Earth's Magnetic Field

The Earth's Magnetic field is a source-free region near the surface of the Earth that satisfies Laplace's equation. The total intensity of the field varies from 22,000 nanotesla (nT) to 67,000 nT. The total intensity of the field is measured in Gauss coefficients, with internal coefficients representing the field generated within the Earth, and external coefficients representing the field generated on the Earth's exterior.

Effects of the Earth's Magnetic Field

The Earth's magnetic field has two poles: the north magnetic pole is at the north pole, and the south magnetic pole is at the south pole. Magnetic field lines travel in a closed loop around the planet, flowing into it at the north pole and outward from the south. The magnetic field lines are distorted due to the rotation of the Earth and the movement of solar winds, which compress the shape of the field on the Earth's dayside, and stretch it on its nightside.

Geomagnetic storms can penetrate the magnetosphere and disrupt communications and power systems. They can also damage spacecraft, including astronauts. One such event, called the Carrington Event, occurred in 1859, when a solar flare accompanied a large magnetic storm. The event caused widespread telegraph failures and a total electrical blackout across the province of Quebec.

Scientists have discovered that the Earth's magnetic poles constantly change position. Since the British Royal Navy officer Sir James Clark Ross first located the magnetic north pole in 1831, the pole's position has drifted 600 miles north-northwest. However, no one is sure of what causes the reversals, as they are a natural phenomenon.