South Atlantic Anomaly: A Growing Dent in the Earth’s Magnetic Field

Caitlin Dempsey


NASA is tracking a dent in the Earth’s magnetic field. The Earth’s magnetic field shields the planet from bombarding cosmic radiation and charged particles from outer space.

Scientists have measured a weakened spot in the field over South America and the southern Atlantic Ocean that they have named the South Atlantic Anomaly (SAA). This region has been expanding westward for more than a decade and is forming a split.

The tilt of the Earth’s axis and the flow of molten metals in the planet’s outer core are responsible for the presence of the SAA. Changes in motion in the core ripple to the surface of the Earth, creating fluctuations in the magnetic field over space and time.

While the presence of the South Atlantic Anomaly has no adverse affects on humans and other life, cosmic particle radiation that penetrates through this weakened area of the magnetic field can interfere with onboard computers on satellites passing overhead and prevent data collection.

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Johnson-Groh, M., & Merzdorf, J. (2020, August 14). NASA researchers track ‘Dent’ in earth’s magnetic Field. NASA.


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About the author
Caitlin Dempsey
Caitlin Dempsey is the editor of Geography Realm and holds a master's degree in Geography from UCLA as well as a Master of Library and Information Science (MLIS) from SJSU.