Why are there so many solar flares these days?

Solar flares are ten million times more powerful than a volcanic explosion on earth. They increase in frequency during the solar maximum phase of the sun's 11-year cycle. This cycle is expected to peak in 2013.

AP Photo/Via National Solar Observatory
Energy leaving the sun's surface was photographed using a coronograph at National Solar Observatory east of Alamogordo in Sunspot, N.M. Solar flares are the largest explosions in this solar system.

At about 7pm Eastern Time on Tuesday, the surface of the sun was rocked by a massive explosion, ten million times more powerful than a volcanic explosion on Earth. And about an hour later, it exploded again. 

Now, two waves of charged plasma are streaming toward our planet at about four million miles per hour, threatening to knock out satellites and induce unwanted currents on power grids around the globe.  

X-class flares, the highest classification of solar eruptions, and their attendant ejections of charged particles, are nothing new these days. On Valentine's Day 2011, the sun produced its first X-class flare since 2007. Then, in August, the sun blew up again with the largest flare since 2006.

What's with all the recent activity? Is the sun going crazy?

The current increase in the number of X-class flares is actually part of a normal cycle. Cycles can be as short as nine years and as long as 14, but they last 11 years on average. Scientists speculate that the timing of solar cycles may be associated with the reversal of the sun's magnetic poles every 10 to 12 years. Just like the Earth, the sun has north and south poles that periodically reverse themselves. The sun's current cycle is expected to peak in late 2013.

During the maximum portion of the sun's cycle, there can be several hundred sunspots, that is, dark areas on the surface of the sun that indicate intense magnetic activity, in a single day. Some of those areas erupt into flares, and, if they are on the side of the sun facing our planet, they can end up sending a cloud of plasma our way. 

Scientists are still unsure exactly how solar flares are produced. One explanation goes like this: electrically charged objects create magnetic fields in the sun’s atmosphere. These plasma currents sometimes get caught in rubberband-like loops, visible as sunspots. Within these bubbles energy builds, with cooler plasma lying beneath hot plasma. As the sun moves, the shape of the magnetic fields becomes more complex. When the rubberband like structure stretches out, it changes the movement of the plasma within, causing a massive release of heat and light, called a solar flare. According to NASA, flares can last from minutes to hours.

Here on Earth, the charged plasma striking the Earth's magnetic field tends to brighten both the northern and southern auroras.

But colorful lights aren't the only impact of the flare on earthlings. Though this magnetic event will be moderate in scale, it may still have the capacity to interrupt satellite communications, power grids, and airplane travel. NASA will also monitor the course of the charged particle cloud for the safety of the astronauts aboard the International Space Station.

Scientists do not expect the solar maximum of this cycle to be catastrophic. They expect it to be similar in size to the last solar maximum in 2002.

Still, they aim to plan for the worst. Increasing dependence on technologies such as satellites may make society more vulnerable to activity on the sun.

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