Earth possesses a second, swirling magnetic field hidden within its magnetosphere

Science · Published 8 October 2026 Swipe more like this →

In short: We have long relied on the geomagnetic field to shield us from solar radiation. However, precision satellites have detected a second, irregular magnetic field. Unlike our stable primary field, this secondary force behaves like floating weather patterns, creating unpredictable patches across our planet.

Earth's primary magnetic field, or geomagnetic field, is generated by a geodynamo within the outer core. This process occurs as molten metal—a mix of iron, nickel, and lighter elements like oxygen and sulfur—swirls in convective currents around a solid inner core. This organized, dipolar field accounts for approximately 80% of Earth's magnetic force, creating a protective magnetosphere that shields life from the solar wind. This core structure is divided into a solid inner layer and a molten outer layer. The metal within these layers includes a cocktail of iron and nickel.

However, the remaining 20% of the field is non-dipolar. Instead of following the predictable, parallel bands of a standard bar magnet, this portion is irregular. Geophysicist John Tarduno describes these sections as swirling and eddying, behaving much like weather patterns that float around the planet. These fluctuations create distinct, localized anomalies in magnetic intensity. These non-dipolar regions create unusual patches in the magnetic field. Such irregular patterns result in unpredictable fluctuations in intensity.

One notable example is the South Atlantic Anomaly, a vast region in the Atlantic Ocean where the magnetosphere's intensity drops significantly. Beyond understanding Earth's internal dynamics, these secondary magnetic signals are significant for space exploration. Scientists believe these irregular signals might provide the key to searching for water on other planets. This specific area represents a large swath of the ocean. Such anomalies demonstrate the complexity of our planet's magnetic environment.

Although Earth remains the sole rocky world in the inner solar system possessing powerful magnetic poles, different planets provide points of comparison. Mercury possesses a weak magnetic field—only 1.1% as strong as Earth's—while Mars and Venus lack significant fields, potentially because they lack plate tectonics. The magnetic poles of our planet are not fixed. Instead, they tend to wander over time.

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