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Why is Earth’s magnetic field strongest near the magnetic poles?

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geomagnetic field The magnetic field of a bar magnet has a simple configuration known as a dipole field. Close to Earth's surface this field is a reasonable approximation of the actual field.

Earth’s magnetic field is strongest near the magnetic poles because the field is primarily dipolar, meaning it behaves similarly to the field produced by a magnetic dipole or a bar magnet.12

In a pure dipole field, the magnetic field lines are vertical along the polar axis and horizontal along the equator. A fundamental characteristic of this geometry is that the field strength at the poles is twice as strong as the field strength at the equator. While Earth’s actual geomagnetic field is more complex due to internal sources like the dynamo in the core and regional anomalies, this dipolar approximation remains a highly accurate description of the field's general structure. Consequently, observations confirm that the largest field magnitudes occur near the magnetic poles, while the weakest field is found along the magnetic equator.12