NASA

NASA investigates mysterious South Atlantic Anomaly


Scientists at NASA are investigating the mysterious South Atlantic Anomaly, a region of weakness in the Earth's magnetic field that is growing in size.


On average, the planet's magnetic field has lost almost 10% of its strength over the last two centuries - but there is a large localised region of weakness stretching from Africa to South America.


Terry Sabaka and Wijia Kuang, geophysicists at NASA, are observing using the European Space Agency's SWARM satellites to investigate how the South Atlantic Anomaly is changing.


The anomaly is caused by processes inside of the Earth where the magnetic field originates, in the outer core where molten metal, rich in iron, churns 1,800 miles (29,000 km) below the surface.


According to Bryan Blair, the Global Ecosystem Dynamics Investigation (GEDI) mission on the ISS has its power boards reset about once a month when it passes through the anomaly.


"Such events have occurred many times throughout the planet's history," said ESA, noting "we are long overdue by the average rate at which these reversals take place (roughly every 250,000 years)".






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