Stormy weather – on the sun! Watch out

In a coronal mass ejection, the sun spews tons of hot plasma. Image: NASA Goddard

Planet Earth is not isolated. Sometimes catastrophes arrive from outside, like the giant asteroid that triggered the extinction of the dinosaurs, apart from tiny ones that evolved into birds while mammals took over. Unwelcome visitors can also come from the sun and could be hugely disruptive to civilization in a different way. This one probably never occurred to you, but it will happen one day, and in that one day our lives could change dramatically.

On Sept. 1, 1859, the English amateur astronomers Richard Carrington and Richard Hodgson noticed an extremely bright spot on the sun, now called a flare. That night the sky lit up with brilliant auroras over much of the world: northern lights as far south as Cuba and southern lights as far north as Santiago. In the U.S. it was bright enough to read a newspaper at midnight, the whole sky eerily glowing with beautiful changing colors.

Wireless was decades in the future, but we had electricity, and 15 years earlier Samuel Morse had sent a message using his dot-dash code 44 miles from Washington DC to Baltimore. Electrical telegraphy was born and changed civilization. But when that “Carrington event” happened, telegraph operators got electric shocks, sparks flew, and equipment broke. Magnetic compasses went haywire; it was a “geomagnetic storm.”

Solar flares are common, but that one was accompanied by what we call a coronal mass ejection, CME, when the sun burped a billion tons of hot plasma (mainly protons and electrons) at several million miles per hour in our direction. Such CMEs are not rare but usually miss the Earth. A near miss happened in July 2012; the plasma cloud would have hit us if it had happened nine days earlier. Continentwide electricity transmission grids could be damaged causing months-long blackouts. Electrical telegraphy has been replaced by wireless everything – radio, television, internet, GPS and communications satellites. Imagine all that crashing – for months or years.

Cheer up – it may never happen! No, that’s wrong – another Carrington event will surely happen one day, but we cannot say when. The next sunspot cycle maximum, when they are most likely, is expected in July 2025. These recur every 11 years, but it may be a hundred years or more before another huge CME hits us. Fortunately, scientists are closely monitoring the sun, and we could get several hours of warning. Disaster can be averted by actions such as emergency landing for all airplanes and controlled shutdowns of power grids if, and only if, we are ready for it. We will not have weeks to decide on a mitigation plan. My Boy Scout motto was “Be prepared.” May we be.