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Thursday, October 23, 2003
Large sunspot makes late appearance
Government space weather forecasters warned yesterday that a strong geomagnetic storm is expected to develop when a severed bit of the sun's corona reaches Earth tomorrow.
Coronal mass ejections occur when part of the sun's outer edge breaks off into space. This one is carrying roughly 10 billion tons of matter at average speeds of 250 miles per second.
Although the Earth's atmosphere blocks this highly energetic material, it dramatically disturbs the planet's magnetic field. This can cause voltage surges in electric power grids on the ground, affect satellites and disrupt some radio communications and navigation systems.
The storm also might make the Aurora Borealis, or Northern Lights, visible at night as far south from the Arctic Circle as Illinois and Oregon.
The eruption began about midnight last night as one of the largest sunspot clusters to emerge in the current 11-year solar cycle developed across the face of the sun. The same region also caused an X-ray radio blackout on some frequencies Monday. The 11-year cycle of activity for sunspots and flares supposedly hit its peak at the end of 2000.
"It's unusual to have this much activity when we're approximately 3 1/2 years past the maximum for the sun," said Larry Combs, a forecaster at the National Oceanic and Atmospheric Administration's Space Environment Center in Boulder, Colo. "In fact, just last week, there was an almost spotless sun."
A second active region is rotating into a position to create more powerful eruptions over the next two weeks.
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