May 2024 solar storms

May 2024 solar storms

VIIRSimage showing the aurora borealis over the Northern Hemisphere on 10–11 May.
Associated solar active region
NOAA regionno.	13664
Largest SXR flares	X8.7
G5 "Extreme" geomagnetic storm
G-scale(NOAA/SWPC)
Initial onset	10 May 2024(2024-05-10)
Peak onset	11 May 2024(2024-05-11)
Dissipated	13 May 2024(2024-05-13)
PeakKp-index	9
PeakAp-index	271
PeakDst	−412 nT
Part ofsolar cycle 25

Thesolar storms of May 2024were a series of powerfulsolar stormswith extremesolar flaresandgeomagnetic stormcomponents that occurred from 10–13 May 2024 duringsolar cycle 25.The geomagnetic storm was the most powerful to affect Earth sinceMarch 1989,and producedauroraeat far more equatorial latitudes than usual in both theNorthernandSouthern Hemispheres.

Solar flares and coronal mass ejections

TheSun's photosphereobserved invisible lighton 10 May. Thesunspot groupassociated with AR3664 is present on the Sun's western limb. The comparative sizes of Earth and Jupiter are shown to scale.

TheSun's coronaobserved inextreme ultraviolet(131 Å) on 8 May. AR3664, located at center disk, produced multiple flares during this time.

On 8 May 2024, asolar active regionwhich had been assigned theNOAAregion number 13664 (AR3664) produced anX1.0-classand multiple M-classsolar flaresand launched severalcoronal mass ejections(CMEs) toward Earth.On 9 May, the active region produced an X2.25- and X1.12-class flare each associated with a full-halo CME. On 10 May, the region produced an X3.98-class flare, and on 11 May at 01:23UTCit produced another X-class flare of magnitude 5.4–5.7 with another asymmetrical full-halo CME.The region also caused an S1solar radiation stormwith spikes reaching S2.On 14 May, as the most active region 3664 rotated beyond the sun's western limb, the strongest flare occurred, an X8.7, causing level R3 (strong) radio blackouts.

Geomagnetic storm

Values of the three-hourK_p-indexfrom 10–14 May 2024

As a result of theinterplanetary magnetic fieldreaching a magnitude of73nanotesla(nT), with the component along Earth's magnetic axis oriented south reaching as much as−50 nT,the moderately highsolar winddensity, and the solar wind speed reaching 750–950 km/s (470–590 mi/s) between 11 and 12 May (UTC time), the event was classified as a G5-class geomagnetic storm (K_p= 9), making it the most intense storm since the2003 Halloween solar storms.Several other CMEs were expected to reach Earth on 11 and 12 May.

Comparison to other geomagnetic storms

Thedisturbance storm time index(Dst index) is a measure in the context of space weather. A negative Dst index means thatEarth's magnetic fieldis weakened.This is particularly the case during solar storms, with a higher negative Dst index indicating a stronger solar storm.

The2003 Halloween solar stormshad a peak Dst index of −383 nT, although a second storm on 20 November 2003 reached −422 nT while not reaching G5-class.TheMarch 1989 geomagnetic stormhad a peak Dst index of −589 nT,while theMay 1921 geomagnetic stormhas been estimated to have had a peak Dst index of−907±132 nT.Estimates for the peak Dst index of theCarrington Eventsuperstorm of 1859 are between−800 nTand−1750 nT.

The May 2024 solar storms reached a peak Dst index of−412 nTat 03:00 UTC on 11 May.

TheA_p-indexof 11 May 2024 was 271, higher than theA_p-indexes of 13 and 14 March 1989, significantly higher than theA_p-indexes of 29 and 30 October and 20 November 2003, and the second-highest ever recorded, after theA_p-index of 13 November 1960, which was 280.

Aurora sightings

A selection of maps showing the typical midnight equatorward boundary of aurorae at differentK_plevels.

All five ofClark's aurora classificationswere documented: glows, patches, arcs, rays, and coronas.Top left: Glow aurora seen inGran Canaria,Spain. Top right: Patch aurora seen inElbe-Parey,Germany. Middle left: Arc aurora seen inOngaonga,New Zealand. Middle right: Rays over an arc aurora seen inVancouver,Canada. Bottom: Coronal aurora seen inCannon Falls,United States.

Comparison between visible light (left) and near infrared light (right) of the aurora overPulsnitz,Germany.

Timelapse of the aurora borealis nearCalgary,Alberta. Pink aurora is produced by nitrogen molecules, green and red aurora is produced by oxygen molecules, and blue and purple aurora is produced by hydrogen and helium molecules, at altitudes of 100 to 400 km.

Three CMEs from 8 May reached Earth on 10 May 2024, causing severe to extreme geomagnetic storms with bright and very long-lasting aurorae.

InNorth America,aurorae were seen across theUnited Statesas far south as theFlorida Keys,as well as from theYucatán PeninsulainMexico,The Bahamas,Jamaica,andPuerto Rico.The aurora was also seen inHawaii.

