Eunice Bradley-Fox inspects the sun through a specially filtered telescope outside Stellar Vision, 1835 S. Alvernon Way. Owner Frank Lopez said heightened solar activity has piqued interest among amateur stargazers.

chris richards / arizona daily star

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The sun is entering a period of increased sunspot activity that could disrupt satellite and broadcast communications and will spur scientific scrutiny of the largest celestial body in our part of the universe.

Solar-activity flare-ups — usually, but not always, near the middle of 11-year cycles — have produced beautiful nighttime light shows — the northern lights — and costly electromagnetic mayhem that caused power outages and turned multimillion-dollar communication satellites into mute orbiting space junk.

Jack Harvey, a veteran solar scientist at the National Solar Observatory, said there is increasing commercial and government interest in predicting solar activity because of these potential costs and risks.

The coming sunspot cycle, the 24th since scientists identified the fairly regular recurring pattern of peaks and valleys in solar activity, is expected to begin in early 2007.

Harvey's speciality, helioseismology — studying pressure waves inside the sun — suggests that the "birthing cycle" of solar activity — sunspots and flares — is going on deep inside the sun.

"These (magnetic) fields at the surface move up to the polar regions and then sink into the interior and they get down to this layer about 30 percent inside the sun and start moving toward the equator," says Harvey.

Eventually, he says, they emerge, "float back up to the surface. So, we may be able to predict the next cycle by what we see happening."

The National Solar Observatory, headquartered in Tucson on the University of Arizona campus, has solar telescopes at Kitt Peak, west of Tucson, and on Sacramento Peak at Sunspot, N.M., and will view and record this cycle in more detail than in the past.

Harvey says the newest solar observation device atop Kitt Peak, the Synoptic Optical Long-term Investigations of the Sun, or Solis, is in its shakedown period, gearing up for the coming cycle.

Solis was designed and built by NSO scientists and technicians, at least in part, to gather information that can help improve solar-activity forecasting.

Harvey says the first recorded observations of sunspot activity are in Chinese journals from about 800 B.C., with the first telescopic solar observations not coming until 2,400 years later, in 1610.

"There were a lot of observations in the first 20 to 30 years of the telescopic era," says Harvey. And then, not much was made of the sun's activities, until 1840, when the sunspot cycle was discovered.

"You've gone 240 years and nobody noticed the number of spots changed in the cycle," said Harvey, incredulous.

But with the spread of the telegraph, and then electric power distribution and radio, the sun's behavior began attracting more and more attention.

In 1848, solar-storm-induced electrical disturbances were first noted on telegraph lines in Italy. Later, solar activity was blamed for interrupting telegraph service, in some cases sending sparks from transmission lines and damaging equipment.

As telegraph and electrical service and radio broadcasting spread around the world, there were accounts of increasingly dramatic events that coincided with solar activity.

The greatest effect, in terms of communications, until recently was disruption of short-wave radio.

Although he says it usually doesn't hurt cell-phone communications, solar activity has been known to cause cell phones here to pick up signals bounced off the atmosphere from as far away as the East Coast.

It's far less amusing when it knocks out electrical trans- mission systems or fries multimillion-dollar communications satellites.

Harvey says the power outages come about when the massive electromagnetic storms that sometimes coincide with intense sunspot activity interrupt Earth's upper atmosphere and induce electrical signals in the planet's crust.

He said solar activity can affect the accuracy of Global Positioning System devices. The thickening of the ionosphere caused by solar storms delays time-critical signals from GPS satellites, throwing off location calculations.

The costs associated with power outages and damage to satellites — as well as concerns about what would happen to astronauts outside Earth's protective layers during a solar radiation storm — have greatly increased business and government interest in predicting solar activity, says Harvey. Communications companies want to know when they should turn their satellites to shield them from radiation and engage protective circuitry.

"That'll be the proof that we really understand what's happening, that we can predict," says Harvey.

It's not likely, but not impossible, we'll see any major activity as we leave the low end of the current sunspot cycle and enter the slow climb to the peak of a new one. That's one of the mysteries of the solar cycle, that solar storms can pop up even during the current "solar minimum."

In early 2005, less than two years from the so-called "solar minimum," an apparently calm sun cooked up a storm that caused disruptions in Earth's upper atmosphere that made the northern lights visible even in parts of Arizona.

Solar activity isn't bad for all business. While the sun lacks the romance of the moon and distant stars, the flash of Mars or Saturn with its rings, Frank Lopez, owner of Stellar Vision, 1835 S. Alvernon Way, says there's growing interest in solar observing among amateur astronomers.