Earth’s magnetic field is very important for the survival of life. It protects against high energy charged particles and solar flares of the sun. Without this magnetic “shield” electrical appliances would not work. Now, recent information gathered from the European Space Agency’s Swarm constellation has thrown light upon strange behaviors of the earth’s magnetic field.
Recently, NASA Mapped electric currents on Mars
WHAT WE ALREADY KNOW
In school, we have been taught that the earth behaves like a giant magnet with its south pole a little bit away from the geographical North Pole. This is called the North Magnetic Pole. Due to this our magnetic compass needles always point northward. This magnetism of the earth occurs due to movements of the molten outer core of the earth which is rich in iron. This movement constitutes electrical currents which are believed to be the origin of the earth’s magnetic field.
VARYING MAGNETIC FIELD
The earth’s magnetic field is never stable. It varies across regions, temporarily increasing and decreasing, and the poles themselves keep shifting and have flipped completely in recorded history. The evidence is obtained by observing solidified metamorphic rocks of earlier times. The magnetic dipoles within the molten magma must have aligned with the magnetic field of that time as it solidified. When we observe the evidence now, we see that the magnetic dipoles are aligned in a completely reverse direction to today’s magnetic field.
It has also been found that over 200 years the magnetic field of the earth has decreased by 9% on a global average.
SOUTH ATLANTIC ANOMALY’S DECREASING MAGNETIC FIELD
In light of this, a large region between South America and Africa has been known where for decades the magnetic field has been dramatically decreasing. The region is called the South Atlantic Anomaly and its origins are not yet understood. Scientists have begun to believe that if a pole reversal is imminent in the near future then the South Atlantic Anomaly will play a major role.
The region of the South Atlantic Anomaly is known for curious effects such as astronauts in low earth orbit seeing flashes in front of their eyes and computers and other communication devices stopping to work which have been noticed in the International Space Station as it passes through the region. This region is also known to affect satellites moving through the region.
DATA FROM SWARM CONSTELLATION
The Swarm Satellite Constellation of European Space Agency launched in 2013 works to measure various magnetic signals constituting the earth’s magnetic field. Analysis of the data showed that the magnetic field in the South Atlantic Anomaly has been decreasing dramatically. The South Atlantic Anomaly itself has been moving westward for decades and increasing in size.
SPLITTING OF SOUTH ATLANTIC ANOMALY
But recently, the region has started acting in a vigorous way. A new center of the minimum magnetic field is developing within the region and it is moving eastward. Scientists have reported that the South Atlantic Anomaly is splitting into two regions of the weak magnetic field. This doesn’t mean we should be worried about it as it is not going to affect our lives dramatically except affecting satellites and spacecraft moving through the region. Instead, these recent developments open up exciting new ways of thinking about the origins of the earth’s magnetic field and processes in the interior of the earth.
The simplistic picture of earth acting as a bar magnet becomes obsolete with these new and strange measurements of the earth’s magnetic field emerge. What puzzles scientists about this recent development is the rapid and unpredictable way this region has started to behave. The changes seem to be random and it is very difficult in such a case to correctly model the geophysics of the earth.
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Author: Raktimabh Das