Weekend-Long Auroral Displays Seen ’round the Globe During Strongest Solar Storm in Twenty Years

The most powerful solar storm in twenty years has just occurred, generated from a large cluster of sunspots that produced five X-class solar flares and three coronal mass ejections that resulted in a weekend-long geomagnetic storm strong enough to cast aurorae as far south as Hawaii, and in the southern hemisphere as far north as Africa’s Namibia and Queensland in Australia.

On May 8 solar active region 13664, a cluster of sunspots with a length equal to roughly fifteen times the diameter of the Earth, produced an X-1.0-class solar flare, along with a number of other smaller M-class flares, projecting several coronal mass ejections (CME) toward Earth; the following day two more flares—X2.25 and X1.12-class in intensity—produced two more CMEs. The region’s flares then increased in intensity, with an X3.98-class erupting on May 10, and May 11 seeing an even stronger X-5.7-class flare.

The CMEs generated on May 8 reached Earth on May 10, sparking a weekend-long display of northern and southern lights in regions that hadn’t seen such displays in over a century: in Europe, aurorae were seen as far south as Cyprus, Portugal, Spain and even the Canary Islands; in Asia, China’s cities of Urumqi and Beijing were treated to the northern lights; and in North America, the aurora borealis appeared over Florida and Mexico, and even stretched as far south as the Bahamas and Hawaii, nearly four-fifths of the way to the equator.

In the southern hemisphere, aurora australis appeared as far north as Uruguay in South America, Namibia in Africa, and the city of Mackay in Australia; at a latitude of 21.14°S, Mackay is situated almost as far north as the Big Island of Hawaii is south.

Despite generating these widespread one-in-a-lifetime aurorae over the course of several days, no significant disruptions to energy grids were reported, despite the strength of this weekend’s geomagnetic disturbance being on-par with the 1989 storm that knocked out power across Quebec; having learned from the previous widespread outage, Canadian utility providers, as well as their counterpart in New Zealand, took steps to prevent such an occurrence.

However, limited disruptions to high-altitude satellites did occur, with global positioning system service disruptions causing brief suspensions to planting operations being carried out by GPS-guided agricultural equipment; customers for SpaceX’s Starlink satellite-based internet service experienced reduced connection strength; and on May 13 the main GOES East geostationary weather satellite, GOES-16, stopped transmitting data for two hours, with a second, 11-minute interruption occurring an hour later.

With the Sun coming off of two back-to-back cycles that saw record-low solar activity, a geomagnetic storm like this hasn’t occurred in twenty years, although this month’s storm was comparable in strength to the previous one: occurring over the course of late October and early November 2003, causing the planet’s magnetic field weakening by -422 nanoteslas (nT), compared to the May 2024 storm’s −412 nT.

For further perspective, these last two events were a little more than two-thirds of the strength of the power grid-busting 1989 storm (−589 nT), and only one-quarter of 1859’s Carrington Event, a geomagnetic superstorm estimated to have reached an intensity as deep as -1,750 nT.

Although it appears that infrastructure authorities are beginning to pay attention to the issue of solar storms, there is still more work to be done. The danger presented by these energetic particle tempests—along with what needs to be done to prepare for them—are outlined by Whitley in his 2012 ebook Solar Flares: What You Need to Know.