PCMag

The Sun roared out a huge solar flare yesterday. NASA caught it on film, ranking the spectacular blast as a Class-M flare, just one spot below the the most disruptive type of flare, X. Even so, NASA says it will give Earth a mere "glancing blow," and the National Weather Service expects it will cause only minor disruptions to satellites and power grids.

It could have been much worse. For centuries, solar flares have been responsible for a multitude of earth-bound calamities, from blackouts to disrupted communications to strange lights in the sky. In 1859, the biggest flare on record hit, creating auroras worldwide and interrupting telegraph service for weeks. Considering today's connected world—and our reliance on satellites—a major solar storm could be disastrous.

The sun is entering a particularly active time, says NASA, and big flares like the one from yesterday will likely be common during the next few years, with solar activity expected to peak around 2013. Most solar flares will only cause minor problems with satellites and power grids, but there's always a chance that a monster like the one from 1859 could hit.

"The worst-case scenario is an extreme event," says Michael Hesse, chief of NASA's Space Weather Laboratory at the Goddard Space Flight Center in Maryland. "If it were to happen and we don't take any precautions, it would probably knock out our power grid for an extended period of time and destroy a sizable fraction of our satellite infrastructure."

"This is not something we expect to happen tomorrow," he cautions. "But it's like the impact of a hurricane on a specific location. You don't expect it to happen tomorrow, but you might want to think about if it were to happen."

Anatomy of a Solar Flare
It helps to understand just what a solar flare is, and how it affects technology. The initial burst from the surface of the sun sends out massive amounts of electromagnetic radiation, particularly x-rays. These travel toward the earth at the speed of light and can cause some problems with communication, but they're typically temporary and not that serious.

Depending on where the eruption is located on the sun, the flare also creates a huge amount of high-energy particles, which can achieve energies in the order of hundreds of millions of electron volts. That's enough to be "very hazardous to spacecraft," says Michael Hesse.

But that's not the worst of it. A solar flare can also shoot out what's called a "corona mass ejection," a stream of particles that moves much slower than the speed of light but still with enough force to cause serious damage. Typically, this mass hits the earth about one to three days after the initial flare. How fast it gets here depends on the magnitude of the burst, and the faster it goes, the greater the danger. However, not all ejections actually hit the earth. Hesse estimates about one in ten flare ejections impact the earth. The ejection from yesterday's flare will apparently miss.

If a corona ejection is powerful enough, and the earth is in its path, look out. Satellites are the most threatened, for obvious reasons, and a serious flare could damage or even destroy them, Hesse says. For regular people, that could mean no GPS, no satellite TV or radio, and disrupted communications for anything that relies on satellites as part of its network. The consequences to businesses can be even more severe, as satellites and GPS are intertwined with many other industries. For example, companies use GPS to time-stamp financial transactions.

"Satellites can get irradiated," Hesse explains. "Radiation levels in the magnetosphere can increase substantially, and that can be harmful to satellites. GPS can be substantially affected. Devices will lose lock."

The interaction between the corona ejection and the earth's atmosphere and magnetic field is how solar flares affect the power grid. When those particles hit the ionosphere, they create a voltage between the atmosphere and the earth. As a result, power systems that use the earth as a grounding voltage (read: all of them) no longer work properly, which can disrupt power delivery to large areas.

Earth's atmosphere and magnetic field shield the surface from any direct effects of a solar flare. Generally, terrestrial communication such as cell-phone networks (2G, 3G, and 4G), TV and radio broadcasting, and Wi-Fi aren't affected much by solar storms, if at all. However, if the power grid goes down for extended periods, so too will wireless networks and cell-phone towers. And good luck switching on your TV or radio.

Keep reading to see what can be done to prepare for a massive solar storm.