The Carrington Event report in MNRAS vol. 20 (1859)

Image of the journal article reporting sunspots seen in the Carrington Event of 1859
MNRAS vol. 20, Issue 1, November 1859, Pages 13–15 (, containing the original report of the Carrington Event. This event in September 1859, caused by a coronal mass ejection from the Sun during solar cycle 10, resulted in widespread disruption to telegraph systems and aurorae seen as far south as the Caribbean. A solar storm of similar magnitude occurring today would be expected to cause extended blackouts and significant damage to the electrical grid.
Royal Astronomical Society