The Storm of 1859

Part One · The Flash

On the morning of September 1, 1859, an English astronomer named Richard Carrington set up his telescope at a private observatory near London and began his usual routine of studying the face of the sun. Carrington was a wealthy brewer's son who had given up a career in the church to pursue science, and for several years he had devoted himself to recording the positions of sunspots, the dark blemishes that drift across the solar surface. He projected the sun's image onto a screen, so that he would not damage his eyes, and then sketched each spot with remarkable accuracy. That particular morning a huge and unusually complicated group of spots lay across the disk, and he started to draw it carefully, unaware that he was about to witness something that no human being had ever recorded before. It was a clear, ordinary Thursday, and nothing in the quiet room gave him the slightest warning of what was coming.

At about eleven twenty, while he was concentrating on his drawing, two patches of intensely brilliant white light suddenly flared up inside the group of spots. Carrington was so startled that he assumed that a flaw in his equipment, or a stray beam of sunlight, had caused a reflection on the screen, and he reached to adjust the shade. The patches shifted slightly, dimmed within a few minutes, and then vanished. Convinced that he had seen something extraordinary, he ran out of the room to find a witness, but by the time he returned with someone, scarcely a minute later, the display had already faded. Still, a second observer, Richard Hodgson, who was watching the sun from another observatory in England, noticed the same bright flash, and both men published reports describing it. Their separate accounts agreed so closely that astronomers have never doubted that the flash was real and that it came from the sun itself.

Nobody at the time understood what Carrington had seen. Today astronomers know that a solar flare is a sudden explosion in the sun's atmosphere, in which magnetic energy that has built up around a sunspot is released all at once in a burst of radiation. The flare that Carrington observed was an exceptionally powerful one, and it is generally believed that the blast also hurled an immense cloud of electrically charged particles out into space. Such a cloud is called a coronal mass ejection. Light from a flare reaches the earth in about eight minutes, but the cloud itself usually takes several days to arrive, so a person who sees a flare through a telescope has no immediate reason to expect that anything will happen to our planet. In 1859, in fact, nobody even knew that such clouds existed, and the word for them was not invented until more than a century later.

Part Two · The Storm

Yet something did happen, and it began unusually soon. About seventeen hours after Carrington's sighting, a magnetic storm of astonishing intensity struck the earth. Instruments at scientific observatories around the world recorded their needles jumping wildly, and some of the devices went off the scale altogether. The storm lasted for most of that day and into the next, and astronomers who studied the records afterward were struck by how widely it had been felt, and the disturbance spread across the entire planet. The unusually short delay between the flare and the storm suggests that the cloud from the sun was traveling at tremendous speed, and that it was packed with a powerful magnetic field pointing in just the right direction to connect with the magnetic field that protects the earth. Researchers still regard that combination as extraordinarily rare, and they have found only a handful of storms in the historical record that can be compared with it.

For ordinary people, the most spectacular result was the sky. During the night of September 1, brilliant displays of the aurora, which are the glowing curtains of colored light that usually appear only near the poles, spread across the heavens and were seen over Cuba, Jamaica, Hawaii, and Colombia, close to the equator. Newspapers reported that the red, green, and purple glow was bright enough to read by, and that in parts of North America some people awakened in the middle of the night, believing that dawn had arrived, and began to prepare their breakfast. Gold miners in the Rocky Mountains were said to have risen and made their coffee. Many observers who had never seen an aurora in their lives became frightened, and a few thought that the world was ending. Church bells rang in some towns, and crowds gathered in the streets to stare upward at the shimmering sky until the glow slowly faded.

The other effect of the storm was even more surprising, and it was felt by the new technology of the age. By 1859 the electric telegraph had spread across Europe and North America, and thousands of miles of copper wire carried messages from city to city faster than any horse or ship could travel. The rush of electrical energy from the storm flowed into these long wires, and telegraph systems on both continents began to behave strangely. Operators received painful shocks from their equipment, sparks leaped from the machines, and in some offices the paper that was used to record the messages was set on fire. In many places, the telegraph could not be used at all, and officials were forced to suspend service until the sky returned to normal. Merchants, newspapers, and ordinary families who had grown used to receiving news within minutes suddenly found themselves cut off from distant cities.

One of the strangest incidents took place on a line between Boston, Massachusetts, and Portland, Maine. Operators in the two cities found that their instruments were unreliable, so they decided to disconnect the batteries that normally powered the line, and then they experimented. They discovered that the electrical current that was produced by the aurora overhead was strong enough to carry their messages without any battery at all. For about two hours the operators chatted back and forth, using nothing but the energy of the storm, and they carried on until conditions changed. Their conversation has been preserved in a newspaper account of the time, and it remains one of the most unusual episodes in the history of communication. The account reported that the messages passed through well, and that the two men were able to keep working for as long as the storm lasted, which seemed to them a remarkable result.

Considering how few people depended on electricity in 1859, the consequences were quite limited. Telegraph operators lost a day of work, a few offices suffered small fires, and a number of people were frightened by the brilliant lights, but nobody was seriously harmed, and the telegraph returned to operation within a day or two. Scientists, however, were deeply impressed. Carrington, who had suspected a connection between the flare he had seen and the storm that followed it, wrote cautiously that one swallow does not make a summer, and he did not claim that he had proved a link. Later research, using much better instruments, eventually confirmed that the sun can indeed affect the earth's magnetic field, and the event was eventually named in his honor. His careful drawing of the sunspots, which he published afterward, is still studied by scientists who want to understand what the sun was doing that morning.

Today the Carrington Event has become a warning as well as a curiosity, because modern civilization is far more dependent on electricity than the world of 1859. A similar storm now could damage satellites, disrupt navigation and radio signals, and overload the electrical grids that carry power to homes and hospitals. In March 1989, a much smaller storm caused a blackout that left millions of people in Quebec without electricity for about nine hours. Scientists therefore watch the sun closely with spacecraft and ground observatories, and they try to give power companies advance notice so that operators can protect their equipment. In July 2012, an enormous eruption missed the earth by only about nine days, and experts concluded that the consequences might have been serious. The incident reminded engineers that a storm on the scale of 1859 is not a matter of whether, but of when, and that preparation costs far less than repair.