From August 28, 1859, until September 2, numerous sunspots were observed on the Sun. Just before noon on September 1, the English amateur astronomers Richard Carrington and Richard Hodgson independently made the first observations of a solar flare.[3] It caused a major coronal mass ejection (CME) to travel directly toward Earth, taking 17.6 hours. Such a journey normally takes three to four days. This second CME moved so quickly because the first one had cleared the way of the ambient solar wind plasma.[3]
Because of a simultaneous "crochet" observed in the Kew Observatory magnetometer record by Scottish physicist Balfour Stewart and a geomagnetic storm observed the following day, Carrington suspected a solar-terrestrial connection. Worldwide reports on the effects of the geomagnetic storm of 1859 were compiled and published by Elias Loomis which support the observations of Carrington and Stewart.
On August 29, 1859, aurorae were observed as far north as Queensland.[4]
On September 1–2, 1859, the largest recorded geomagnetic storm occurred. Aurorae were seen around the world, even as far south as the Caribbean; those over the Rocky Mountains were so bright that their glow awoke gold miners, who began preparing breakfast because they thought it was morning.[3] People who happened to be awake in the northeastern US could read a newspaper by the aurora's light.[5] The aurora was visible as far from the poles as Cuba and Hawaii.[6]
Telegraph systems all over Europe and North America failed, in some cases giving telegraph operators electric shocks.[7] Telegraph pylons threw sparks.[8] Some telegraph systems continued to send and receive messages despite having been disconnected from their power supplies.[9]
On Saturday, September 3, 1859, the Baltimore American and Commercial Advertiser reported, "Those who happened to be out late on Thursday night had an opportunity of witnessing another magnificent display of the auroral lights. The phenomenon was very similar to the display on Sunday night, though at times the light was, if possible, more brilliant, and the prismatic hues more varied and gorgeous. The light appeared to cover the whole firmament, apparently like a luminous cloud, through which the stars of the larger magnitude indistinctly shone. The light was greater than that of the moon at its full, but had an indescribable softness and delicacy that seemed to envelop everything upon which it rested. Between 12 and 1 o'clock, when the display was at its full brilliancy, the quiet streets of the city resting under this strange light, presented a beautiful as well as singular appearance."[10]
In June 2013, a joint venture from researchers at Lloyd's of London and Atmospheric and Environmental Research (AER) in the United States used data from the Carrington Event to estimate the current cost of a similar event to the world economy at $2.6 trillion (£1.67tr).[11]