When the space weather is just right, one of nature’s grandest spectacles unfolds over Earth’s poles. Visible on clear nights, clouds of glowing green slowly morph into gyrating arcs that cover the sky — then vanish. And repeat. At times the lights appear straight overhead, falling as cosmic rain in shades of green, red and blue. It’s a phenomenon humanity has marveled at for millennia. Yet scientists are still unraveling its mystery.
Carrington Event
Our modern understanding begins on Sept. 1, 1859. British astronomer Richard Carrington was tracking sunspots when a group unlike any other he’d seen appeared. It sent out two intense flashes of white light and vanished minutes later. Those bright flashes signaled that an enormous eruption — the largest geomagnetic storm in history — was heading for Earth.
When it hit, the storm was so intense that sparks shocked telegraph operators through their machines and set their paper on fire. Rare red auroras appeared as far south as Hawaii and El Salvador. Called the Carrington Event, the incident showed auroras were caused by solar activity — but half a century passed before science could explain how.
Forecasters still struggle to predict this space weather, and scientists have yet to understand its subtleties. That ongoing effort is vital to protecting power grids and satellites, which are sensitive to the same power surges that have inspired awe for thousands of years.
