Seventeen hours later
On 1 September 1859 Richard Carrington observed a remarkable solar brightening. NASA’s chronology says that around seventeen hours later auroras reached Cuba and telegraph systems failed, caught fire or shocked operators.
The observation, infrastructure and effects were recorded in different places. Tracing the sequence takes several kinds of evidence.
What the precedent tells us
A technology can be exposed to an external natural shock. That does not mean an event today would have identical effects: networks and protections have changed. The useful questions concern exposure, defences and duration, not a promised date or probability for the next storm.