Earth’s magnetic field is up to something strange once again.
The European Space Agency (ESA) has been keeping tabs on Earth's magnetic field using their Swarm satellites, and observed an unusual spot in the magnetic field over the South Atlantic between Africa and South America. In the past 50 years, it appears this patch of reduced magnetic intensity has grown weaker and weaker – so much so, the freak blob might soon split into two separate zones of weakness.
The magnetic field helps to shield Earth from harmful cosmic radiation and charged particles from the Sun. It might seem like a "constant force of nature," but it’s prone to some wild undulations and changes – as we’ve recently seen in the North Pole – because it’s guided by an ocean of superheated liquid iron that sloshes deep within the planet's interior.
The Van Allen radiation belts are two large belts of radiation that surround Earth where energetic charged particles are being held at bay by the planet's magnetic field. In recent decades, scientists noticed a phenomenon they've named the South Atlantic Anomaly, a spot of weakness in Earth’s magnetic field that causes the Van Allen radiation belt to dip extremely close to Earth's surface at an altitude of just 200 kilometers (120 miles).
As the recent data from ESA shows, the South Atlantic Anomaly is getting progressively weaker, too. Since the 1970s, the area has dropped from around 24,000 nanoteslas to 22,000 nanoteslas (the unit of magnetic induction equal to 1 billionth of a tesla). In the past five years alone, scientists have also seen the blob of magnetic weakness splitting apart into two separate blobs, one on either side of the Atlantic.
“The new, eastern minimum of the South Atlantic Anomaly has appeared over the last decade and in recent years is developing vigorously,” Jürgen Matzka from the German Research Centre for Geosciences said in a statement from ESA.
“The challenge now is to understand the processes in Earth’s core driving these changes.”
Some speculate that this could be another indication that Earth is heading for a pole reversal, a colossal event in which the north and south magnetic poles switch places over a period of hundreds to thousands of years. In the shorter term, changes to the Anomaly are also pitched to cause some technical difficulties for the satellites orbiting Earth. But don’t fret, the phenomenon shouldn't be anything for us Earthlings to lose sleep over and it could provide some insights into the mystery of our planet’s interior and the strange forces that lurk beneath our feet.