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

Caitlin Dempsey

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Source: NASA, https://heasarc.gsfc.nasa.gov/docs/rosat/gallery/display/saa.html

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. https://www.nasa.gov/feature/nasa-researchers-track-slowly-splitting-dent-in-earth-s-magnetic-field

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Caitlin Dempsey

Caitlin Dempsey is a geographer, writer, and founder and editor of Geography Realm. She holds bachelor's and master's degrees in Geography from UCLA and a Master of Library and Information Science (MLIS) from San José State University.

For more than two decades, she has written about geography, maps, geographic information systems (GIS), remote sensing, satellite imagery, and environmental science. Her work focuses on making geography accessible to a broad audience through articles, tutorials, and educational resources.

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