From Live Science….

Something beneath the surface is changing Earth’s protective magnetic field, which may leave satellites and other space assets vulnerable to high-energy radiation.

The gradual weakening of the overall magnetic field can take hundreds and even thousands of years. But smaller, more rapid fluctuations within months may leave satellites unprotected and catch scientists off guard, new research finds.

A new model uses satellite data from the past nine years to show how sudden fluid motions within the Earth’s core can alter the magnetic envelope around our planet. This represents the first time that researchers have been able to detect such rapid magnetic field changes taking place over just a few months.