Magnetic north

A compass points toward magnetic north, not true north. True north is the geographic axis on which the planet turns, while magnetic north is where a compass points.

Magnetic north is the point on Earth's surface at which the magnetic field lines point vertically downwards.

Even away from the pole, a compass needle does not aim at the pole. It follows the horizontal component of the magnetic field where the compass is, and not any single point.

Magnetic declination, sometimes called magnetic variation, is the angle between magnetic north and true north. It is positive when east of true north and negative when west.

Declination changes over time and from place to place, so the correction a walker needs depends on both where and when.

To find a true bearing, add the declination to the magnetic bearing, counting degrees west as negative. A declination of 10 degrees west is written as -10.

Lines of equal declination, called isogonic lines, converge at the pole.

Sir James Clark Ross first located the North Magnetic Pole in northern Canada in 1831.

Since 1831, the pole has been moving across the Canadian Arctic toward Russia.

Magnetic records show the pole meandering about Canada from 1590 until 1990, when it sped up. Over the next 30 years its speed went from less than 10 kilometres a year to almost 60 kilometres a year.

A 2007 survey by a Canadian and French collaboration found the pole moving north-northwest at about 55 kilometres a year. NOAA's account, updated in 2021, says the latest International Geomagnetic Reference Field (IGRF) put the speed at about 45 kilometres a year in the same direction.

In December 2019 the British Geological Survey described the pole as moving at around 50 kilometres a year.

The World Magnetic Model places the North Magnetic Pole at 85.762°N, 139.298°E in 2025. The South Magnetic Pole is at 63.851°S, 135.078°E.

While the north pole sped up, the South Magnetic Pole moved very slowly, drifting around the coast of Antarctica.

Earth's magnetic field is generated by the flow of liquid iron in the core, which creates electric currents in a way similar to a bicycle dynamo.

The fluid outer core is about 2,250 kilometres thick and made of molten iron and nickel. Nearly all of Earth's magnetic field originates there.

Irregular changes in the liquid outer core are known, but it is not yet possible to say exactly why magnetic north is changing so fast.

When tectonic plates form at oceanic ridges, the field present is frozen into the rock as it cools below about 700°C. This lets scientists reconstruct the field's history for roughly the last 160 million years.

The field has reversed many times, so magnetic north and south have swapped places. The most recent reversal took place about 780,000 years ago.

The World Magnetic Model is a spherical harmonic model of Earth's main magnetic field and its slow change over time. It is developed jointly by NOAA and the British Geological Survey.

Because the pole's movement is rapid and unpredictable, the model is updated at least every five years.

Smartphone and consumer electronics companies rely on the model for compass apps, maps and GPS services, and it is the standard model for the UK and US governments and for NATO.

The 2025 release added a high-resolution version, with a spatial resolution of about 300 kilometres at the equator compared with 3,300 kilometres for the standard model.

The model also marks blackout zones near the North and South poles, where the field can be unusable for navigation.