Mystery of one of the earliest recorded space weather impacts solved

The first practical electric telegraph networks were deployed during the 1840s and, as solar activity increased during the following years, Victorian telegraph operators began to experience unexplained electrical effects caused by geomagnetic disturbances.

An international group of researchers, led by Lancaster University and including BGS, has re-examined a widely cited account of a train delay in Exeter that was reportedly caused by geomagnetic disturbance from the Sun interfering with railway’s telegraph systems. The event has previously been cited as potentially the earliest recorded example of space weather affecting human technology, but the team’s research contradicts this assumption.

The original account described how the 22:05 train departing Exeter in Devon on 18 October 1841 was delayed by 16 minutes when a ‘very intense magnetic disturbance’ interfered with the electric signalling telegraph equipment used to determine whether the railway line ahead was clear. However, the researchers found a critical problem: the railway line referenced in the account did not open until 1846, almost five years after the alleged 1841 incident.

To discover what really happened, the team combined evidence from railway timetables, historical newspapers, solar observations, aurora reports and digitised geomagnetic records. The BGS magnetogram archive shows a strong geomagnetic disturbance on 18 October 1848, alongside reports of sunspots and aurorae seen across the UK and Europe, providing compelling evidence that the date in the original account was a typographical error.

The findings show that, while the Exeter incident remains one of the earliest documented examples of space weather disrupting technology, it was not the first. The earliest credible report currently known to be due to interference with telegraph systems was actually on the Midland Railway in March 1847.

Using BGS’s historic archive of magnetic records from Greenwich Observatory in London, we were able to confirm that 18 October 1848 experienced very large auroral disturbances. Preserving long-term records is vital for informing research on the vulnerabilities of modern technology.

Dr Ciarán Beggan, geophysicist, BGS.

Space weather is often discussed as a modern challenge because of our dependence on technologies such as satellites, communications systems and electricity networks. What this study shows is that society has been experiencing the effects of space weather on technology for almost as long as electrical technologies have existed.

Prof Jim Wild, Lancaster University School of Physics and Astronomy and lead author of the study.

The research paper is available to read on the American Geophysical Union’s journal Space Weather.