The Earth's Magnetism

The Earth’s Magnetism

• The Earth’s magnetic field is comparable to a bar magnet with a north and south pole. This comparison is useful, but not completely accurate as the magnetic field of Earth is not perfectly symmetrical nor aligned with the geographical poles.

• The Earth’s magnetic field is primarily generated by a self-sustaining dynamo in its liquid outer core. This core is made of molten iron and nickel, which circulate and create electric currents, thus generating a magnetic field.

• Magnetic North, where compass needles point, does not align exactly with Geographic North, the actual north pole of the Earth. The difference is called Magnetic Declination and it can vary depending on the location on Earth.

• The Earth’s magnetic field is not static; it has reversed direction multiple times throughout geological history. These flips, known as geomagnetic reversals, do not occur at regular intervals and the last reversal happened about 780,000 years ago.

• The Earth’s magnetic field plays a critical role in shielding the planet from harmful solar radiation. Charged particles from the Sun are deflected by the magnetic field, preventing them from reaching the Earth’s surface and causing damage to life and technology.

• Satellite data and ground measurements are used to model and monitor changes in the Earth’s magnetic field. This data is critical for understanding geological processes as well as supporting technologies like GPS.

• Magnetic fields are represented by field lines, which show the direction of the force a north magnetic pole would experience if it were free to move at that position. Field lines from Earth’s magnetic field emerge from the magnetic South pole and enter at the magnetic North pole.

• When a current-carrying conductor, like a wire, is placed in a magnetic field, it will experience a force. The direction of the force can be determined by Fleming’s left-hand rule, which takes into account the direction of the magnetic field, the direction of the current and the resulting direction of the motor force.

• The Earth’s magnetic field extends into space and forms the magnetosphere. This structure helps protect Earth from solar wind - a stream of charged particles released from the upper atmosphere of the Sun.

• The interaction of solar particles with Earth’s magnetic field creates a phenomenon known as the Northern and Southern Lights, or Aurora Borealis and Aurora Australis. These are most commonly seen close to the Earth’s magnetic poles.