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The Honolulu Advertiser
Posted on: Thursday, October 23, 2003

Cluster of sunspots moving across sun

By Jan TenBruggencate
Advertiser Science Writer

A cluster of sunspots 16 times the size of Earth is passing across the face of the sun this week.

Sunspots, seen as dark spots on the solar disk, can generate solar flares that can blast the Earth with radiation.

Photo courtesy UH Institute of Astronomy

That's still pretty small by solar standards, representing about a sixth of a percent of the sun's surface, but it could be associated with solar flares capable of disrupting communications and power grids, said Donald Mickey, a solar astronomer with the University of Hawai'i's Institute for Astronomy.

"It's big for a sunspot," Mickey said.

Sunspots are regions on the sun's surface where the magnetic field from within the star rises through the surface. They appear as dark spots on the bright solar disk.

Sunspots themselves have little impact on Earth, but can generate solar flares that can blast the planet with radiation and particles.

"(Sunspot) regions that are big and complex and growing like this have more flares. There have been several since the weekend," he said.

It is never safe to look directly at the sun without proper eye protection, and sunglasses are not sufficient protection. But with proper eye protection, such as that used to view recent solar eclipses, the sunspot cluster is big enough to be seen without magnification.

The NASA Web site, sunearth.gsfc.nasa.gov/eclipse/SEhelp/safety.html, recommends commercially available solar eclipse viewers, No. 14 welder's glass, available through welding supply outlets, or mylar film.

By today, the sunspot cluster should be near the center of the sun as viewed from Earth, and by the weekend it will have moved to the edge, Mickey said.

"These happen infrequently, and we can expect more geomagnetic disturbances," said solar astronomer Jeff Kuhn, associate director of the Institute for Astronomy's facilities atop Haleakala.

If the solar flares are big enough, it could mean problems with cellular phone reception and satellite television signals, he said.

Reach Jan TenBruggencate at jant@honoluluadvertiser.com or (808) 245-3074.