an occasion when the magnetic field (= the area of magnetic force around something) of the earth or another planet, a star, etc. is disturbed (= interrupted or changed)

Telecommunications had been affected by a magnetic storm. 无线电通讯受到了磁暴的影响。

Our sun's magnetic storms can destroy satellites and cause massive power outages on Earth. 太阳的磁暴可以摧毁卫星，在地球上造成大规模的电力中断。