May 14, 2009

Solar storms ahead: Is Earth prepared?

Updated: May 13, 2009 09:39 AM EDT

Solar flares are a product of the sun's complex chemistry, says Haimin Wang, director of the Space Weather Research Lab at the New Jersey Institute of Technology in Newark. The internal processes of the sun create whirlpools of magnetic force, which slightly lower the surface temperature of the sun, causing what we see as sunspots.

Every 11 years, the sun flips its magnetic north and south. This swap churns up an increased number of sunspots, with the next volatile peak due in 2012. Magnetic energy can build up on the solar surface and then suddenly be released in a massive burst.

This flare, a wave of particles moving at near the speed of light, arrives at Earth shortly after the light itself, which takes about eight minutes to cross the 93 million miles. In other words, sky-watchers won't know there has been a solar flare until shortly before the radiation arrives.

The burst poses little risk to people on the ground. However, airplanes at cruising altitude and spacecraft are much more vulnerable. The flash also can zap electronics on satellites, which lie entirely outside the safety of Earth's atmosphere.

While this initial burst can be dangerous, there's a much slower wave of energy - a coronal mass ejection (CME) - that really can mess with electronics.

Not every flare produces a CME, and they often occur when no flare is present. When they do spew out, CMEs send strong waves of electromagnetic force our way. The most visible signs of this are the colorful northern and southern lights. But it also has more serious consequences.

For one, it can cause electrical transformers to trip or fail, which can lead to widespread power outages. A particularly powerful CME storm hit Earth in 1921, before electricity played as big a role in daily life. If a burst of similar magnitude hit today, it would interrupt power for as many as 130 million people, according to a recent report by the National Academy of Sciences. In 1989, a geomagnetic storm knocked out power to 6 million people in Quebec.

CMEs also can cause the Earth's atmosphere to expand temporarily. This can cause low-orbit satellites, such as the constellation of Global Positioning System markers used for navigation, to drag in the denser air. Combined with changes in the transmission of radio waves caused by CMEs, this can lead to errors in positioning. The magnetic field also can induce glitches or even damage satellites.

As scientists gather more information, satellite companies have a few tricks to protect their space-bound electronics. It's hard to determine the effectiveness of shielding - mostly because experts don't fully know what the sun is capable of spewing out. Another satellite defense would be "safe modes," where administrators turn off most of the on-board electronics to protect it from going haywire. This can save the satellite but would interrupt whatever services it offered. Safe modes also require some kind of early warning - technology that is nascent at best.

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