Introduction
The geomagnetic storm of 1859 (Carrington Event) goes down in history as the strongest observed geomagnetic storm to date. At that time, astronomer Richard Christopher Carrington observed several intense solar flares that caused auroras as far south as Cuba and Hawaii.
Chronology
Kick-off (speculative): August 28, 1859, early morning hours (UTC)
A superflare occurs on the sun - unnoticed by humans and magnetometers. At this time, there is likely only one magnetometer capable of reliably registering a solar flare effect (mag. Crochet) due to its uninterrupted recording technique, namely at the Kew Observatory in London. However, at this location, the sun is still below the horizon during the flare. A massive CME leaves the sun. Although the sunspot group responsible for the flare is not yet centrally on the solar disk, the coronal mass ejection will reach the Earth within a few hours in the late evening of the same day.
Alternative Kick-off (speculative): August 26/27, 1859
The outbreak on the sun happens earlier, the CME is in transit longer, but it already reaches the Earth in the morning of 8/28/1859. Magnetometers record an SI (Sudden Impulse) around 7:30 UT. Due to a very strongly northward directed magnetic field within the magnetic bubble of the CME, a geomagnetic storm initially does not occur. However, in the course of the evening, the magnetic field turns. It now shows an exceptionally strong southward orientation.
August 28, 1859, late evening hours (UTC)
A massive geomagnetic storm sets in. Central and Southern Europe are flooded with auroras. Even from the west coast of Africa, only 560 km north of the equator, from St. George del Mina (5º 09' N, 1º 19' W), auroras are reported. North America also experiences a spectacular auroral storm with nightfall. The impressive display can be observed as far south as the Caribbean island groups. At the same time, there are multi-hour, severe disturbances and outages in the telegraph network in previously unknown proportions.
August 30, 1859
The Earth's magnetic field calms down again.
September 1, 1859, ~11:20 UTC
Superflare on the sun! The responsible sunspot group is now almost centrally on the solar disk.
Astronomer Richard Carrington, during his regular solar observations, accidentally witnesses the very bright solar white-light eruption. For the first time ever, people (there was at least one other independent observer) see this phenomenon. At the same time, the Kew magnetometer also records a very strong solar flare effect. A CME leaves the sun at a speed of well over 2000km/s and heads towards Earth.
September 2, 1859, ~05:00 UTC
Magnetometers record a severe SI (Sudden Impulse) - the CME has already reached Earth after about 17.5 hours. The "perfect storm" takes its course. It surpasses in magnitude the event of August 28/29. Auroras are sighted beyond the Caribbean, up to Venezuela. Due to the onset of daylight, Europe misses the peak auroral storm phase. However, very massive disruptions of the telegraph network are again experienced here. In the evening, auroras are observed at least as far as Athens and Rome. The DST index was at -1600 nT.
Observed sunspots on 01.09.1859 (Drawing by Richard Carrington)
Aurora sightings on 02.09.1859 (Data: Courtesy J.L. Green, NASA)
September 3/4, 1859
The geomagnetic disturbances are decreasing again. Until September 6, auroras are still occasionally sighted at middle geomagnetic latitudes.
Text: Peter Kuklok