It was a clear and sunny morning on September 1, 1859, as Richard Carrington sat down at the telescope in his private observatory just outside of London — perfect weather for observing the sun, which had become one of life’s great joys for him. Richard wasn’t an astronomer in the classic sense of academic training and university work. But he was one of the best in the field. Supported by his wealthy father, who provided the financial means, Richard devoted himself fully to a passionate study of the sky.

By this point in life, he had spent years tracking sunspots and mapping their shapes with methodical precision. But what Richard saw as he peered into the telescope that morning startled him. Two sudden flashes of brilliant, white, and blinding light erupted from one of the sunspots. As he later wrote, “[I observed] two patches of intensely bright and white light broke out. My first impression was that by some chance a ray of light had penetrated a hole in the screen, for the brilliancy was fully equal to that of direct sun-light.”

Richard quickly realized there were no issues with his telescope. Still feeling shocked, he stepped away to call someone else to witness the strange occurrence. But the flare vanished by the time they arrived. It had only lasted about five minutes.

What Richard had seen was the first documented solar flare, though he did not yet know the scale of what was coming. His careful record of the moment would later allow scientists to link his observations of the Sun to what was about to happen on Earth.

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About 1.4 billion people lived on the planet in 1859, most of them in rural areas where they survived by farming. Only five cities had populations over one million, and four of those were in China. London, the exception, had crossed the one-million mark a few decades earlier, around 1825.

At the time, nearly everyone lived without anything we’d recognize as electronic today. There were no power plants, no light bulbs, no electric grids humming in the background. Telephones hadn’t been invented.

The big electrical invention of the day was the telegraph, which had seen its first long-distance message sent by Samuel Morse in 1844. It was a monumental invention, virtually an overnight change for a country such as the U.S., which had struggled to stay connected across its vast expanse. People could now instantly exchange information, connecting them in ways they had never been. But most machinery of the age ran on waterwheels and steam engines, fueled by wood or coal.

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What Richard saw on that sunny morning turned out to be the beginning of a massive solar storm heading right for Earth. It hit about eighteen hours later.

To the casual observer, the scene must have been beautiful and terrifying as green and crimson auroras danced across skies worldwide. Some places were so bright that people reportedly read newspapers in the evening under the glow. But it also looked like a fire in the sky in some places. “Half-past eleven. The appearance now is positively awful. The red glare is over houses, streets, and fields, and the most dreadful of conflagrations could not cast a deeper hue abroad,” wrote a reporter in the San Francisco Herald. In some parts of the world, people woke up in the middle of the night thinking it was daytime. Yet the spectacle masked something far more serious.

Telegraph systems began to fail. Operators were shocked by their equipment; one was thrown out of his chair, paper caught fire from sparks leaping from the machines, and in some cases, the lines continued to send messages even after being unplugged, powered by the electric current coming from the sky.

The cause of all this was a coronal mass ejection — a giant cloud of charged solar particles hurling through space at astonishing speed. In this instance, the storm reached Earth with such overwhelming force that it disrupted the planet’s magnetic field, compressing and warping the invisible shield that protects Earth from solar radiation. The deflected charged solar particles were forced into the upper atmosphere, where they collided with atmospheric gases leading to a release of energy as light. The result was a brilliant aurora.

But the shield couldn’t fully deflect the storm’s energy. Electric currents surged through the ground and into the telegraph wires, which caused the nascent technology to suddenly come under the storm’s control.

Then, almost as quickly as it had arrived, the storm faded. The skies dimmed and the air stilled. The auroras slipped back into darkness. It was over. And when the storm ended, most of the impact stopped as well. The telegraphs resumed operation largely as though nothing permanent had happened.

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