The Sun isn't a steady lamp — it's a storming star that flings billion-tonne clouds of plasma across the Solar System. Its weather has knocked out power grids, dropped satellites from orbit, and it runs on a cycle you can follow.
A star with a temper
The Sun's surface is a churn of magnetic field lines, twisted by the star's uneven rotation until, like overwound rubber bands, they snap. A snap can release a solar flare — a flash of X-rays that reaches Earth at the speed of light, eight minutes later — and often hurls a coronal mass ejection: a cloud of magnetized plasma weighing billions of tonnes, ballooning outward at millions of kilometers per hour. Flares are the lightning; CMEs are the hurricane. The hurricane takes one to three days to arrive, which is exactly what makes forecasting possible.
When the sky reached the ground
In September 1859, the strongest solar storm on record — the Carrington Event — hit a world whose only electrical network was the telegraph. Compasses wandered, aurora was seen near the tropics, and telegraph lines carried so much induced current that some offices sparked and operators disconnected their batteries and kept sending on storm power alone. The modern rehearsal came in March 1989, when a CME collapsed Quebec's power grid in about 90 seconds, leaving six million people in the dark for nine hours. A Carrington-class storm hitting today's grid- and satellite-dependent world is one of the few natural disasters engineers formally plan for.
Weather that satellites feel
Space weather's day-to-day victims orbit overhead. Storms puff up the upper atmosphere, thickening the thin drag that satellites feel — in February 2022 a single geomagnetic storm dragged about 40 freshly launched Starlink satellites out of their low deployment orbits before they could climb. Radiation surges force astronauts to shelter in shielded parts of the Station, degrade solar panels, and can flip bits in spacecraft computers. GPS accuracy wobbles; polar airline routes divert. None of this is exotic anymore — it's operational weather, with forecasts to match.
The eleven-year drumbeat
The Sun's mood follows a cycle of roughly 11 years, tracked the same way since Galileo: by counting sunspots, the dark magnetic bruises where storms are born. At solar minimum the disk can be blank for weeks; at maximum it's freckled and crackling. Each cycle's peak means more flares, more CMEs — and more auroras. The practical takeaway is the forecast chain: a big Earth-directed CME is spotted leaving the Sun, and the world gets a day or three of warning. What that warning looks like from your backyard is the next lesson's story.