Aurorae were seen acrossEuropefrom as far south asPortugal,Spain,andSardinia.Aurorae were also visible inAlgeriaand theCanary IslandsinAfrica.

InAsia,aurorae could be seen fromTurkey,Cyprus,Iran,Japan,northernIndia,and across northernChina,including near the cities ofUrumqiandBeijing.

InAustralia,aurorae were seen as far north asTownsvilleandMackayinQueensland,while in the rest of the Southern Hemisphere aurorae were seen inNew Zealand,Chile,Argentina,South Africa,and as far north asNew Caledonia,Uruguay,southernBrazil,andNamibia.

While aurorae were able to be seen on camera from many locations across the globe, at locations farther away from the poles where the aurora is less bright, the aurora can often appeardesaturated,achromatic,or even invisible to the naked eye as a result of thePurkinje effect.

Camera technology has improved since the last G5-class geomagnetic storm in2003,with even standard cell phone cameras having enough sensitivity to pick up the colours of an aurora.Consequently, images of aurorae were spread widely acrosssocial media,with much public excitement being generated during the event.The ability to document aurorae at such a wide scale has provided a large opportunity to learn more about the phenomenon.

Impact

The storm negatively affected ground-based broadcasting and two-way radio communications, especially on theHFband and to a lesser extent theVHFandUHFbands, because it increased the density of the D layer of theionosphere,causing absorption and thus interfering withpropagation.

In Canada, power companiesBC HydroandHydro-Québecstated that they had prepared for the storm, and monitored it as its ejecta struck Earth on 10–11 May. Unlike in 1989 wherea previous solar stormcaused a nine-hour long power outage inQuébec,no outages were reported as a result of the storm's effects.

In New Zealand,Transpowerdeclared a grid emergency, and took some transmission lines out of service as a precaution against the storm.

In the United States, telecommunications companiesAT&TandT-Mobilestated that they were prepared to respond to disruptions in their networks, but it was predicted that significant impacts to cell service were unlikely because the networks rely on different frequencies than the HF bands affected by the solar storm.While theNational Oceanic and Atmospheric Administration(NOAA) reported that there were power grid irregularities and degradation inGPSandhigh-frequencyradio communications,both theFederal Emergency Management Agency(FEMA) and theUnited States Department of Energyreported no significant impacts to the population.

Agricultural users ofJohn DeereRTKGPSequipment reported significantly degraded positional accuracy during the geomagnetic storm. As the GPS receivers are used to guide tractors inprecision agriculture,certain agricultural workers were forced to suspendplantingactivities entirely.

University of Victoriaresearchers discovered that the geomagnetic storm triggered compasses in sub-sea observatories deployed as deep as 2.7 km under the ocean’s surface.

Someaerial droneusers flying during the storm experienced unusual behavior, including difficulty maintaining a stable hover, disruption of GPS signals, and in some cases a sudden loss of control which resulted in a crash.Drones rely on GPS and magnetic signals to maintain position during flight, which are affected by geomagnetic activity.

At 00:19 UTC on 13 May, theGOES-16satellite, the primary operational geostationaryweather satellitein the GOES East position, providing a view centered on the Americas, stopped transmitting all data. The transmission of data resumed nearly 2 hours later at 02:00 UTC.There was a second loss of data transmission shortly after, lasting 11 minutes from 03:19 UTC to 03:30 UTC.

Other impacts to satellite services includeStarlink's fleet of low-orbiting satellites, which experienced degraded service because of the intensity of the solar storms, but remained operational.

Gallery

Auroras were visible in many regions around the world, and far from the magnetic poles. These figures demonstrate the spread of the aurorae on the night of 10 and 11 May. Captions indicategeographic latitude(GLAT) first, andmagnetic latitude(MLAT) second, using the quasi-dipole latitude ofIGRF-13model.

• 
  Aurora at zenith,Onawa, Iowa,U.S. (42°N GLAT, 51°N MLAT)
• 
  Viola, Arkansas,U.S. (36°N GLAT, 46°N MLAT)
• 
  Pawleys Island, South Carolina,U.S. (33°N GLAT, 43°N MLAT)
• 
  Mazatlán,Mexico (23°N GLAT, 31°N MLAT)
• 
  Aurora at zenith,Brastad,Sweden (58°N GLAT, 55°N MLAT)
• 
  Cwmbran, Wales,U.K. (51°N GLAT, 47°N MLAT)
• 
  Kraków,Poland (50°N GLAT, 46°N MLAT)
• 
  Oria,Italy (40°N GLAT, 34°N MLAT)
• 
  Altay,China (48°N GLAT, 44°N MLAT)
• 
  Perth,Australia (32°S GLAT, 43°S MLAT)
• 
  Melbourne,Australia (38°S GLAT, 48°S MLAT)
• 
  Auckland,New Zealand (37°S GLAT, 42°S MLAT)
• 
  Quillón,Chile (36°S GLAT, 24°S MLAT)

See also

• List of solar storms