The Carrington Event was the most intense geomagnetic storm in recorded history, peaking on 1–2 September 1859 during solar cycle 10. It created strong auroral displays that were reported globally and caused sparking and even fires in telegraph stations. The geomagnetic storm was most likely the result of a coronal mass ejection (CME) from the Sun colliding with Earth’s magnetosphere.

The geomagnetic storm was associated with a very bright solar flare on 1 September 1859. It was observed and recorded independently by British astronomers Richard Carrington and Richard Hodgson—the first records of a solar flare. A geomagnetic storm of this magnitude occurring today has the potential to cause widespread electrical disruptions, blackouts, and damage to the electrical power grid.