An 1859 Solar Storm Set Telegraph Equipment on Fire, and Operators Sent Messages With No Battery Connected
On the night of September 1, 1859, the largest geomagnetic storm in recorded history slammed into Earth. Auroras were visible as far south as the Caribbean. Telegraph lines across Europe and North America sparked, papers caught fire, and operators reported sending messages even after they had disconnected their batteries — the wires were carrying enough induced current to power the system on their own.
On the morning of September 1, 1859, the British amateur astronomer Richard Carrington was at his private observatory in Surrey, sketching sunspots projected through his solar telescope. He saw, briefly and clearly, a sudden white flash on the surface of the Sun. Another observer, Richard Hodgson, saw the same flare. Carrington carefully noted the time. It was the first detailed scientific record of what we now call a solar flare.
About seventeen hours later, the resulting geomagnetic storm reached Earth. By every available measure, it remains the most powerful one in the modern record.
Auroras, normally confined to high latitudes, became visible across the world. They were reported as far south as Hawaii, Cuba, Colombia, and the Caribbean. Some people in the Rocky Mountains woke up around 1 a.m. thinking sunrise had come early and began making breakfast. Newspapers in Boston reported being printed by the light of the aurora alone.
The serious damage was on the wires. The telegraph network — the high-tech communication infrastructure of the era — had spread rapidly across Europe and North America in the 1840s and 1850s. Tens of thousands of miles of metal cable now ran across continents and beneath the Atlantic. The geomagnetic surge induced enormous transient currents in all of it.
Operators across the United States and Europe reported sparks shooting from their telegraph keys. Several reported shocks and burns. Papers on their desks ignited. In one widely reported exchange between Boston and Portland on September 2, both operators disconnected their batteries entirely and discovered they could still send and receive messages — the lines were carrying enough induced current to power the system on their own.
The 1859 event is now called the Carrington Event. Geological evidence from ice cores and tree rings suggests storms of comparable size occur on the order of once every several centuries on average, with smaller but still major storms happening on much shorter timescales.
If a Carrington-class storm struck the modern grid-connected world, the cascading damage to high-voltage transformers, satellites, and power infrastructure is estimated to run into the trillions of dollars and take years to repair. We have not yet been hit.