On Sept. 1 and 2, 1859, telegraph systems around the world failed catastrophically. The operators of the telegraphs reported receiving electrical shocks, telegraph paper catching fire, and being able to operate equipment with batteries disconnected. During the evenings, the aurora borealis, more commonly known as the northern lights, could be seen as far south as Colombia. Typically, these lights are only visible at higher latitudes, in northern Canada, Scandinavia and Siberia.
What the world experienced that day, now known as the Carrington Event, was a massive geomagnetic storm. These storms occur when a large bubble of superheated gas called plasma is ejected from the surface of the sun and hits the Earth. This bubble is known as a coronal mass ejection.
The plasma of a coronal mass ejection consists of a cloud of protons and electrons, which are electrically charged particles. When these particles reach the Earth, they interact with the magnetic field that surrounds the planet. This interaction causes the magnetic field to distort and weaken, which in turn leads to the strange behavior of the aurora borealis and other natural phenomena. As an electrical engineer who specializes in the power grid, I study how geomagnetic storms also threaten to cause power and internet outages and how to protect against that.
Geomagnetic storms
The Carrington Event of 1859 is the largest recorded account of a geomagnetic storm, but it is not an isolated event.
Geomagnetic storms have been recorded since the early 19th century, and scientific data from Antarctic ice core samples has shown evidence of an even more massive geomagnetic storm that occurred around A.D. 774, now known as the Miyake Event. That solar flare produced the largest and fastest rise in carbon-14 ever recorded. Geomagnetic storms trigger high amounts of cosmic rays in Earth’s upper atmosphere, which in turn produce carbon-14, a radioactive isotope of carbon.
A geomagnetic storm 60% smaller than the Miyake Event occurred around A.D. 993. Ice core samples have shown evidence that large-scale geomagnetic storms with similar intensities as the Miyake and Carrington events occur at an average rate of once every 500 years.
Nowadays the National Oceanic and Atmospheric Administration uses the Geomagnetic Storms scale to measure the strength of these solar eruptions. The “G scale” has a rating from 1 to 5 with G1 being minor and G5 being extreme. The Carrington Event would have been rated G5.
It gets even scarier when you compare the Carrington Event with the Miyake Event. Scientist were able to estimate the strength of the Carrington Event based on the fluctuations of Earth’s magnetic field as recorded by observatories at the time. There was no way to measure the magnetic fluctuation of the Miyake event. Instead, scientists measured the increase in carbon-14 in tree rings from that time period. The Miyake Event produced a 12% increase in carbon-14. By comparison, the…
