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Here comes the sun: Scientists have their eye on solar flares

This article first appeared in the St. Louis Beacon, June 29, 2011 - Like a lot of people, Madhulika Guhathakurta is trying to predict the weather.

"We might see a storm forming and we might say, this storm has the potential to produce a hurricane," she said. "We can't say ahead of time whether that hurricane will happen."

But the storms Guhathakurta watches are a bit farther afield than those a meteorologist might predict.

About 93 million miles farther.

Guhathakurta is a solar physicist at the National Aeronautics and Space Administration and one among many trying to discern the murky intricacies of weather on the sun, a relevant job of late since our nearest stellar neighbor has been quiet recently -- a little too quiet, as the old cliche goes.

Now it's waking up, and there's growing disagreement in the scientific community about just what that means -- and what the effects might be on Earth.

Much of the prediction and debate rages over sunspots, areas of intense magnetism, some bigger than our planet, that roil the hot plasma on the sun's surface. These sometimes produce solar flares, massive explosions of radiation that, if they shower our planet with a soup of tiny particles, can cause disruptions in all manner of electrical equipment.

Earlier this month, telescopic video of a huge solar flare blasting from the sun's corona went viral on the Internet.

"We have had two or three big ones in the past four months or so," said David Ritchey, associate director of the James S. McDonnell Planetarium. "But they have not been directed toward Earth. That's another thing that comes into play here. The sun is a sphere 360 degrees around and it takes a pretty good targeted shot for any of that to reach us."

While flares can happen at any time, they are more numerous during the solar maximum, which tends to arrive on a roughly 11-year cycle during which the sun's magnetic restlessness begins to ramp up. That's precisely what's happening now as the star starts to kick into high gear after years of extreme quietude. In fact, in a recent New York Times oped piece, Guhathakurta and Daniel Baker, director of the Laboratory for Atmospheric and Space Physics at the University of Colorado, wrote that 2008 and 2009 saw less solar activity than at any time in the past century. This cycle's solar minimum was both deeper and longer than the last several cycles.

But the sun's placidity, say scientists, can have consequences.

"The same thing happened in 1859," said Ritchey. "It was a below-average solar cycle but when the sun came out of it, it unleashed one of the most powerful storms of the century."

According to NASA, that incident, called the Carrington Event, was so strong, it brought the famed Northern Lights as far south as Hawaii and even caused electrical surges that set telegraph offices on fire.

What concerns many solar researchers today is the modern world's reliance on items far more sensitive than crude 19th century Morse Code transmitters. Intense solar flares have been known to wreak havoc on everything from power grids to GPS systems, sometimes causing blackouts. Even airline passengers traveling over polar regions could be exposed to higher than normal doses of radiation. One report from the National Academy of Sciences estimated potential financial damages from a particularly nasty solar flare running as high as the equivalent of 20 Hurricane Katrinas.

"The sun has done this for millennia," said Guhathakurta. "Why is it that we are talking about this today? That is really because of the dependence of our infrastructure on technology. This is what makes modern civilization very sensitive to space weather."

Slowing Down?

While there is general agreement about both the sun's unusually tranquil minimum and the consequences of an unfortunately positioned solar flare, there is less consensus on whether the former will lead to an increased chance of the latter.

Frank Hill, associate director of the National Solar Observatory, which watches the sun from outposts in Arizona, New Mexico and Hawaii, said the sun's recent mellow attitude may only be the beginning of a longer-term personality shift. Hill was part of a team that released research earlier this month that argues that the star may be entering a decades-long period of docility. While he agrees solar activity is on the increase as the maximum, set to peak around 2013, revs up, he believes the climax may feature fewer flares than usual. The following maximum, around 2020, could make the trend even clearer.

"That's one we're definitely going to watch," he said. "We've got indications it will be weaker and may not even occur at all."

A less boisterous sun could also have consequences for earthlings. It wouldn't be unprecedented either. Richard Mewaldt, a senior research associate in physics with the California Institute of Technology, said less solar activity could mean a cooler Earth. He notes the so-called Little Ice Age, a period of cooling that began around the mid-1600s that lowered temperatures for decades causing glaciers to advance in some areas while rivers and harbors froze solid during harsh winters.

"Whether that's because solar activity was at a minimum is not directly proven but some people suspect that that's the case," he said.

Astronauts could also find work in outer space more difficult as they are exposed to higher levels of cosmic rays that the sun's lessened magnetic field will be unable to filter out.

Predictions All Over The Map

Mewaldt, who earned his PhD in physics from Washington University, said there is evidence to support Hill's theory about a solar slowdown, though he notes that only time will tell whether predictions will come true. Beyond a few hundred years, most data scientists obtain comes from ice core deposits of beryllium 10, a radioactive isotope formed by the interaction of cosmic rays with Earth's atmosphere.

"I think whoever you talk to who says we don't really know what's going to happen is right," Mewaldt said.

Largely, that's what Guhathakurta thinks. She doesn't believe any firm conclusions can be drawn now since much of the solar cycle's mechanics remain a mystery and people are drawing different conclusions using various models.

"I think both ends of the spectrum are too drastic," she said.

What got the attention of researchers was the sharp drop off of solar activity in the past few years.

"The last five or six cycles in the Space Age have been more active and unusually high from the average and we've gotten used to that," she said. "The question immediately was, if we've had such a long solar minimum [this time], is it going to continue on this path?"

Hill, too, said consensus can be hard to come by.

"There was actually a panel that was formed a few years ago by the Space Weather Prediction Center and it was entertaining," he said. "Half the participants said it was going to be a big cycle and half said it was going to be a weak cycle."

In the end however, everyone agrees that preparation is vital since solar flares can happen even when the sun is in a more dormant state. The National Oceanic and Atmospheric Administration is in charge of issuing any potential solar storm warning, though NASA is responsible for much of the underlying science.

Mewaldt said that power grids may try to lower the flow on lines during an alert while those reliant on the precise readings of GPS systems will need to be aware of the potential for inaccuracy.

Guhathakurta notes that even the massive Carrington flare didn't occur during the heart of the solar maximum.

"That particular cycle wasn't even a very active one," she said. "It was a fairly ordinary solar cycle, might have been even below average."

Hill said that while he feels the probability will drop with a less active sun, it still exists.

"It's not going to zero by any means so we shouldn't let our guard down," he said.

David Baugher is a freelance writer. 

David Baugher
David Baugher is a freelance writer in St. Louis who contributed to several stories for the STL Beacon.