Across September 1 and 2, 1859, the Earth experienced the most intense geomagnetic storm in recorded history. It is known as the Carrington Event and caused aurorae visible almost to the equator and damage to electrical systems, which at the time mostly consisted of telegraphs. None comparable have hit Earth since, but we came really close in 2012, as a new NASA visualization shows. The rest of this article is behind a paywall. Please sign in or subscribe to access the full content.

Geomagnetic storms are caused by extremely fast releases of plasma from the Sun known as Coronal Mass Ejections (CMEs). Their speed depends on many factors, and they are usually associated with solar flares, which can cause radio blackouts independently of the CMEs. The Carrington Event is believed to have b

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