May 2024 solar storms

May 2024 solar storms
	Aurorae taken with long exposure from Viola, Arkansas, United States (36°N), on 10 May 2024
Date	May 2024
Type	Coronal mass ejection
	Part of Solar cycle 25

The solar storms of May 2024 are a series of powerful solar storms with intense to extreme solar flare and geomagnetic storm components that have been ongoing since 10 May 2024 during solar cycle 25. The geomagnetic storm was the most powerful to affect Earth since 2003, and produced aurorae at far lower latitudes than usual in both northern and southern hemispheres.^[1]

Solar flares and coronal mass ejections[edit]

Video of solar activity from AR3664 at 10 AM UTC on 9 May 2024

On 8 May 2024, a solar active region which had been assigned the NOAA region number 3664 produced an X1.0-class and multiple M-class solar flares and launched several coronal mass ejections (CMEs) toward Earth.^[2] 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 01:23 UTC it produced another X-class flare of magnitude 5.4–5.7 with another asymmetrical full-halo CME.^[3]^[4]^[5] The region also caused a S1 solar radiation storm with spikes reaching S2.^[6]

Geomagnetic storm[edit]

Values of the three-hour K_p-index for 11 May 2024

Three CMEs from 8 May reached Earth on 10 May 2024, causing severe to extreme geomagnetic storms with bright and very long-lasting aurorae. Aurorae could be seen from the remote village of Hanle in northern India,^[7] near the city of Urumqi in northwestern China,^[8] and in Europe from as far south as Croatia^[9] and southern Spain.^[10] In North America, aurorae were seen as far south as Florida^[11]^[12]^[13] and Mexico.^[14]^[15] In the Southern Hemisphere, the aurora was seen in New Zealand,^[16] Australia,^[17] Chile, Argentina,^[18] and as far north as Uruguay^[19] and Namibia.^[20] Due to the interplanetary magnetic field reaching a magnitude of 73 nT with the component along Earth's magnetic axis oriented strongly south, reaching −50 nT, as well as due to moderately high solar wind density and speed reaching 750–800 km/s (470–500 mi/s),^[when?] the event was classified as a G5-class geomagnetic storm, making it the most intense storm since the 2003 Halloween solar storms.^[21] Several other CMEs were expected to reach Earth on 11 and 12 May.^[22]

Comparison to other solar storms[edit]

The disturbance storm time index (Dst index) is a measure in the context of space weather. A negative Dst index means that Earth's magnetic field is weakened. This is particularly the case during solar storms. The 2003 Halloween solar storms had a peak Dst index of −422 nT,^[23] while the March 1989 geomagnetic storm had a peak Dst index of −589 nT.^[24] The May 1921 geomagnetic storm has been estimated to have had a Dst index of −907±132 nT. Estimates for the Carrington Event superstorm of 1859 are between −800 nT and −1750 nT.^[25]

As of 11 May 2024, the highest negative measurement for the May 2024 solar storms is −412 nT.^[26]

Impact[edit]

It was reported that Starlink, an internet satellite constellation with over 6,000^[27] satellites in low earth orbit, was experiencing degraded service due to the intensity of the solar storms and was "under a lot of pressure, but holding up so far" according to Elon Musk, the CEO of their parent company SpaceX.^[28]^[29] However, while the National Oceanic and Atmospheric Administration (NOAA) reported that there were power grid irregularities and degradation in GPS and high-frequency radio communications,^[30] both the Federal Emergency Management Agency (FEMA) and the United States Department of Energy reported no significant impacts to people in the United States.^[31] The storm has been negatively affecting ground-based broadcasting and two-way radio communications on the HF, VHF and UHF bands due to preventing the ionosphere from forming and thus interfering with propagation.^[32]