Earth's magnetic field reversal

Earth's magnetic field is generated by the movement of molten iron in its outer core. Occasionally, these movements cause the magnetic poles—where compass needles point—to weaken, shift, or even flip entirely, reversing the magnetic polarity. This process, called a magnetic reversal, can take thousands of years and occurs irregularly, roughly every few hundred thousand years. During a reversal, magnetic field strength diminishes, providing less protection from solar radiation temporarily. Although these events can seem dramatic, they are a natural part of Earth's geologic history and do not directly threaten life, but they can affect navigation and animal migration patterns.