NASA is Tracking a Vast, Growing Anomaly in Earth's Magnetic Field

upstart writes in with an IRC submission:

NASA Is Tracking a Vast, Growing Anomaly in Earth's Magnetic Field:

The South Atlantic Anomaly (SAA) - likened by NASA to a 'dent' in Earth's magnetic field, or a kind of 'pothole in space' - generally doesn't affect life on Earth, but the same can't be said for orbital spacecraft (including the International Space Station), which pass directly through the anomaly as they loop around the planet at low-Earth orbit altitudes.

[...] The primary source is considered to be a swirling ocean of molten iron inside Earth's outer core, thousands of kilometres below the ground. The movement of that mass generates electrical currents that create Earth's magnetic field, but not necessarily uniformly, it seems.

A huge reservoir of dense rock called the African Large Low Shear Velocity Province, located about 2,900 kilometres (1,800 miles) below the African continent, disturbs the field's generation, resulting in the dramatic weakening effect - which is aided by the tilt of the planet's magnetic axis.

"The observed SAA can be also interpreted as a consequence of weakening dominance of the dipole field in the region," says NASA Goddard geophysicist and mathematician Weijia Kuang.

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