The Earth’s magnetic North has never sat still. Since it was first calculated in 1831, it has lumbered ever-northward, driven by the planet’s liquid outer core some 1,800 miles beneath the surface. According to the European Space Agency, Earth’s magnetic North has picked up speed, sending it galloping across the Northern Hemisphere.
The changes were so large that scientists began working on an emergency update to the World Magnetic Model, a mathematical system used extensively for navigation and in attitude and heading reference systems by the UK Ministry of Defence, the US Department of Defense, the North Atlantic Treaty Organization (NATO) and the International Hydrographic Organization.
The Earth has three north poles
Three north poles? This may come as a surprise to many people, but let’s explain. First, there is “True North.” This is the northern end of the axis on which the Earth turns. Now, that’s simple. But the planet’s protective magnetic bubble, or magnetosphere, is not perfectly aligned with the planet’s spin.
This is because the dynamics of the planet’s core creates a magnetic field that’s a bit tilted from the planet’s rotational axis. This feature makes the Earth a gigantic, planet-sized bar magnet and is known as the Geomagnetic North – a point sitting off the northwest coast of Greenland that has changed very little over the last century or so.
Then there is the Magnetic North. It is the one we use for our compasses and other devices dependent on the WMM to calculate true bearings. Magnetic North is also used in checking Google Maps on our smartphones and other devices. This third north pole is more responsive to the surge and flows of the liquid iron in the Earth’s core.
Changes in the liquid outer core affect the magnetic North Pole as well as Earthquakes, with the outer core transmitting seismic waves. The outer core is about 2,200 kilometers (1.367 miles) thick and is made of liquid iron and nickel alloy. The temperature of the outer core nearest the mantle is 4,400 degrees Celsius (7,952 degrees Fahrenheit).
“The north magnetic pole is quite a sensitive place,” says Phil Livermore, a geophysicist at the University of Leeds.
Keeping track of the North Magnetic Pole
Even though scientists update the actual location of the Magnetic North Pole every five years, this does not mean it is ignored in between those years. Between each update, scientists check the model’s accuracy against data from ground magnetic observatories and the European Space Agency’s Swarm mission
Launched in November 2013, ESA’s Swarm constellation is the fourth in a series of pioneering Earth Explorer research missions, following on the heels of GOCE, SMOS, and CryoSat. Swarm is also the first mission dedicated to unraveling how the Earth’s magnetic field works.
The Swarm Mission uses three identical satellites to measure the magnetic signals that stem from Earth’s core, mantle, crust, and oceans, as well as from the ionosphere and magnetosphere. Data from the satellites is combined with ground-based observations to give a very reliable reading of the Magnetic North Pole.
Information from the Swarm Mission is as close as your smartphone. Nils Olsen from DTU Space said, “Your smartphone contains a magnetometer that measures Earth’s magnetic field.
“In order to make sense of this information, Android and iOS operating systems use the magnetic model to correct the measurements to true geographic north. So, in this model update, the latest Swarm data have been used to provide up-to-date information for users of numerous navigation systems.”
