CHICAGO (AP) - Computer date confusion about the Year 2000 is not the only problem Earth's technology is going to face when the new year rolls in. Astronomers say they're also worried about an angry sun.

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.

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, Joselyn said.

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.