From August 28 until September 2, numerous sunspots and solar flares were observed on the sun. Just before noon on September 1, the British astronomer, Richard Carrington, observed the largest flare, which caused a massive coronal mass ejection (CME), to travel directly toward Earth, taking eighteen hours. This is remarkable because such a journey normally takes three to four days. It moved so quickly because an earlier CME had cleared its way.

From the 1st to the 2nd, the largest recorded geomagnetic storm occurred, causing the failure of telegraph systems all over Europe and North America. Auroras were seen all over the world, most notably over the Caribbean; also noteworthy were those over the Rocky Mountains that were so bright, the glow awoke gold miners, who began preparing breakfast because they thought it was morning.

The strongest geomagnetic storm on record is the Carrington Event of August-September 1859, named after British astronomer Richard Carrington who witnessed the instigating solar flare with his unaided eye while he was projecting an image of the sun on a white screen. Geomagnetic activity triggered by the explosion electrified telegraph lines, shocking technicians and setting their telegraph papers on fire; Northern Lights spread as far south as Cuba and Hawaii; auroras over the Rocky Mountains were so bright, the glow woke campers who began preparing breakfast because they thought it was morning. Best estimates rank the Carrington Event as 50% or more stronger than the superstorm of May 1921.

What's the solution? The report ends with a call for infrastructure designed to better withstand geomagnetic disturbances, improved GPS codes and frequencies, and improvements in space weather forecasting. Reliable forecasting is key. If utility and satellite operators know a storm is coming, they can take measures to reduce damage—e.g., disconnecting wires, shielding vulnerable electronics, powering down critical hardware. A few hours without power is better than a few weeks.