Geomagnetic storms caused by solar activity pose a huge risk to technology on and around Earth, but we’re getting better at predicting them thanks to new data.
From our vantage point on Earth, the Sun seems like such a stable fixture in the sky—it looks pretty much the same every day, as far as we can tell. But our local star is actually highly temperamental and goes through periods of hyperactivity. These temper tantrums are called coronal mass ejections (CMEs), and they are exactly what they sound like: the Sun heaves tons of magnetized plasma into space, at speeds that can exceed a million miles per hour.
Under the right conditions, CMEs can create a geomagnetic storm around Earth that devastates navigation systems and power grids, threatening astronauts and airline travelers with radiation. On the plus side, these storms also generate fantastic displays of auroras, or northern lights.
Luckily, astronomers have developed tools that can predict these solar storms and their potential damage. Data from the MErcury Surface, Space ENvironment, Geo-chemistry, and Ranging (MESSENGER) spacecraft allows close-up study of the Sun’s activity. By watching the evolution of a CME as it leaves the surface and moves toward the planets, scientists can build models that will improve our ability to forecast the resulting geomagnetic storm. This will enable them to prevent damage to electronic equipment, a must in the 21st century.
The most famous geomagnetic storm to affect Earth was the Carrington Event of 1859. A single solar flare caused a series of CMEs that shut down global telegraph lines and filled the sky with northern lights as far south as Cuba. Scientists believe that if another storm of such magnitude hit Earth again, the effects on modern technology would be catastrophic.
In fact, in July 2012 we came incredibly close to such a disaster. A paper in the journal Space Weather describes the massive CME that ripped from the Sun’s surface and only just missed our planet. Instead, it hit the STEREO-A spacecraft. If STEREO-A had been orbiting Earth at the time, the storm interacting with the planet’s magnetic field would have completely destroyed it. Since it was traveling between planets, however, it not only survived the deal, but captured data on the event.
Based on this data, space physicists have estimated that this July 2012 CME would have generated a storm about as severe as the Carrington Event—twice as bad as a storm in 1989 that caused a 9-hour blackout throughout Quebec. A NASA study estimates that the storm would have cost $2 trillion in damages.
Since that peak in activity, the Sun has calmed down a bit and may be entering a minimum in its 11-year cycle. Still, based on past trends, the chances of another Carrington-level geomagnetic storm hitting Earth are a grim 12 percent. With new forecasting technology, we can hopefully be a bit more prepared.
Check out the more aesthetic results of CMEs: