In January, just as computers around the world are coping with the Y2K bug, the sun will enter the most violent and disruptive phase of its 11-year cycle.
Massive bursts of energy from the sun could mean celebrating the new millennium in the dark, with dead cellular phones. Ships and planes relying on satellites for navigation might have to haul out old-fashioned maps. Even spacewalking astronauts could be at risk, according to reports Monday at the national meeting of the American Astronomical Society.
Researchers using new techniques are forecasting the sun's cycle to peak during the months of January to April. The sun is expected to be busy with solar flares and coronal mass ejections, solar explosions that can equal a million 100 megaton hydrogen bombs.
Waves of solar energy can trigger power blackouts, block some radio communications and create phantom commands capable of sending satellites spinning out of their proper orbits.
There were two pieces of good news: The solar cycle is not expected to be as severe as some in the past, and, for the first time, there may be some warning, thanks to a government satellite that will detect bursts of solar energy and send about an hour's notice.
JoAnn Joselyn of the National Oceanic and Atmospheric Administration says the warning, posted on the Internet and relayed through a special system, will give power companies time to align circuits to minimize or avoid damage from electrical surges. Satellite operators can power down equipment or prepare to send corrective signals to their spacecraft.
Scientists have plotted 23 solar cycles, using historic and modern measurements. But the current cycle may be the most disruptive ever because much of the vulnerable communications technology now in use is new and has not been exposed to maximum solar activity.
"The explosion in technology is intersecting with an extremely disturbed space environment," Joselyn said. "There is much higher risk now because we depend more on technology that is vulnerable."
Joselyn said energy bursts from the sun can cause an electrical charge to build up on the surface of satellites, triggering phantom signals.
In an earlier solar cycle, she said, small rocket thrusters on a satellite suddenly started firing, sending the spacecraft out of position. Control of another satellite was lost when its gyroscopes were disrupted.
Cellular telephones may be vulnerable because they can use the ionosphere Â— the region of electrically charged gases in the upper atmosphere Â— to send radio signals, and bursts from the sun can disturb the ionosphere. Some cellular phone systems depend on satellites that are at risk too.