Our Violent Star: Solar Storms and Space Weather
By Sydney Kaufman
On a November night, when most of the world was sleeping, scientists and engineers at NOAA’s Space Weather Prediction Center in Boulder, Colorado, were watching live satellite pictures of the sun, looking for a bright flash that would tell them a strong solar storm was on its way, the effects of which could have been dramatic and expensive.
At that point, a tangled magnetic field on the sun’s surface was spinning towards the “kill zone,” the geographical location on the sun where an eruption would send energy and charged particles on a direct path to earth.
Luckily, the effects of this particular solar event on November 1, 2011, were minimal, resulting in only a brief radio blackout the following day. However, these NOAA scientists watch the sun 24/7 to ensure that when a blast of solar wind comes our way, we’ll be as ready as possible for the potential effects on communication signals, electrical power and the GPS systems many industries rely on. While the storm last November had little effect, a solar spot erupted last week and a minor geomagnetic storm is expected to peak today.
“The sun doesn’t give a hoot about where we are,” said Joe Kunches, an aerospace engineer at the Space Weather Prediction Center, during an interview in November. “It just goes about its business throwing off stuff and sometimes we happen to get in the way.”
Space weather encompasses a variety of phenomena that occur on Earth as a result of changing conditions on the sun. It can come in many forms that result from different processes on the sun — some more benign than others. The sun’s shifting magnetic fields and subsequent expulsion of charged particles result in natural phenomena such as the aurora borealis – the northern lights. Some space weather events can also lead to power outages and disruptions in satellite communications and GPS systems.
The radiation that comes from the sun is concentrated at the Earth’s poles because of the influence of the Earth’s magnetic field on incoming particles. The Earth acts like a giant dipole magnet as a result of iron motion at the Earth’s core, with the positive and negative ends at the poles. Just like a magnet, when charged particles from the sun come into contact with earth’s magnetic field, they are pulled towards the charged ends.
During a solar event, aircraft must avoid flying near the poles where the radiation is concentrated because of disturbances in GPS signals as well as possible effects of the radiation on passengers. These detours around the poles cost the airline industry between $10,000 and $100,000 per flight.
Solar flares are one form of destructive space weather where charged particles and atoms are ejected through the surface of the sun and out towards the Earth or whatever else happens to be in their way. These usually occur in 11-year cycles of activity, with periods of relative quietude followed by dramatic increases in solar activity.
At present, the sun is nearing the tail end of an active cycle that is predicted to peak in late 2013 or early 2014. This means there could be some wild space weather on the way.
During the active part of the solar cycle, the sun’s rotation leads to swirling and knotting of magnetically charged gas on the surface and deep within. Huge amounts of energy can become concentrated at knot points until no more can be held. Under immense pressure the knot then explodes, spewing charged particles and strong magnetic fields out into space.
Out in space, these particles and magnetic output are mostly traveling through empty space where they can do little damage, unless a spacecraft or astronaut happens to get in the way. But when they hit the earth’s magnetic field they thrust it into motion, which in turn generates electrical currents and turbulence in the magnetic fields in our atmosphere. These disrupt the accuracy of the information sent by GPS satellites for a variety of applications, but the power grid experiences the most dramatic effects. Changing magnetic fields generate an external electrical current that can muddle the precise current present in power lines.
In March 1989, Eastern Canada was plunged into nine hours of darkness when a powerful wave of radiation, the result of a solar flare 93 million miles away on the sun’s surface, hit Hydro-Québec, one of the largest electric utilities in North America.
“Their whole system went from proper, graceful functioning to a total blackout in 92 seconds as a result of the induced currents that came from a strong magnetic storm,” said Kunches. “The province of Quebec had 6 million people in the dark for nine hours.”
While Kunches and his colleagues can monitor the sun and predict with reasonable accuracy when space weather is headed our way, they’re still only in the first stages of truly understanding the sun. For now, scientists must be satisfied with acting as sentinels: watching the sun, waiting for an eruption, and warning power grid operators, airlines, and an alphabet soup of government agencies when a wayward magnetic fluctuation is on its way.
“We are crazy about this stuff,” said Kunches. “I mean, we just love looking at the sun and we see these eruptions and everybody ‘oohs and ahs.’” But not everyone feels the same way. “The truth be told, the airlines and the satellite and GPS users, they are not so happy when you call them up on the phone and say, ‘Hello, guess what just happened?’” he said.
Sydney Kaufman received a B.Sc. from McGill University, then worked on rural energy issues in Alaska. She is currently a PhD candidate in chemical physics at the University of Colorado Boulder at JILA. She has been a co-director of the Forum on Science Ethics and Policy (FOSEP) since 2010. Sydney is a contributing editor at Solar Novus Today where she writes about solar energy and energy policy. She tweets here.