Carrington Event

After astronomer Richard Carrington watched a brilliant flare on the Sun, Earth was hit by a storm so strong that telegraph lines sparked and auroras were seen from the Caribbean. It remains the benchmark worst-case space weather event.

A fast CME (transit <18 hours) drove an estimated Dst near −900 nT. Modern recurrence studies treat Carrington-class storms as roughly once-per-century events with major implications for power grids and satellites.

It defines the ceiling: a reminder that auroras can, rarely, reach almost anyone's sky — and that space weather monitoring is not just for skywatchers.