Electronics get an industrial-strength sunburn

Friday, April 13, 2001

When they're designing sensitive electronic products, engineers must try to shield against EMI/RFI (electromagnetic interference and radio frequency interference).

Usually, the radiation is a consequence of other electronics, with low-frequency EMI waves emanating from electrical devices, and high-frequency waves (RFI) radiating from microchips. And usually it's easily blocked by adding a layer of EMI/RFI shielding around the most sensitive electronics.

But when the sun gets involved, it's a whole new story.

On Thursday, the sun turned stormy, popping out a pair of "coronal mass ejections," which spat billions of tons of radiation particles and ionized gas into space. The flare sent an immediate flash of radiation that disturbed military and commercial marine and aircraft radio channels for about an hour. Some pilots were even kept waiting on runways, rather than risking takeoff without radio contact. Some satellites and radar were also affected.

And the rest of the storm hasn't even arrived yet-it's still traveling the 93 million miles, a trip that usually takes sun bursts a little over a day. So it'll hit Earth on Friday or Saturday.

The sun has been in a foul mood in recent months, reaching the peak of an 11-year cycle of solar storms. A more aesthetic effect of all this weather is the colorful "northern lights" that are usually only visible at extreme latitudes, but this April have been seen as far south as Mexico. The storms result from sunspots-dark, cool regions on the sun's surface that are caused by temporary magnetic field fluctuations. Sunspots measure a mere 4,000C, compared to the sun's average surface temperature of 5,500C.