Earth's Magnetic North Pole Is about to Cross the Path of the U.K.'s 'True North' for the First Time in 360 Years

Compasses in Greenwich, London, are about to point to the "true north" for the first time since 1660—when Charles II was on the throne and the first English settlers were setting about colonizing the Americas.

True north is based on Earth's axis, with the direction pointing to the physical north pole.

But this is not what compasses are based on—they use the Earth's magnetic north pole.

"The main magnetic field is created by the motion of the liquid iron outer core, deep in the centre of the Earth," Ciaran Beggan, from the British Geological Survey, told Newsweek. "Like a bicycle dynamo, movement is converted to electricity (like making the bike light glow) and creates a secondary magnetic field. Overall, the liquid outer core flows westward which pulls the magnetic field with it."

At the moment it is over the Canadian Arctic—but it is quickly moving eastwards towards Siberia. It has been moving at a rate of about 31 miles per year for the last five years.

For the last 360 years, compasses in London have pointed to the west of true north. Over the next two weeks, experts at the British Geological Survey say the two lines will match up at the Royal Greenwich Observatory—the home of the Prime Meridian line (the zero of longitude).

The true and magnetic north are expected to line up for a short period before moving to the east. "By 2040, all compasses will probably point eastwards of true north," Beggan said in a statement.

In the next two weeks, compasses in Greenwich will line up with the "true north." This has not happened for 360 years, scientists say. iStock

Earth's magnetic north pole used to move at a rate of about nine miles per year, but it has sped up in recent decades: "The magnetic north pole has moved quite fast in the last 20 years," Beggan told Newsweek. "Over the past five years it has moved close to the geographic North pole but on the far side of it as we see it from the U.K. Hence the line of zero declination is now moving across the U.K. and Ireland."

Beggan said it is impossible to forecast how the magnetic field will change over the coming decades and centuries—and that the BGS is currently tracking the magnetic north pole using data from the European Space Agency and ground based observatories around the world.

Understanding its precise location is extremely important as this information is used for the World Magnetic Model—the spatial representation of the magnetic field that GPS and navigation systems across the globe are based on.

At some point in the future—possibly thousands of years from now—the magnetic field will reverse. This is where the magnetic north and south wander towards the equator then swap places for a period, before returning to their original hemisphere. This has happened many times over Earth's history, with the last partial reversal taking place about 22,000 years ago.