Magnets lose their magnetic properties at a specific temperature known as the Curie Point.

The Curie Point is named after the French physicist Pierre Curie, who discovered the phenomenon in 1895. He demonstrated that magnetic materials undergo a sharp change in properties at a critical temperature. This occurs because thermal energy overcomes the exchange interaction that keeps electron spins aligned in a single direction. Without this alignment, the material becomes paramagnetic and loses its spontaneous magnetism.In the context of Earth, the inner core reaches temperatures estimated at 5,430°C (9,806°F), which is nearly as hot as the surface of the Sun. This temperature is nearly seven times higher than the Curie Point of iron. If Earth relied on a solid magnetic core, the magnetic field would have vanished as the planet's internal heat rose during its formation 4.5 billion years ago. This realization led scientists to develop the Dynamo Theory.The Dynamo Theory explains that Earth's magnetic field is maintained by the convection of liquid iron in the outer core. As the Earth rotates, the Coriolis effect twists these moving conductive fluids into long tubes. This motion generates electric currents, which in turn create the global magnetic field we use for navigation today. This process is self-sustaining as long as the core remains liquid and continues to lose heat to the mantle.