Before investigating Earth's core, it helps to understand what a magnet is and how magnetic attraction and repulsion behave, because everything else builds on those fundamentals. A magnet attracts other magnets, and it also attracts some iron and steel things, such as pins and paper clips. Every magnet has a north pole and a south pole, and opposite poles attract each other, and the same poles push each other away. Here is a rule to keep, and it is a simple one: magnets are not for mouths or small children, since loose magnets can hurt children if they are swallowed. If a child swallows more than one, the magnets can pull together inside the body and cause serious damage. Two kinds of magnets exist, permanent magnets and temporary magnets, and in a permanent magnet tiny magnetic regions called domains line up in the same direction. Permanent magnetization cannot occur above about 650 degrees Celsius (1,200 degrees Fahrenheit).

Magnetism is caused by the motion of electric charges. In space, on the Sun and in Earth's core, electric currents are the only source of magnetism. In 1820 Hans Christian Ørsted's discovery showed that electricity and magnetism are related. In 1831 Michael Faraday discovered electromagnetically induced currents, and a changing magnetic field near a conductor can create an electric current in the conductor. The current depends on the rate at which the field changes, and electromagnets are not permanent, but they can be far stronger than the strongest permanent magnet. These discoveries made electricity and magnetism a single field of investigation.

Some special materials are called superconducting materials. Superconducting materials expel magnetic fields as they transition to the superconducting state, and superconducting wires can be wound into coils to create powerful magnets. A Maglev is a kind of train that uses such magnets. In a Maglev train, superconducting magnets suspend the train car above a U-shaped concrete guideway, and the powered guideway drives the train. The magnets in the train repel one another when matching poles face each other, just as ordinary magnets do, so the same rule of poles that applies to a small magnet applies to a whole train.

Now we can go down to the place where Earth's field is made, and examine how that process continues, which matters for every compass reading. Earth is a really big magnet, and its magnetic field begins in its core. Earth's core lies some 2900 km below the surface. The motion of electrically conducting iron in the outer core makes electric currents, and those currents generate Earth's magnetic field. The process by which electric currents in the core generate magnetic fields is self-sustaining so long as an energy source maintains convection. Direct observations of Earth's magnetic field extend back just a few centuries, so scientists rely on indirect evidence. The position of Earth's magnetic north pole was first precisely located in 1831. As of November 2026, that pole is moving, and this gradual shift must be regularly accounted for in navigation.

Earth's field is not fixed, and the evidence indicates that it has changed in the past, so it is worth considering what a change would involve and how frequently it has occurred. During a pole reversal, Earth's magnetic north and south poles swap locations. The magnetic field weakens but does not completely disappear, and it becomes jumbled, so multiple magnetic poles can emerge in unexpected places. The last time Earth's magnetic field reversed was about 750,000 to 780,000 years ago. Consecutive reversals have been spaced from 5 thousand years to 50 million years apart, and even if Earth's field were beginning a reversal, it would take several thousand years to complete. Excursions happen about 10 times as frequently as pole reversals, and excursion events are generally regional, rather than global.

What is the field doing today, and would a change matter? In the past 200 years, Earth's magnetic field has weakened about nine percent on a global average, as of November 2026. Scientists have no reason to believe a pole flip is imminent, as of November 2026. Plant and animal fossils from the period of the last major pole reversal do not show any big changes. There is little scientific evidence of any significant links between Earth's drifting magnetic poles and climate. That is where the evidence stands as of November 2026.

Words to know

• convection: heat-driven flow
• superconducting: without resistance
• excursion: brief field swing
• reversal: a swap