The Earth’s geomagnetic armor suit has a resentment and grows.
A weak point in our planet’s magnetic field, located above the South Atlantic Ocean, has grown in size over the past two centuries and is beginning to split in two.
For us on the ground, this is not a cause for concern: the field of protection continues to protect the planet from deadly solar radiation.
But the South Atlantic Anomaly, as it is aptly called, affects satellites and other spacecraft passing through an area between South America and South Africa.
This is due to the fact that larger amounts of charged solar particles are leaking through the field there, which can cause malfunctions in computers and circuits.
The source of this growing “depression”, as NASA calls it, is a bit mysterious. But scientists expect it to expand further.
“This is going to increase in size in the future,” Julien Aubert, a geomagnetism expert at the Institute of Earth Physics in Paris, told Insider.
Aubert believes the core could be connected to two giant patches of dense rock buried 2,897 kilometers (1,800 miles) inside the Earth. Due to their makeup, the blobs disrupt the liquid metal in the outer core that generates the magnetic field.
Both spots are “millions of times larger than Mount Everest in terms of volume,” according to Qian Yuan, a researcher studying geodynamics at Arizona State University.
Yuan’s team believes that the blobs have a different origin: after an ancient planet, the size of Mars, entered Earth, they may have left these pieces behind.
Pieces of a 4.5 billion year old planet from inside the Earth
Almost 3,219 kilometers below the Earth’s surface, the iron that spins in the outer core of the planet generates a magnetic field that extends as far as the space around our planet.
This rotation is generated, in part, by a process in which the hotter and lighter material in the core rises in the semi-solid mantle above. There, it changes places with a colder and denser cloak material, which sinks into the core below. This is known as convection.
The problem is that something at the boundary between the core and the mantle beneath South Africa wreaks havoc on that convection, thus weakening the strength of the magnetic field above it.
It is plausible, Aubert said, that one of the spots the Yuan team is investigating is to blame.
Yuan’s research claims that the blobs are remnants of an ancient planet called Theia, which struck Earth from the beginning 4.5 billion years ago. The collision helped create the Moon.
Following this accident, it is thought that two parts of Theia sank and were kept in the deepest part of the Earth’s mantle.
The animation below, based on a 2016 analysis, shows the location of these planetary fragments.
(Sanne.cottaar / WikimediaCommons / CC-BY-4.0)
Yuan said that these blobs – their technical name is large provinces with low shear rate – are between 1.5 and 3.5 percent denser than the rest of the Earth’s mantle and also hotter.
So when these pieces get involved in convection, it could screw up with regular flow. This, in turn, can cause the iron in the core below South Africa to rotate in the opposite direction to the iron in other parts of the core.
The orientation of the Earth’s magnetic field depends on the direction in which the iron moves inside. To have a strong magnetic field, the whole thing must be oriented in the same way. So all areas that deviate from the usual pattern weaken the overall integrity of the field.
However, these low-shear provinces may not be to blame for the weakness of the field.
“Why doesn’t the same weakness appear in the magnetic field above the Pacific, where the other province is?” Christopher Finlay, a geophysicist at the Technical University of Denmark, told Insider.
A “hostile region”
A weaker field allows more charged particles from the solar wind to reach satellites and other spacecraft in low Earth orbit. This can cause problems with electronic systems, interrupt data collection, and lead to premature aging of expensive computer components.
In the 1970s, 1980s and 1990s, satellite failures were common in the South Atlantic Anomaly, Aubert said.
Even today, the European Space Agency found that satellites flying through the region were “more likely to experience technical malfunctions”, such as short errors that could disrupt communications.
Therefore, it is common for satellite operators to turn off non-essential components as objects pass through the area.
The Hubble Space Telescope also goes through an anomaly in 10 of its 15 orbits around the Earth each day, spending nearly 15% of its time in this “hostile region,” according to NASA.
The weak point is getting weaker and weaker
Researchers are using a set of three satellites, collectively nicknamed the Swarm, to keep track of the South Atlantic Anomaly.
Some studies suggest that the total area of the region has quadrupled in the last 200 years and continues to expand from year to year. The anomaly has also decreased by 8% since 1970.
In the last decade, Swarm has also noticed that the anomaly has split in half: one area of magnetic weakness has developed over the ocean in southwest Africa, while another is east of South America.
This is bad news, according to Finlay, because it means the spacecraft’s hostile region will grow.
“The satellites will have problems not only in South America, but will also be affected when they come to southern Africa,” he said.
This article was originally published by Business Insider.
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