The Carrington Event

Summary

On the morning of 1 September 1859, an English amateur astronomer sketching sunspots watched two points of white light flare on the face of the Sun. They lasted about five minutes. He ran to find a witness, and by the time he came back they were gone.

Seventeen hours later the Earth was struck by the largest geomagnetic storm ever recorded. The aurora was seen in the Caribbean. Telegraph systems failed across two continents, operators were shocked at their keys, and in some offices the telegraphs kept transmitting after their batteries were disconnected, running on the current the sky was inducing in the wires.

Richard Carrington had just become the first human being to see a solar flare, and he had seen the biggest one on record.

What is documented

The observation. Carrington was at his private observatory at Redhill, in Surrey, projecting an image of the Sun and sketching an unusually large and complex sunspot group. At around a quarter past eleven in the morning, two intensely bright beads of white light appeared within the group. They brightened, moved, and faded over roughly five minutes.

He left to fetch someone to confirm what he was seeing. In the minute he was gone, they had largely disappeared.

The independent witness. Richard Hodgson, another English astronomer, observed the same event separately and reported it. Two independent observations, on the same morning, of a phenomenon nobody had ever recorded.

The magnetometers. At Kew Observatory, the magnetic instruments recorded a disturbance at almost exactly the moment of the flare. That is the signature of the flare's radiation reaching Earth at the speed of light.

The storm. Seventeen and a half hours later, the main event arrived: a coronal mass ejection, an immense cloud of magnetised plasma, struck the Earth's magnetic field.

The transit time is itself remarkable. Such ejections normally take three or four days. This one took less than a day, which means it was travelling extraordinarily fast, and which is generally taken to indicate that an earlier ejection had cleared the path ahead of it.

The aurora. Normally confined to high latitudes, the aurora was seen over the Caribbean, over Cuba, over Hawaii, over Colombia, and over Queensland. In parts of the northeastern United States it was reported to be bright enough to read newsprint by. People got up believing it was dawn.

The telegraph. The world's only electrical network at the time was the telegraph, and it failed comprehensively across Europe and North America.

Operators received shocks from their equipment. Sparks jumped from telegraph pylons. Paper caught fire in some offices.

And in a detail that remains the single most striking thing in the record: some operators found they could disconnect their batteries entirely and continue to send messages, powered by nothing but the current the geomagnetic storm was inducing in the wires. Two operators in Boston and Portland did exactly this and conducted a conversation for around two hours on the storm's current alone.

Leading explanations

A coronal mass ejection and the resulting geomagnetic storm. Fully established.

A solar flare is a sudden release of magnetic energy in the Sun's atmosphere. A coronal mass ejection is a great cloud of plasma and magnetic field thrown outward from the Sun. When such a cloud strikes Earth's magnetosphere, it compresses and disturbs it, driving powerful electric currents in the upper atmosphere. Those currents produce the aurora, and they induce currents in any long conductor on the ground.

In 1859 the only long conductors were telegraph wires. That is the entire reason humanity got away with it.

The physics is now completely understood and routinely observed. Carrington's flare was the first ever seen, and his event remains the benchmark against which every subsequent storm is measured.

Nobody knew any of this in 1859. The connection between something happening on the Sun and something happening to a telegraph wire in Boston was not obvious, and Carrington himself was cautious about drawing it. That connection, once made, founded the field of space weather.

Current status

Later explained. The mechanism is entirely understood and the case is scientifically closed.

The registry keeps it for the same reason it keeps Tunguska. Both are anomalies that were resolved, and both resolved into a warning rather than into a footnote. The explanation of the Carrington Event is also a statement about what will eventually happen again, to a civilisation that has since wired itself together with several million kilometres of exactly the sort of conductor that the storm of 1859 found so interesting.

Last reviewed: July 2026. Records are provisional. Where the evidence changes, the entry changes. Found an error? Tell us.