Are the poles begining to shift?

[Nom De Plume]

Earth's magnetic field, which is vital to protecting life on our planet from solar radiation, is mysteriously weakening.
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.

Known as the South Atlantic Anomaly, the field strength in this area has rapidly shrunk over the past 50 years just as the area itself has grown and moved westward.

Over the past five years a second centre of minimum intensity has developed southwest of Africa, which researchers believe indicates the anomaly could split into two separate cells.
The anomaly is causing technical difficulties for satellites orbiting the Earth.

European Space Agency (ESA) scientists from the Swarm Data, Innovation and Science Cluster (DISC) are using data from ESA's Swarm satellite constellation to study the anomaly.
Swarm satellites are designed to identify and precisely measure the different magnetic signals that make up Earth's magnetic field.

Dr Jurgen Matzka, from the German Research Centre for Geosciences, said: "The new, eastern minimum of the South Atlantic Anomaly has appeared over the last decade and in recent years is developing vigorously.
"We are very lucky to have the Swarm satellites in orbit to investigate the development of the South Atlantic Anomaly. The challenge now is to understand the processes in Earth's core driving these changes."
One speculation is that the weakening of the field is a sign that the Earth is heading for a pole reversal - in which the north and south magnetic poles flip.

This flip doesn't happen immediately, but instead would occur over the course of a couple of centuries during which there would be multiple north and south magnetic poles all around the globe.
"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)".

That said, the space agency also noted that the dip occurring in the South Atlantic was "well within what is considered normal levels of fluctuations".
For people on the surface the anomaly is unlikely to cause any alarm, but satellites and other spacecraft flying through the area are experiencing technical malfunctions.
Because the magnetic field is weaker in the region, charged particles from the cosmos can penetrate through to the altitudes that low-Earth orbiting satellites fly at.
"The mystery of the origin of the South Atlantic Anomaly has yet to be solved," added ESA.
"However, one thing is certain: magnetic field observations from Swarm are providing exciting new insights into the scarcely understood processes of Earth's interior."

https://news.sky.com/story/earths-magne ... g-11992022

[Juliar]

Why does the North Pole move?
BY TRACY V. WILSON


In the last 150 years, the pole has wandered a total of about 685 miles (1102 kilometers).
IMAGE COURTESY KENAI NATIONAL WILDLIFE

The Earth has several poles, not just two. It has geographic north and south poles, which are the points that mark the Earth's axis of rotation. It also has magnetic north and south poles, based on the planet's magnetic field. When you use a compass, it points to the magnetic north pole, not the geographic North Pole.

The Earth's magnetic poles move. The magnetic North Pole moves in loops of up to 50 miles (80 km) per day. But its actual location, an average of all these loops, is also moving at around 25 miles a year [ref]. In the last 150 years, the pole has wandered a total of about 685 miles (1102 kilometers). The magnetic South Pole moves in a similar fashion.

The poles can also switch places. Scientists can study when this has happened by examining rocks on the ocean floor that retain traces of the field, similar to a recording on a magnetic tape. The last time the poles switched was 780,000 years ago, and it's happened about 400 times in 330 million years. Each reversal takes a thousand years or so to complete, and it takes longer for the shift to take effect at the equator than at the poles. The field has weakened about 10% in the last 150 years. Some scientists think this is a sign of a flip in progress.

The Earth's physical structure is behind all this magnetic shifting. The planet's inner core is made of solid iron. Surrounding the inner core is a molten outer core. The next layer out, the mantle, is solid but malleable, like plastic. Finally, the layer we see every day is called the crust.


The Earth's layers include the inner core, outer core, mantle and crust.
IMAGE COURTESY USGS

The Earth itself spins on its axis. The inner core spins as well, and it spins at a different rate than the outer core. This creates a dynamo effect, or convections and currents within the core. This is what creates the Earth's magnetic field -- it's like a giant electromagnet.

Exactly how the dynamo effect changes the field isn't widely understood. Shifts in the core's rate of spin and the currents within the molten material most likely affect the planet's field and the location of the poles. In other words, the poles move because the convection in the core changes. These changes might also cause the poles to switch places. Irregularities where the core and mantle meet and changes to the Earth's crust, like large earthquakes, can also change the magnetic field.

AURORA
The magnetic North Pole is responsible for more than just the direction a compass points. It's also the source of the aurora borealis, the dramatic lights that appear when solar radiation bounces off the Earth's magnetic field. This happens at the South Pole as well. In the southern hemisphere, the lights are called the aurora australas.

https://science.howstuffworks.com/envir ... ion782.htm