But our planet's protective magnetic bubble, or magnetosphere, isn't perfectly aligned with this spin. Instead, the dynamo of Earth's core creates a magnetic field that is slightly tilted from the planet's rotational axis. The northern end of this planet-size bar magnet is what's known as geomagnetic north—a point sitting off the northwest coast of Greenland that's changed position little over the last century.

Then there's magnetic north, what your compass locates, which is defined as the point at which magnetic field lines point vertically down. Unlike geomagnetic north, this position is more susceptible to the surges and flows in the swirl of liquid iron in the core. These currents tug on the magnetic field, sending magnetic north hopping across the globe.

“The north magnetic pole is quite a sensitive place,” says Phil Livermore, a geophysicist at the University of Leeds.

What is the World Magnetic Model?

James Clark Ross first located magnetic north in 1831 in the scattered islands of Canada's Nunavut territory. Since then, the pole has largely marched north, traversing hundreds of miles over the last several decades. (Curiously, its polar opposite, magnetic south, has moved little during this time.)

Read the full article on National Geographic’s website