Threat: Solar Storms & Coronal-Mass Ejection
Solar storms are one of the biggest threats to modern society. Like an EMP attack, solar storms can knock out the electrical power grid. These solar storms are like other natural disasters, like hurricanes, earthquakes, tornadoes, and floods -- we know they will happen. The question is, how often and how severe?
We estimate the odds of a solar "superstorm" to be about double the chance of a fire in your home. The last superstorm was in 1859. The odds of another go up during certain times of solar storms, but another could happen at any time.
Blast From the Sun
The sun creates a solar storm when opposing magnetic fields collapse and "reconnect." This magnetic reconnection releases a huge amount of energy, blasting solar material into space.
These ejections of solar mass are huge. The amount of material shot out can be like shooting Mount Everest into space.
The very hot, electrified gasses travel quickly. If the storm is pointed toward the earth, the solar gasses can reach us between 17 hours to four days later.
The number of CMEs varies based on the 11-year solar cycle. At the low point, CMEs average about 40 per month, but at the peak the sun "erupts" about 120 times per month.
Is It Headed Our Way?
Most CMEs blast into empty space, but about three percent of them head toward earth. These are called Halo CMEs because they look like a ring of energy coming toward us. (See NASA animated photo, at right.)
CMEs hit the earth an average of one to four times each month, varying based on the solar cycle.
Most Only Cause Auroras
On Earth, most solar storms only brighten the auroras and spread them over a larger area. Stronger solar storms may interfere with satellite reception and radio communication.
Auroras are the beautiful side of solar storms, but the other results are more serious.
Extreme Solar Storms
About 36 times each century, the sun unleashes an extreme CME on the earth. NOAA calls these G5 storms.
A March, 1989 G5 storm triggered a 12-hour blackout across Quebec, Canada. Power companies across the United States struggled to balance power loads, but most were able to stay online.
These G5 storms have widespread impact. The image at right shows the extent of auroras during a G5 storm called the Bastille Day Flare. People as far south as El Paso, Texas saw auroras caused by that storm. The Bastille Day event also sent a satellite tumbling in orbit, caused limited power outages in several areas, and damaged at least one transformer.
Geomagnetic Superstorm: Waiting for the Next One
The 1989 solar storm was only one-third the size of a storm in 1859. That "Superstorm" was so powerful that it caused telegraphs to catch fire. A storm of that size or larger may cause extreme damage to modern power networks.
Experts argue about how much damage the next superstorm will cause. The main debate is whether the superstorm will destroy very large power transformers. These transformers are key to getting electricitys from many power stations. If these transformers fail, the power stations would be offline for a year or longer.
In addition, many smaller transformers could be damaged. This would make it hard to restore power from surviving power stations.
"Widespread functional collapse of the electric power system
US EMP Commission's Report to Congress, Volume 1: Executive Report
in the area affected by EMP is likely."