A smidge over 100 years ago, from the 13th to the 15th of May 1921, Earth received its worst gut punch from the sun in the 20th century. Many people are familiar with the Carrington Event of 1859 – our first real interaction with solar storms and coronal mass ejections – but few know about the 1921 event, which is considered almost as severe. Places like the Stockholm Telephone Switchboard, pictured below, were on the receiving end of hundreds of volts of electricity as their telephone wires got a charge induced on them by Earth’s rapidly changing magnetic field.
The exchange in Karlstad, about 150 miles to the west, caught fire and had to be evacuated. Train service coming into and out of Grand Central Station in New York was disrupted, as the voltage on the railroad lines prevented communications with the signaling equipment. Trains had to be guided in manually.
The cause? A one-two-three ejection from the sun known as a “Coronal Mass Ejection”: the first and third were big punches, but the second one was enormous. The sun belched millions of tons of charged particles right at Earth, three times in a row. The huge influx of solar radiation bent, twisted, and tortured the Earth’s magnetic fields – and the rapidly changing magnetic field induced a voltage on anything long and metallic … like a telephone cable or a railroad track. Depending on the location, up to ten volts of electric potential were generated in every kilometer of ungrounded wire. Telephone switchboard operators could be sitting on the wrong end of a 600 volt line.
Today, such a storm would wreak havoc on our intricate network of electrical and phone wires; we have 100x more wires strewn around now than we did in 1921, and the Western World is faaaar more dependent on electricity than it was 100 years ago. The intensity of the storm was measured at -900 nanoTeslas; the solar storm of 1989 (the most significant one in ‘recent memory’) was only -589 nanoTeslas.
We are not prepared.