Solar activity could be big news for Northern Lights fans
By MICHAEL MILSTEIN
Gazette Wyoming Bureau
Imagine the explosion of a trillion tons of TNT, two million times as powerful as the Hiroshima bomb, strong enough to blast a million tons of matter outward at a million miles an hour.
Many such explosions are likely during the next several months - and not very far away, either. Not far, at least, in terms of space: these explosions, called coronal mass ejections, will erupt from the sun, which lies just 93 million miles away, a hop, skip and a jump when it comes to the infinite size of the entire universe.
Energy from the massive solar blasts covers that distance in a few days and, once it does, illuminates the night skies of Earth with the shimmering red and green Northern Lights, or aurora borealis. With the sun now entering an especially active and explosive period called a solar maximum, scientists expect auroral displays to stretch farther south than usual in coming months, making Montana and northern Wyoming prime viewing stands for the Northern Lights through this summer.
"I expect to see a number of them this summer," said Matthew Benacquista, an associate professor of physics at MSU-Billings. "This will definitely be the time to be watching."
For a few hours on Sunday, NASA satellites showed the aurora extending across as many as 10 of the Lower 48 states, including Montana and Wyoming. Scientists on Monday said a large sunspot promised intense solar flares that could prompt renewed Northern Lights displays.
The Northern Lights typically dance across the skies most often farther to the north - in Northern Canada and Alaska, for instance - where they should appear even more vivid during the current solar maximum. But Montana residents can also expect as many as 10 times as many Northern Lights shows this year than four or five years ago, a low point in solar activity, said Richard Canfield, a professor at Montana State University in Bozeman who studies solar physics.
"We can certainly expect some good auroral shows here," he said. "We should see many more than usual during the next year or so."
Internet Web sites operated by NASA and the National Oceanic and Atmospheric Administration provide real-time satellite images illustrating the intensity of the aurora and forecasts of solar activity over the coming three days. Forecasts are important because the same explosive solar energy that sets off striking displays of the Northern Lights can also damage satellites and disrupt power and communications on the Earth's surface: During the last solar maximum in 1989, a powerful surge of such energy knocked out power in part of Canada.
Solar maximums take place every 11 years when the sun's magnetic field, stretched and twisted over the preceding few years, snaps back into place like a rubber band.
"It's that snapping that blows all these charged particles out our way," Benacquista said.
A solar maximum reveals itself on the sun as a peak in the number of sunspots, which are darker spots on the sun caused by the twisting and warping of the sun's magnetic field. The same process triggers solar flares and the even more powerful coronal mass ejections, large-scale explosions of matter and energy from the sun's surface.
Although such explosions can erupt from the sun in any direction, only those that head toward Earth trigger displays of the Northern Lights. Earth's magnetic field protects most of the planet from the charged particles spewed by the explosions, but the field curves down to the Earth's surface at the north and south poles. The charged particles ride those curves in the field, which carries them towards the poles, where their collision with Earth's atmosphere in the Northern Hemisphere triggers the Northern Lights.
Especially strong bursts of such charged particles spread the aurora's glimmer farther away from the pole - in other words, farther to the south. There have been reports during past solar maximums of aurora displays as far south as the Florida Panhandle, said David Hathaway, a solar physicist at NASA's Marshall Space Flight Center in Huntsville, Ala.
"The more energy there is, the farther south the effects can reach," he said.
Since it takes the solar particles anywhere from two to four days - depending on their speed - to reach earth, NOAA often issues advance warnings on its Web site of particularly powerful bursts of solar energy.
Satellites in orbit around the earth do not enjoy the shielding effects of Earth's magnetic field and the solar particles can fry their computer chips "just like sticking them in the microwave," Benacquista said. Satellite operators heed warnings by turning their spacecraft away from the direction of the solar particles, called the solar wind.
Northern Lights enthusiasts can take advantage of the same warnings and alerts by scanning the horizon for green and red curtains of light. Anyone with access to e-mail can receive free alerts of especially intense auroral activity by signing up for "Space Weather News" at the NASA Web site www.spaceweather.com.
"It's kind of a chaotic thing - it's worse than the stock market in many respects," Hathaway said. "But we think we understand enough bits and pieces to say, 'Yes, this is the year it ought to happen.' "
Satellite images of current auroral activity-- http://www.sec.noaa.gov/pmap/index.html
Sunspot cycle predictions-- http://science.msfc.nasa.gov/ssl/pad/solar/predict.htm
Sunspots and the solar cycle-- http://www.sunspotcycle.com
Today's space weather -- http://www.sec.noaa.gov/today.html
Montana State University solar physics page-- http://solar.physics.montana.edu/