Earth’s magnetic field

Earth’s magnetic field protects us from cosmic radiation and solar wind. It serves as a shield to the ozone layer and reduces the impact of ultraviolet radiation on our planet. This dynamic force, generated by the movement of liquid iron in Earth’s outer core, undergoes periodic changes and experiences magnetic north-south flips every few hundred thousand years. Earth’s magnetic field has long been used to aid navigation by aligning compasses to the North pole.

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  • Unlike the stable geographic north pole, the magnetic north pole has been known to wander since its first measurement in 1831, slowly drifting from the Canadian Arctic towards Siberia. However, starting in the 1990s, this drift has accelerated significantly, increasing from a historical pace of 0-15 km per year to an astonishing speed of 50-60 km per year. Satellite data (including those from ESA's Swarm mission) show the north magnetic pole moving rapidly towards Siberia due to two magnetic blobs at Earth's outer core edge. Fluctuations in molten material flow cause changes in magnetic strength, leading to its ongoing drift for decades.

  • Like its northern counterpart, the south magnetic pole also experiences constant shifts due to changes in Earth's magnetic field. It moves north-westward at a rate of approximately 10 to 15 kilometres per year and is currently about 2,860 kilometres away from the actual Geographic South Pole. Unlike the north magnetic pole, the south magnetic pole's movement did not experience a significant increase in speed during the mid-1990s.

  • Over the past two centuries, the global average strength of Earth's magnetic field has decreased by approximately 9%. An intriguing phenomenon called the South Atlantic Anomaly emerged between Africa and South America, characterised by a significant reduction in magnetic intensity. This anomaly has indirectly led to temporary disruptions in satellites known as 'Single Event Upsets' due to their exposure to strong radiation in this region.

  • Auroras are captivating natural light displays that occur on Earth when the solar wind, a stream of charged particles emitted by the Sun, interacts with our planet's magnetic field. This interaction creates an array of colours in the polar night skies. When high-energy particles from the solar wind collide with gases in the atmosphere, they elevate the energy levels of atoms and particles. As these atoms and particles return to their normal energy states, they emit vibrant and colourful light, which we observe as the mesmerising auroras.

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