Was There Aurora Last Night?

The strongest geomagnetic storm since Halloween 2003. Active Region 13664 produced a rapid series of X-class solar flares (including X2.2 on May 8 and X4.5 on May 9) whose CMEs combined in transit and struck Earth together. Aurora appeared across Europe, North America, and as far south as Florida, Texas, and parts of Australia and New Zealand.

A strong CME impact produced widespread aurora across Scandinavia, the British Isles, and central Europe. Iceland experienced full-sky displays for several hours. The event was widely photographed and shared across social media.

A solar wind high-speed stream triggered strong geomagnetic activity across Nordic countries. Clear skies over northern Iceland allowed excellent viewing, with aurora curtains reported from multiple sites.

A CME impact drove a severe geomagnetic storm with vivid aurora across the Northern Hemisphere. Reports from multiple countries documented curtain and pillar displays. This event marked one of the strongest storms in the early years of Solar Cycle 25.

Active Region 12673 erupted with the largest solar flare of Solar Cycle 24 — an X9.3 on September 6. Successive CMEs drove a G4 storm peaking at KP 8.3 on September 8. Aurora was photographed across Scotland, Scandinavia, and the northern United States. The event was intensely studied as a benchmark for near-maximum-of-cycle activity.

The first major geomagnetic super-storm of Solar Cycle 24. Two successive CMEs merged in transit and struck Earth together, sustaining G4 conditions. It was the strongest storm since 2005. Aurora reached well into the mid-latitude United States with reports from Tennessee, Oregon, and Colorado.

Multiple X-class solar flares from Active Region 10486 — including an X17.2 on October 28 — drove back-to-back G5 geomagnetic storms over several days. Power outages struck southern Sweden. Aurora was photographed as far south as Texas, California, and Florida. It remains the benchmark event for extreme space weather preparedness planning.

An X5.7 solar flare from Active Region 9077 launched a CME traveling at roughly 1,674 km/s toward Earth. The resulting storm produced aurora visible at unusually low latitudes, with sightings documented from El Paso, Texas (32°N). Multiple geosynchronous satellites reported anomalies and Nozomi, a Japanese Mars mission, was damaged.

One of the most consequential space weather events of the 20th century. The storm collapsed the Hydro-Québec power grid within 92 seconds, leaving approximately 6 million Canadians without electricity for up to 9 hours. Ground-induced currents damaged high-voltage transformers across North America. Aurora was reported in Texas and Cuba, and the Space Shuttle Discovery was in orbit during the event.

Estimated by modern analysis as the strongest geomagnetic storm of the 20th century by Dst index. A series of interplanetary CMEs drove extreme induced currents through telegraph infrastructure across Australia, Brazil, Denmark, France, Japan, Norway, Sweden, the UK, and the USA — with voltages reaching 1,000 V on some US telegraph lines. Aurora was visible in Texas and, in the Pacific, as far south as Samoa and Tonga. Note: the K-index was not established until 1938 and the planetary Kp index until the 1940s; the Dst value is reconstructed from historical magnetometer records.

The most intense geomagnetic storm in recorded history. British astronomers Richard Carrington and Richard Hodgson independently observed the associated solar flare on September 1, 1859 — the first solar flare ever recorded. Telegraph systems worldwide failed, sparked fires, and in some cases operated spontaneously without external power source. Aurora was witnessed in Cuba, Colombia, Hawaii, and across Central America — far below the latitudes where aurora is normally possible. Modern ice-core analysis suggests this storm may have been the most powerful space weather event in at least 500 years. Note: the Dst value is a modern model estimate; instruments to measure it did not exist in 1859.