magnetic storm 
noun
A disturbance of the magnetic field of the earth (or other celestial body).Finally, Birkeland's theory of electron beams failed to account for the occurrence of magnetic storms close to Earth's equator....
- After he published his results, Edward Sabine and other scientists compared the rise and fall of sunspot numbers with the frequency of magnetic storms around Earth.
- Stewart collected magnetic field measurements from several observatories but particularly from Sabine, who had concluded seven years earlier that the pattern of magnetic storms around Earth tracked closely with the sunspot cycle.