A powerful solar flare caused a coronal mass ejection that struck Earth a few hours later, generating the most intense geomagnetic storm ever recorded and causing bright aurorae visible in the middle latitudes.

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.

A coronal mass ejection (CME) is a significant ejection of plasma mass from the Sun's corona into the heliosphere. CMEs are often associated with solar flares and other forms of solar activity, but a broadly accepted theoretical understanding of these relationships has not been established.

A geomagnetic storm, also known as a magnetic storm, is a temporary disturbance of the Earth's magnetosphere that is driven by interactions between the magnetosphere and large-scale transient plasma and magnetic field structures that originate on or near the Sun.

An aurora is a natural light display in Earth's sky, predominantly observed in high-latitude regions around the Arctic and Antarctic. The plural form is pl. aurorae or auroras, and they are commonly known as the northern lights or southern lights. Auroras display dynamic patterns of radiant lights that appear as curtains, rays, spirals or dynamic flickers covering the entire sky.

The middle latitudes, also called the mid-latitudes or moderate latitudes, are spatial regions on either hemisphere of Earth, located between the Tropic of Cancer and the Arctic Circle (66°33′50.5″) in the northern hemisphere and between the Tropic of Capricorn (-23°26′09.5″) and the Antarctic Circle (-66°33′50.5″) in the southern hemisphere. They include Earth's subtropical and temperate zones, which lie between the two tropics and the polar circles. Weather fronts and extratropical cyclones are usually found in this area, as well as occasional tropical cyclones or subtropical cyclones, which have traveled from their areas of formation closer to the Equator.