On 1 September 1859 a solar storm hit Earth hard enough that auroras were seen over Cuba, and telegraph operators in Boston disconnected their batteries and kept sending messages for two hours on the current the sky was pushing through the wires.

On 1 September 1859 a solar storm hit Earth hard enough that auroras were seen over Cuba, and telegraph operators in Boston disconnected their batteries and kept sending messages for two hours on the current the sky was pushing through the wires.

The date in the familiar Carrington Event story needs one adjustment. On 1 September 1859, the English astronomers Richard Carrington and Richard Hodgson independently saw patches of intense white light appear over a large sunspot group. The main geomagnetic storm reached Earth roughly 17 hours later, early on 2 September. Then the night sky changed colour far outside the latitudes where auroras were expected. Reports came from the Caribbean, in…