HERE COMES SOLAR MAX.

Think El Nino was trouble? Watch out for the sun's own "bad boy"--solar max

Think the sun was created just for great tans and knock-out weather? Well, for folks in Quebec, Canada, 1989 was a year they'll never forget. A burst of solar particles slammed into Earth's magnetic field, causing an electromagnetic storm that blew out electrical power lines. Thousands of homes were plunged into darkness.

NASA/Marshall Space Flight Center in Huntsville, Alabama, wasn't spared either. High-speed solar winds caused one of its satellites to plummet and crash to Earth. The villain: stormy weather on the sun--the solar equivalent of Earth's disruptive El Nino--that occurs every 11 years.

Well, get ready for 1999. Electric companies and satellite operators are bracing themselves for another bout of riotous solar weather and its impact on Earth. Starting around mid-year and continuing through 2001, the sun reaches the peak of its natural 11-year solar cycle, in which the sun's magnetic field waxes and wanes. But at its peak, or solar maximum, the sun's magnetic field goes ballistic.

Dark blemishes known as sunspots whip up by the hundreds on the sun's surface. They trigger solar flares, thunderous explosions that hurl massive amounts of energy into space. Coronal mass ejections (CMEs), in which the sun spews huge magnetic clouds, erupt several times a day. (During solar minimum, CMEs occur about once every other week.)

All this frenzy on a star 150 million kilometers (93 million miles) away can spell bad news for Earth. In fact, the National Weather Service now includes space-weather forecasts along with regular weather reports. Don't be surprised to hear: "A coronal mass ejection is likely to shake Earth's magnetic field this week. Brace for impact!"

TO THE MAX!

Scientists aren't sure exactly what causes the sun's 11-year weather cycle. "That's one of the major mysteries of solar astronomy," says David Hathaway, a solar physicist at NASA/Marshall Space Flight Center. But they do know that the sun's magnetic field is the force behind the tumultuous solar cycle.

The sun's magnetic field originates well below its surface, generated by the flow of electrically charged ions (atoms that have gained or lost electrons) and free-floating electrons. At the start of the cycle--for instance, during solar minimum in 1995--the magnetic field resembled something like a bar magnet (see miniposter, p. 13). Magnetic field lines emerge out of the sun's north pole, loop away from the sun, then return at the sun's south pole.

Near the sun's equator, however, a cauldron of swirling gases rotates at a much faster rate than those near the poles. These gases yank and stretch magnetic field lines out of shape, much like a rubber band.

"You can take magnetic fields, stretch them out, twist and fold them, and you end up with a field twice as strong," Hathaway explains. As the lines wrap around and around the sun, their strength soars. By the time solar max strikes, magnetic fields burst through the surface and appear as sunspots.

BOMBS AWAY!

While sunspots themselves don't directly impact Earth, the solar flares they produce more than make up for it. Solar flares almost always erupt from sunspots. "The magnetic field lines in sunspots get twisted so severely they explode, giving off as much energy as a million atom bombs," Hathaway says.

Solar flares eject massive blasts of radiation and charged particles--electrons and protons--that flash through space at nearly the speed of light. If you happen to be flying in a jet that day, you'll get a those of radiation equal to a medical X-ray!

Earth's own magnetic field acts as a protective shield, up to a point. "The particles get caught up in Earth's magnetic field like a web," Hathaway explains. They stream down Earth's magnetic field lines, enter at Earth's north and south poles, and produce the aurora borealis--the spectacular curtain of light seen year-round in the atmosphere near the poles.

Solar flares' other effects aren't as alluring, however. Satellites that orbit about 37,000 km (23,000 mi) above Earth's surface, more than halfway near the edge of the protective shield (which extends about 65,000 km from the surface), become vulnerable. Charged particles can score a knockout to satellites' electrical systems. Results can be mildly annoying, such as scrambled phone signals, or potentially dangerous, like faulty data for passenger jets relying on satellites for navigation.

Even the Solar and Heliospheric Observatory (SOHO), a satellite designed to study the sun, is not immune. Last April, a blast of high-energy protons zapped cameras aboard SOHO, producing blinding static.

HOW'S THE WEATHER?

You can feel some of solar max's effects on the ground, as well. Coronal mass ejections erupt from the sun and travel at speeds as high as 2,000 km (1,240 mi) per second. When one slams into Earth, it shakes the planet's magnetic field. That shake-up causes power surges in power lines, knocking out electrical transformers. Entire cities can kiss electricity goodbye.

To minimize chaos caused by wild solar weather, scientists are trying to improve solar-weather predictions, giving us two- or three-day advance warning of incoming CMEs and solar flares. "We're not there yet," says NASA's Hathaway. "It's coming though. Give us another solar cycle." Can we wait???

RELATED ARTICLE: SOHO Lost and Found

Imagine losing a car in a parking lot, then finding it. Now imagine losing a Volkswagen Beetle-size satellite in space--and then finding it!

That's what happened to NASA scientists last summer. They lost contact with the $1-billion Solar and Heliospheric Observatory (SOHO), only to find it again one month later.

SOHO was launched in April 1996 to snap thousands of pictures of the sun's surface and collect data to help astronomers predict solar storms. These massive gas flare-ups can zap electric power on Earth, wreak havoc with satellites, and endanger astronauts.

On June 24, 1998, SOHO suddenly disappeared. Two computer glitches and controllers' mistakes signaled SOHO to fire its thrusters. Its solar panels turned away from the sun. Without solar energy, SOHO's batteries drained, shutting down power.

For weeks, controllers tried to reestablish contact, with no luck.

Finally in mid-July, physicist Alan Kiplinger of the University of Colorado had an idea: Why not use radar to search for SOHO, the way flight controllers look for airplanes?

Scientists used the world's largest radio telescope, a 305-meter (1,000-foot)-diameter dish in Arecibo, Puerto Rico, to transmit a radio signal 1 million miles away toward the site where SOHO should have been. Success! The signal bounced off the satellite and was received 10 seconds later by NASA's radio telescope in Goldstone, California.

Check out images from SOHO on the Internet: http://sohowww.nascom.nasa.gov