Tag Archives: earth’s core

What’s Going on with the South Atlantic Anomaly?

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Bob Rubila

NASA Is Growing Concerned As A Massive Anomaly Spreads Across Earth, Scientists Believe It’s Linked To Deep Earth Forces.

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At the heart of the US  agency’s concerns is a geomagnetic phenomenon that is as fascinating as it is worrying: the South Atlantic Anomaly (SAA). This immense region is characterised by a significantly reduced magnetic intensity compared with the surrounding areas. Far from being a mere scientific curiosity, this weakness acts like a breach in our natural protective shield, allowing high- solar particles to come dangerously close to the Earth’s surface.

To understand AAS, we need to delve deep into the heart of our planet. Its origin is closely linked to geodynamics, the complex process that takes place in the Earth’s outer core. There, the movement of molten iron and nickel generates the magnetic field that envelops us. However, this generation is not uniform.

Two main factors contribute to the formation of the AAS. Firstly, the inclination of the Earth’s magnetic axis in relation to its axis of rotation plays a role. Secondly, the influence of a gigantic, dense structure known as the African province with low shear velocity, located almost 2,900 kilometres beneath the African continent, disturbs the generation of the magnetic field in this region. NASA geophysicists explain that the anomaly is also associated with a  polarity inversion within the Earth’s magnetic field, which further weakens the overall strength of the dipole field in this specific area. As Weijia Kuang from NASA’s Goddard Space Flight Center explains, a field of reversed polarity has developed in the region, creating a sort of “pothole” in the Earth’s magnetic armour.

A danger for space technology

This magnetic vulnerability is not without consequences. Satellites passing through the AAS are exposed to high levels of high-energy protons. These particles can cause what engineers call Single Event Anomalies (SEUs). These incidents can lead to temporary malfunctions, data corruption or even permanent damage if a critical system is affected.

Faced with this risk, many satellite operators are taking preventive measures, in particular by shutting down non-essential systems as they pass through the anomaly. The International Space Station (ISS) itself passes through the AAS during each orbit. While its shielding effectively protects the astronauts, the external instruments are more exposed. Bryan Blair, deputy principal investigator for the Global Ecosystem Dynamics Investigation (GEDI) instrument installed on the ISS, reports occasional “misfires” and resets, resulting in a few hours of data loss each month, an impact deemed manageable. Other missions, such as the Ionospheric Connection Explorer (ICON), are also closely monitoring the AAS and adapting their operations.

Far from being static, the South Atlantic Anomaly is a dynamic phenomenon. Recent data, notably from ESA’s Swarm constellation and historical measurements from NASA’s SAMPEX mission, confirm a number of worrying trends. The anomaly is slowly drifting north-westwards, expanding at the surface and, most notably since 2020, it is splitting into two distinct lobes, creating two centres of magnetic minimum. This bifurcation, corroborated by various studies, increases the number of dangerous zones for spacecraft and complicates the task of scientists developing predictive models of geomagnetic conditions. Understanding the changing morphology of the AAS is crucial for the safety of current and future satellites,” stresses NASA’s Terry Sabaka.

To refine their understanding and forecasts, NASA combines satellite data with simulations of the dynamics of the Earth’s core. This information is fed into global models such as the International Geomagnetic Reference Field (IGRF), which tracks changes in the Earth’s magnetic field. These models are essential not only for planning space missions, but also for gaining a better understanding of our planet’s internal structure. The approach is similar to weather forecasting, but on much longer time scales, making it possible to estimate Secular Variation, i.e. slow but persistent changes in the magnetic field over years and decades.

While the current evolution of the AAS is unprecedented on the scale of the space age, the geological record suggests that such anomalies are not exceptional over long periods of time. A 2020  even suggests that similar anomalies may have existed 11 million years ago. It is important to stress that, according to the scientists, the current AAS is not a precursor of a magnetic pole reversal, a natural but rare phenomenon that takes place over hundreds of thousands of years. The study of the AAS therefore remains an active area of research, essential to protect our technologies in orbit and to deepen our understanding of the deep forces that drive our planet.

from:    https://farmingdale-observer.com/2025/04/29/nasa-is-growing-concerned-as-a-massive-anomaly-spreads-across-earth-scientists-believe-its-linked-to-deep-earth-forces/

New Findings RE: Earth’s Core

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Scientists find oddly behaving ‘inner-inner core’ at Earth’s center

Using the coda waves from earthquakes, geologists have discovered that our planet’s core isn’t quite what we thought it was.

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The newly discovered core at the center of the Earth has a different polarity than its surrounding core, represented by the purple lines. Lachina Publishing Services

Though the seismic waves from earthquakes are best known for their destructive capabilities, in the hands of geologists, they can be powerful tools of discovery. A research team at the University of Illinois has just used the rumbles from quakes to more closely examine the inner core of our planet, and what they found there was quite a surprise. It seems there’s another core inside the inner core that measures about half its diameter.

What demarcates this “inner-inner core” is that the iron crystals it contains are oriented on an east-west axis, unlike the iron crystals in the “outer-inner core” which organize along a north-south axis.

“The fact that we have two regions that are distinctly different may tell us something about how the inner core has been evolving,” Xiaodong Song, a professor of geology at UI who worked on the project with visiting postdoctoral researcher Tao Wang, said in a University of Illinois report about the findings. “For example, over the history of the Earth, the inner core might have had a very dramatic change in its deformation regime. It might hold the key to how the planet has evolved.”

While multiple components of the inner core have been suggested before, this is the first time the difference in polarity has been noted. “Indeed, the layering of the inner core has been suggested more than 10 years ago, at shallow depths of the inner core and at deeper parts of the inner core as well,” Song told Crave. “Everyone assumed before the crystal alignment was north-south. But here we found alignment in the inner-inner core to be nearly east-west.”

If all this inner and inner-inner talk sounds confusing, perhaps a quick geology refresher is in order. The Earth consists of three layers: the crust where we live; the mantle, a layer of scalding-hot liquid rock; and the core. The core consists of a liquid outer core containing mainly nickel and iron and a solid inner core made up mostly of iron. Even though the inner core is even hotter than its surroundings, the intense pressure at the Earth’s center means the inner core is unable to melt and remains solid, according to a National Geographic entry about the topic.

And now we can add another layer to our Earth’s composition: the inner-inner core, which is still mostly solid iron, but has a different polarity than the substance surrounding it.

In “unearthing” the inner-inner core, the research team relied on seismic sensors that pick up the waves that penetrate the planet after an earthquake hits, known as the quake’s coda. “The earthquake is like a hammer striking a bell; much like a listener hears the clear tone that resonates after the bell strike, seismic sensors collect a coherent signal in the earthquake’s coda,” the report says.

“It turns out the coherent signal enhanced by the technology is clearer than the ring itself,” said Song. “The basic idea of the method has been around for a while, and people have used it for other kinds of studies near the surface. But we are looking all the way through the center of the Earth.”

The researchers’ findings were published in the journal Nature on Monday.

from:    http://www.cnet.com/news/theres-a-newly-discovered-core-inside-our-earths-core-and-it-behaves-oddly/