A long-standing mystery about the earliest known space weather disruption to technology has been solved. An anonymous report published in Nature in 1871 described a "very intense magnetic disturbance" that delayed a train in Exeter, England, in October 1841. If true, that would have been the first such event on record. But a new study in Space Weather argues the date was a typo, and the real event occurred seven years later.
The researchers, led by Jim Wild of Lancaster University, found that the railway line between Exeter and Plymouth wasn't approved by Parliament until July 1844 and didn't open until May 1846—five years after the claimed disruption. They also examined magnetograms from the Greenwich observatory, which showed no unusual geomagnetic activity on October 18, 1841, but strong activity on October 18, 1848, confirmed by contemporary newspaper accounts and sunspot observations. Railway timetables from that period list a 10:05 pm express train departing Exeter between March 1848 and July 1849, matching the report's details.
The study corrects the historical record, making the 1848 event the earliest documented example of space weather affecting technology. As Wild notes, society has experienced space weather effects on technology for almost as long as electrical technologies have existed. Understanding past events like this helps scientists improve predictions for future geomagnetic storms, which could otherwise damage power grids and satellite communications today.