The Sun is in the messy back half of its 11-year cycle, the phase that has produced history's worst storms. Here is how one would unfold, hour by hour.
Every big storm starts as a knot of twisted magnetic field above a sunspot. When that field suddenly reconnects, it dumps its energy in a matter of minutes.
Light and X-rays cross 93 million miles in about eight minutes. They ionise the upper atmosphere, and shortwave radio across Earth's daylit half fades out.
High-energy protons follow within the hour. Astronauts move into the best-shielded modules, and airlines pull flights off polar routes where the shielding is thinnest.
The plasma itself usually needs one to three days to reach us. The 1859 Carrington storm crossed in roughly 17.6 hours, among the fastest transits ever recorded.
The aurora oval swells toward the equator. In 1859 red auroras were logged over Cuba and Hawaii, bright enough for people to read a newspaper by at night.
The storm drives current through bedrock and through any long conductor sitting on it. On 13 March 1989 Quebec's grid collapsed in 90 seconds, blacking out six million people.
Quebec had power back in about nine hours. Damaged high-voltage transformers are the slow part: they are custom-built to order, and replacements run to months.
A storm heats the upper atmosphere until it swells outward. In February 2022 the extra drag dragged 38 of 49 freshly launched Starlink satellites down to burn up.
A churning ionosphere smears satellite navigation signals. Work that normally runs to centimetre accuracy, like guided harvesting and surveying, loses its precision.
Every step above has already happened, just never all at once. That is why the Sun is now watched around the clock, so grid operators get hours of warning instead of none.