Late Monday, March 13, the Sun ejected a coronal mass ejection (CME) traveling at at least 3,000 kilometers per second (6,700,000 miles per hour), possibly the fastest on record. The ejected particles reached Earth orbit in less than a day. Had they hit Earth, the results could have been catastrophic, but fortunately the CME was pointing almost directly in the opposite direction. However, the explosion reminds us that next time we might not be so lucky.
Although it comes from the other side of the sun, it seems that way caused a small radiation storm on earth. A smaller and much slower CME on Saturday, which was predicted to brush Earth, may also have contributed. CMEs can affect each other, with one clearing the way for the charged particles from the other. Spaceweather.com predicts shortwave radio blackouts for planes flying over the poles.
CMEs involve bursts of the Sun’s plasma and associated magnetic field being fired into space, usually in conjunction with solar flares. CMEs are common, but most are too small to do any major damage and aren’t usually pointed at Earth anyway. Preliminary estimates say yesterday’s event is “extremely rare” and likely to occur once or twice in several decades.
In 1989, two CMEs and an X-15 class solar flare combined to fill Earth’s magnetosphere with charged particles, causing auroras as far north as Florida and tripping Quebec’s power grid and causing a nine-hour province-wide blackout. That may seem small on the scale of natural disasters, but the solar activity that triggered them was small compared to what we think is possible.
A much larger storm known as the Carrington Event in 1859 destroyed telegraph systems throughout North America. If it happened today, the consequences would be staggering, collapsing power grids, satellites being pulled from orbit, and disrupting water supplies and the internet. One model puts the cost at $2.6 trillion in North America alone, but this could be drastically reduced if preparatory action is taken.
How yesterday’s CME compares to the Carrington event is not yet clear. In part, it never will be, since in the 19th century we lacked the capacity to accurately measure the strength of such storms. Still, there is little doubt that a storm like the one we have just witnessed could do great damage to an unprepared earth.
The Sun is approaching a maximum in its 11-year cycle. Despite many predictions that this cycle would be mild, the opposite appears to be the case. We are already reaching levels of activity, as measured by the number of sunspots and the strength of CMEs and solar flares, similar to the peaks of the last two cycles, and we may still be years away from the peak.
As such, the chance of a powerful CME leading the way in the near future is significantly higher than usual. Long-term preparations for such an event may include infrastructure upgrades, but in most cases it’s probably too late for this cycle for that.
If an outbreak is upon us, shorter-term measures can be taken, e.g. B. switching off power grids to prevent overloading of the transformers. However, the faster a CME develops, the less time governments and infrastructure companies have to decide whether to endure temporary pain to reduce the risk of a major meltdown. Many fear possible backlash from the same people who have resisted pandemic interventions as a curtailment of their rights.
Estimates of the risk of a Carrington-style CME hitting Earth vary widely, ranging from about 1 percent in a decade to 12 percent. Paleontologists have looked for markers of such events using radioisotope records in tree rings and ice cores in hopes of finding out how often they hit Earth, but the question remains unanswered.