Next time your cell phone drops acall, don't rush to blame your service provider. The culprit may well be anangry Sun.

A new study of 40 years of solardata shows that during peaks in activity, bursts of energy from the Sun canpotentially cause dropped calls for some cell phone users across wide areastwice per week. The problem is caused when radio waves associated with thebursts hit cell phone towers, creating static that overwhelms the signal at thetower, where calls are relayed.

The result, for you, may often besudden silence.

These flashes of radio energyarrive at the speed of light, roughly 8 minutes from the Sun to Earth.

"There's absolutely nowarning," said Dale Gary, a physicist at New Jersey Institute ofTechnology and leader of the study.

Confusion

In a telephone interview, Garyexplained that the problem has to do mostly with the fact that cell phone towersneed to face the horizon in order to communicate with users and other towers.Those that face east or west look directly into the Sun at sunrise or sunset.If a burst occurs then, the tower sustains a direct hit and is unable to sortout wireless calls from unwanted signals.

Which, for commuters, could meanisolation during drive-time. The events can last anywhere from a few minutes toa couple of hours.

"If you have poor servicenormally, you'll have worse service when there's an event like this goingon," Gary said, adding that there is no way for you to know if your callsare cut off due to spotty service or an solar event.

Gary and his colleagues studiedfour decades of solar data provided by the National Oceanic and AtmosphericAdministration. A paper on their work will be published March 7 in the journal Radio Science, published by the AmericanGeophysical Union.

The Sun's activity runs inroughly 11-year cycles, and the study covered four peaks in this cycle. Duringpeaks, the Sun has more sunspots and spits out more hot gas in the form ofsolar flares and coronal mass ejections, along with the increased radioemissions.

The researchers found that, onaverage, bursts powerful enough to disrupt wireless communications occur 10-20times per year.

Or maybe more

In a follow-up study that has yetto be published, however, Gary and his colleagues looked deeper into the dataand found hints of more events that were missed by an evolving monitoringsystem that dates back to 1960. Gary said the newer study shows that duringpeaks of solar activity, when bursts are much more likely, potentiallydisruptive radio spikes can strike every 3.5 days. During the years-long lullsin the solar cycle, as many as one disruption every 18.5 days might occur.

The most recent peak in the solarcycle -- a stretch of time that actually last for months -- occurredin July 200, but NASA scientists say asecond peak surprisingly cropped up in recent months.

Gary said there's little chanceof solving the problem soon. Future reception might be improved, though. Towerscould be positioned to point anywhere but east and west, he said. And cellphones might be designed to handle higher levels of noise. But that meansmaking them more powerful, raising possible health concerns.

The research team also includedLouis Lanzerotti of Lucent Technologies' Bell Labs, along with BalaBalachandran and David Thomson, who were at Bell Labs when the research wasdone.

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