Geomagnetic storms and solar flares occurred more frequently in 1982 (3 years after the solar maximum of the current 11-year sunspot cycle) than is usual for that portion of the cycle. Among the most notable events were two X-12 flares and one X-7 flare. Although less intense, the X-7 flare triggered the most fierce geomagnetic storm in a decade; it distorted the earth's magnetic field, disrupted long-range communications and low-frequency navigational systems, interfered with ham radio activities, and spread a brilliant auroral display over much of the nation.
Solar flares are divided into three classes depending on the output of X radiation: the common C class, the moderate M class, and the intensive X class. The numerical designation indicates the level of radiation intensity; an X-12, which is t h e most intense that instruments can measure, is 12 times more intense than an X-1 . An X-1 flare releases 10 times more radiation than an M-1, and 100 times more than a C-1.