Take care as magnetic field declines

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iol scitech dec 12 aurora australis


As the polar reversal goes ahead, the aurora australis, or southern lights, usually only seen over the South Pole, will become visible closer to the equator.

Durban - In the next 1 000 years, the north and south poles will switch as the earth’s magnetic field declines, meaning people will have to take extra precaution against sun damage to their skin.

Dr Pieter Kotze, research physicist at the South African National Space Agency, explained that the magnetic field is essentially a force field generated from within the earth that protects us from energetic particles in outer space.

“Magnetic fields generally fluctuate by around 10 percent every 100 years. However, the magnetic field over the southern Africa region has decreased by 21 percent since 1941.

“At the present rate of decay, which is 20 times faster than on planets with a frozen core, the Earth’s magnetic field may undergo significant changes and experience a minimum value of intensity in the next millennium,” said Kotze.

The decline of the magnetic field is linked to the polar reversal, which happens four times every million years, taking about 10 000 years from start to completion.

“Earth is about 500 000 years overdue for a polar reversal so, over the next thousand years, the poles will be completely reversed.”

Kotze emphasised that this did not spell the end of the world.

“Polar reversals have taken place about 100 times in the Earth’s history and the magnetic field always reappears.”

Mars had a magnetic field, but this disappeared 4 billion years ago, leaving solar winds to blow away the atmosphere.

“We believe that Mars’s core solidified, causing it to lose its magnetic field.

“There were oceans and rivers on Mars, but it lost all those with the magnetic field.”

As the polar reversal goes ahead, the aurora australis, or southern lights, usually only seen over the South Pole, will become visible closer to the equator.

Kotze said compasses would also begin to point haphazardly, affecting orientation, but this would be in the next 1 000 years.

According to Kotze, evidence supporting the shift of the poles indicates a growing deviation between true north and magnetic north over southern Africa in the past decade, with the magnetic north pole drifting towards Russia at 55km a year.

“We don’t understand why the reversal of poles happens; we can only speculate that it’s inherent in any dynamo activity.”

Three Swarm satellites had been launched from Russia to gather data to help scientists understand the workings of Earth’s magnetic field over the next four years. - Daily News

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